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Theory 01 - 08

Exercise - 1 09 - 13





Answer Key 25 - 25

Contents

CARBOXYLIC ACIDS

Name : ____________________________ Contact No. __________________

SyllabusCarboxylic acids, Methods of preparation, physical properties, chemicalproperties & formic acid

Carboxylic Acids_Advanced # 1A-479 Indra vihar, kotaPh. - 9982433693 (NV Sir) 9462729791(VKP Sir)

Physical & Inorganic By

NV SirB.Tech. IIT Delhi

Organic Chemistry By

VKP SirM.Sc. IT-BHU

CARBOXYLIC ACIDS

INTRODUCTION

(a) Organic compounds in which – COOH group is present are called as ‘Carboxylic Acid’.(b) These compounds are also called fatty acids because their higher members like Palmitic acid or

stearic acid were usually obtained from animal fats.(c) The term ‘Carboxylic’ was firstly proposed by scientist ‘Bayer’.(d) Their general formula is

CnH2nO2 or CnH2n+1–COOH(e) Hybridisation state of carboxylic carbon is sp2.(f) In carboxylic acids, both oxygen-carbon bond lengths are equal due to resonance. It is 1.28 Aº.(g) On the basis of number of –COOH group, they are called mono, di or tri carboxylic acid.(h) Acids shows chain and functional isomerism. They shows functional isomerism with ester.

eg.

(functional isomers)

(chain isomers)

&

METHODS OF PREPARATION

From Alcohol :(a) By oxidation :

R – CH2 – OH [ ]O

H O 2

R – CHO [ ]O R – COOH

Acidic KMnO4 or K2Cr2O7 may be used in the above reaction.

(b) By reaction with CO : –

R – O – H + CO BF

Catm

3

200 300200

º

.

From Aldehyde and Ketone :

R – CHO + [O] acidicKMnOor

K Cr O

4

2 2 7

R – COOH

From Alkyl Cyanide : Cyanides gives acid on complete hydrolysis.

R – C N H O3

R – COOHFrom Trihaloalkane : 1,1,1- Trihaloalkane reacts with aq. KOH and forms respective acid.

H O2





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From Acid derivative (By hydrolysis) :

R – O – C – R + H – O – H

R – C – NH + H – OH2

From Dicarboxylic Acid (Decarboxylation) :

glycerol H BO

CO C

3 3

2 110( º ) HCOOH

NOTE : The above reaction is lab method to prepare formic acid.

CO2

CH2COOH

H

ethanoic acidFrom Grignard Reagent :

From Carbonylation of sodium alkoxide :

Sodium alkoxide+CO High temp

essure

.

Pr

RCOONa H O3

NaCl + RCOOH

From Alkenes : (CO,H2O)

RCH = CH2 + CO + H2O H PO

highpressure3 4 /

R CH CH

COOH

— —|

3

From Arndt-Eistert Process :This reaction is used in ascendig series. In this reaction alkanoyl halide reacts with diazomethane andacid is obtained on hydrolysis.

CH3COCl+CH2N2 HCl CH3COCHN2 2

2

N

OAg

CH3 – CH = C =O H O3

CH3 – CH2 – COOH





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Manufacture of formic acid only :

(a) NaOH+CO 210

6 10

o

atom .

HCOONa

HCOONa H SO2 4 HCOOH

(b) CO + H2O high

pressure BF

/ 3HCOOH

(c) CH3OH+CO200º

high pressureHCOOCH3

dil H SO. 2 4 HCOOH + CH3OH

METHODS OF PREPARATION OF CARBOXYLIC ACID

Ex.1 Which of the following products is formed when adipic acid is heated -

(A) (B)CH – CH2 2

CH – CH2 2

C = O

(C)CH – CH CO2 2

CH – CH CO2 2

O (D)

(Ans.B)

Sol. HOOC(CH2)4COOH 300ºC

cyclo pentanone

Ex.2 Malonic acid and succinic acid are distinguished by -(A) Heating (B) NaHCO3 (C) Both A & B (D) None of these

(Ans.A)

Sol. O

CH CO2

CH CO2succinic anhydride

CH3COOH + CO2

two – COOH group on one carbon atom gives CO2 on heating.two – COOH group an adjacent carbon atoms lose H2O to give an hydride on heating.

CO2 + H2O + CO,

CH2COOHCOOH

CH3COOH + CO2,CH – COOH2

CH – COOH2





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Ex.3 Hydrolysis of 1,1, 1-trichloro derivative (A) of alkane gives a molecule (B) on alkaline hydrolysis whichproduces red coloration with aqueous FeCl3. The compound (A) is -(A) CH3CH2CCl3 (B) CH3CCl3 (C) CHCl3 (D) None

(Ans.B)Sol. CH3CCl3 KOH CH3COOH Fecl aq3 ( .) (CH3COO)3 Fe (Red)

Ex.4 Which of the following is the best representation of the structure of the carboxylate ion -

(A) (B) R – CO

O

–

–

(C) R – CO

O

(D) None of these

(Ans.B)Sol. Both C – O bonds are identical and each O possesses partial negative charge.

PHYSICAL PROPERTIES

(a) Carboxylic acids are colourless with specific smell liquid. They are in liquid state upto 9 carbonand above 9 carbon they are solids.

(b) Lower carboxylic acids are soluble in water. It is due to H–bonding. Higher carboxylic acids areinsoluble in water due to increase in covalent character.

