Draw the structure of the starting material needed to make 2-methylhept-3-yne using sodium amide in liquid ammonia

3,4-dibromo 2-methylheptane

Explanation:

Alkynes can be synthesized by using sodium amide in liquid ammonia, when the starting material is a vicinal dibromoalkane. This means an alkane in which there's a Br group in two carbons next to one another.

In the attached picture you can see the reaction.

see picture

Explanation:

Although the previous answer may be correct, the question is incomplete, the completed question is:

Draw the structure of the starting material needed to make 2-methylhept-3-yne using sodium amide in liquid ammonia followed by 1-bromopropane.

Now, the previous answer is also incorrect, because the starting material with the two bromine in carbon 3 and 4, the first reaction taking place is the substracting of the hydrogen from carbon 5, and not carbon 3 because it's bulkier than carbon 5. So the majority product formed will be a double bonded product and not a triple bond. Therefore, this answer is incorrect.

Now, that we have completed the question the Starting material would have to be the following:

CH3 - CH(CH3) - C ≡ CH

When this reactant, is in presence of NaNH2, the NH2 substract the Hydrogen from carbon 1, and then, this will attack as nucleophyle to the carbon 1 of the bromopropane and formed the desired product.

The mechanism is as following in the picture.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.