shriver, the manipulation of air-sensitive compounds book

8/16/2019 Shriver, The Manipulation of Air-Sensitive Compounds BOOK

1/334


2/334

s

ls

JNNNlH


3/334

THE

MANIPULATION

F

AIR.SENSITIVE

OMPOUNDS

SECOND

EDITION

D. F.SHRIVER

Nort hu'es

ertt U tt

vers

I

v

Evonstott.

Illinois

M. A. DREZDZON

Antoco

C

hetn cu s

Contpurty,

Nuperville, Illittois

A Wiley-lnferscience

ublicotion

JOHNWITEY SONS

New York

/

Chichester

/

Brisbqne

/

Toronlo

/

Singopore


4/334

Copvr ight

i ' 1986bv

John

Wile l

ct

Sons.

nc.

A l l r i gh t s ese rve 'd .

ub l i shed

in ru l t aneous l t

n Canada .

Reproduct ion

r t ranslat ion

of anv part of

thrs

u

ork

be1'ond

hat

pernr i t ted

b1'Sect ion107or l0U of

the

1976

United StatesCopl ' r ight

Acr

\ \ ' i thout

he

pcrnr iss ion

o f

the cop l ' r i gh t unc r s

un lau fu l . l cqucs t sor

pcrnr iss ion

r fur ther

in{ornrat ion

houldbc addressed

t,

t he Pe rm iss ions

epa r tmcn l .

ohn

Wi lo

& Sons . nc .

Libru4' td

Congre.ss

Cutaloging in Publication

Data:

Sh r i ve r ,D . F ' .

Du* ' a rd

F . ) . 193 .1 -

The

manipulat ionof

a i r -sensi t ive onrpounds.

A

Wile- , - - ln terscience

ubl icat ion.

lnc ludes

bib l iographical

eferences

nd index.

l . Chem is t r v -Man ipu la t i on .

2 . Vacuumtechno logy .

3 . P ro tec t i ve

tmosphe res . , { .

A i r - sens i t i ve

on tpounds .

I . D rezdzon .

M . A .

(Mark

A. )

I I . T i t l e .

QD6l .557

l9rJ6

542

lsBN

0- .171-86773-X

8 6 - 10 l 2

Pr inted n the Uni ted States f Amer ica

r0

9 8

7

6

5

,1

3 2 I


5/334

PREFACE

The continued

mportance

of research nd development

with

air-sensitive

om-

pounds,

coupledwith the

general

ack

of

publications r undergraduatenstruc-

tion

on the

techniques sed

n

this

area,

prompted

us

to

revise his monograph.

The

levelof

presentation

s designed o make he book useful o t he chemist

who

is

beginning

work in the field.

In

addition, considerableechnicaldata and

in-

formation are

given

that should aid chemistsat

all levels

of

proficiency

n the

design

of experiments.

In

the belief

that the beginner

needs

a selective pproachand the

more sea-

sonedworker will exercise is ngenuity,wehave efrained rom presenting rief

references

o

many

similar

items of equipment,

but

have attempted o

present

rational approaches

o the

common operations nvolved

n

the synthesis, epara-

tion, and characterization

f air-sensitivematerials,and to il lustrate hese

with

typical apparatus.

Whenever

possible,

heseexamples

are

based

on

equipment

with which we havehad experience r on firsthand

observation f

the equipment

usedby others.This has resulted n

a

somewhat

ersonalized

ccount,

which we

hope

will

ensure

eliability

without

being objectionable

o established

workers

with

different

preferencesn

equipment design.The techniques iscussed

ere

were

argelydeveloped

or

use

with

inorganic and organometallic ompounds;

however, hey are

generally

useful

or problens involving

gases

nd

air-sensitive

solidsor

liquids,

so

they find application n all areas

of

chemistry,as

well

as

biology and

physics.

We had two

goals n

mind

while

writing this second

dition. The first was

o

bring the

text

up to date. Alt hough there have been no

radical new develop-

ments, here

has

beena

steady mprovement

n

technique.

Our

second bjective

was

o make the book more accessibleo the reader

nterestedn a specifi c ech-

nique. Thus more sectionheadingsare used and more detailed

examplesare

given.


6/334

PREFACE

The

continued

mportanceof research nd

development

with air-sensitive om-

pounds,

coupled

with

the

general

ack of

publications

r undergraduatenstruc-

tion on the techniques sed

n this area,

prompted

us

to

revise his monograph.

The level

of

presentation

s designed

o make

he book

useful o the

chemist

who

is

beginning

work in

the

field. In addition,

considerableechnical

data and in-

formation are

given

that should aid chemists

at all levelsof

proficiency

n the

designof

experiments.

In the belief that

the beginnerneeds

a

selective

pproachand

the more sea-

sonedworker will exercise is ngenuity,we have efrained rom presenting rief

references

o

many

similar

items

of equipment,

but have attempted

o

present

rational

approaches

o

the common

operations nvolved

n

the

synthesis. epara-

tion, and characterization f air-sensitive

materials,and

to

il lustrate hese

with

typical

apparatus.Wheneverpossible,

heseexamples

are

based

on

equipment

with which we have

had

experience r on

firsthand

observation f

the

equipment

used

by

others.

This

has resulted n

a somewhat

ersonalized

ccount,

which we

hope will ensure

eliability without

being objectionable o established

workers

with

different

preferences

n equipment

design.

The techniques iscussed ere

were

argely

developed

or use

with

inorganic and organometall ic ompounds;

however, hey are

generally

useful

or

problems

nvolving

gases

nd air-sensitive

solids

or

liquids, so they find application n all areasof

chemistry,

as

well

as

biology and

physics.

We

had two

goals

n mind

while

writing

this second

edition. The first

was

o

bring

the

text up to date. Although there have been no radical new develop-

ments, here has beena

steady

mprovement n technique.Our

second bjective

was

o make

the

book more

accessible

o

the

reader nterestedn a speci fic ech-

nique. Thus more

section

headings

are used

and more detailedexamples

are

given.


7/334

PREFACE

In

the

preparation

of the

first

editionof

this book aid

u'as

eceivedrom nrany

people:

. L . Al l red,

F. Basolo,

R. L. Burwel l ,Jr . ,E. W. Schlag, au lTre ichel ,

R.

W.

Fowells,

and Shirley Shriver.

Useful suggestionsor

the

second

edition

were providedby L. Aspry, R. L. Burwel l , Jr . , P. Bogdan. N. J . Cooper,

D. Kurtz .

J.

Malm,

and S. H. Strauss.

or a id n

proofreading

e

appreciatehe

help

of Ann Crespi ,

Cynth iaSchauer,

Danie l Shr iver nd Ralph Spindler .

D. F. Ssnrvrn

M.

A.

DnpzpzoN

Evanston.

Illinois

Nuperville. Illinois

Februum,

I986


8/334

CONTENTS

INTRODUCTION

PART INERT-ATMOSPHEREECHNIOUES

'l

grNcx-rop

NERT-ATMospHERETEcHNToUES

l . l Techniquesor

Purg ing

and Dry ing Apparatus,

1.2 Adaptat ions

f

StandardGlassware,

I

1.3 Syr inge nd Cannula

Techniques,3

1.4

Quant i ta t ive

Gas Manipulat ion,

24

I .5 Schlenk

Iechniques,

30

1.6

Cappable

Pressure eactors,4 l

l

7

Hot Tube and Sealed

ube

Technioues.

2

General

References.44

2

INERT-ATMosPHERELovEBoxEs

2.1

General

Designand Appl icat ions,

5

2.2 Replacement f Air by an

Inert

Atmosphere. 7

2.3 Sources f and Reduction

of

Impurities

n

Glove

Box

Atmospheres. 1

2.4 Glove

Box

Hardware and

Procedures, 9

2.5 Typical

Glove

Box Systems, 2

2.6 Equipmentand

Operat ions,

4

General References. 6

3

INERTASESNDTHErR

uRrFrcATroN

3 .1

Sources

nd

Pur i t y ,68

3.2

Pur i f icat ion f Gases. 9

45

68

vl l


9/334

v i i i

3 .3 Inert-Gas

Pur i f icat ionSystems, 0

3.4 Detect ion

f

Impur i t ies,83

General

References.

3

4

puRrFrcATroN

F sotvENTs

NDREAGENTS

4.1

Solvent

Pur i f icat ion. 4

4.2

SolventStorage,

89

4.3 Detect ing

mpur i t ies,

89

4.4 Pur i f icat ion f Speci f ic o lvents,

0

4.5 Pur i f icat ion

f

Some

Commonly

Used

Gases,

2

4.6 AnhydrousMeta l Hal ides,

5

GeneralReferences.96

PART VACUUM

LINE

MANIPULATIONS

5

vAcuuM

LINE ESTeNND PERAIToN

5.1

GeneralDesign,

9

5.2 In i t ia l Evacuat ion.

03

5.3

Manipulat ionof

Volat i le

L iquidsand

Condensable ases.