(c) Their melting point and boiling point molecular mass.

1

No of branches.

(d) Boiling point of acids are comparatively higher than equivalent esters due to H – bonding. Forexample, methyl formate (HCOOCH3) has a boiling point 57ºC whereas acetic acid has a boilingpoint 118ºC.

(e) Formic acid is used in leather industries, also known as corrosive.

(f) 8 – 10% acetic acid is called ‘Vinegar’.

(g) At 16–20ºC pure acetic acid converts into ice like solid called glacial acetic acid.

(h) In industries, acetic acid is prepared by oxidation of ethanol and oxidation occurs by aceto bacteraceti or micoderma aceti bacterias. The process is called quick vinegar process.

(i) Boiling point of formic acid is 100.5ºC while acetic acid has 118ºC. For removal of water from formicacid we can use reagent PbCO3 (lead carbonate) and H2S.

(j) Acidic strength of an acid can be increased by the addition of – I groups in place of -hydrogenatoms. Acidic strength can be decreased by addition of + groups.

Cl CH C – H 2

::

Omore acidic

CH C – H3

::

Oless acidic





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CHEMICAL PROPERTIES Chemical reaction of carboxylic acids are classified in five categories.

Reaction of Hydrogen Atom of Carboxylic Acid.Reaction of – OH group of Carboxylic Acid.

Reaction of group of Carboxylic Acid

Reaction of – COOH group of Carboxylic Acid.Reaction of Alkyl group of Carboxylic Acid.

Reaction of Hydrogen Atom of Carboxylic Acid

(a) Carboxylic acid reacts with base and forms salt, thus showing acidic character.

(a)

(b) R – C – O – H + H – O – KO

R – C – OK

Pottasium alkanoateO

(c) R – C – O – H + H – O – AgO

R – C – OAg

Sliver alkanoateO

(d)R – C – O – H H – O

R – C – O – H H – O

O

O

+ CaR – C – O

R – C – O

Calcium alkanoateO

O

Ca

(e)

R –

O

C||

– NH2 + H2O

Ammonium alkanoate

Reaction of – OH group of Carboxylic Acid :(a) Reaction with PCl5 or PCl3 or SOCl2 :

R – C – O – H + PCl5O

R – C – Cl + SO + HCl2

OAlkanoyl chloride





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(b) Dehydration : P O

H O2 5

2

(c) Reaction with Alcohol : conc H SO

H O

. 2 4

2

conc H SO

H O

. 2 4

2

Reaction of – C – group of Carboxylic Acid : || O

(a) Reduction : LiAlH4 R – CH2OH

NOTE : In the above reaction group converts into – CH2 – group.

Reaction of – COOH group of Carboxylic AcidFor this reaction initially we form salt of carboxylic acid with base.

(a) Alkane Preparation :

R – C – O – H + H – O – NaO

NaOH CaO

R – C – OK

O

Kolbe s reaction'

R – Ralkane

(b) Alkyl Halide Preparation : –

AgOH Br CCl2 4/

(c) Carbonyl Compound Preparation (Pyrolysis of calcium salts) :

Ca dry distillation





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(d) Alkyl Cyanide Preparation :

O

R C OH||

NH..

3

O

R C ONH||

4

O

R C NH||

2 P O2 5 , R – C N

(e) Schimdt Reaction :

O

R C OH||

+ :..NH N N

———

O

R C NH N N||

..

..

N2 ——— O = C N RH O

RNH

B |3

2

Reaction of Alkyl group of Carboxylic Acid

(a) Hell – Volhard – Zelinsky Reaction : –

Red P

NOTE : Formic acid does not show the above reaction due to absence of alkyl group.

SPECIAL FEATURES OF FORMIC ACID

(a) Formic acid shows acidic character due to the presence of – COOH group as well as showsreducing character due to the presence of – CHO group.

(b) It reduces Tollen’s reagent and forms silver mirror.

(c) It reduces mercuric chloride and forms black ppt. of mercury.

(d) It decolourises the pink colour of acidic KMnO4.

(e) It forms brown ppt. of MnO2 with basic KMnO4.

(f) It converts the orange colour of acidic K2Cr2O7 into green colour.

(g) It reduces Fehling solution but benzaldehyde cannot reduce Fehling solution.





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DISTINCTION BETWEEN FORMIC ACID AND ACETIC ACID

S. No. HCOOH CH3COOH1 Stable

2 Stable

3

4 No action

5

6 No action

7 Methane is produced

8 Ethane is obtained

9 No action

10 No action

Reduces ammoniacal silvernitrate and Fehling's Calcium salt on heatinggives formaldehyde.

Calcium salt on heating gives

Dichromate soln. Turns into green coloured solution

Sodium salt on heating gives sodium oxalate + hydrogenSodium salt + soda limegives hydrogen on heatingElectrolysis of alkali saltsolution gives hydrogenDecolourises acidified KMnO4 Solution

Decomposes on heating togive carbon dioxide andhydrogen.With concentrated sulphuricacid gives carbon monoxideand waterWith halogens, there is noaction

Substituted acids are formed

Chemical Reactions

Ex. 5 Reaction of CH3 COOH with CH3CH2 MgBr yields :(A) An alkene (B) An ester (C) An alkane (D) A tertiary alcohol(Ans. C)

Sol. Grignard reagents with compounds containing active hydrogen atom form alkanes corresponding to thealkyl group of the Grignard reagent.

