A Level ChemistrySynthetic Routes

AS Chemistry: Slides 2-21A2 Chemistry: Slides 22-70

You can convert an alkene to an alcohol by:

A.Adding concentrated H2SO4.

B.Adding dilute H2SO4 then add H2O.

C.Adding concentrated H2SO4 then add H2O and warm.D.Adding concentrated H2SO4 and warm.

The mechanism of reaction between an alkene and concentrated H2SO4 to make an alcohol is:

A.Electrophilic substitution.B.Electrophilic addition followed by hydrolysisC.Hydrolysis.D.Nucleophilc addition followed by hydrolysis

The major product formed when CH3CH=CH2 reacts with concentrated sulphuric acid followed by addition of water is:

A.CH3CH2CH2OH.

B.CH3CH(OH)CH3.

C.CH3CH(OH)CH2(OH)

The reagent and mechanism to convert an alkene to haloalkane are:

A.X2 (X= halogen) in an electrophilic substitution

B.X2 in a nucleophilic addition.

C.HX in a nucleophilic additionD.HX in an electrophilic addition

CH3

H

CH3

H

CC

OSO3H

H+

-

OSO3H

carbocation

2-butylhydrogensulphate

CH3

H H

CC

H

CH3

CH3

H H

CC

H OSO3H

CH3

How many mistakes are shown below?

A. One error. B= two errors C = three errors

The reagents and conditions to convert a haloalkane (RX) to a nitrile RC≡N are:

A.HCN in a fume cupboardB.KCN in ethanol in fume cupboard.C.KCN in ethanol, heat in a fume cupboard.D.HCN and heat in a fume cupboard

The name of CH3CN is:

A.methanitrileB.ethanitrileC.ethanenitrileD.methanenitrile

To convert CH3CH2CN to CH3CH2COOH you need:

A.HCl and water (acid hydrolysis)

B.HCl and NH3

C. NaOH and water (alkaline hydrolysis)

The reaction between a haloalkane and hot ethanolic KCN to produce a nitrile:

A.KCN is the nuclephileB.:CN- is the electrophileC.:CN- is the nucleophileD.KCN is involved in a neutralisation reaction

The reagent, conditions and mechanism to convert a haloalkne into an alchol (e.g.CH3CH2Cl into CH3CH2OH) are:

A.Ethanolic NaOH in nuclephilic substitution.B.Ethanolic NaOH in nucleophilic elimination.C. NaOH aqueous, warm in nucleophilic addition.D.NaOH aqueous in nucleophilic substitution.

The reagent, conditions and mechanism to convert a haloalkane into an alkene (e.g. CH3CH2Cl into CH2=CH2) are:

A.Ethanolic NaOH in an addition- elimination.B.NaOH aqueous in an addition- elimination.C.Ethanolic NaOH in an elimination, OH- as the

base.D.NaOH aqueous in an elimination with the OH- as

the base.

The make a 10 amine from a haloalkane (e.g CH3CH2NH2 from CH3CH2Cl ) you need:

A.Excess haloalkane in a nucleophilc substitutionB.Excess NH3 in a nucleophilic substitution.

C.Excess NH3 in an electrophilc substitution.

The name of CH3(CH3CH2)NH is

A.Methylethyl amine.B.AminopropaneC.Ethylmethyl amine.D.Propanamide

How many mistakes are shown?

A= 4 error, B= 5 errors, C= more than 5 errors

aminoethane

CH3

H

BrC

H

Br-

H

CH3

H

NH2C

H

CH3

H

NH2C

H

NH3

H NH3+Br -

reaction equation

NH3

a) Draw the mechanism for the reaction between bromoethane and the cyanide ion. Name the organic product formed.

b) Check your answer against the next slide.

+ -CH3

H

BrC

H

CN -

CH3

H

CNC

H Br-

cyanide ion with bromoethane

Nucleophilic substitution mechanism

propanenitrile

reaction equation

a) Draw the mechanism to show the reaction between 2-bromopropane and NaOH (in ethanol).

b) Compare your answer against the next slide.

Elimination of HBr from 2-bromopropane

CH3

H H

H

CC

OH -

CH3

H H

HCC

Br H

propene

H OHBr -

CH3CHBrCH3 + OH- CH3CH=CH2 + H2O + Br-

(in ethanol)

acting as a base

Elimination of HX from haloalkanes

The reagents and conditions to convert CH3CH2CH2OH to CH3CH2CHO are:

A.Acidified potassium dichromate K2Cr2O7 , heat and reflux.

B.Add Tollen’s reagent until you get a silver mirror.

C.Acidified K2Cr2O7 heat and distil.

D.Add aqueous NaBH4

Alcohols can be converted into alkenes by:

A.An elimination reaction using concentrated H2SO4 as a catalyst (dehydration).

