The major product of the following reaction is : $${\rm{C}}{{\rm{H}}_3}{\rm{CH = CHC}}{{\rm{O}}_2}{\rm{CH_3 }}\buildrel {LiAl{H_4}} \over \longrightarrow $$

LiAlH4 reduces esters to alcohols but does not reduce C = C. $${\rm{C}}{{\rm{H}}_3}{\rm{CH = CHC}}{{\rm{O}}_2}{\rm{CH_3 }}\buildrel {LiAl{H_4}} \over \longrightarrow $$ CH3CH = CHCH2OH + CH3OH

Alcohols, Phenols and Ethers — Page 3 | NEET Chemistry

Q21

The general molecular formula, which represents the homologous series of alkanols is

A C n H 2n+2 O

B C n H 2n O 2

C C n H 2n O

D C n H 2n +1 O

Correct Answer

Option A

Solution

General molecular formula of alkanols is C n H 2n+2 O or C n H 2n+1 OH

Q22

The major organic product in the reaction is CH 3

-

O

-

CH(CH 3 ) 2 + HI

\to

products

A CH 3 I + (CH 3 ) 2 CHOH

B CH 3 OH + (CH 3 ) 2 CHI

C ICH 2 OCH(CH 3 ) 2

D

Correct Answer

Option A

Solution

In case of unsymmetric ethers when treated with HI then I – attaches to smaller and less complex alkyl group as it follows S N 2 mechanism CH 3 $-$ O $-$ CH(CH 3 ) 2 + HI $\to$ CH 3 I + (CH 3 ) 2 CHOH

Q23

Which one of the following compounds is most acidic?

A Cl

-

CH 2

-

CH 2

-

OH

B

C

D

Correct Answer

Option C

Solution

Phenols are more acidic than alcohols as they are resonance stabilised whereas alcohols are not.

Further –NO 2 is an electron withdrawing group which increases acidic character and facilitates release of proton, whereas –CH 3 is an electron donating group which decreases acidic character, thus removal of H + becomes difficult.

Q24

Which one of the following will not form a yellow precipitate on heating with an alkaline solution of iodine?

A CH 3 CH(OH)CH 3

B CH 3 CH 2 CH(OH)CH 3

C CH 3 OH

D CH 3 CH 2 OH

Correct Answer

Option C

Solution

Formation of a yellow precipitate on heating a compound with an alkaline solution of iodine is known as iodoform reaction.

Methyl alcohol does not respond to this test.

Iodoform test is exhibited by ethyl alcohol, acetaldehyde, acetone, methyl ketones and those alcohols which possess CH 3 CH(OH) – group.

Q25

n-propyl alcohol and isopropyl alcohol can be chemically distinguished by which reagent

A PCl 5

B reduction

C oxidation with potassium dichromate

D ozonolysis.

Correct Answer

Option C

Solution

n-propyl alcohol on oxidation with K 2 Cr 2 O 7 gives an aldehyde which on further oxidation gives an acid.

Isopropyl alcohol on oxidation gives a ketone with the same number of carbon atoms as original alcohol.

Q26

Which of the following is correct?

A On reduction, any aldehyde gives secondary alcohol.

B Reaction of vegetable oil with H 2 SO 4 gives glycerine

C Alcoholic iodine with NaOH gives iodoform.

D Sucrose on reaction with NaCl gives invert sugar.

Correct Answer

Option C

Solution

C 2 H 5 OH + 4I 2 + NaOH $\to$ CHI 3 + NaI + HCOONa + H 2 O Iodoform is a pale yellow solid which crystallises in hexagonal plates.

Q27

Match with $$ value)

List - I		List - II
(A)	Ethanol	(I)	10.0
(B)	Phenol	(II)	15.9
(C)	m-Nitrophenol	(III)	7.1
(D)	p-Nitrophenol	(IV)	8.3

A A-I, B-II, C-III, D-IV

B A-IV, B-I, C-II, D-III

C A-II, B-I, C-IV, D-III

D A-III, B-IV, C-I, D-II

Correct Answer

Option C

Solution

\begin{aligned} & \text{ Ethanol } \rightarrow 15.9 \\ & \text{ Phenol } \rightarrow 10 \\ & \text{ M-Nitrophenol } \rightarrow 8.3 \\ & \text{ P-Nitrophenol } \rightarrow 7.1 \end{aligned}

Q28

The major product of the following reaction is :

{\rm{C}}{{\rm{H}}_3}{\rm{CH = CHC}}{{\rm{O}}_2}{\rm{CH_3 }}\overset{{LiAl{H_4}}}\longrightarrow

A CH3CH2CH2CHO

B CH3CH2CH2CO2CH3

C CH3CH = CHCH2OH

D CH3CH2CH2CH2OH

Correct Answer

Option C

Solution

LiAlH4 reduces esters to alcohols but does not reduce C = C.

{\rm{C}}{{\rm{H}}_3}{\rm{CH = CHC}}{{\rm{O}}_2}{\rm{CH_3 }}\overset{{LiAl{H_4}}}\longrightarrow

CH3CH = CHCH2OH + CH3OH

Q29

During dehydration of alcohols to alkenes by heating with conc. H2SO4 the initiation step is

A formation of carbocation

B elimination of water

C formation of an ester

D protonation of alcohol molecule

Correct Answer

Option D

Solution

The dehydration of alcohol to form alkene occurs in following three step. Step

(1)

is initiation step.

Q30

Given below are two statements : Statement (I) : p-nitrophenol is more acidic than m-nitrophenol and o-nitrophenol. Statement (II) : Ethanol will give immediate turbidity with Lucas reagent. In the light of the above statements, choose the correct answer from the options given below :

A Statement I is true but Statement II is false

B Both Statement I and Statement II are true

C Both Statement I and Statement II are false

D Statement I is false but Statement II is true

Correct Answer

Option A

Solution

Acidic strength Ethanol give lucas test after long time Statement (I) $\rightarrow$ correct Statement (II) $\rightarrow$ incorrect