Question Set B

Carbonyl Compounds

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Questions:

Multiple Choice Question

13 x 1 = 13

The order of reactivity of carboxylic acid derivatives is _______.

(a)

Acid chloride > Ester > Amide > Acid anhydride

(b)

Acid chloride > Acid anhydride > Ester > Amide

(c)

Acid chloride > Amide > Acid anhydride > Ester

(d)

Acid anhydride > Ester > Amide > Acid chloride

The product is __________.

(a)

CO+H₂O

(b)

HCOOH

(c)

H₂+CO₂

(d)

HCHO+O₂

The aldehyde derived from vitamin B6 is __________.

(a)

pyridoxal

(b)

pyridoxine

(c)

CH₃CHO

(d)

glyoxal

Aldehydes and ketones are reduced to hydrocarbons by zinc amalgam and cone.HCI. This is__________ reaction.

(a)

Clemmenson's reduction

(b)

Wolff krishner reduction

(c)

Rosenmmunds reduction

(d)

catalytic reduction

6 - 8% solution of acetic acid in water is called __________.

(a)

Vinegar

(b)

Glacial acetic acid

(c)

Formalin

(d)

Both (a) and (b)

Chloroacetic acid is stronger than acetic acid due to _______.

(a)

+ I effect

(b)

- I effect

(c)

+ M effect

(d)

- M effect

Which one of the following gives oxime with hydroxyl amine?

(a)

Benzene

(b)

Phenol

(c)

Benzaldehyde

(d)

Bezoicacid

Which of the following does not give iodoform test?

(a)

aceto phenone

(b)

benzophenone

(c)

\({ CH }_{ 3 }-\underset { \overset { | }{ { CH }_{ 3 } } }{ CHOH } \)

(d)

\({ CH }_{ 3 }-\underset { \overset { | }{ OH } }{ CH } -{ { CH }_{ 2 }{ CH }_{ 2 }-CH }_{ 3 }\)

Methyl ketones are usually characterised by _______.

(a)

the Fehling's solution

(b)

the iodoform test

(c)

the Schiff's test

(d)

the Tollen's reagent

10.

Identify 'X'.

(a)

(b)

(c)

(d)

11.

Of the following, which is the product formed when cyclohexanone undergoes aldol condensation followed by heating?

(a)

(b)

(c)

(d)

12.

Which one of the following reduces tollens reagent

(a)

formic acid

(b)

acetic acid

(c)

benzophenone

(d)

none of these

13.

Reaction of acetone with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is _______.

(a)

Grignard reagent

(b)

Sn / HCl

(c)

hydrazine in presence of slightly acidic solution

(d)

hydrocyanic acid

Assertion and reason

3 x 2 = 6

14.

Assertion: Ethyl benzene and methyl benzene both are oxidised to benzoic acid with acidified KMnO₄.
Reason: The entire side chain of aromatic carboxylic acid is oxidised to COOH irrespective of the length of the side chain.
Codes:
a) (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true but (R) does not explain (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

15.

Assertion: Formic acid reduces Tollens reagent.
Reason: Formic acid contains an aldehyde as well as acid group.
Codes:
a) (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true but (R) does not explain (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

16.

Assertion: p – N, N – dimethyl amino benzaldehyde undergoes benzoin condensation
Reason: The aldehydic (-CHO) group is meta directing.
Codes:
A) if both assertion and reason are true and reason is the correct explanation of assertion.
B) if both assertion and reason are true but reason is not the correct explanation of assertion.
C) assertion is true but reason is false
D) both assertion and reason are false

(a)

if both assertion and reason are true and reason is the correct explanation of assertion.

(b)

if both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

assertion is true but reason is false

(d)

both assertion and reason are false

Generic 5

2 x 5 = 10

17.

Explain why carboxylic acids behave as acids. Discuss briefly the effects of electron withdrawing and donating substituents on acid strength of carboxylic acids.

18.

