Q15E

Question


From what alkyne might each of the following substances have been made? (Green = Cl.)

Step-by-Step Solution

Verified
Answer
  1. The alkyne required to form 4-Methylpentanal is 4-Methylpentyne.
  2. The alkyne required to form 1,1-dichloroethyl-2-methylcyclohexane is 1-Ethyne-2-methylcyclohexane.
1Definition of alkynes

Molecular compounds containing triple bonds are referred to as alkynes

2Draw the structure of compound


Black sphere represent Carbon 

Grey sphere represent Hydrogen atom

Red sphere represent Oxygen atom

By consider above representation the structure of the given compound is drawn.

The IUPAC name of the aldehyde is 4-Methylpentanal.

3Formation of given aldehyde


Synthesis of aldehyde can occur by hydroboration – oxidation of an alkyne. 

There are 5 carbon atoms in the parent chain along with a methyl group substituent at the fourth position. Therefore the alkyne must be 4-Methylpentyne.



4Draw the structure of compound


Black sphere represent Carbon atom

Grey sphere represent Hydrogen atom

Green sphere represent Chlorine atom

By consider above representation the structure of the given compound is drawn.



The IUPAC name of the dihalide is 1,1-dichloroethyl-2-methylcyclohexane.

5Formation of given dihalide.


The addition of two molecules of    to the alkyne can give the desired dihalide.

With the use of 1-ethyne-2-methylcyclohexane, given 1,1-dichloroethyl-2-methylcyclohexane can be formed.