Huckel's rule states that an aromatic compound must have delocalized electrons. The electrons in each double bond are delocalized for this molecule. There are nine double bonds, and thus eighteen delocalized electrons.

If 4n+2=18, then n=4.

2-butone is a carbonyl compound that can readily be reduced by into a secondary alcohol, 2-butanol. When 2-butanol is heated in acid, we get dehydration, which leads to 2-butene.

This is an addition reaction with 3 products. The unknown reactant reacts with and gives those three products. Addition reactions begin with double bonded compounds and so these electrons are used to react with some reagent . One needs to work backwards to figure out how something was formed and in this case, there are mechanistic pathways, and one of the pathways involves a hydride shift. These 3 products often exist in different concentrations after the reaction.

Below is the mechanism for the reaction given to form the alkene:

The reason this is the major product is because on tertiary alcohols are best dehydrated based on the E1 mechanism below:

Metallic sodium in liquid ammonia creates solvated electrons which can convert an alkyne to an E alkene. The same will not happen when sodium is combined with water, where sodium reacts violently to create sodium hydroxide and hydrogen gas. Lindlar's catalyst is a poisoned catalyst used to form alkenes from alkynes, bud results in a Z conformation. Without the poisoned catalyst, an alkane will be formed.

The reason this is the major product is because tertiary alcohols are best dehydrated based on the E1 mechanism below:

Two sets of reagents are required to convert butanone into 2-butene. First, we use to reduce the butanone into a 2-butanol. Second, we use heat and acid to dehydrate the butanol and yield the final desired product.

1. ; 2. Heat/ may seem like an acceptable answer choice. However, note that the Grignard reagent converts the butanone into a tertiary alcohol, rather than a secondary alcohol as needed.

You must begin counting the carbons so that the first functional substituent has the lowest possible number. In this case, C1 is connected to C2 by the double bond, meaning we start counting from the left.

The longest carbon chain is seven carbons so the parent molecule is heptane. With this numbering, there are methyl groups on carbons 3 and 6 and a chlorine on carbon 5.

Substituents are named in alphabetical order and two double bonds result in a diene. Thus, the correct answer is 5-chloro-3,6-dimethyl-1,5-heptadiene.