Tag: chemical properties

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Questions Related to chemical properties

Multiple choice chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

Which optically active compound on reduction with $\displaystyle LiAlH _{4}$ will give optically inactive compound?

  1. $CH _3-CH(OCH _3)-COOH$
  2. $CH _3-CH _2-CH(OH)-COOH$
  3. $CH _3-CH _2-CH(CH _2OH)-COOH$
  4. $CH _3-CH(OH)-CH _2-COOH$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Reduction of CH3-CH2-CH(CH2OH)-COOH with LiAlH4 yields CH3-CH2-CH(CH2OH)-CH2OH. This molecule has a chiral center at the carbon attached to the ethyl group, but the two CH2OH groups are not identical in a way that would make it achiral. Wait, actually, the reduction of the carboxylic acid to a primary alcohol creates a molecule where the two groups attached to the chiral center might become identical. Let's re-evaluate: CH3-CH2-CH(CH2OH)-COOH reduces to CH3-CH2-CH(CH2OH)-CH2OH. The chiral carbon is attached to H, ethyl, CH2OH, and CH2OH. Since two groups (CH2OH) are identical, it becomes achiral.

Multiple choice chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

The organic product formed in the reaction. $C _{6}H _{5}COOH \xrightarrow[(II)H _{3}O]{(I)LiAIH _{4}}$?

  1. $C _{6}H _{5}CH _{2}OH$
  2. $C _{6}H _{5}OHCH _{4}$
  3. $C _{6}H _{5}CH _{3} and CH _{3} OH$
  4. $C _{6}H _{5}CH _{3} and CH _{4} $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

using LAH (lithium aluminium hydride), the COOH group is reduced to  $ CH _{2} OH$  group

Multiple choice chemistry alcohols, esters and carboxylic acids reduction of carboxylic acids chemical properties chemical properties of carboxylic acids

Consider the following reaction $CH _3-(CH _2) _{14}-COOH \overset{LiAlH _4}{\longrightarrow} \,X \overset{HCl}{\longrightarrow}$
Palmitic acid
$ Y \overset{1.\, Mg/Et _2O}{\underset{2.\, Oxirane}{\longrightarrow}} Z \overset{KMnO _4}{\longrightarrow} W$
The correct identity of the compounds is/are :

  1. $X \,is \,CH _3-(CH _2) _{14}-CH _2OH$
  2. $Y\, is \, CH _3-(CH _2) _{14}-CH _2Cl$
  3. $Z \,is\, CH _3-(CH _2) _{16}-CH _2OH$
  4. $W \, is\, CH _3-(CH _2) _{16}-CHO$
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Reaction:
$CH _3-(CH _2) _{14}-COOH \overset{LiAlH _4}{\longrightarrow} \,CH _3-(CH _2) _{14}-CH _2OH \overset{HCl}{\longrightarrow} CH _3-(CH _2) _{14}-CH _2Cl$
$ CH _3-(CH _2) _{14}-CH _2Cl \overset{1.\, Mg/Et _2O}{\underset{2.\, Oxirane}{\longrightarrow}} CH _3-(CH _2) _{16}-CH _2OH \overset{KMnO _4}{\longrightarrow} CH _3-(CH _2) _{16}-COOH$