CH3 COOH+CH3CH2MgBr

Ex. 6 CH3CH2COOH Cl Fe2 / X alc

KOH

. Y Compound Y is :

(A) CH3CH2OH (B) CH3CH2CN (C) CH2=CHCOOH (D) CH3CHCICOOH(Ans.C)

Sol. CH3CH2COOH Cl Fe2 / alc

KOH

.

Ex. 7 Benzoyl chloride is prepared from benzoic acid by :(A) Cl2, h (B) SO2Cl2 (C) SOCl2 (D) Cl2, H2O(Ans.C)

Sol. C6H5COOH+SOCl2 C6H5COCl+SO2+ HCl

Carboxylic Acid_Advanced # 9A-479 Indra vihar, kotaPh. - 9982433693 (NV Sir) 9462729791(VKP Sir)




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OBJECTIVE QUESTIONS

PREPARATION & TARGET COURSE

1. Which of the following products is formed when adipic acid is heated -

(A) (B) CH – CH2 2

CH – CH2 2

C = O

(C)CH – CH CO2 2

CH – CH CO2 2

O (D)

2. Malonic acid and succinic acid are distinguished by -(A) Heating (B) NaHCO3 (C) Both A & B (D) None of these

3. Hydrolysis of 1,1, 1-trichloro derivative (A) of alkane gives a molecule (B) on alkaline hydrolysis whichproduces red coloration with aqueous FeCl3. The compound (A) is -(A) CH3CH2CCl3 (B) CH3CCl3 (C) CHCl3 (D) None

4. Which of the following is the best representation of the structure of the carboxylate ion -

(A) (B) R – CO

O

–

–

(C) R – CO

O

(D) None of these

5. Which of the following compounds does not have a carboxyl group :(A) Methanoic acid (B) Ethanoic acid (C) Picric acid (D) Benzoic acid

6. Hydrolysis of an ester gives acid A and alcohol B. The acid reduces Fehling’s solution. Oxidation ofalcohol B gives acid A. The ester is -(A) Methyl formate (B) Ethyl formate (C) Methyl acetate (D) Ethyl acetate

7. Which one of the following on oxidation will not give a carboxylic acid with the same number of carbonatoms -(A) CH3COCH3 (B) CCl3.CH2CHO (C) CH3CH2CH2OH (D) CH3CH2CHO

8. Identify Z in the sequence

CH3COONH4 ( )

( )

i heat

ii P O

2 5 Y H O H2 ( ) Z -

(A) CH3CH2CONH2 (B) CH3CN (C) CH3COOH (D) (CH3CO)2O

9. When oxalic acid is heated, which one of the following is formed along with CO2 -(A) Acetic acid (B) Glyceric acid (C) Formic acid (D) None of these

10. Which one of the following reacts with Grignard reagent to form an addition product which can behydrolysed to a carboxylic acid?(A) O2 (B) CO2 (C) SO2 (D) None





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11. A halogen compound ‘A’ on hydrolysis with dilute alkali followed by acidification gives acetic acid. Thecompound X is -(A) ClCH2CH2Cl (B) CH3CHCl2 (C) ClCH2CHCl2 (D) CH3CCl3

12. Acetic acid is obtained when -(A) Methyl alcohol is oxidised with potassium permangnate(B) Formaldehyde is oxidised with potassium dichloromate and sulphuric acid(C) Acetonitrile is hydrolysed with a dilute mineral acid(D) Glycerol is heated with sulphuric acid

13. In Quick Vinegar Process, the aerial oxidation of ethyl alcohol to acetic acid is brought about by -(A) Acetic (B) Maltase (C) Invertase (D) Mycoderma aceti

14. Sodium salt of formic acid on strong heating followed by acidification gives-(A) Formic acid (B) Oxalic acid (C) Formaldehyde (D) Acetaldehyde

15. When malonic acid is heated, it gives -(A) Formic acid (B) Oxalic acid (C) Acetic anhydride (D) Acetic acid

PHYSICAL PROPERTIES

16. The acid D obtained through the following sequence of reactions is -

C2H5Br Alc.KOH A 4

2

CClBr B

(excess)

KCN C OH3

(A) Succinic acid (B) Malonic acid (C) Maleic acid (D) Oxalic acid

17. In the following reactions -

(i) CH3CH2ONa pressureunder

ΔCO, AA

(ii) CH2 = CH2 + CO + H2O pressureunder

POH 43 B

A and B respectively are :(A) CH3CH2COOH in both cases (B) CH3CH2CHO in both cases(C) CH3CH2COOH, CH3CHO (D) CH3CHO, CH3COOH

18. Acetic acid exists as dimer in C6H6 due to-(A) Condensation reaction (B) Hydrogen bonding(C) Presence of a carboxyl group (D) Presence of hydrogen at -carbon

19. Carboxylic acid group can be detected by -(A) Sodium bisulphite test (B) Fehling’s solution test(C) Tollen’s reagent (D) With NaHCO3

20. The pKa values of the four carboxylic acids are given below. Which of the following is the weakest acid?(A) 4.38 (B) 2.87 (C) 1.26 (D) 0.64

21. Phenol is a weaker acid than acetic acid because -(A) Phenoxide ion is better stabilized by resonance than acetate ion(B) Acetate ion is better stabilized by resonance than phenoxide ion(C) Phenol is less soluble in water than acetic acid(D) Both phenoxide ion and acetate ion are equally stable





