Tag: chemical properties

Questions Related to chemical properties

$PhCOOH\xrightarrow{DIBALH} $ 

  1. $PhCHO$

  2. $PhO$

  3. $PhCH _2OH$

  4. None of these


Correct Option: A
Explanation:

Benzoic acid on reduction with di-isobutyl aluminium hydride (DIBALH) gives benzaldehyde.
$\displaystyle PhCOOH \xrightarrow {DIBALH} PhCHO $
Di-isobutyl aluminium hydride (DIBALH) is a reducing agent. It reduces carboxylic acids to aldehydes.

How  - $COOH$ can be converted into $CH _3$ group?

  1. $\;Na\;&\;alcohol$

  2. $\;Zn+HCl$

  3. $\;LiAlH _4$

  4. $\;Hl\;&\;red\;phosphorous$


Correct Option: D
Explanation:

$-COOH$ can be converted into $CH _3$ group by heating with a mixture of HI and red phosphorus.
$CH _3COOH  \xrightarrow {\;Hl\;&\;red\;phosphorous} CH _3-CH _3$

Which of the following reagents can convert acetic acid into ethanol?

  1. $Sn + HCl$

  2. $H _{2} + Pt$

  3. $LiAlH _{4}+$ Ether

  4. $Na +$ Alcohol


Correct Option: C
Explanation:

$CH _{3}COOH\xrightarrow[]{LiAlH _{4}}C _{2}H _{5}OH$.
$ LiAlH _{4} $ being a strong reducing agent can reduce acids to alcohols.

Which of the following reduces carboxylic acid directly to primary alcohols?

  1. $LiAlH _{4}$

  2. $Na + C _{2}H _{5}OH$

  3. $\text{Lindlar's Catalyst}$

  4. $H _{2}$


Correct Option: A
Explanation:

$LiAlH _{4}$ is a very strong reducing agent. It can reduce acids directly to alcohols.

Which of the following reaction is not the oxidation?

  1. $CH _{3} - CHO \rightarrow CH _{3}COOH$

  2. $C _{2}H _{5}OH \rightarrow CH _{3} - CHO$

  3. $C _{2}H _{5}OH \rightarrow CH _{3} - COOH$

  4. $CH _{3}COOH \rightarrow C _{2}H _{5}OH$


Correct Option: D

$RCOOH \rightarrow  RCH _{2}OH$

This mode of reduction of an acid to alcohol can be effected only by

  1. Zn/HCl

  2. Na - alcohol

  3. Aluminium isopropoxide and isopropyl

    alcohol

  4. LiAlH$ _{4}$


Correct Option: D
Explanation:

D

$CH _{3}COOH \xrightarrow[]{LiAlH _{4}}(A)\xrightarrow[H _{2}]{Ni} B$ In this reaction A and B respectively are :

  1. $CH _{3}OH and CH _{4}$

  2. $C _{2}H _{5}OH and C _{2}H _{6}$

  3. $CH _{3}CHO and C _{2}H _{5} OC _{2}H _{5}$

  4. $C _{2}H _{5}OH and CH _{3}OCH _{3}$


Correct Option: B
Explanation:

B
$LiAlH _{4}$ reduces ethanoic acid to ethanol and then $H _{2}$ / Ni reduces it further to alkane.

The reagent(s) used for converting ethanoic acid to ethanol is/are :

  1. $LiAlH _{4}$

  2. $BH _{3}$ in $THF$

  3. $PCl _{3}$

  4. $K _{2}Cr _{2}O _{7}/H^{+}$


Correct Option: A,B
Explanation:

$BH _3$ in $THF$ being a strong reducing agent, can efficiently convert carboxylic acid into the corresponding primary alcohol. Also, $LiAlH _4$ being a strong reducing agent, releases $H^-$ ions in enough quantity to convert carboxylic acid to the corresponding alcohol. So, ethanoic acid can be converted to ethanol using $BH _3$ in $THF$ and $LiAlH _4$.

Methyl alcohol when reacted with carbon monoxide using cobalt or rhodium as catalyst , compound $'A'$ is formed. $'A'$ on heating with HI in the presence of red phosphorus as catalyst $'B'$ is formed. $'B'$ is:

  1. $CH _3COOH$

  2. $CH _3CHO$

  3. $CH _3CH _2I$

  4. $CH _3CH _3$


Correct Option: D
Explanation:

$CH _3OH+CO\xrightarrow [ (High\quad Pressure) ]{ CO/Rh } \underbrace{ CH _3COOH} _{Compound A}$

Alcohol with carbon monoxide in presence of  $CO/Rh$ gives carboxylic Acid.
$CH _3COOH\quad \underrightarrow{Red P+HI}\quad CH _3-CH _3$
$Red P+HI$  is areducing agent and reduces carboxylic acid into hydrocarbons.

Alcohols can be obtained from carboxylic acids by reduction using one of the following reagents:

  1. $LiAIH _{4}$

  2. $N/alcohol$

  3. $Zn/HCl$

  4. $H _{2}/Ni$


Correct Option: A
Explanation:

$RCOOH  +  LiAlH _4 \rightarrow RCHO  \rightarrow RCH _2OH $

Carboxylic acids along with lithium aluminium hydride, initially gives aldehyde and then reduced to primary alcohols.