04

5.4 Lorv-Tenrperatureaths.109

5.5 Vapor Pressure

s

a

Characteristic

Property, l3

5.6

Manipulat ionof Noncondensableases,

l3

5 .7 Sa fe ty , 16

GeneralReferences.

l7

6

PUMPsoRRoUGH NDHIGH AcuuM

6.1

Rough-Vacuunl ystems,

l8

6 .2

H igh -Vacuum

ump ing

Sys tems ,

l 9


7 PRESsURENDFLOw

MEAsUREMENTND

IEAK

DETECTION

7.1

Manometry

l-760

torr) , 129

7 .2

Med ium-

and

High -Vacuum

Measuremen ts

10

r -10 6

to r r ) . 137

7.3

Leak

Detect ion.143

7.4

Flow

Measurement. 46

7.5 Flow Contro l . 149

GeneralReferences.

50

CONTENTS

. t . t8

84

99

t29


10/334

CONTENTS

8

JorNTs,ToPcocKs,

ND ALVES

8 .1

Jo in ts , 52

8.2

Stopcocks, 61

8.3 Valves.

164

9 spEcrALrzED

AcuuM

LINE eutpMENT

ND pERATtoNs

.r68

9.1 Character izat ion.

68

9.2

Separat ions,

90

9.3

Storage

of Gases

and Solvents,

00

9.4

Sealed

Tube Reactions.

02

9.5

Miscel laneousechniques,

06

General

References.

08

'10

MEIAL

YsTEMS

l0 . l

Compressed

ases,

10

10.2 Cutt ingand BendingTubing, 214

10.3

Tubing,

Joints,and

Fit t ings,

215

10.4

Heavy-Wal led ubing

and

Pipe

Joints, 19

10 .5

Va lves .

22

10.6

Pressure

Gauges,

227

10.7

Typica l

Meta l

Systems,

27

General

References.

36

APPENDIX

SAFETY

I . l Combust ib les,37

I.2

Unstable

Compounds,

38

I.3 Some

Dangerous

Mixtures,

238

L4 Disposal

of

Reactive

Wastes,

239

I.5 High-Pressure

as

Cyl inders.

40

I.6 Asphyxiat ion

y Inert

Gases,

40

I.7 Ext inguish ing

ires,

240

General References.

41

APPENDIX

I GLASS ND

GLASSBLOWING

I I . l Propert ies

f

Glasses, 42

IL2 Equipment

and

Mater ia ls ,

45

II .3 Sequence

f Operat ions.

47

I I .4 Annea l ing ,247

l l .5 Cutt ing

Glass

Tubing,248

IL6 Bending

Glass

Tubing,249

II .7 Test-Tube

Ends

and Fire

Cutof fs .249

210

237

242

I X

152


11/334

I I .8 End- to -End

ea ls . 51

IL9

T-Seals. 53

I I . l0

R ing

Sea ls . 53

I . I

I

ClosedCircu i ts .

255

II . l2 Meta l- to-Glass eals. 55

I I . l3

Heal ing

Cracksand Pin

Holes,

256

IL14

Seal ing ubing

under

Vacuum,257

General

References.

58

APPENDIX II PLASTICSAND ELASTOMERS

II I . I

Plast ics:

Genera l

Propert ies

nd Fabr icat ion.260

I lL2

Cel lu larPlast ics.

65

II I .3

Propert ies

f Speci f ic last ics, 67

I I I .4 E las tomers .272

l l l .5

Propert ies

f Speci f ic

lastonrers,

72

General

References.

74

APPENDIX

V

METATS

IV. l

Propert ies

f Speci f icMeta ls ,276


APPENDIX

V

VAPOR PRESSURES

F PURESUBSTANCES

V.l Analy'ticalRepresentation f Vapor

Pressure ata.

281

V.2 Least-Squares

itting Procedure or

the

Anto ine

Equat ion,28.1

V.3 Corre lat ion

nd

Est imat ion

f

Vapor Pressures,

86

V.4 Table

of

Vapor

Pressures.

89

V.5 Sources f Vapor

Pressure ata. 313

APPENDIX

I

PRESSURENDFLOW ONVERSIONS

INDEX

CONTENTS

259

275

28tl

3,15

3.19


12/334

INTRODUCTION

A.

Generol

Mefhods. The mostwidelyusedmethods

or handlingair-sen-

sitive

compounds

are

based

on the useof an inert

gas

atmosphere

o excludeair.

This approachmay be

urther

subdivided nto

(

1)

hose echniques

which nvolve

bench-top

operationswith

special

glassware

often

called Schlenk

echniques,

Chapter

1)

and

(2)

glove

box techniques n

which

conventionalmanipulations

are

perfornred

n an inert-atmosphere

ox

(Chapter

2). Both

of these

methods

may be used

o

handle arge

quantities

of solids

and

liquids;

however, he

Sch-

lenk

type equipment s

generally

much more efficient

and

more

secure rom

the

atmosphere han the dry box. Th e

principal

advantages

f the

dry

box lie in its

use

or

intricate manipulationsof

solidsand for

the

containment

of

radioactive

and/

or highly

poisonous

ubstances.

More rigorous

exclusionof air and the

quantitative

manipulationof

gases

s

achieved

n a

previously

vacuated pparatus.

This vacuum

ine method s

out-

lined in Chapter5, where

he basicoperations

are described,

uch as

quantita-

tive

transferand

pressure-volume-temperature

easurement

f

gases,

rap-to-

trap separations of volatile materials,

and

the use of vapor

pressures

o

characteriz e ubstances. ucceeding hapters

6-8)

describe n

detail

the

indi-

vidual

vacuum ine components

uchas stopcocks,

oints,

diffusion

pumps,

and

manometers.Many accessorytems such as spectroscopy ells,vapor-pressure

thermometers, nd

gas-chromatography

pparatusare described

n Chapter

9.

This set

of

chapters,

plus

supplementary

material in

the Appendixes,

orm

a

guide

to modern

glass

vacuum ine

practice.

This

techniquehas

beenused

suc-

cessfully

n

the synthesis

nd

manipulationof hydrides,

halides,

and manyother

volatile substances.However,

glass vacuum

systems

are

not

appropriate

for

hydrogen luoride

and

someother

reactive

luorides.These

are best

handled n

the

metal or fluorocarbonapparatus

described n Chapter 10. The

strengths f

these

various

echniques

or

handling air-sensitive

materialsare summarized n

Table

l


13/334

z

INTRODUCTION

Toble

1

Comporison

of lnert-Almosphere

nd Vocuum

LineTechniques

Technique

Exclusion

of

Air

Quantit ies

OutstandingFeatures

Schlenkand

syringe

Glovebox

Vacuum

ine

Good

to

very

good

Poor

to very

good

Very good

to

excellent

Medium

to

large

Small

to

very

large

Very

small

to

medium

Rapid

and easymanipulat ion

of solut ions;

imple ansfer

of sol ids

lntr icate transferoperat ions;

containmentof poisonous nd

radioact ive ubstances

Quantitat ive

gas

handling;

transferand

storage

f

volat i le

so lvents i thout

contamina l ion

Verysmal l , about I mgl smal l . about 100mgl medium, several ramsl arge,hundredsof grams;

very arge.

k i logranrs.

B. Plonning

lhe Expeliment. Whatevergeneral

echnique s used, t is

m-

portant

to

plan

each new

experiment n

detail.

Impasses

an

be

avoided

b1'

sketching

he

setup

at

eachstep

with

due attention

paid

to

the

method or

trans-

ferring materials.

f measurements

re nvolved,

a simple

estimate

f

the

poten-

tial errors shouldprecede

he

newly planned

experiment

o ensure hat

results

will

be determined

with

meaningful

accuracv.

Frequently.

uchan estimate

will

suggest onditions

and apparatus

designswhich will

minimize he

errors

without

in troducing

ny new

compl icat ions.

C.

Appololus

Design. Sometimes

t i s necessary

o designand

construct

specialapparatus.

Three criteria for

a

good

design

are:

(1)

Is

it the sinrplest

designconsistentwith its

intended purpose?

2)

Is it robust?

(3)

Is

it easy o

clean?

To

ensure

hat an item

is

sturdy t

shouldbe

designed

o

hat

stresses

re

not concentratedn small sections f glass.For pernranentnstallations, uchas

a vacuum ine.

a l l

heavy tents

are

ndiv idual ly

upported.

vh i le

he

ighter

sec-

tions

are

clampedat

the

minimum number

of

points

u'hich

suffice o

support

he

apparatusand

avoid

everage.

Generall,v.

ortableglass\Ä'are

houldbe designed

as

one

strong,

compact

unit \r 'hich

may

be supportednear a

point

of balance.