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22. Which of the following is the weakest acid ?(A) Cl3CCOOH (B) Cl2CHCOOH (C) ClCH2COOH (D) CH3COOH

23. Formic acid is a stronger acid than acetic acid. This is due to the fact that ?(A) Formic acid is a reducing agent(B) Formic acid molecule is of smaller size(C) There is no alkyl group on -carbon in formic acid(D) Formic acid does not undergo association

24. Which of the following dicarboxylic acids contains the most acidic hydrogen ?(A) Maleic acid (B) Fumaric acid (C) Succinic acid (D) Malonic acid

25. Increasing pKa of o, m- and p-nitrobenzoic acid is ?(A) p < m < o (B) o < m < p (C) o < p < m (D) m < p < o

CHEMICAL PROPERTIES

26. Amongst the acids,(i) CH CCOOH (ii) CH2 = CHCOOH and(iii) CH3CH2COOH, the acid strength follows the sequence(A) (i) < (ii) > (iii) (B) (i) > (ii) > (iii) (C) (i) = (ii) = (iii) (D) (i) = (ii) > (iii)

27. The increasing order of acidity of and -chlorobutyric acids is -(A) < < (B) < < (C) < < (D) < <

28. Which of the following is a polyprotic acid -(A) Acetic acid (B) Benzoic acid (C) Salicylic acid (D) Oxalic acid

29. Which of the following acids combines the properties of an aldehyde and an acid ?(A) Benzoic acid (B) Acetic acid (C) Formic acid (D) Oxalic acid

30. Formic acid reacts with PCl5 to form -(A) Acetyl chloride (B) Methyl chloride(C) Carbon monoxide and hydrogen chloride (D) formyl chloride

31. The Hell-Volhard Zelinsky reaction is used for preparing a/an -(A) -Haloacid (B) -Haloacid (C) Acid halide (D) -Haloacid

32. When excess of chlorine is passed through acetic acid in presence of red phosphorus, it forms -(A) Acetyl chloride (B) Chloral(C) Trichloroacetic acid (D) Methyl chloride

33. Identify Z in the following reaction sequence CH3I Ether

Mg X ice

Dry Y PRed

Cl2 Z -

(A) CH3COOH (B) CH3MgI (C) CH3COCl (D) ClCH2COOH





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34. Ethyl alcohol can be obtained in one step from acetic acid by reduction with -(A) Zinc and acetic acid (B) Lithium aluminium hydride(C) HI and red phosphorus (D) Nickel and hydrogen

35. Kolbe’s electrolysis of aqueous potassium ethanoate leads to the formation of -(A) Ethene (B) Methane (C) Ethane (D) Ethyne

36. When a bee bites, it mainly injects into body :(A) Formic acid (B) Acetic acid (C) Carbonic acid (D) Hydrochloric acid

37. Carboxylic acids do not give the characterstic properties of -(A) R – group (B) – COOH group (C) > C = O group (D) None is correct

38. In the molecule CH3CHCl – CH2COOH, Cl atom is attached to -(A) – Carbon atom (B) –Carbon atom (C) –Carbon atom (D) –Carbon atom

39. Which of the following test is not carried out to examin the presence of –COOH groups -(A) Litmus test (B) Sodium bicarbonate test(C) Ester test (D) Bromine water test

40. Reaction of a fat or oil with alkali is called -(A) Esterification (B) Saponification (C) Etherification (D) Epoxidation

41. Which of the following lacks chirality -(A) 2-Hydroxy propanoic acid (B) 2-Aminopropanoic acid(C) 2,3-Butene-dioic acid (D) 2,3-Dihydroxy butanoic acid

42. (CH3)2C = CHCOCH3 can be oxidised to (CH3)2C = CHCOOH by -(A) Chromic acid (B) NaOI (C) Cu at 300 ºC (D) KMnO4

43. Select the compound which does not give acetic acid on hydrolysis -(A) CH3CCl3 (B) CH3CN (C) CH3COCl (D) CH3CH2Cl

44. The simplest dicarboxylic acid is -(A) Vinegar acid (B) Carbolic acid (C) Oxalic acid (D) Succinic acid

45. The acid formed when propyl magnesium bromide is treated with CO2 is -(A) CH3CH2COOH (B) C3H7COOH(C) CH3CH2CH2CH2COOH (D) None

46. Which of the following skeleton gives the strongest acid if COOH is attached to the free valency - C |

(A) C – C – (B) C – C – C – (C) H – (D) C – C –

47. A red P

HI CH3COOH LiAlH4 B. What is not true for A and B -

(A) A is hydrocarbon of general formula CnH2n+2 while B belongs to alkanol(B) A can be obtained by reducing CH3CH2Cl while B by its hydrolysis(C) A is alkene while B is alkanal(D) A and B both belongs to different homologous series





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48. The product A, B, C and D in the reaction A + B Heat H – COOH Heat

H SO

2 4 C + D are given

by the set -(A) CO, H2O, CO2, H2 (B) CO2, H2O, CO, H2(C) CO2, H2, CO, H2O (D) CO, H2, CO2, H2O

49. Ozonolysis of fatty acid is carried out to ascertain -(A) Number of –OH group (B) Number of – COOH group(C) Position of carbonyl group (D) Position of double bond

50. Dry distillation of calcium acetate gives -(A) Acetaldehyde (B) Acetone (C) Ethane (D) Propanal

1. When crystalline oxalic acid is heated to 110º with ... a monocarboxylic acid containing one carbonatom is obtained -(A) 1,2-Propane diol (B) Ethylene glycol (C) 1,2,3-Propane triol (D) Glyoxal

