Question 1
Please propose a plausible mechanism for the following transformation.
Question 2
Propose a plausible mechanism for the following transformation. Include lone pairs and charges in your answer. Do not draw out any hydrogen explicitly in your products. Do not use abbreviations such as Me or Ph.
Question 3
Propose a plausible synthesis for the following transformation:
Answer to question 1
The given reaction is the conversion of (5-(1-hydroxyethylidene) cyclohex-1-enyl) (phenyl)methanone to 1-(3-(hydroxy(phenyl)methylene) cyclohex-1-enyl)ethanone. It can be accomplished by protonating the molecule using H3O+H3O+ . Using this, the carbonyl oxygen is protonated and the transfer of electrons from the adjacent position takes place. Finally, on deprotonation from the alcoholic -OH group produce the product 1-(3-(hydroxy(phenyl)methylene) cyclohex-1-enyl)ethenone. The reaction mechanism is shown below,
Answer to question 2
The given reaction is the conversion of 2-methyl-1-phenylpropan-2-ol to (1-chloro-2-methylpropyl) benzene. In this reaction, 2-methyl-1-phenylpropan-2-ol is protonated using HCl followed by the loss of a molecule of water. Then 1,2-hydride shift takes place. The chloride ion gets attached to the intermediate formed and yields to (1-chloro-2-methylpropyl) benzene.
The reaction is shown below,
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Answer to question 3
In the above example, reaction 1-bromo-2-methylpropane is going through SN1SN1 mechanism due to the presence of weak nucleophile water. Solvolysis of reactant provides energy to form primary carbocation by the heterolytic breaking of C-Br bond.
This primary carbocation rearranges to more stable tertiary carbocation through 1,2 hydride shift. Water molecule attacks as nucleophile on the tertiary carbocation to give the corresponding product 2−methylpropan−2−ol2−methylpropan−2−ol.
The reaction product as follows :
The reaction mechanism as follows :