Final ly , he mater ia ls

f

construct ion

ust v i thstand

he chemicals nd so lvents

which

are to

be

handled. The

most f requent problems

ar ise

with

stopcock

greases,\'axes,

ubbers,

and

plastics.

These

problen'ls

may

be minimized

by se-

lectingmaterialson

the

basisof

the information

on chemicaland solvent

esis-

tance

which is preserrted

n

Chapter

8 and Appendix

IIl. To aid in

the

proper

choiceof metals, nformationon their corrosion esistancesgiven n Chapter10

and Appendix

V.


14/334


15/334


16/334

A

PARII

Inert-Atmosphere

Techniques


17/334

8 eENcH-Top

NERI-ATMoSpHERE

EcHNtoUE

evacuat ion f the

apparatus, nd f there

are

no eaks n

the apparatus,

repet i -

tions of

the

pump-and-fil l

process

will reduce

he

fraction

of

atmospheric ases

A ,

to

The

second

method

or removing

atmospheric

ases

nvolves weeping

ir out

of

the apparatusby a flush of inert gas.

The

factors

which nfluence

his type of

process

re discussedn

detail

in

Chapter

2.

For

the

present. t is

adequate

o

note

that a conti nuous lush of inert gas, u'hich pushes

he atmospheric

ases

from

one extremeof

the apparatus

o an outlet

on

another

extreme,

as in Fig.

1.1,

s most

ef f ic ient . h is

so-cal led

lug

low

s

dif f icu l t

o achieve

i th

s ingle-

neck

lasksand

similar

apparatus.

A

flow of inert

gas

which

bypasses

art

of

the

apparatus

s

relatively

nefficient.

B.

Purging on

Open Vessel. In

many

operations

described

n

this chap-

ter,

it

is necessary

o open he apparatus

briefly

while

an

inert-atmosphere

lush

is maintained out

of

the opening o minimize the entranceof air. Even under

conditions

n

which

there is

litt le

turbulence

n

the flowing

inert gas

stream,

Iner l -gas

rn le t

2

+

To

nooo

--\

+

( l )

\

water

Mine ra l

o i l bubb le r

F ig.

l . l . Three-necked

eact ion

lask wi th

dropping

funnel .

st i r rer ,

and ref lux condenser .With

the dropping

unnel stopcock

n

the

open posi t ion.

a f lou

of iner t gas

rom in let I through

he min-

era l o i l bubbler

ef f ic ient lypurges

he

apparatus

of atmospher ic ases.

Dur ing

react ion

and subse-

quent cool ingof the react ionmixture. a s low low of inen gas ronr in let 2 through he mineraloi l

bubbler prevents

tmospher ic

ases rom

backing

up into the system.

nd th is

conf igurat ion

mini-

mizes

exposure f

the react ion

mixture to impur i t ies

n thc-

ner t gas.


18/334

TECHNIOUES

ORPURGING

ND DRYING PPARATUS

therewill be

countercurrent

diffusion

of atmospheric

ases.

An

estimateof

the

flow

rate

necessaryo maintain the

partial pressure

P11

f

an atmospheric om-

ponent

at somedesired

partial pressure

P inside

he apparatus s

given

by

the

equationl

L

-

-(ADt.2/X)ln(P/Po)

Q)

where,4 s he cross-sectionalreaof the tube hroughwhich hegas s ssuing,X

is

he lengthof this tube, and D1.2 s

the diffusioncoefficient

f

the mpurity

gas

I in

the

inert

gas

2. In round

numbers, the diffusion coefficient

of

oxygen n

nitrogen

s 0.2 cm2ls at I atm

total

pressure,

nd

a

desirable

artial pressure

or

oxygenwithin

the apparatusmight

be

10-r

orr. If

we

assume

hat the

neck

of a

flask s 1.5

cm

in

diameterand 5 cm long. Eq.

(2)

ndicates

hat a

nitrogen low

rate

of only 50 cm3/min would

be

required

o

maintain

this

low level

of oxygen.

Experience eaches s

that

far larger low rates

are

required;

somethingon the

order

of several

iters

per

minute would

be typical under heseconditions.Even

though Eq.

(2)

doesnot appear

o apply o the rather argeopenings ommon o

many preparative- scalepparatusdesigns, t is probably much more accurate

for the

less

urbulent flow

of

gas

from

smaller-diameterubing. The

general

form of t he equation s sensible,

uggestinghat the

entrance f air is reduced

by

a lon g-necked lask with

a small

cross

section

or

this

neck.

C. Monifold fot

Inert

Gos ond Vocuum.

Pure nert gas.generally

itro-

gen

but sometimes

rgon or helium,

is required or the

operations

escribed n

this

chapter. As describedearlier, equipment

s fi l led with

the

gas

by

purging

with a large volume of

gas,

or

evacuation

ollowed

by fi l l ing

with

the

gas.

To

accomplish hesepurging operations n an efficientmanner t is handy o have

an

inert-gasmanifold

with

severalheavy-walledlexible vinyl or rubber

tubes

attached o

provide

nert gas

o separate

ieces f

apparatus.A mineraloil bub-

bler,

or occasionally mercurybubbler, is attached o

the

gas

outlet on

the

ap-

paratus

o

protect

against

excessive

ressure.

When

the

pump-and-fil l

technique

s used,

a

more complexmanifold or the

distribution

of

inert gas

and vacuunl s

generally

mployed,

n

conjunction

with

a

liquid nitrogen-cooled

rap,

mechanical acuum

pump,

and

pressure

elease

bubblers

Fig.

1.2) .

This manifold

can be used o

purge

several

ieces

f apparatus

at once,

and

the two-way stopcocksor valvesprovide a ready means of switching between n-

ert

gas

and vacuum.

Sources

f

purified i nert gas and vacuum

are

attached

o

this

manifold.

An oil bubbler

on

the

nert gas

nlet

serves

s

an approximate

low

indicator.

The inert

gas s controlledat the tank

with

a high-quality

dual-stage

diaphragm

regulator

which is designed

or

good

regulation

around 3

psig

(915

torr).

A

pressure elease ub bler

is often included on

the inert

gas

ine. Glass

stopcocks

ttached o these

manifolds

will becomedislodged

y the small

posi-

tive

pressure f

inert gas.Therefore,

t is essential

o

secure hese

topcocks,

nd

rG.

Antos.

Ph.D.

Thesis,Nor thwesternUnivers i tv .1973.

I


19/334

,10

BENCH.TOPNERT-ATMOSPHERE

ECHNIQUES

To vacuum

pump

Pressure

elease

bubbler

To

apparatus

Low-temoerature

trao

Fig.

1.2. Mani fo ld for medium vacuumand

nert

gas.A

low-temperaturerap,

on the r ight s ide

of

the igure, s used

n the vacuum ine

o

protect

he

pump

from

harmful

vapors.When

the apparatus

is

being i l led

u ' i th gas

or

purged * ' i th

iner t gas.

he

valveon the pressure e lease

ubbler

(uhich

conta ins

checkvalve

o

prevent

i l

f rom

backingup into

the

ine) s opened o avoid

excess

ressure

u'h ichwould

blo*

the apparatus pär t . Of len a mineralo i l bubbler

nol

shownhere)

s

connected

n

l ine u ' i th

the

iner t -gas

ource o

providevisual ndicat ion

of the iner t -gas

low.

al l o thers used on

inert-atmosphere

quipment,

wi th h igh-qual i ty p lug

retainers.2

Details on

the

purification

of

inert gases

can

be found in

Chapter

3. The

source

of vacuum s

generally

a rotary

mechanical

acuum pump. The pump is

protected

rom

chemicals

nd solvent apor

by

means

of

a

trap cooled y

Dry

Ice

or,

preferably,

iquid nitrogen.

CAUTION: A

liquid nitrogen rap

must

neverbe

connected

o

a

manifold

where

he

vacuum

sourcehas been

urned

off. Failure to

remove

a

liquid

nitrogen

trap from a manifold

after shutting

off

the

vacuum

will

result

in the

condensationof liquid

air

in

the trap. If warmed

up,

this liquid

air

will evaporateand may pressurize he apparatus, presentingan extreme explo-

sion hazard.

It

is

desirable or

this

trap to

be

deepenough o extend o the bot-

tom of

a

l-L

Dewar, thus permitting

ong-term

cooling.

The

trap shouldbe eas-

ily removed

so that accumulated

ondensables an

be

readily

(and

frequently)

discarded.

D. PUrging

Sylinges. Syringes

re

conveniently

urged

rom an inert-gas

source

uch sa tube

with

a

rapidly

lowing nert-gas

tream

r

a special eptum

attached

o

the

nert-gas

anifold.Two

or threecycles f filling, emoving

he

'Excel lent

reta iners

K-809000) .

which

must

be used

u' i th

stopcock

lugs

ront

the

sanremanufac

turer , are avai lable ronr

KontesGlassCo. Vineland

NJ.