2. Ka will have the highest value for which of the following acids. -(A) Fluoroacetic acid (B) Trichloroacetic acid(C) Trimethyl acetic acid (D) Lactic acid

3. red P

[ Product ] The product of the above reaction is -

(A) -Dibromo acid (B) ,’ - Dibromo acid(C) ,’,’’-Tribromo acid (D) No reaction takes place

4. HVZ reaction is specific for -(A) Replacement of - hydrogen (B) Replacement of - hydrogen(C) Replacement of - carbons (D) Replacement of - carbons

5. Bifunctional organic compound is -(A) HCOOH (B) CH3COOH (C) (CH3)2CO (D) HCHO

6. Acetic acid vapours when passed over aluminium phosphate forms -(A) CH3CHO (B) Ketene (C) C2H6 (D) C2H4

7. The rate of esterfication of acetic acid with methyl alcohol (I), ethyl alcohol (II) , isopropyl alcohol (III)and tert. butyl alcohol (IV) follows in the order -(A) I > II > III > IV (B) IV > III > II > I (C) II > I > IV > III (D) III > IV > I > III

8. Arrange the following compounds in decreasing order of acidity -ClCH2CH2CH2COOH CH3CHClCH2COOH CH3CH2CHClCOOH

I II III(A) I > II > III (B) III > II > I (C) I > III > II (D) III > I > II

9. Arrange OHCH2COOH ( I ), HOCH2CH2COOH (II) and CH3COOH ( III ) in order of acidity -(A) I > II > III (B) III > II > I (C) I > III > II (D) II > III > I





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10. The rate of esterfication of HCOOH (I), CH3COOH (II), (CH3)2CHCOOH (III) and (CH3)3CCOOH (IV) withethanol follows in the order -(A) IV > III > II > I (B) I > II > III > IV (C) II > I > IV > III (D) III > IV > I > II

11. X and Y in the reaction sequence R – C N H O3

X diazomethane Y, are given by the set :(A) Carboxamide , Carbonitrile (B) Carboxylic acid, Carbonitrile(C) RCOOH, RCOOCH3 (D) RCONH2, RCOCH3

12. In the electrolysis of the aqueous solution of CH3CH2COONa, anion goes to anode the possibility offormation of following compounds takes place -(A) CH3 – CH2 – CH2 – CH3 (B) CH2 = CH2, CH3 – CH3(C) CH3CH2COOC2H5 (D) All the above

13. Which of the following organic acid decolourises bromine water as well as forms anhydride -(A) HOOC – COOH (B) HOOC – CH2 – COOH

(C) (D)

14. The general formula of dicarboxylic acid is -(A) (COOH)2 (B) (CH2)n(COOH)2 (C) (CH2)n–2 (COOH)2 (D) (CH2)n–1 (COOH)2

15. The product A, B and C in the reaction sequence A NaOH B Heat

C

360ºC are -

(A) HCHO, HCOONa, CH3OH (B) HCHO, Na2CO3, NaHCO3(C) HCHO, HCOONa, (COONa)2 (D) HCHO, HCOONa, Na2CO3

16. CH2COOH NaNO HCl2 / CH2COOH | | X Yglycine glycollic acidHere X and Y respectively are -(A) OH, NH2 (B) NH2, OH (C) Cl, OH (D) None

17. The reagent used to step up in the homologous series of acids is -(A) (CH3)2SO4 (B) Diazomethane (C) CH3NH2 (D) CH3 – C N

18. A compound with molecular formula C4H10O4 on acylation with acetic anhydride gives a compound withmolecular formula C12H18O8. How many hydroxyl groups are present in the compound -(A) One (B) Two (C) Three (D) Four

19. The carboxylic acid that does not undergo HVZ reaction is -(A) CH3COOH (B) (CH3)2CHCOOH(C) CH3CH2CH2CH2COOH (D) (CH3)3C COOH

20. The end product ‘C’ in the following sequence of chemical reactions is

CH3COOH 3CaCO A heat B OHNH2 C -

(A) Acetaldehyde oxime (B) Formaldehyde oxime(C) Methyl nitrate (D) Acetoxime





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21. Which of the following carboxylic acids undergoes decarboxylation easily?(A) C6H5 – CO – CH2 – COOH (B) C6H5 – CO – COOH

(C) C H – CH – COOH6 5

OH

(D) C H –CH–COOH6 5

NH2

22. CH3CH2COOH Pred

Cl2 a KOHAlc. b

The compound b is -(A) CH3CH2OH (B) CH3CH2COCl (C) CH2 = CHCOOH (D) CH3 – CHCl – COOH

23. A compound undergoes the following sequence of reactions :

C3H5N Hydrolysis C3H6O2 /PCl2

(a)

C3H5O2Cl 3NH C3H7NO2

(b) (c)The compound C is -(A) 1-Nitropropane (B) 2-Nitropropane(C) 2-Aminopropanoic acid (D) 2-Hydroxypropanamide

24. R – CH2 – CH2OH can be converted into RCH2CH2COOH. The correct sequence of reagent is (A) PBr3, KCN, H+ (B) PBr3, KCN, H2 (C) KCN, H+ (D) HCN, PBr3, H+

