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Aldehydes, Ketones and Carboxylic Acids

Multiple Choice Questions

Benzaldehyde on refluxing with aqueous alcoholic KCN produce

cyanobenzene
cyanohydrin
benzoyl cyanide
benzoin

benzoin

Key Idea: Benzaldehyde on reaction with ale KCN undergo condensation reaction to give benzoin.

$2 C_{6} H_{5} CHO \overset{KCN (alc)}{\to} \underset{Benzoin}{C_{6} H_{5} - CHOH - CO - C_{6} H_{5}}$

Reaction of cyclohexanone with dimethylamine in the presence of catalytic amount of an acid forms a compound if water during the reaction is continuously removed. The compound formed is generally known as

a Schiff’s base
an enamine
an imine
an imine

an enamine

231 Views

The increasing order of the rate of HCN addition to compounds A – D is
(A) HCHO
(B) CH3COCH3
(C) PhCOCH3
(D) PhCOPh

A < B < C < D
D < B < C < A
D < C < B < A
D < C < B < A

D < C < B < A

244 Views

Identify the wrong statement.

Salicylic acid is a monobasic acid
Methyl salicylate is an ester
Salicylic acid gives violet colour with neutral ferric chloride as well as brisk effervescence with sodium bicarbonate
Methyl salicylate does not occur in mineral oils

Methyl salicylate does not occur in mineral oils

Methyl salicylate (oil of wintergreen or wintergreen oil) is an organic ester naturally produced by many species of plants, particularly wintergreens. The compound was first extracted and isolated from plant species Gaultheria procumbens in 1843. It can be manufactured synthetically and it used as a fragrance, in foods, beverages, and liniments. It forms a colorless to yellow or reddish liquid and exhibits a characteristic odor and taste of wintergreen. For acute joint and muscular pain, methyl salicylate is used as a rubefacient and analgesic in deep heating liniments. It is used as a flavoring agent in chewing gums and mints in small concentrations and added as antiseptic in mouthwash solutions.

Among the following the one that gives positive iodoform test upon reaction with I₂ and NaOH is

CH₃CH₂CH(OH)CH₂CH₃
C₆H₅CH₂CH₂OH

448 Views

The number of mesa forms in the following compound is

$HOOC \cdot CH ({CH}_{3}) \cdot CH (OH) \cdot CHCl \cdot CH (OH) CH ({CH}_{3}) \cdot COOH$

Number of mesa structures in compound having odd number of chiral carbon atoms and symmetrical molecule = $2^{(\frac{n}{2} - \frac{1}{2})}$

Given, n = 2

$∴ Number of meso forms = 2^{5 / 2 - 1 / 2} = 2^{2} = 4$

The best reagent to convert pent -3- en-2-ol into pent -3-en-2-one is

Acidic permanganate
Acidic dichromate
Chromic anhydride in glacial acetic acid
Chromic anhydride in glacial acetic acid

Chromic anhydride in glacial acetic acid

472 Views

The compound 'C' in the following reaction is

$C_{7} H_{8} \overset{3 {Cl}_{2} / ∆}{\to} A \overset{{Br}_{2} / Fe}{\to} B \overset{Zn / HCl}{\to} C$

o-bromotoluene
m-bromotoluene
p-bromotoluene
3-bromo-2, 4, 6-trichlorotoluene

m-bromotoluene

Key Idea: Side chain hydrogen atoms are substituted in presence of light or heat. Ring hydrogens are substituted in presence of Lewis acid.

p-cresol reacts with chloroform in the alkaline medium to give the compound A which adds hydrogen cyanide to form, the compound B. The latter on acidic hydrolysis gives chiral carboxylic acid. The structure of the carboxylic acid is