.r'


20/334

ADAPTATIONS

F STANDARD LASSWARE

needle rom the inert-gas

source,

and expelling he gas

are sufficient.

f

the sy-

ringe

is

going

to be used

o remove

iquid

fronr

a flask

which is

being

rapidly

flushed,

he

inert gas

may be

drawn from

the

flask and expelledoutside

of the

flask

to

purge

the syringe.

When

highly

moisture-sensitive aterials,

such

as

aluminum alk yls and activeborohydrides,

are being

handled,

he

syringeparts

should

be

stored in

a

drying oven

around 130"C and removed

ust

prior

to

purging.

E. Drying

Glosswore. The

purging procedures

escribed

hus far remove

relatively itt le of

the moisture

which

is adsorbed

n

glass

surfaces.When

han-

dling compoundswhich

are

highly

moisture sensitive.

uch as

aluminum hy-

drides.

borane

adducts, and

lithiunr

alkyls,

t is often

n'rportant

o employspe-

cial drying

procedures.

A drying oven

set at around

l30oC can

be

used

o bake

out

glassware

or severalhours

prior

to use. This

glassware

hould be flushed

with dry inert

gas

as t cools.To prevent

apparatus rom

sticking

ogether,stan-

dard taper

joints,

stopcocks,and

syringes hould be completelydisassenrbled

before hey are placed n the oven.

Alternatively,

he

glasswaremay

be

flushed while

it is

being heatedwith

a

Bunsen

burner

or

heat

gun.

CAUTION: When

using a Bunsen

burner or heat

gun

to dry

glassware,

all flammable

materials must be removed

rom

the area.

If

the glassware

has been rinsed with

a volatile

solvent, such

as acetone

or metha-

nol, to aid the drying

process,

he residual

solvent vapors should

be removed

from the

glassware rior

to

drying by

purging

severalminutes

with inert

gas.

The

heating s startednear he nert-gas nlet and

carriedalong

he apparatus

ou'ard

the gasout le t .

Silylating

agentshavealsobeenused o treatglassrvareeforehandlingnrttis-

ture-sensi t ive

ompounds.

or example,

ch lor ine-ternr inated

ol-yd inteth-y l

i -

loxane s

avai lab le

ontnterc ia l ly . r

lhese

reagents

uppress

he basic i t l 'o f

he

glass

and

provide

a

hydrophobicsurface.

4.2

ADAprATroNs

FsTANDARDrAsswARE

Many operations

vith

air-sensitiveiquids

can be

perfornred

n

standard

aper

glassware

itted

with

a bubbler and inert-gas

ource.NOTE: To avoid blowing

apparatus apart, stills and reaction pots should be vented to a bubbler before

they

are heated.Figure I . i l lustrates

a typical

setup

or

a

three-neck eaction

flask equipped vith

a dropping funnel,

stirrer, and reflux

condenser. his

ar-

rangementprovides

several mportant features

or

safeand

efficientoperation.

Inert-gas nlet

I and the

oulet

hrough

the mineral oil

bubbler are

positioned

or

efficient nitial

purge.

Pressure

uildup, especially

uring heating, s

avoided y

allowingpressure

eleasehrough the

bubbler. A constant

slow low of inert

gas

rThis

nrater ia l s so ld under

he

nanre

Glassclad v Petrarch

Slstcms. nc. .

Bar t ranrRoad. Br isto l .

PA 19007.

1 1


21/334

o

HJ

St r

-head

the rmomete r

Insu la ted

v

rgera

x

c o l u m n

t o

nooo

Iner l -ga

in le t

3

Mrne ra l

o i l bubb le r

Receiver

Heatrng

man t le

Fig. 1.3. Dist i l la t ion

under iner t a tnrosphere

sing modi f iedstandard

aper

r 'are.Note

he

side-

arnr added o

the

standard

single-necked t i l l

pot

and

receiver .

he s idearmon the st i l l

pot

a l lows

ef f ic ient n i t ia l

purg ing

of

the

apparatus,

whi le

he s idearmon the receiver l lou 's

ne

o mai ntain a

br isk iner t -gas

low over he d ist i l ledsolventwhen

he receiver

s

renroved rom the st i l l .

The

appa-

ratus

s

ni t ia l l l '

purged

as o l lon

s:

(

)

The

ent i reapparatus,

xcept

or the receiver.s assembled.

2)

Iner t -gas n let

I

is

opened

uhich

purges he

st i l l

pot . co lunrn,

and

condenser .

3)

The receiver

s

at tached o inen-gas n let

3 and

purged

separate ly.

4)

Af ter

both the

receiver nd the main

pan

of

the

apparatus

have been suf f ic ient lypurged

(about

3-5 min) , the receiver s at tached

o

the main

apparatus

'h i le

mainta in ing he iner t -gas low

fronr both in lets and 3.

When

the

receiver

s at-

tached, here

wi l l

be

a

vigorous ner t -gas lou '

through

the mineral o i l bubbler .

(5)

A

slow

low of

iner tgas

s

star ted

rom in let 2. The ner t -gas lou ' f rom inlets and

3

is nou terminated.

Dist i l la t ion

may nou be gin.The

slo* f lo* of iner t -gas rom

inlet 2 through he mineral

o i l

bubbler

wi l l prevent

a ir

from

backing

up into

the

apparatus h i le

min imiz ing

exposure f

the

solvent

o any

impur i t ies

present

n the iner t gas.

I f the

iner t -gas

lou is mainta ined

hrough

he st i l l

pot

dur ing

the

dist i l la-

t ion, the

ef f ic iency

f

the

separat ion

ould

be degraded.

When

the d ist i l la t ion s complete. he ner t -

gas low

from in let

J is

resunred

eforedisconnect ing

he

receiver

rom the

apparatus.

1 2


22/334

SYRINGEND

CANNULA

ECHNIOUES

:hrough

nlet

2,

with no

flow

from inlet 1,

prevents

ir

contaminationduring

the

.rru15. *

the

reaction

while not

exposing he entiresystem o any

mpurities

hat

:rav

be

present n

the

inert-gas tream.This slow nert-gas

low from inlet 2

also

rrevents

air

from

being sucked

n while

the apparatus

s coolingafter

he

reac-

:ron

l' las

been

completed.

Finally,

this arrangement

prevents

he depletionof

:

iqhly

volatilesolvents.

An apparatus

or disti l lation under

nert

atmosphere,

llustrated n Fig. 1.3,

:ncorporates

he

same eaturesseen n

the

inert-atmosphere

eactionapparatus

Fig. l . l ) . The d is t i l la t ion apparatus

also

conta inssome s l ight ly

modif ied

round-bottom

lasks

or

more efficient

nitial purging. Thesemodificationswill

re

discussedn

greater

detail

n

the

following

section.

To minimize eakage,

oints

areeither ightly

greased

r equipped

with

Teflon

.lc-eves,

nd are

held ogether

with

springs, pecial

l ips,or r ubber bands.

When

rr

can be used,

grease

rovides

he tightest

seal;

however,

eflon sleeves re

gen-

.:rally

used or

connections o stil l

pots

and

similar

harsh

environnents.

The

rarious

types of

stopcock

grease,

ncluding the

new

solvent-resistant

eflon-

hased ubricants, are summarized n Chapter8. Greased tandard aper oints

rre

readilyavailableand are

adequate or mos t

purposes;

owever,

O-ring

oints

.rre

superior

or most inert-atmosphere pparatus.

The

advantages

f

O-joints

are

hat they are

resistant o solvents, nd the clamps

usedwith

these

oints

hold

rhe

apparatus ogether

much more

positively

han do the

springsand other

de-

rices

usedon

standard aper

oints.

Very

satisfactory peration

s

possible

with

either standard O-joints

or

the

Teflon-supportedO-ring

joints

(Solv-Seals).

These

ypesof

joints

are described urther

in

Chapter8. If

standard

O-joints

are

used, the O-ring material

should match the solventsbeing

handled;

again,

Chapter

8

should

be

consulted

or

details.

The principal drawbacksof the standard apparatus s that it is diff icult to

flush

efficiently

and

liquid

transfer

operationsare awkward.

With litt le

addi-

rional

complexity, he

apparatuscan be adapted

or

efficient

purging and solu-

tion

transfer

by syringeor

cannula.

{ ,3

syRrNeE

ND

ANNULA

EcHNrouEs

A.

TypicolAppololus.

A simplemodification

which mproves

he

util ity of

a

one-neck

til l

pot

or solvent eceiver

s

a sidearm,which

can

be used

or flush-

ing the flask. This simple modification acilitates he initial f lush of the appa-

ratus

shown

n

Fig. 1.3. Furthermore,

he sidearm

provides

everal lternatives

for the

removalof

solvents

rom

a receiver, uch as lushing he

flask while sol-

vent

s removed hrough the

standard aperjoint, or

removal

of solve nt hrough

the

sidearm,

as

llustrated n

Fig.