25. The correct order of decreasing acid srength of trichloroacetic acid (a), trifluoroacetic acid (b), aceticacid (c), and formic acid (d) is -(A) a > b > c > d (B) a > c > b > d (C) b > a > d > c (D) b > d > c > a

26. Which of the following compounds will react with NaHCO3 solution to give sodium salt and carbondioxide -(A) Acetic acid (B) n-Hexanol (C) Phenol (D) Both (B) and (C)

27. Which of the following statements are false about HCOOH -(A) It is a stronger acid than CH3COOH(B) It forms formyl chloride with PCl5(C) It gives CO and H2O on heating with conc. H2SO4(D) It reduces Tollen’s reagent

28. The only acid which contains a carboxylic group is -(A) Sulphanilic acid (B) Picric acid (C) Carbonic acid (D) Glycine

29. Which of the following acid does not form anhydride -(A) Formic acid (B) Acetic acid (C) Propanoic acid (D) Phthalic acid





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30. In a set of the given reactions, acetic acid yields a product C -

CH3COOH + PCl5 A3

66

AlClAnhy.

HC B EtherMgBrHC 52 C Product C would be -

(A) CH3CH(OH)C2H5 (B) CH3COC6H5 (C) CH3CH(OH)C6H5 (D) CH –C–(OH)C H3 6 5

C H2 5

31. Lactic acid, CH3CH(OH)COOH molecule shows -(A) Geometrical isomerism (B) Metamerism(C) Optical isomerism (D) Tautomerism

32. In the given reaction final compound (C) is-

OCO Et2

OH(ii)

NaOH/(i)

3

(A) (B) NaOH (C)

(A)OHO

(B)

OH

O(C)

OHO(D)

OHO

33. Methyl malonic acid on heating to 160°C yields -(A) Formic acid (B) Propanoic acid (C) CO + CO2 (D) Acetic acid

34. Which of the following sets of reagents X & Y will convert propanoic acid into alanine (an amino acid)?

CH –C–OH 3

O X CH –CH–C–OH 3

OBr Y

CH –CH–COO 3

–

NH3

X Y(A) Br2 NaNH2(B) Br2/P NaOH(C) Br2/P NH3(D) Br2/HBr NaNH2

35. Formic acid and formaldehyde can be distinguished by treating with -(A) Benedict’s solution (B) Tollen’s reagent(C) Fehling’s solution (D) NaHCO3

36. Which of the following has the highest pKa value ?

(A) O

OH(B)

O

OHNO2 (C)

O+

OHNMe3 (D)

O

OHNC





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37. (A), (B) and (C) are three dicarboxylic acids such that -

(a) carboxylic acid + CO2 (b) acid anhydride + H2O

(c) cyclic ketone + H2O + CO2

then :(a) (b) (c)(A) adipic acid malonic acid succinic acid(B) Malonic acid adipic acid succinic acid(C) adipic acid succinic acid malonic acid(D) Malonic acid succinic acid adipic acid

Statement based Questions

Each of the questions given below consist of Statement – I and Statement – II. Use the followingKey to choose the appropriate answer.

(A) If both Statement- I and Statement- II are true, and Statement - II is the correct explanationof Statement– I.

(B) If both Statement - I and Statement - II are true but Statement - II is not the correct explanationof Statement – I.

(C) If Statement - I is true but Statement - II is false.(D) If Statement - I is false but Statement - II is true.

1. Statement I : Acetic acid does not give haloform reaction.Statement II : Acetic acid has no -hydrogen.

2. Statement I : Formic acid reduces mercuric chloride solution.Statement II : Formic acid has reducing aldehydic group.

3. Statement I : (CH3)3C–COOH does not give HVZ reaction.Statement II : It does not have any -hydrogen.

4. Statement I : Carboxylic acids have a carbonyl group but it does not give the test of carbonyl group.Statement II : Due to resonance, the bond character of group is greatly reduced.

5. Statement I : Carboxylic acids

OH–C–R||O

have a carbonyl group but it does not give the test of carbonyl group.

Statement II : Due to resonance the double, bond character of

O

C group is greatly reduced.

6. Statement I : Acetic acid does not give haloform reaction.Statement II : Acetic acid has no -hydrogen]





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Passage based Questions

Passage-1 (Q. 7 to 9)Carboxylic acids having at least one -hydrogen react with Cl2 or Br2 in the presence of phosphorus (or aphosphorus halide) to give -halo acids. This reaction is known as Hell-Volhard-Zelinsky reaction (HVZreaction),

R–CH2–COOH 2Br/P

Br

R–CH–COOH

The HVZ reaction is limited to the formation of -chloro and -bromo acids and it is sometimes awkward tocarry out. The reagents (X2 and P) are noxious and the reaction time is often long and the conditions ofreaction are harsh.

7. Which of the following carboxylic acids will not give HVZ reaction ?

(A) CH3–COOH (B) CH3

CH –CH–COOH3 (C) CH3–CH2–COOH (D)

CH3

CH3

CH –C–COOH3

8. Which of the following will be obtained when acetic acid is subjected to HVZ reaction ?

(A) BrCH2COOH (B)

Br

H

Br–C–COOH (C)

Br

Br

Br–C–COOH (D) All of these

9. CH3–COOH /PBr2 (A) NaCN (B) HOH/H . The product (C) will be :

(A) COOH

COOHCH2 (B)

CH –COOH2

CH –COOH2(C)

CH –CO2O

CH –CO2(D)

CO

COOCH –CH3

Passage-2 (Q. 10 to 14)

Variety of products are obtained when dicarboxylic acids are heated. The nature of products dependson the carbon chain length separating the two carboxylic groups.(I) 1,2 and 1,3-dibasic acids on heating give monocarboxylic acid.

