[GamerTheRock]

The problem is a tree diagram of the following molecule, what will the molecule change to with each regent. i also have pictures of the problem . i have done the synthesis but part C does the aldehyde open back up or not and the secondary alcohol would it change to a ketone ?


The starting molecule is : 4-bromobutanal

A) Ethylene Glycol/ HA
B)Mg, Et20
C) 1) CH3CHO 2) H+
D)CH3OH / H+

[discodermolide]

The problem is a tree diagram of the following molecule, what will the molecule change to with each regent. i also have pictures of the problem . i have done the synthesis but part C does the aldehyde open back up or not and the secondary alcohol would it change to a ketone ?


The starting molecule is : 4-bromobutanal

A) Ethylene Glycol/ HA
B)Mg, Et20
C) 1) CH3CHO 2) H+
D)CH3OH / H+

What do you mean "does the aldehyde open up"?
There is no oxidising agent anywhere I can see so how can you form a ketone?
By the way the pictures are not much of a help, half the information is missing and they are difficult to make out.

[GamerTheRock]

What I mean to say is that under ethylene glycol is a protecting group with protects the aldehyde then mgbr (ginyard) is formed and when that is reacted with ch3cho it should make an 2 alchol. I don't understand with that job of h+/ h20 is after this attack. And then last reagent attach the product with ch3oh / h+ would that make an acetal at the carbonyl.

[discodermolide]

The acid added after the Grignard reaction is for the work up of the reaction, nothing else.

[Dan]

It is hard to tell what was intended because "H⁺, H₂O" are very vague conditions, .

It could be a simple protic workup, or it could be acetal hydrolysis. Unless there is a multiple choice answer for compound III you can't be sure.

Compound IV will be the same regardless of whether the acetal hydrolyses.

[GamerTheRock]

these are the multiple choices i have figured out that compound C has to be choice C and the H+/h20 are just part of the reagents but i don't understand how does compound D turn into a cyclic molecule and what would be the best choice. please help

[Dan]

these are the multiple choices i have figured out that compound C has to be choice C

Compound III is C, agreed.

i don't understand how does compound D turn into a cyclic molecule and what would be the best choice. please help

You mean how is compound III turned into a cyclic molecule IV?

Look up acetal formation, and bear in mind that it is reversible under acidic conditions. Sugars may give you some inspiration..