Gamma Question Bank for Engineering Chemistry>Chapter -1 - Aldehydes, Ketones and Carboxylic Acids>EXERCISE>Q 33

EASY

JEE Main/Advanced

IMPORTANT

Earn 100

Phthalic acid is

50% studentsanswered this correctly

Important Points to Remember in Chapter -1 - Aldehydes, Ketones and Carboxylic Acids from Embibe Experts Gamma Question Bank for Engineering Chemistry Solutions

1. Methods of preparation of carbonyl compounds:

Question Image

*only used for preparation of aldehyde $.$

2. Chemical properties of carbonyl compounds:

Question Image

3. Some other important reactions:

(i) Perkin Condensation:

$C_{6} H_{5} C H O + {({C H}_{3} C O)}_{2} O \overset{H_{3} C C O O N a}{\to} C_{6} H_{5} C H = C H - C O O H$

(ii) Beckmann Rearrangement:

The acid catalyzed conversion of ketoximes to $N$ -substituted amides is known as Beckmann rearrangement.

Question Image

(iii) Cannizzaro’s reaction:

This reaction is preferentially given by those aldehydes which do not contain α-hydrogen. In Cannizzaro reaction, one molecule of the aldehyde is oxidized to acid at the expense of the other which is reduced to alcohol i.e., disproportionation reaction takes place. The reaction occurs in the presence of concentrated solution of any base.

${2 H C H O}_{F o r m a l d e h y d e} + N a O H \to {H C O O N a}_{S o d . f o r m a t e} + {{C H}_{3} O H}_{M e t h y l a l c o h o l}$

4. Some important points of carbonyl compounds:

(i) Distinction between formaldehyde, acetaldehyde, and acetone:

S.No.	Reagent/Test	$H C H O$	${C H}_{3} C H O$	${C H}_{3} {C O C H}_{3}$
I.	Brady reagent/DNP	Colored crystal	Colored crystal	$\times$
II.	Tollen's reagent	Silver mirror	Silver mirror	$\times$
III.	Fehling's solution	Red	Red	$\times$
IV.	Benedict’s solution	Red	Red	$\times$
V.	$C o r r o s i v e s u b l i m a t e ({HgCl}_{2})$	Black	Black	$\times$
VI.	Schiff's reagent	Pink	Pink	$\times$
VII.	Iodoform test	$\times$	yellow	Yellow
VIII.	Pyrogallol test	White	$\times$	$\times$
IX.	Legal test $(S o d i u m n i t r o p r u s s i d e / N a O H)$	$\times$	Red	Red
X.	$m - n i t r o b e n z a l d e h y d e t e s t$	$\times$	$\times$	Blue

(ii) Chloral $(C C l_{3} C H O)$ is an important intermediate in the manufacture of chloroform and D.D.T.

(iii) Popoff's rule: Oxidation of unsymmetrical ketones largely take place in such a way that the smaller alkyl group remains attached to the $C O$ group during the formation of two molecules of acids.

Question Image

(iv) Formaldehyde is used in preparation of urotropine (Hexamethylenetetramine), a urinary antiseptic and Bakelite (phenol-formaldehyde resin) polymer, throat lozenges (formalin $+$ lactose).

(v) Formaldehyde is used as disinfectant and preservative for biological specimens in the form of formalin.

5. Methods of preparation of carboxylic acids:

Question Image

6. Chemical properties of carboxylic acids:

Question Image

Heating effect on carboxylic acids

7. Carboxylic acid derivatives:

These are formed by the replacement of $- O H$ group of acid by some other ${s u i t a b l e g r o u p e . g . R C O C l, R C O N H}_{2} {, R C O O R a n d (R C O)}_{2} O .$

(i) Acid halides:

Chemical Properties:

Question Image

(ii) Acid Anhydrides:

$(R C O)_{2} O,$ prepared by dehydration of carboxylic acid.

Chemical Properties:

Question Image

(iii) Esters:

$R C O O R$ prepared by reaction of acid with alcohol or acid chloride or anhydrides with alcohol.

Chemical Properties:

Question Image

(iv) Acid amides:

${R C O N H}_{2} -$ It is prepared by reaction of carboxylic acid or its derivatives with ${N H}_{3}$ . It is amphoteric in nature. Acid amides act as weak acids as well as weak bases. Lone pair of $N$ is delocalized with $π$ electrons of $C = O g r o u p .$

Chemical Properties:

Question Image

Learn and Prepare for any exam you want !

|

|

|

|

|

|

|

|