(II) 1,4 and 1,5-dibasic acids on heating give cyclic anhydride.

(III) 1,6 and 1,7-dibasic acids give cyclic ketones. Indicate whether the following reactions are right or wrong.

10. COOH

COOHOxalic acid

C200 CO2 + CO + H2O

(A) Right (B) Wrong

11. CH2COOHCOOH

Malonic acid

acidAcetic

COCOOHCH 23

(A) Right (B) Wrong





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12.H–C–COOHH–C–COOHMalaic acid

acidCrotonicCOOHCOCHCH 22 –

(A) Right (B) Wrong

13. (CH2)4COOHCOOH

Adipic acid

O

Cyclohexanone

(A) Right (B) Wrong

14.CH2–COOH

CH2–COOHSuccinic acid

CH2–CO

CH2–COO + H O2

Succinic anhydride

(A) Right (B) Wrong

True/False

15. The IUPAC name of acetic acid is methanoic acid.

16. Hell-Volhard-Zelinsky reaction is given by those acids which have -hydrogen.

17. All the C–O bond lengths in carboxylate ions are identical.

18. Formic acid acts as a reducing agent while acetic acid does not show this property.

Match the following

Q.19 Match the Column

(A) Acetic acid (1) Soda lime (M) ClCH2COOH(B) Formic acid (2) Poisonous (N) Dicarboxylic acid(C) Decarboxy- (3) Phosphorus (O) Soap lation(D) Hell-Volhard (4) Kolbe’s (P) Fermentation of-Zelinsky synthesis sugar reaction(E) Oxalic acid (5) Saponification (Q) Carbon monoxide(F) Electrolysis (6) Vinegar (R) Alkane of CH3COOK(G)CH3COOC2H5 (7) Dehydration (S) Reducing acid + NaOH(H) Formic acid (8) Red ants (T) Ethane + conc. H2SO4





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PART - A : IIT-JEE PROBLEMS (PREVIOUS YEARS)

1. The major product of nitration of Benzoic acid is - [IIT-1993](A) 3-Nitrobenzoic acid (B) 4-Nitrobenzoic acid(C) 2-Nitrobenzoic acid (D) 2,4-Dinitrobenzoic acid

2. The organic product formed in the reaction C6H5COOH OHII

LiAlHI

2

4 [IIT-1995]

(A) C6H5CH2OH (B) C6H5COOH & CH4(C) C6H5CH3 & CH3OH (D) C6H5CH3 & CH4

3. Which of the following carboxylic acids undergo decarboxylation easily – [IIT-1995]

(A) C6H5CO — CH2COOH (B) C6H5COCOOH

(C) C6H5 — COOH (D) C6H5

2

2

NH|CH — COOH

4. The molecular weight of benzoic acid ;in benzene as determined by depression in freezing point methodcorresponds to – [IIT-1996](A) Ionization of benzoic acid (B) Dimerisation of benzoic acid(C) Trimerisation of benzoic acid (D) Solvation of benzoic acid

5. CH3CH2COOH PdRe

Br2 X .)alc(NH3 Y.. Y in the above reactions is - [IIT-1996]

(A) Lactic acid (B) Ethylamine (C) Propylamine (D) Alanine

6. When propionic acid is treated with aqueous NaHCO3, CO2 is librated. The ‘C’ of CO2 comes from -[IIT-1999]

(A) Methyl group (B) Carboxylic acid group(C) methylene group (D) bicarbonate

7. Benzoyl chloride is prepared from benzoic acid by – [IIT- 2000](A) Cl2, h (B) SO2Cl2 (C) SOCl2 (D) Cl2, H2O

8. Which of the following acids has the smallest dissociation constant ? [IIT- 2002](A) CH3CHFCOOH (B) FCH2CH2COOH (C) BrCH2CH2COOH (D) CH3CHBrCOOH

9.Acidic

Hydrolysis Products formed by P & Q can be differentiated by [IIT- 2003]

(A) 2 & 4 DNP (B) Lucas reagent (ZnCl2) conc. HCl

(C) NaHSO3 (D) Fehlings solution





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Passage (Q.10 to Q.12)In the following reaction sequence, products I, J and L are formed. K represents a reagent.

Hex-3-ynal3

4

PBr2.

NaBH1. I

OH3.

COM1.

3

2.2ether/g

J K Me Cl

O

quinoline

Pd/BaSO

H

4

2 L [IIT-2008]

10. The structure of the product I is-

(A) Me Br (B) MeBr (C) Me Br (D) Me Br

11. The structures of compounds J and K, respectively, are-

(A) Me COOH and SOCl2 (B) Me and SO Cl2 2O

OH

(C) MeCOOH

and SOCl2 (D) Me COOH and CH SO Cl3 2

12. The structure of product L is-

(A) Me CHO (B) Me CHO (C) MeCHO (D) Me CHO

13. The compound that does NOT liberate CO2, on treatment with aqueous sodium bicarbonate solution, is :[JEE Advanced_2013-P-1]

(A) Benzoic acid (B) Benzenesulphonic acid(C) Salicylic acid (D) Carbolic acid (Phenol)

