Question

In each reaction box, place the best reagent and conditions from the list below. In each reaction box, place the best reagent and conditions from the list below. In each reaction box, place the best reagent and conditions from the list below. Your reagent for the first step is incorrect. This reaction involved a double elimination of HBr to form an alkyne. Which reagent is a strong base capable of carrying out this reaction ?

Answer 1

Concepts and reason

One or more substances that react together to form a product is called chemical reaction. Most chemical reactions undergo with the help of reagents. Reagents are the substances used to transform one form of substance to other. The reaction undergoes series of steps like deprotonation of alkyne, substitution and addition reactions to attain a final product.

Fundamentals

The reagents play a vital role in a reaction. Each reagent plays a different role in the chemical reaction.

Deprotonation of alkynes: Alkyne undergoes deprotonation with the help of a reagent sodium amide. Acetylide ion is formed when sodium amide reacts with alkyne. Acetylide ion acts as a good nucleophile and undergoes substitution reaction with alkyl halides to form a new carbon chain.

Substitution: The nucleophilic substitution reactiontakes place when a nucleophile reacts with alkyl halides.

Addition of halogens: The bond in alkyne act as a nucleophile and reacts with halogen to form haloalkene as product.

Addition of hydro halogen: Alkynes react with hydrogen halide and form halogenated alkene. It further reacts with hydrogen halide and form halogenated alkane as product. The addition of hydrogen and halogen to alkene follows Markonikov’s addition.

Markonikov’s addition: In the addition of hydrogen halide to alkene or alkyne, the hydrogen in hydrogen halide will form a bond with carbon atom that contains more hydrogen atoms in the starting alkene or alkyne, while halogen will attach to more carbon substituted end.

The given reaction was written as follows

Mechanism:

The given reaction was written as follows

Mechanism:

The given reaction was written as follows

Mechanism:

Ans:

Best reagent and conditions for the given reaction is mentioned below:

Best reagent and conditions for the given reaction is mentioned below:

Best reagent and conditions for the given reaction is mentioned below: