When Grignard reagent is added to - unsaturated ketone - is 1-4-addition product obtained as major product

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Standard XII

Chemistry

Elimination Reactions of Alkyl Halides

When Grignard...

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When Grignard reagent is added to α,β- unsaturated ketone , is 1,4-addition product obtained as major product

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Q. When Grignard reagent reacts with ketone, it yields:

Q. Michael addition is conjugate addition i.e.,

1 - 4

addition. The substrates of the reaction that are involved are the compounds like

α, β -

unsaturated carbonyl compounds, esters, cyanides, quinones and

α, β -

unsaturated nitro compounds. The reagent must have at least one acidic hydrogen and must be converted into electrophile in the presence of bases like

O H, O R

, secondary amine etc.
In the following reaction, the product formed is:

C H_{2} = C H - O | | C - C H_{3} + C H_{3} - C H_{2} - N O_{2} [(C H_{3})_{2} C H]_{2} N H - --------- \to C H C l_{3}

Q. Which of these methods would serve to prepare 1-Phenyl-2-propanol?

\begin{matrix} a. & Addition of benzyl Grignard reagent to acetaldehyde (ethanal), followed by hydrolysis. b. & Addition of phenyl lithium to propylene oxide (methyloxirane), followed by hydrolysis. c. & Addition of phenyl Grignard reagent to acetone (2- propanone) followed by hydrolysis. d. & Acid- catalysed hydration (addition of water to) of 2-Phenyl-1- propene. e. & Addition of methyl Grignard reagent to acetophenone (methyl phenyl ketone), followed by hydrolysis. f. & Addition of methyl Grignard reagent to phenylacetaldehyde, followed by hydrolysis. \end{matrix}

Q. The addition reaction of enol or enolate to the carbonyl function of aldehyde or ketone is known as aldol addition. The

β - hydroxyaldehyde

β - hydroxyketone

so obtained undergo dehydration in second step to produce a conjugated enone. The first part of reaction is an addition reaction and the second part is an elimination reaction. Find out major product of following reaction.

When hot concentrated potassium hydroxide is added to lead, potassium oxide is obtained as the major product and hydrogen gas is liberated in the process.

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