1.4. The

sidearmalso

permits

he

flask to

be

maintainedunder a constant lush of

inert

gas

when it is attached o another

p iece

f

apparatus

Fig.

1.5) .

43


23/334

BENCH.IOPNERT.ATMOSPHERE

ECHNIOUE

Fig. 1.4. Transfer

of so lvent y syr inge rom

a storage

lask u ' i th

he exclusion

f a i r .

(a)

Solvenl

s

removed hrough he neck of the

storage

lask whi le

mainta in inga br isk f lorvof iner t

gas

rom

the

sidearnt .

6)

Solvent

lso

may be

removed hrough

he

sidearmwhi le r ra inta in ing

atm of

pressure

in the

lask

by admit t ing ner t gas

hrough

he n let . n both

(a)

and

(b) ,

the syr inge

s

ni t ia l ly

purged

by sampl ing ner t

gas

rom the storage lask

and expel l ing h is

gasouts ide

he storage lask.

B. Septo

ond Olher Closules. Rubber septamay be attached

n

a

variety

of

ways,

as llustrated n Fig. 1.6. The

flat

variety s held n

place

by screw aps,

crinped

caps,

or

beveledholders. Various manufacturers

provide

apparatus

with

these

ypesof septumclosures.a

f

greater

versatil ityare

he sleeve eptum

stoppers

Fig.

1.7), which

can

be attached o

straight

ubes or standard aper

joints

without any

special ixtures.s

Two problems

with

all septaare

heir sensitivityo solvents nd

chemicals

nd

leakage

hrough the

punctured

septum. Flat

compositesepta

minimize

these

problenrs.

These

consistof

a central coreof a

compliant

rubber,

such

as a

soft

( b )

aSpecia l

septum closures nd apparatuswith

these

closures

re

manufactured y

Ace

Aldr ich

Chenr ica lCo. .

KontesGlassCo., and WheatonGlass

Co.

in the

Uni ted

States,

in France.

sSleeve- type

septunr

c losures re

u ' ide ly

avai lable rom

chemicaland hospi ta l

supply

excel lent leeve eptunr

topper,producedby

the

Suba

Seal

Co.

n

the

Uni ted

Kingdom,

there rom

Gal lenkamps

and

from

Strem ChemicalCo. in

the Uni ted States.

GlassCo.,

and Sovire l

houses.

An

is avai lable


24/334

SYRINGEND CANNUTA

ECHNIOUES

Fig. 1.5. Jo in ing wo

pieces

f equipmentunder ner t -gas lush. Both

pieces

re

in i t ia l ly purged

with inert gas separately before joining. Note the use of wire hooks and rubber bands to secure

indiv idual

p ieces

f

g lassware.

f the

glasswares constructed

sing O-r ing

oints,

the O-r ing

oint

c lampshold the apparatus ogether .

silicone ubber, sandwiched etween hin sheets f Teflon. The

silicone

ubber

imparts

good

sealingaction, and the Teflon s highly resistant

o solvents nd to

permeation

by atmospheric

gases.

Direct

contactof solventswith septashould

be

minimized and septa

should

be replaced

often.

When

organic solvents re

being used,

one must

be

wary of impurities

extracted

rom

septa,

oints,

and

tubing. Theseextracted mpurities may foul reactionsand causeconsiderable

confusion n the interpretation f IR and NMR spect ra.The

prime

offenders re

hydrocarbon

nd sil icone topcock

reases,

ibutyl

phthalate

and similar

plasti-

cizers

rom Tygon

tubing, and

various

extracts

rom rubber goods.

Somespec-

tral

methods or identificationof

these

nuisances

re collected

n Table 1.1. The

pickup

of impurities from septacan be

greatly

minimized by

prior

extraction

with

an appropriate

hot

solvent

ollowed

by

pumping

off the absorbed solvent

beforeuse.Septa

make

poor

closures

or

containers sed or

the

long-termstor-

age of highly air-sensitivematerials, since

atmospheric

gases

diffuse through

,15


25/334

R u b b e r

e P t u m

G l o s s

T o ooDoro tus

( o )

F ig.

1.6.

Methods or at taching

ubber septa o

glass

apparatus.

a)

A modi f ied

Swagelok- type

f i t t ing. The

l ip on one end of the

f i t t ing is turned

dorvnon a

lathe, and the

septum

eplaces

he

ferru les.

On the

other

end,

a

Tef lon ront fer ru le

s used

o

nrake he

connect ion

th a

glass

ube.

ä)

An a l l -g lass

eptunr o lder .

c)

Cross ect ion

f a

plast ic

hreaded

ap

septumholder

on a threaded

glass

sidearm

manufactured

y

Wheaton

Glass

Co.) .

F ig, 1.7. Secur ing

Suba-seal

nto

a

glass

ube.

(a)

Cross ect ion f

Suba-seal

s

t is nser ted nto a

glass

ube.

(b)

Af ter inser t ing.

he

lap

on the

Suba-seal

s

oldedover he

tube.

(c)

The f lap

may be

secured o the tube

by

wirc.

Ioble '1.'l SpeclrolSignolures f lmpuriliesrom SfopcockGreoseond

Rubber

ond

Ploslic

fems

Source Ni r ture

f Inrpur i t Spectroscopicdent if cat ion

\ _

/ @ \

t_ lT l

ltt

Itl

U/r

( b )

nn

W

NN

\trN

( a )

( b )

Rubber septa

or

tub ing

T_vgon nd other

f lex ib le

o ly (v iny l

ch lor ide) ub ing

Stopcocks nd

jo in ts

Dyes.ant iox idants ,

etc.

D ibuty l phtha la te

nd

other

plast icizers

Sil icone

rease

Apiezon

L

Vis-UVabsorption

NMR:

Mult .

7 .5.

ub.

.5

M u l t .

. l - 1 . 9 ,

Mult .0 .92

pm

NMR:

ca .0 .1

ppm

NMR:ca.

1.25,

.9

ppm

t i 6


26/334

SYRINGEND

CANNULA

ECHNIOUES

\cpta

and the

rubber is l ikely

to

undergo

chemical

breakdown.

One

possible

.:rception

o this

statement s the use of unpunctured Teflon-coated epta as

>c'als;

ut even

here one is better off using sealed

lass

ampules

or

storage.

C. Syringes.

The principal

variations

n

available yringes re n

the

design

,rf

he tips and

plungers.

For

most preparative-scale

ork, syringes ith remov-

ableneedles re employed.The removable eedlewith a female oint hub is at-

rached

o

a male

tapered

oint

on

the syringe.

This male Luer

tip

may

be a

straight nner

oint

fashioned rom

glass

or metal or a metal

oint

with

surround-

ing

locking devicewhich holds

the

needlesecurely n

place.

The metal locking

variety

is

preferable

because

t prevents

the detachment of the needle during

critical

transfer

operationsand

the

metal

tip

is more robust

than a

glass

ip.

Glass

ips are desirable

when highly

corrosive

iquids

are

handled. The

Luer

taper

oints

are

widely

adopted but not universal .Nonstandard

apers

do not

sive

an air

tight

seal f mixed with

a

Luer

component.Microliter syringes,

hich

are

useful

or

sampling small volumesof

liquids,

often

have needleswhich

are

permanentlyattached o the barrels.

The

standard small syringesare often constructedwith individually matched

plungers

and barrels which are

given

matching

code

numbers.Theseplungers

and

barrels are

not interchangeable

with

those

from other syringes.Larger

sy-

ringes

often have interchangeable

parts.

Leakage of air

past

the

plunger

is a

constant

problem

with

these ypesof syringes.

When

a light coatingof mineral

,ri l

on the

plunger

can be tolerated,

his

provides

an effective

means

of reducing

the leakage. t al so s

possible

o

reduce

he entranceof air

past

he

plunger

by

forcing

he

solution nto

the syringe

with

a small

positivepressure

ather

than

sucking he material nto the syringe

y

pulling

on the

plunger.

For example, he

three-needleechnique llustrated n Fig. 1.8 may be used o fil l a syringeunder

controlled

positivepressure.

he

variousmethodsof forcing he solution nto

the

svringe

are done

with

the

greatest

control

by

using

a

metal

syringe

holder which

limits

plunger

raveland thus avoids

he

possibil ity

f

the

plungerpopping

out of

the syringe

one

such holder s i l lustrated n

Fig.

1.9).

t is especially elpfulto

use

a

metal

syringe

holder when pyrophoric

materials,

such

as neat

aluminum

alkyls,are transferredby syringe.The metal holder

also

has

he convenience f

permitting

one-handed

perationof the syringe.

