Question

Choose the correct alkyne which gives alkanal on hydroboration and hydrolysis.
(A)- $C{{H}_{3}}-C\equiv C-C{{H}_{3}}$
(B)- $C{{H}_{3}}-C{{H}_{2}}-CH=CH-C\equiv CH$
(C)- $C{{H}_{3}}-C\equiv CH$
(D)- $C{{H}_{3}}-C{{H}_{2}}-C\equiv C-C{{H}_{3}}$

Answer 1

Hint: Alkanes also known as aldehyde are a class of organic compounds in which a carbon atom shares a double bond with an oxygen atom, a single bond with a hydrogen atom and a single bond with another group of atom or atoms.

Complete answer:
-Let us first understand hydroboration and hydrolysis.
-Hydroboration is the process in which the hydrogen boron bond is added to a double bond between either carbon and carbon or carbon-nitrogen atoms. Hydroboration can also be performed on a carbon-carbon triple bond.
-Hydrolysis is a chemical process in which a molecule of water is added to a substance.
-Let us now consider each option one by one.
-In option A, $C{{H}_{3}}-C\equiv C-C{{H}_{3}}$ is given which is an internal alkyne. This alkyne on hydroboration and hydrolysis gives $C{{H}_{3}}-C{{H}_{2}}-CO-C{{H}_{3}}$.
-In option B, $C{{H}_{3}}-C{{H}_{2}}-CH=CH-C\equiv CH$ is given which is a terminal alkyne. This alkyne on hydroboration and hydrolysis gives $C{{H}_{3}}-C{{H}_{2}}-CH=CH-C{{H}_{2}}CHO$.
-In option C, $C{{H}_{3}}-C\equiv CH$is given which is a terminal alkyne. This alkyne on hydroboration and hydrolysis gives $C{{H}_{3}}-C{{H}_{2}}-CHO$which is an alkanal.
-In option D, $C{{H}_{3}}-C{{H}_{2}}-C\equiv C-C{{H}_{3}}$is given which is an internal alkyne. This alkyne on hydroboration and hydrolysis gives $C{{H}_{3}}-C{{H}_{2}}-CH=CH-C{{H}_{2}}CHO$ .

Hence, the correct answer is option C.
$C{{H}_{3}}-C\equiv CH\xrightarrow[hydrolysis]{hydroboration}C{{H}_{3}}-CH=CHOH\xrightarrow{\text{keto-enol tautomerism}}C{{H}_{3}}-C{{H}_{2}}-CHO$

Note:
-Alkanes are organic molecules which contain only carbon (C), hydrogen (H), and oxygen (O) atoms.
-Alkanes belong to the group of organic compounds known as aldehydes.
-Aldehydes contain a carbonyl function group.
-A straight-chain alkanal consists of a chain of 1 or more carbon atoms joined to each other by single covalent bonds, with a carbonyl functional group attached to the terminal carbon atom in the chain of carbons.