B.An elimination reaction using concentrated H2SO4 as a catalyst (hydrolysis).

C.An addition reaction using H2O and concentrated H2SO4 as a catalyst.

CH3

C= O to CH3CH2OH using:

H

A.NaBH4 (aq) as the oxidising agent

B.NaBH4 (aq) as the reducing agent.

The mechanism of reactions exhibited by aldehydes and ketones is:

A.Electrophilic addition.B.Electrophilic substituion.C.Nucleophilc substituion.D.Nucleophilic addition.

The reagent and conditions to convert RCHO to RCH2OH or a R1R2CO to R1CH(OH)R2

A.NaBH4 (aq) with NaBH4 as the nucleophile.

B.NaBH4 (aq) with BH4 as the nucleophile.

C.NaBH4 (aq) with :H- hydride ion as the nucleophile

(a) Draw the mechanism for the reaction between propanone and sodium tetrahydridoborate NaBH4.

(b) Check you answer against the following slide.(c) What type of mechanism is it?

+

-

reduction of propanone

H+

NaBH4 is a source of hydride ions

CH3

CH3

C

O

CH3

CH3

C

O

H

H

propan-2-ol

H

CH3

CH3

C

O

H

H

from the solvent

The name of CH3CH(OH) CN is:

A.2-hydroxyethanitrile.B.2-hydroxypropanitrile.C.Butan-2-ol.D.2-hydroxypropanenitrile.

The name of CH3CH(OH) CH2 COOH

A.2-hydroxybutanoic acid.B.3-hydroxybutaneoic acid.C.3-hydroxybutanoic acid.D.2-hydroxycarboxylic acid.

The reagent and conditions to convert RCHO to2-hydroxynitrile RCH(OH)CN then to a 2-

hydroxycarboxylic acid are:

A.KCN (aq) and H2SO4 in a fume cupboard, followed by acid hydrolysis.

B.HCN in a fume cupboard, followed by acid hydrolysis.

C.HCN and H2SO4 in a fume cupboard, followed by acid hydrolysis

(a) Draw the mechanism of the reaction between propanone and the cyanide ion as the nucleophile. Name the organic product.

(b) Check your answer against the next slide.

Nucleophilic Addition Mechanismhydrogen cyanide with propanone

H+

NaCN (aq) is a source of cyanide ions

CH3COCH3 + HCN CH3C(OH)(CN)CH3

CH3

CH3

C

O

CH3

CH3

C

O

CN

H

H+

2-hydroxy-2-methylpropanenitrile

from H2SO4 (aq)

+

-

CN

C N

CH3

CH3

C

O

CN

• Explain why, in a laboratory synthesis, the reaction between ethanal and :CN- gives rise to a racemic mixture.

Recap: How can you can carry out the following conversion?

Alkene Alcohol ketonee.g. Propene propan-2-ol propanone

Haloalkane Nitrile 10 Amine

CH3CH2Cl CH3CH2CN CH3CH2CH2NH2

Step 1: Reflux haloalkne with ethanolic solution of KCN

Step 2: Reduction using H2/Nickel catalyst

How would you carry out the following conversions?

10 Alcohol Aldedyde Carboxylic Acid

Ester

The compound CH3CH(CH3)CH2COOH is:

A.2-methylbutanoic acid.B.3-methyl butanoic acidC.Pentanoic acid

The compound O CH3 C

OCH2CH2CH(CH3)2

A.Methyl pentanoateB.2-methylbutyl ethanoateC.3-methylbutyl ethanoateD.3-methylbutyl methanoate

The reagents to make HCOOCH2CH3 are:

A. CH3CH2COOH and CH3OH

B. HCOOH and CH3CH2OH

C. HCOONa and CH3CH2OH

The products of the alkaline hydrolysis of esters:RCOOR’ + NaOH →

A.RCOOH + R’ONaB. RCOO-Na+ + R’OHC.RCOH + R’OONa

The name of HCOO-Na+ is:

A.Methanoic sodiumB.Sodium methanoateC.Sodium methanoic acid

The following is the preferred method to regenerate the carboxylic acid as it:

RCOOR’ + NaOH RCOO-Na+ + R’OH HCl RCOOH + NaCl A.Uses non-toxic raw materials.B.Gives higher yieldC.It’s a faster reaction

Name the compound CH3CH2COCl

propanoyl chloride

Complete the following general equations and state the type of mechansim.

RCOCl + H2O →

RCOCl + R’OH →RCOCl + NH3 →

RCOCl + RNH2 →

Nucleophilic addition-elimination

The name of CH3CH2CONH2 is:

A.Propyl amineB.PropaneamideC.N-ethylethanamideD.Propanamide

State the reagents and conditions for makingCH3COOCH3 starting with an acyl chloride.

CH3COCl ethanoyl chloride and CH3OH methanol. Anhydrous conditions.

Give the formula, conditions used and name of the organic product for:CH3COCl + CH3CH2CH2NH2 →

CH3CONHCH2CH2CH3

N-PropylethanamideAnhydrous conditions

Complete the following reaction. State the conditions, and name of the organic product formed.CH3CH2COCl + NH3 →

→ CH3CH2CONH2 + NH4Cl

PropanamideUse excess NH3

NH3 first behaves as a nucleophile , then as a base (proton acceptor).

A) Write the mechanism for the reaction between ethanoyl chloride and propanol. Name the organic product formed.

B) Compare your answer against the next slide.

+

-

Nucleophilic Addition Elimination Mechanism

CH3

Cl

C

O

OCH2CH2CH3

H

CH3

Cl

C

O

OCH2CH2CH3

H

+

CH3C

O

OCH2CH2CH3

H

+

CH3C

O

OCH2CH2CH3 Cl

nucleophilic addition

elimination

reaction equation

H-Cl

Name the compound (CH3CH2CO)2O

Propanoic anydride

Write an equation to show how ethanoic anhydride is formed.

Complete the following equation and name the products formed.

(CH3CH2CO)2O + CH3OH →

→ CH3CH2COOCH3 + CH3CH2OH

methylpropanoate and ethanol

a) State the three methods for making esters.b)Compare the methods mentioned in (a)

Draw the mechanism for the reaction between an acid chloride RCOCl and excess NH3.

State the role of NH3

Compare your answer against the next slide.

+

-

Nucleophilic Addition Elimination Mechanism

R

Cl

C

O

NH2

H

R

Cl

C

O

NH2

H

+

R C

O

NH2

H

+

Cl NH3

R C

O

NHCH2CH2CH3

H

+ NH3

Cl

nucleophilic addition

elimination

reaction equation

Name the compound: CH2CH3

CH3 N

H

Ethylmethylamine

Name the compound CH3CHCH3

NH2

2-aminopropane

Name the compound CH3

CH3CHCH2NH2

1-amino,2-methylpropane

Recall the two methods for making amines:a)RX + NH3 (excess) →

b)Reduction of nitriles RCN

Why must NH3 be in excess?What is the reducing agent in (b)?

Write equations for the reaction between excess CH3CH2Br and NH3.

Name all the organic products formed.

Identify the organic product and state its uses:(CH3CH2)4N+Br-.

Quaternary ammonium saltUsed as cationic surfactant in fabric conditioners

and shampoos to reduce static.

State the reagents and conditions for the following reaction. Name the organic product.

C6H6 → C6H5NO2

Concentrate HNO3 and concentrated H2SO4

Temperature: 500C

Benzene C6H6 undegoes:

A. Electrophilic addition.B. Nucleophilic addition.C. Electrophilic substitution.D. Nucleophilic addition-elimination

a) Name the electrophile in the nitration of benzene.

b) Write relevant equations to show how this electophile is formed.

NO2+ nitronium ion.

H2SO4 + HNO3 ↔ HSO4- + H2NO3

+ then,

H2NO3+ → H2O + NO2

+

Draw the mechanism for the nitration of benzeneCompare you answer against the next slide.

Electrophilic substitution mechanism (nitration)

2. Electrophilic attack on benzene

NO2

NO2

+

3. Forming the product

+

NO2

H

reaction equation

and re-forming the catalyst

Name the reagnets and condtiosn fro the reaction C6H6 → C6H5COCH3

CH3COCl Ethanoyl chloride

AlCl3 aluminium chloride catalyst

Anhydrous conditionsTemperature: 0-250C

a) Write an overall equation to show the reaction between C6H6 and CH3COCl

b)Show how the electrophile is formed.b)State the role of AlCl3 in the acylation of

benzene.

CH3C Cl

O

Acylation example

Three steps in electrophilic substitution mechanism

1. Formation of the electrophile (an acylium ion).

2. AlCl3 behaves as a Lewis acid

AlCl3 [AlCl4] -

With ethanoyl chloride overall reaction equation

C6H6 + CH3COCl C6H5COCH3 + HCl

+CH3C

O

Draw a mechanism for the reaction between benzene and CH3COCl.What type of mechanism is it?

Compare your answer against the next slide.

+H

CH3C

O

Acylation electrophilic substitution mechanism 2

2. Electrophilic attack on benzene

phenylethanone

-Cl AlCl3

AlCl3 + H Cl

3. Forming the product

and re-forming the catalyst

+CH3C

O

CH3C

O

+ H+