Tighter

seals etween he

plunger

and barrel are achievedwith so-called

as

tight syringesn which a Teflon-tippedplunger

or an O-ring-equipped

lunger s

employed.Very good leak resistances also displayed

by the

inexpensive dis-

posable

yringes,"which consistof

a

polypropylene

hell and a

rubber-tipped

plunger.

Unfortunately, the rubber swellsand sticks n

the barrel

when most

organic

solventsare transferred; but

these

disposable

syringesare excellent

or

work

with aqueous

solutions.

D. Sytinge Needles. Syringe

annulae,

which will

be referred

o

asneedles

throughout

his

discussion, re most commonly

constructed

rom

stainless teel

tubing fitted to a metal or

plastic

hub. Chromium-plated rasshubs are

perhaps

1 7


27/334

Ne --r

Ven t

S e r u m b o t t l e

c o p

\ w i r s

Fig,

l .E. The three-needle

echnique or

u i thdrau ' ing

iquid f rom a storage

ube.

The

syr inge

s

in i t ia l lypurged

by sampl ing ner tgas rom

the ube and expel l ing he

gas

outs ide he ube.To f i l l the

syringe, he vent is briefly covered

with

a finger, forcing

the

solution

into the syringe.

B - D

C o r n w o l l

e t o l

/ , p r P e t t r n g

h o l d e r

l /

1

C Cs t z e

- o o o o

o o o S N \

o o o o o

' \

G r o d u o t i o n s , c c

L u e r - L o k

v o l v e

8 - D

N oM S 0 9

B - D Y o l e e g u l o rp o r n

2 0

g o u g e

h y p o d e r m i cn e e d l e

( L u e r - L o k )

n .

o n g

A s s e m b l e dh y p o d e r m r c

y r i n g e

n m e t o l

p r p e f t i n g

h o l d e r

P l u n g e r

T e n s r o n

p r r n g

R e t o n e . w o s h e r

B - D

C o r n w o l J

y r r n g e

L u e r - L o k )

t

c c s j z e

P l u n g e r

o s s e m b l y

F ig . 1 .9 .

Assembled hypodermic

syr inge

in

meta l

p ipet te ho lder .

,t8


28/334

SYRINGE

ND CANNUTA

ECHNIQUES

rhe

most common

variety.Leaks n

the

Luer taper

oint

between he needle

and

svringe

ody nraybe

minimized

by the

useof a s mall amount of stopcock

rease

on

the

syringe

oint.

A check

or

gross

eaks

s

performed

by

pulling

air

into

the

svringe,

nserting the needle

nto

a

rubber stopper, compressing he

syringe

plunger

o

about half of the original volume,

and noting

whether

he

plunger

returns

o

its

original volume

mark when

released.Poorly itt ing needles

r

sy-

ringeparts shouldbe discarded.Needle ips are easilyblunted and bent

over n

rhecourse

f laboratorywork, so a small,

ine-grained

whetstone

hould

be kept

handy

o

resharpen he

point.

A needle ip that

is

curled back

or has

a

burr on

rhe

point

is

especially

amaging

o

septa.

A sharp needlenot only makes

nser-

tion easier

but also

reduces eakage

hrough

the

punctured

septum.

The so-

callednoncoring

or deflecting ip,

which has

a side

openingor

a

l2o

beveled

ip,

is

preferredoverother ypesof needles ecause

t does he leastdamage

o septa.

A flat-cut

point

should

be avoided.

When

working

with

unstable r reactive

ub-

stances,

t is important to flush a needle

and syringe

with pure

solvent

mntedi-

ately after

use. Stiff metal cleaning

viresare often

providedwith

neu'

needles

and are useful or removingdeposits rom the interior of the needle.

The

outside

diameterof the

needle s

generally

pecified

n

the United

States

by its wire

gauge. Table 1.2

presents

he

metric equivalentof comnron

wire

gauges nd the

sizesof matching syringes.

The latter are

provided

as

a conve-

nient

guide and not as a setof

rules.Teflon

needles

re convenient

or transfer-

ring highly corrosive

materials;however.

heseare

not

general

substitutes

or

metal

syringes

ecause

hey cannot

penetrate epta.

A rangeof

special

syringe

fitt ings s

available. uchas

crosses,ilters,

T's. and stopcocks.b

he

small

stop-

cocks r

va lvesind use

n reta in ing iqu ids

n syr inges. hese reespecia l ly

se-

fu l in

conjunct ion

with large-volume

syr ingesor

u 'hen handl ing

highly

pyrophor icmater ia ls , uch as a luminum alky ls .A setup ncludinga syr inge

stopcock

longwith a syr inge

olderhasalready

een l lustrated

Fig.

1.9) .

An-

other application

of these

tems s

the adapter

or the removalof aluminum

al-

kyls

and

other

reactive iquids from a small

cylinderdescribed

n

the

following

example.

Iob le

'1 .2.

Needle

Sizes

nd Molching syr inges

Gauge

o.d.

(nrnr )

Approx i r r ra te

o lunre f Match ingSv l inge

19

25

23

20

l 8

l 4

0.46

0 .57

0 . 8 1

1 . 0 2

r . 6 3

Microliters

0.2-2nL

l -5 mL

5-50nrl

50-100 rL

'The

construct ion

f a largesyr inge

or

dispensing

ases

s descl ibed 1 'G.

W.

Kranter ,J.

Chcm'

Edac. .50.

221

\1973) .

Syr inge

T's, s topcocks. nd

needlestock or cannulaeare avai lablc

rom

Ald r i chChen r i ca l

o . . P .O . Box

355 .

M i l uaukcc .

Wl

53201 .


29/334

20 BENCH.TOPNERT-ATMOSPHERE

ECHNIQUES

Lead

gaskel

32 hread

Stopcock

Lue

- lo

Iner t

gas

Me ta lcy l r nde r

Wrench

o r

va l ve

Three

way

Lue r - l ok

Syr inge

needle

5

l 6

@'

{u---'

t fl-ll n

Ht /

r - 1 \ l /

@iM

l+J'

V

E. Exomple:

Wifhdrowol

of

Highly Reoclive iquids from Mefol

Tonks. Highly

reactive iquids

such as aluminum alkyls can be

withdrawn

from

a

low-pressure

yl inder

using he apparatus hown

n

Fig.

l . l0a. CAU-

TION: Highly reactive

liquids should be handled in a hood

which

contains a

minimum

of

flammable

material

or chemicals.

After

attaching the syringe

appa-

ratus

to

the

cylinder,

the

needle

s

purged with

inert

gas

for severalminutes.

While purging, he needle s nserted hrough he septum nto the reaction lask.


30/334

'QINGE

ND

CANNULA

ECHNIOUES

Fig.

1.10, Transfer of a i r -sensi t iveiquids

from metal cy l inders.

a)

A

three-way

metal

stopcock

. , 'nstructed or usewith syr ingesmay be modif ied by the addi t ion of a threaded i t t ing so that i t

: ra tes

with

a lecture

bot t le .

The s ide

nlet

s used

o

purge

he

apparatus n i t ia l ly

and to

blou, l iqu id

,ut

of

the

syr inge

eedle

t

the complet ion f

the t ransfer .

The cyl inder

s

put

under a lou '

pressure

I

:ncr t

gas before

he t ransfer

s

begun.

(ö)

Somet imes i r -sensi t ive

iquids

are sold in s iphon- type

;r l inders,and

the l iqu id

f ronr

such a cyl indercan

be

dispensed s shownhere.As wi th

the

previous

rrample, iner t gas s

used

o

force he

l iquid

out

of the cyl inder .

The three-wayvalve s then switched o allow liquid dispensing.When the de-

sired

quantity

of

liquid has been

removed

rom

the cylinder,

the

cylinder

is

closedand

the three-way

alveswitchedback

to

inert gas,

so hat

the

needle

s

purged

by inert

gas

before

it

is

removed rom

the

reaction

flask.

An

apparatus or

the

withdrawal

of reactive iquids

rom metal cylinders

av-

ing

a

siphon tube is shown

n

Fig.

1.10ä.

This setup s operated n

much

the

same

way as he syringeapparatus,

he main

difference

eing he useof

inert gas

to

force

he

liquid

out

of the

cylinder

containing

he siphon

ube.

24


31/334

22

BENCH.TOP

NERT.AIMOSPHERE

ECHNIQUES

F.

Liquid

llonsfer Connuloe. The

transfer

of l iquids

between

wo flasks

may be accompl ished

i th a cannulaalone

Fig.