A Compound (A) with molecular formula C₂H₃N on acid hydrolysis gives (B) which reacts with thionylchloride to give compound(C). Benzene reacts with compound (C) in presence of anhydrous AlCl₃ to give compound(D). Compound (D) on reduction with Zn/Hg and Conc.HCl gives (E). Identify (A), (B), (C) (D) and (E). Write the equations.

Generic 2

3 x 2 = 6

19.

Write any three uses of acetaldehyde.

20.

What type of aldehydes undergo Cannizaro reaction?

21.

How will you convert benzaldehyde into the following compounds?
(i) benzophenone
(ii) benzoic acid
(iii) α-hydroxyphenylaceticacid.

Generic 3

2 x 3 = 6

22.

An organic compound, C₂H₄O gives a red precipitate when warmed with Fehling's solution. It also undergoes aldol condensation in presence of alkali.
(i) Write IUPAC name of the compound.
(ii) Predict the hybridization of carbon atoms in the compound?
(iii) Write equation for the reaction

23.

Complete the following reaction
\({ CH }_{ 3 }-{ CH }_{ 2 }-{ CH }_{ 2 }-\underset { \overset { || }{ O } }{ C } -{ CH }_{ 3 }\overset { HO-{ CH }_{ 2 }-{ CH }_{ 2 }-OH }{ \underset { { dry }{ HCl} }{ \longrightarrow } } ?\)

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Answers Key:

Multiple Choice Question

13 x 1 = 13

(b)
Acid chloride > Acid anhydride > Ester > Amide

(a)
pyridoxal

(a)
Clemmenson's reduction

(a)
Vinegar

(b)
- I effect

(b)
benzophenone

(b)
the iodoform test

10.

11.

12.

13.

Assertion and reason

3 x 2 = 6

14.

a) (A) and (R) are true and (R) is the correct explanation of (A)

15.

a) (A) and (R) are true and (R) is the correct explanation of (A)

16.

B) if both assertion and reason are true but reason is not the correct explanation of assertion.

Generic 5

2 x 5 = 10

17.

Acidic nature of acids:
(i) Acid molecule ionises to produce H⁺ ions in solution.

(ii) The carboxylate anion is stabilised by resonance.

Hence the cleavage of -COOH bond to release H⁺is favoured, thereby making it to behave as acids.
(iii) Any factor that weakens the -COOH bond will facilitate the cleavage to release H⁺ more easily. The degree of ionisation is increased and acid becomes relatively a stronger acid.
(iv) When the following acids are compared
Their strength varies as the above order.
(v) Methyl group is a + I group (electron pair repelling group). Acid strength decreases: with increasing number of electron repelling substituent attached to the α- carbon atom.

The +1 effect is felt in increasing the strength of the -OH bond and the cleavage to form H+ becomes difficult. Hence they are weaker acid than formic acid (HCOOH) which does not have + I methyl group.
(vi) Acid strength increases with increase in electronegativity of substituents

This effect weakness the -O- H bond there by facilitating the removal of H⁺ from -OH group. This acid becomes stronger than formic acid.

18.

Generic 2

3 x 2 = 6

19.

Acetaldehyde is used:
(i) Acetaldehyde is used for silvering of mirrors
(ii) Paraldehyde is used in medicine as a hypnotic.
(iii) Acetaldehyde is used in the commercial preparation of number of organic compounds like acetic acid, ethyl acetate etc.,

20.

Aldehydes that do not have a-hydrogen atom undergo Cannizaro reaction.
Eg: HCHO, C₆H₅CHO.

21.

(ii) benzoic acid

(iii) α - hydroxyphenylaceticacid.

Generic 3

2 x 3 = 6

22.

(i) Ethanal
(ii) sp²
(iii) CH₃CHO + 2Cu₂⁺ + 3OH^-⟶CH₃COO^- + 2Cu⁺ + 2H₂O
\({ CH }_{ 3 }CHO+{ CH }_{ 3 }CHO\overset { NaOH }{ \longrightarrow } { H }_{ 3 }C-\overset { \underset { | }{ H } }{ \underset { \overset { | }{ OH\\ Aldol } }{ C } } -{ CH }_{ 2 }-CHO\)