14. The total number of carboxylic acid groups in the product P is : [JEE Advanced_2013-P-1]

Paragraph for Question Nos. 15 to 16

P and Q are isomers of dicarboxylic acid C4H4O4. Both decolorize Br2/H2O. On heating, P forms the cyclicanhydride.Upon treatment with dilute alkaline KMnO4, P as well as Q could produce one or more than one from S, T andU. [JEE Advanced_2013-P-2]

S T U





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15. In the following reaction sequences V and W are, respectively :

Q 2H /Ni

V

(A) and

V W

(B) and

V W

(C) and

V W

(D) and

V W

16. Compounds formed from P and Q are, respectively :(A) Optically active S and optically active pair (T, U)(B) Optically inactive S and optically inactive pair (T, U)(C) Optically active pair (T, U) and optically active S(D) Optically inactive pair (T, U) and optically inactive S





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PART - B : AIEEE PROBLEMS (PREVIOUS YEARS)

1. End product of the following reaction is – [AIEEE-2002]

CH3CH2COOH

(1) CH CHCOOH3

OH(2) (3) CH2 = CHCOOH (4)

2. In the anion HCOO— the two carbon-oxygen bonds are found to be of equal length. What is the reason for it ?[AIEEE-2003]

(1) The anion HCOO— has two resonating structures

(2) The anion is obtained by removal of a proton from the acid molecule

(3) Electronic orbitals of carbon atom are hybridised

(4) The C=O bond is weaker than the C—O bond

3. Which one of the following does not have sp2 hybridized carbon ? [AIEEE-2004](1) Acetone (2) Acetic acid (3) Acetonitrile (4) Acetamide

4. Consider the acidity of the carboxylic acids : [AIEEE-2004](a) PhCOOH (b) o – NO2C6H4COOH (c) p – NO2C6H4COOH (d) m – NO2C6H4COOHWhich of the following order is correct ?(1) a > b > c > d (2) b > d > c > a (3) b > d > a > c (4) b > c > d > a

5. The compound formed as a result of oxidation of ethyl benzene by KMnO4 is : [AIEEE-2007](1) benzophenone (2) acetophenone (3) benzoic acid (4) benzyl alcohol

6. A liquid was mixed with ethanol and a drop of concentrated H2SO4 was added. A compound with a fruity smell

was formed. The liquid was : [AIEEE-2009]

(1) CH3OH (2) HCHO (3) CH3COCH3 (4) CH3COOH

5

NCERT QUESTIONS

1. Arrange the following compounds in increasing order of their property as indicated :

(i) Acetaldehyde, Acetone, Di-tert-butyl ketone, Methyl tert-butyl ketone (reactivity towards HCN)

(ii) CH3CH

2CH(Br)COOH, CH

3CH(Br)CH

2COOH, (CH

3)2CHCOOH, CH

3CH

2CH

2COOH (acid strength)

(iii) Benzoic acid, 4-Nitrobenzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic acid (acid strength)

2. How will you prepare the following compounds from benzene? You may use any inorganic reagent and any

organic reagent having not more than one carbon atom

(i) Methyl benzoate (ii) m-Nitrobenzoic acid (iii) p-Nitrobenzoic acid

(iv) Phenylacetic acid (v) p-Nitrobenzaldehyde.





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3. How will you bring about the following conversions in not more than two steps?

(i) Propanone to Propene (ii) Benzoic acid to Benzaldehyde

(iii) Ethanol to 3-Hydroxybutanal (iv) Benzene to m-Nitroacetophenone

(v) Benzaldehyde to Benzophenone (vi) Bromobenzene to 1-Phenylethanol

(vii) Benzaldehyde to 3-Phenylpropan-1-ol

(viii) Benazaldehyde to -Hydroxyphenylacetic acid

(ix) Benzoic acid to m- Nitrobenzyl alcohol

4. Complete each synthesis by giving missing starting material, reagent or products.

(ii) (vi)

5. Give plausible explanation for each of the following :

(iii) During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst,

the water or the ester should be removed as soon as it is formed.

6. An organic compound contains 69.77% carbon, 11.63% hydrogen and rest oxygen. The molecular mass of

the compound is 86. It does not reduce Tollens’ reagent but forms an addition compound with sodium

hydrogensulphite and give positive iodoform test. On vigorous oxidation it gives ethanoic and propanoic acid.

Write the possible structure of the compound.

7. Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a

stronger acid than phenol. Why?





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EXERCISE - 1

Qus. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25Ans. B A B B C A A C C B D C D B D A A B D A B D C A CQus. 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50Ans. B D D C C D C D B C A C B D B C B D C B C C C D B

EXERCISE - 2

Qus. 1 2 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25Ans. C B D B A B A B A B C D C B C B B D D D A C C AQus. 26 27 28 29 30 31 32 33 34 35 36 37 38Ans. C A B D A D C D B C D A D

EXERCISE - 3

Q.No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18Ans. C A A A A C D D A A A B B A FALSE TRUE TRUE TRUE

Q.No.Ans.

19A -6-P, B-8-S, C-1-R, D-3-M, E-2-N, F-4-T,G-5-O, H-7-Q

EXERCISE - 4

SECTION-A

Q.No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Ans. A A A B D D C C D D A C D 2 A B

SECTION-B

Q.No. 1 2 3 4 5 6Ans. 3 1 3 2 3 4

contents acid.pdf · distinction between formic acid and acetic acid s. no. hcooh ch 3cooh 1 stable...

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