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Primary alcohol

for this the answer is B but makes no sense. surely it’s A as u get the C bonded to two Hs making a primary alcholol

https://share.icloud.com/photos/04j_vw-kMy1XkDcLTRH2r6W8A

Reply 1

CriticalMuppet

I'm a little rusty on this but the answer B makes sense to me - wouldn't reducing A form a secondary alcohol rather than a primary alcohol as cyclohexanone is a ketone? Please do correct me if I'm wrong though, I haven't been over this in ages!

Reply 2

Claisen

A will give a secondary alcohol. A primary alcohol must mean the OH is terminal. If it is C-(OH)-C then it is secondary.

Reply 3

Pigster

Original post by Joey6272

for this the answer is B but makes no sense. surely it’s A as u get the C bonded to two Hs making a primary alcholol

https://share.icloud.com/photos/04j_vw-kMy1XkDcLTRH2r6W8A

Reducing A (cyclohexanone) would form cyclohexanol. Draw that out and tell me how many H's are attached to the C with the hydroxyl group.

Reducing B (cyclohexylmethanoic acid) would form cyclohexylmethanol. Draw that one out too.

Reply 4

Joey6272

Original post by Claisen

A will give a secondary alcohol. A primary alcohol must mean the OH is terminal. If it is C-(OH)-C then it is secondary.

i don’t get this mechanism for B. normally if u reduce that carboxylic acid wouldn’t u change that double bond O to a Oh so there’s two Oh groups.

Reply 5

Joey6272

Original post by Pigster

i don’t get this mechanism for B. normally if u reduce that carboxylic acid wouldn’t u change that double bond O to a Oh so there’s two Oh groups.

Reply 6

Claisen

Original post by Joey6272

i don’t get this mechanism for B. normally if u reduce that carboxylic acid wouldn’t u change that double bond O to a Oh so there’s two Oh groups.

No, not to my knowledge. Google the mechanism (alcohol reduction to acid with LiAlBH4) and you will see what happens. You can use BH3 to isolate the intermediate reactive aldehyde and treat this to give a dialcohol. In reality, with this strong reducing agent, it goes straight to a primary alcohol.