Question

Use retrosynthetic analysis to suggest a way to synthesize 3-ethyl-3-hexanol using the Grignard reaction. (Click and drag the appropriate images to the reactant positions in the following reaction.)

Answer 1

General guidance

Concepts and reason

Retrosynthetic analysis:

• It is a way of planning an organic synthesis in which it involves transformation of complex target molecule to simple precursor structures.

• The reagent in which it donates electrons and undergoes the formation of a new carbon\u2013carbon bond is known as the Grignard\u2019s reagent.

• The Grignard\u2019s reagent is an organometallic reagent with a formula${\\rm{RMgX}}$. Here, ${\\rm{R}}$represents the alkyl group or aryl group, ${\\rm{Mg}}$represents magnesium, and ${\\rm{X}}$represents halogen.

• In this reagent, ${\\rm{R}}$(alkyl group or aryl group) acts as a nucleophile.

Fundamentals

In ketones, the Grignard\u2019s reaction takes place in two steps:

1)Nucleophilic attack

2)Protonation

Example:

\u043e\u043d R' R' CH3 CH3 protonation H3CMgBr nucleophilic attack on carbonyl carbon

Step-by-step

Step 1 of 2

+CH,CH2CH2MgBr

Explanation | Common mistakes | Hint for next step

In the given reactants, only ketones and Grignard reagents are present. Therefore, only 2 step mechanisms are possible. By counting the carbon atoms present in the product, the reactants and products are selected from the given reactants.

Step 2 of 2

MgBr \u043e\u043d H30 \u0398\u7530 CH3CH2CH2 MgBr

MgBr \u043e\u043d H30 \u0398\u7530 CH3CH2CH2 MgBr

The alkyl group in the Grignard\u2019s reagent attacks the carbonyl carbon on ketone and leaves a negative charge on oxygen. Then, it undergoes protonation with the help of an acid $\\left( {{{\\rm{H}}^{\\rm{ + }}}} \\right)$ and forms alcohol as the product.

Answer

\u043e\u043d H2O+ 3-ethyl-3-hexanol

Answer only

\u043e\u043d H2O+ 3-ethyl-3-hexanol