Single Choice

What sequence of steps represents the best synthesis of 4-heptanol $${ \left( { CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 } \right) }_{ 2 }CHOH $$?

A$${ CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 }MgBr$$ (2 moles) + formaldehyde ($${H}_{2}C=O$$) in diethyl ether followed by $${H}_{3}{O}^{+}$$
B$${ CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 }MgBr$$ + butanal ($${ CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 }CH=O$$) in diethyl ether followed by $${H}_{3}{O}^{+}$$
Correct Answer
C$${ CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 }MgBr$$ + acetone$$ [{({CH}_{3})}_{2}C=O$$) in diethyl ether followed by $${H}_{3}{O}^{+}$$
D$${ \left( { CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 } \right) }_{ 2 } CHMgBr$$ + formaldehyde ($${H}_{2}C=O$$) in diethyl ether followed by $${H}_{3}{O}^{+}$$

Solution

$$O$$
(A) $$CH_3CH_2CH_2MgBr+H\overset {||}{C}H \longrightarrow \underset {\downarrow H_3O^+}{CH_3CH_2CH_2CH_2OMgBr}$$
$$CH_3CH_2CH_3+CH_3CH_2CH_2CH_2OH \xrightarrow [(ii) H^+]{(i)CH_3CH_2CH_2MgBr} CH_3CH_2CH_2CH_2OH$$
[Acid base reaction]

(B) $$CH_3CH_2CH_2MgBr \xrightarrow [(ii) H_3O^+]{(i) CH_3CH_2CH_2CHO} CH_3CH_2CH_2-\underset {|}{CH}-OH$$
$$\underset {4-heptanol}{CH_3CH_2CH_2}$$
$$O$$ $$CH_3$$
(C) $$CH_3CH_2CH_2MgBr \xrightarrow [(ii) H_3O^+]{(i) H_3C\overset {||}{C}CH_3} CH_3CH_2CH_2-\underset {|}{\overset {|}{C}}-OH$$
$$\underset {2-Methyl-2-pentanol}{CH_3}$$

(D) $$(CH_3CH_2CH_2)_2CHMgBr \xrightarrow [(ii) H_3O^+]{(i) CH_2=O} CH_3-CH_2-CH_2-\underset {|}{C}-CH-CH_2OH$$
$$H_3CH_2CCH_2$$
Therefore the reaction B only gives our desired product $$4-heptanol$$. All the reactions involve treatment of Grignard reagent with carbonyl compounds giving alcohol after hydrolysis.

SIMILAR QUESTIONS

Physical World

Which one of the following reagents reacts with both acetaldehyde and acetone?

Physical World

The reaction of $${Me}_{3}C{Mg}Cl$$ and $${ Me }_{ 3 }C-\overset { O\\ \parallel }{ C } -C{ Me }_{ 3 }$$ after hydrolysis gives a gas $$(A)$$ and a $${2}^{o}$$ alcohol $$(B)$$ rather than the expected tri-t-butyl carbinol. Provide the structures of $$(A)$$ and $$(B)$$ with explanation.

Physical World

Acetone on addition to methyl magnesium bromide forms a complex, which on decomposition with acid gives $$X$$ and $$Mg\left(OH\right)Br$$. Which one of the following is $$X$$?

Physical World

Upon reaction with $$CH_3MgBr$$ followed by protonation, the compound that produces ethanol is:

Physical World

$$CH_{3}CH_{2}-\underset{\underset{Ph}{|}}{\overset{\overset{OH}{|}}{C}} - CH_{3}$$ cannot be prepared by:

Physical World

The aldehydes which will not form Grignard product with one equivalent Grignard reagents are:

Physical World

The correct sequences of reagents for the following conversation will be:

Physical World

Reaction between acetone and methylmagnesium chloride followed by hydrolysis will give :

Physical World

Considering all possible isomeric ketones, including stereoisomers of a compound having a molecular weight of $$100$$. All these isomers are independently reacted with NaBH$$_4$$. The total number of ketones that give a racemic product(s) is/are: [Note: stereoisomers are also reacted separately]

Physical World

Which among the following compounds will give a secondary alcohol on reacting with Grignard reagent followed by acid hydrolysis? I. $$HCHO$$ II. $$C_{2}H_{5}CHO$$ III. $$CH_{3}COCH_{3}$$ IV. $$RCOOC_{2}H_{5}$$ the correct option is:

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