1.11).These annulae

sual ly

are constructed

rom syringeneedlestock which is

commerciallyavailable

n

convenientengths.6n addition o simple iquid transfer,special i ltration can-

nulaecan

be

constructed. n a

recent

designby M. L. H. Green,a

stainless-steel

cannula is cemented

with

epoxy

resin

to a

short length

of heavy-walled

lass

capillary tubing

which

has a slightly flared and

fire-polishedopening

Fig.

l. l2a). This opening

s covered

y

hardened ilter

paper which is

neatly

olded

back

on

the

glass itt ing

and

wired n place,

as

llustrated n Fig.

|.l2b . A sleeve-

type

septum stopper s

pushed

onto this fi lter apparatus,

with

the

stopperend

toward the fi lter. This assemblymay then be attached o a

receiver nd flask as

i l lustrated

n

Fig. 1 .11. Fi l t ra t ionwith more convent ional

quipment

s i l lus-

trated

n Fig. 1 .13.

In comparisonwith syringe echniques, he useof cannulaeprovidesbetter

air exclusion

and

greater

convenience

or

the

transferof

large

volumes

of

solu-

tion. However,syringe echniquesare much

better suited or the

quantitative

dispensing f

Iiquids,

as demonstrated

n

the

following example.

G. Exomple: Quonlitotive Dispensing of

Liquids. Moderate accuracy

in liquid-transfer

operationscan be achievedusing syringe

graduations.

Air

should first be expelled

rom

the

fil led syringeby

pointing

the

needle

up and

squirtingout all bubbles.Higher

accuracy an

be

achieved

y

weighing he dis-

pensed

iquid. The syringe s fi l led and

the

needle ip

is stoppered y insertion

into a small rubber

stopper.

This

assembly

s weighed, he

iquid dispensed, nd

the syringe

plus

rubber

stopper s

reweighed. f

the

syringe s not

going

o be

re-

Fig. L l l .

Solut ion tansferus ing

a sta in less

teel

annula.The so lut ion s

forced

hrough he nee-

dle by meansof the

pressute

differential

createdby opening he inert

gas nlet,

which pressurizes

he

right-hand lask. The receiv ing lask is e i ther maintainedat I a tm by opening he s idearm o a

bubbler, or is

mainta inedat s l ight ly ess

han

I

atm by

opening

he s idearm

brie f ly

to

a vacuum

source.


32/334

SYRINGE

ND

CANNULA ECHNIQLJES

lr rt

l lu ra l l

l f

Lösausecanr

| |

| | , -Eporv

cement

| |

11 K / - t \ -wr re t re .down

l l l l , -Grassr t tng W^

ä5

@FrterPaPer

( D )

Fig. 1.12. Assenrbly

f a f i l ter cannula

or

"Green

f i l ter . "

(a)

A

piece

of

g lass

capi l lary

ubing,

u

hich

hasbeenblou 'nopenand f i re-pol ished

o form

a

l ip

on one

end. s attached

o the

cannulau i th

cpoxycement.

ä)

F i l tcr

paper

s fo lded

over

he

glass

api l lar l

and secured i th u ' i re .

I ne r t

gas

T o

bubb le r

t

i g . 1 .13 . Va r ia t i on

n

the

cannu la

echn iquc . heg lass

ubc

u i t h

f r i t t ed

i l t e rand

he

g lass

e l i r -

- : \ 1ubesa rea t t ached to theg lasss tanda rd tape r jo in t sbJ 'meanso fp las t i cadap to r s (e .g . ,

on tesK-

I- ' rE00) .

The f lex ib lc p last ic

ubing connect ing

he t$o

par ts

should be inrper i ' ious

o solvents.

I

r i lon

tubing

is

bestand.

to

prcvcnt

contaminat ion

f thc f i l t ra te, T1 'gon

ubing

should

be avoided

r r r ' l l

, r gan i c

o l ve r r t s

rc

used .

used mnlediately, t should be rinsed u' ith degassed olvent mmediatelyafter

use,

o avoid

the buildup of

depositsof

decomposition

roducts

n

the syringe

and needle.

However, f it

is to be re-used

oon

with

the same

solution,

he stop-

per

may

be

left

on

the

needle

ip and both rinsing

and inert-gas lush

may

be

omitted

before

he syringe s fi l led

again.

H.

Specfloscopic

Meosuremenls.

The

sampling

of air-sensitiveiquids

for

NMR

and IR spe ctroscopys

often most

conveniently erformed

by syringe.

Small ubber

septa

are availablewhich

it 5-mm

and other sn.rall MR

tubesand

23

( 4 . )


33/334

2A

BENCH-TOPNERT-ATMOSPHERE

ECHNISUE

also i t the Luer n letson

IR cel ls . he NMR tubemay

be purged

y

purnp-and

f i l l

operat ions,

'hereas

R cel lsareeasi ly lushed y

inert

gas.The

i l l ing of the

IR

cell

s

accornplished y

inserting

he syringe

eedle nto

the septum

on

the

cel

in le t .and he out le tseptum s p ierced vi tha smal lneedle. n excess f l iqu id s

f lushed

hrough he cel l o exc lude

as

bubbles.

A

somewhat

ess i r - f ree pera

t ion

is achieved

y

f lushing

he cel land then at tachine

svr inge onta in inghe

l iqu id by

jo in ing

he Luer

f i t t ings

on the syr inge

nd cel l .

An

empty

syr inge

s

attached o the cell exit

to

serveas a

reservoir or

excess

iquid u'hich s force

through he cel l .

Once the ce l l

is f i l led.

the

in let

and out le t

are capped v i t

Teflon stoppers.Conventional isible-UV cells can also be fitted

rvith

syring

caps

or air-freespectroscopy.

visible-UV cell

that

has

been

used

or

a

u'id

variety

of air-sensitivenorganicand biologicalcon.rpounds

s il lustrated n Fig

1.14.More

sophist icatedpectroscopic

e l ls .

ome

of

rvh ich

resui tab le or us

in conjunctionwith syringe echniques.are described n Chapter9.

4 4

euANTrTATrvEASMANIPULATToN

A. Dispensing

Goses. The d ispensing f

gas

o a so lut ion an

be accom

pl ished

n severa l 'ays.

For example, so lut ionmay be saturated y bubbl in

N e e d l e

-

v o l v e

l - c m

, s i n g l e -

p i e c e

C U V C T T E

R e s e T v o r r ' :

F ig. L l4.

Evacuable e l l or UV-r ' is ib le

pectra. ' I 'h is e l l

s

evacuated

nd

hen

lushed hroughar

iner t -gas nlct at tached o thc O-r ing oint .

' l 'he

Tef lon stenrof the valvc s removedunder f lush

solut ions

re ntroducr-d hrough

his opening.and then

t ipped over nto the culet te af ter he

valr

stem has bcen replaced.

Al tcrnat ive l l . c t>ndensablet> lve 'ntsnd

solutcsma1'

e condensed

nto th

reservoir n a vacuunr ine.


34/334

:,

ANIITAIIVE

AS

MANIPULAIION

-::

through it from a syringeneedleattached

o a tube and low

pressure as

u rce

F ig .

1 .15 ) .

'f

he

quantitative

delivery

of a

gas

s somewhatmore nvolved.While it

is true

'-

JI a vacuumsystem

ften

permits

he mostsatisfactory

method

of

quantitative

-,,:

handling, some

adequate

procedures

xist

which

are

based

on simple, con-

:

ntional

nert-atmosphere

pparatus.A

large

gastight

syringe s oneof the most

rvious

devices

or

the

measurement f

an aliquot of

gas.bA

sampleof

gas

may

^.:drawn nto the syringe rom a streamof the gasconnectedo an exit bubbler.

\nother

method

or

dispensing

iven quantities

of gas s

a

gas

buret, similar

to

re described ater

in connection

with

the measurement f evolved

ases.T

til l

i:r()ther

implescheme s to

flush

a bulb of known volume

with

the

desired

gas,

,nd

then

bubble

this

gas

into

the

reaction

lask by meansof

a slow

nert-gas

.:ream

Fig

1.16).

Condensable

ases

may

be trapped.measured y vo lume

of

'.re

liquid,

and dispensed y

controlledwarming

of

the

gas.A

suitableapparatus

',r

this

purpose

s il lustrated n

Fig

1.17.

Gases

which

are condensable

t

Dry

:re

temperature,

78oC,

can be handled

by th is

technique.

Finally, it is often possible o generatequantitatively he desiredgas from

:reasured

mountsof l iquid

or

solid eagents. he generated as

s then

quanti-

:. lt ively ransferred

by

inert-gas

lush

into

a reaction mixture. The

automatic

:lsimeter

developed y C.

S.

Brown and H. C. Brown s usefulwhen t is

neces-

.rrv

to kno w the

quantity of gas

consumed n the

course

of

a reaction.sThis

rpparatus

can

be applied o

the

generation

of a varietyof

gases,

uch

as

H2,E

Tobubbler

_>

Fig. 1.15. Dispensing as

direct ly

rom

a tank. l -he

needle

alve

s

used o contro l

he

gas

low nto

thc solut ion,

and a

mercury- f i l led

ubbler prevents

xcessive

ressure

ui ldup.

T. N. Sorre l l

and

M.

R. Malachou'ski ,norg. Chem., 22. l88J

(1983) ,

provide

a recent

descr ipt ion

, , f

gasuptake

exper iments

with

a

gas

buret .

'C .

A . B rownand H . C .

Bro$ 'n , . / .O rp . Chem. .31 .3989

196b ) .

To

hood


35/334

26

BENCH.TOP

NERT.ATMOSPHEREECHNIOUES

T o reac t r on

vesse

Reagent

as

rn

e I

Ca l i b ra ted

o lume

--.>

V

Tobubbler

In hood

Fig. 1.16, Gas-sampl ing ube.

The

tube

is f lushed

with

the

reagent

as

by

opening

o the

reagent

gas

nlet and

vent ing

o a

mineralo i l bubbler . Af ter severalminutes,

he flush s terminated

by f i rs t

c losing he in let s topcock, hen the out le t s topcock.

This

ensures

hat the

pressure

nside he

(ube

equals hr- aboratoryatmospher ic

pressure.)

he laboratorJ

eniperatureand

pressure

re

then

measured

or

use n calculat ing he anount of gasdispensed.

inai iy . he known

quant i t ] '

o f

reagent

gas

s d ispensedo the

react ion essel y opening he n let stopcock o

iner t

gas.

he out le t s topcock

to

the react ionvessel ,

nd

f lushing

he tube

rv i th ner t gas or seYeral r inutes.

CO,e

hydrogen

al ides,r0 ' r

02,

2

ethy lene,rrnd SOt,

r

but notgases h ich eact

with mercury. By

meansof

a

clever

iquid

inlet

device,

gas s produced n

the

generator n

response

o

the

amount consumed n

an

attached

eactor.This liq-

u id in le tva lve

Fig.

1.18),

onsis ts f

a tube

part ia l ly

i l led u ' i th mercury.The

tube

has

provision

or the

nlet

of l iquid from a needle ttached o a buret and for

the controlled l or.r ' f

this

liquid into

the reaction

vessel ia several

mall

holes

above he mercury evel.

Liquid from

this

inlet

valve

drops nto the

gasgenera-

tor, and the

evolved

as

s

conducted rom there o a reaction lask.

The flou'of

liquid

can be initially

adjusted

by

the depth o

which

the needle

rojects

nto the

mercury

pool

of the

valve.When

the

system

s

properlybalanced. he

pressure

drop caused

y

gas

consumption n the reactorpulls

the

reagent

or gasgenera-

tion

in

through

the liquid

control valve.As the

pressure

uilds

up,

this

flow

of

reagent

stops,

only

to resumeagain when

the

reactionconsumes ome

of

the

generated as.

When

the

quantitative

measurement f ga s consumption

s

re-

quired, the exit bubbler serves nly as a safety evice nd the systemmust be set

up so hat there s no gasexpelled

hrough he bubbler during the course

f

the

reaction.

B.

Meosuremenf

of

Evolved

Goses.

The measurement f

evolved

ases

provides

a

ready

meansof

conductingcertainanalyses

nd following he course

' qM .

W.

Ra thke

and H .

C .

Broun . , / .

An t .

Chen t .Soc . . 88 .2606

1966 ) .

l "H .

C .

Bro * ' nand

N. -H .

Re i , " / .

O re . Chen t . , 31

1090

19b6 ) .

I rG.

W. Kranter . A. B. Levv,and M. M. Mid land. in H. C. Brorvn,Organr 'c . i . r ' r r / l tcsesiaBorunes,

Ne l 'Yo rk l

W i ley ,

1973 , .

218 .

r2H .

C .

Brown .M . M . M id land ,

and G .

W.

Kaba lka , . An t . Chen t .Soc . . 93 ,

1024

1971 ) .

t

Inert

gas


36/334

OUANIITATIVEAS MANIPULAIION

To

reactron

VESSCI

To

gas

absorber

or hood

Ar . r t rDac

u

p

t rap

Mercury

bubbler

Ca l rb ra ted

ow

empera tu re

t r ap

to r

l t qu r t t ed

as

Fig. 1.17.

Apparatus or

d ispensing

noun quant i t ies

f condensable ases. he

trap

may

be

cal i -

'orated

by using

water

( for

large volumes)

or mercury

for

smal l

vo lumes) .

A

nrercury

bubbler is

rncluded o pre\ent

b lowing the apparatusapart.

Af ter assembl ing

he apparatus, he ent i resystem s

thoroughly

purgcdui th

iner t gas.Stopcock

B is

then turned

to route

gas

o a h ood or

gas

absorber ,

he

iner t -gas low is

ernr inated,

nd

a

slou

f lou

of the desired

gas s

adnr i t ted ronr a

cyl inder

equippedwith a

pressure

egulatorand

needle

ra lve

or f lou 'contro l .

A

Deuarconta in ing

efr igerant apable f l iqu i fv ing he gas

see

able

5. I )

is

then ra isedaround the trap. Af ter the desired o lumeof l iqu id is co l lected, he reagent as lou is

terminated, topcockA

is

closed,and stopcockB is turned to d i rect gas o

the react ion

essel . he

Dewar s then owered

rom the t rap.

a l lorv ing

he col lected

as

o boi l o f f . The rate of

vapor izat ion

mayby contro l led y rais ingand ower ing

he

Deuar. When

the t rap appears o

have

beenempt ied.

a f lush of

iner t gas

nray be used o f lush out

remain ing

eagent apor .

of a reaction.For

example, he analysis f activehydrides

and alkyl compounds

can often be conductedby

quantitative

hydrolysis

o

produce

hydrogen

or

al-

kane.A simple

gas

buret system,

llustrated n Fig. 1.19, s useful or

these ypes

of measurements.t alsomaybe used o dispense pecific uantitiesof gas o an

inert-gas tream or introduction nto a reactionmixture.

The

procedure or us-

ing this

gas

buret

apparatus or

the analysisof active hydridesor alkyl com-

pounds

by hydrol ysis s

described

n

the followingexample.

C.

Exomple:Anolysis

f AcfiveHydrides r AlkylCompounds sing

o

Gos Bure l . This

procedure t i l izes

he

gas

buret

l lustratedn

Fig.

l . l9

to

analyze ctive

hydrides

or

alkyls.First,

the

water evels

n

the

reservoir nd buret

s ides re

adjusted

o

equal

height

and an n i t ia l

buret eading s

aken.

A

sample

of known

weight s

ntroduced

nto

the

hydrolysislask usinga syringe.

After

gas

27

I ne r t ' gas

n le t

,1,


37/334

Reagentnlet

trom

buret

Reagent verflow

o

generator

lask

ng

Fig. I .18.

Bro*nl gas

generator

ncl

apparatus

or react ions

with

gases.

Reagents

re mixed

n the

gas

generator

nd the resulr ing

ases

re

passed

nto

the react ion essel .

he nrercurv

ubbler

on

the

far le f t

has

a f loat check

valYe vhich

prevents

nrcrcury

and

air f ronr

being

suckedback

into

the

react ion essel . he key to th is apparatus s the automat ic iqu id intetvalve,shou'n n deta i lon the

r ight .

A drop in

gas pressure

vi th in

he apparatus

pul ls

iquid

fronr

the

buret

through

he

syr ing

needle

nd the

ntercurv.

The rate

of

del iver t

of reagent

s

adjustedby ra is ing

or lower ing

he

bure

and

at tached

s-yr inge

eedle.

React ionessel

28


38/334

t ig . 1.19. A gas buret for the measurement r del iveryof gases.When the e lbou (on lef t ) is at-

' ' r rhed

to the

top of

the

buret , gas

s

col lected

nd

i ts vo lume

s measured

f ter

equal iz ing

he mer-

' u r r l e v c l s . F o r e x a n r p l e , a h y d r o l y s i s f l a s k s i n r i l a r t o t h e r e a c t i o n f l a s k i n F i g .

l . l 8 m a y b e a t t a c h e d

'

'

lh ls

e lbow.When

the

stopcock

ssembly

s

used

ar

the

r ight) ,

the

buret

can be i l led

ui th

sas

and

,

n)easured

oluntc

of th is gas

can

be in jected

nto

a stream

of f lou, ing

ner t gas.

29


39/334

30

BENCH.TOP

NERT.AIMOSPHERE

ECHNIQUES

evolutionhas ceased.

he

water

evels re again

matched.and

both a buret and

barometric

pressure

measurement re

aken.

A correction

must

be made

or

the

vapor pressure

f the solventused

n

the

system, specially

f

the solvent

s

very

volatile.

'1

,5 scHLENK

EcHNToUES

A. Bosic Apporolus.

The

shriver, the manipulation of air-sensitive compounds book

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