Hi all, I'm new here. I needed some help with my organic homework, and I stumbled across your forums. Here are my questions. I appreciate any help! Thanks!

 

a) propyne to 2-hexyne using propyne as the only carbon source

b) butane to (2E,5E)-2,5-heptadiene, again with propyne as the carbon source

c) propane to butanal (yes, that "a" is right. it's not butanol). Ethyne as an additional carbon source

d)propane to a racemic mixture containing (2R,3S)-hexanediol (propane is only carbon source)

Have you tried working out any of these synthesis problems on your own yet? If so, please show us what effort you have tried putting into solving these questions

I believe I have solved problem a. (see solution below)

 

Also on c, I have made some headway. I have found a mechanism to go from propane to butanal using CO. However, my carbon source must be ethyne. For b) and d) however I am at a complete loss as to how to proceed.

 

a) propyne + H2/lindlar catalyst ----> CH3CH=CH2

CH3CH=CH2 + Hg(OAc)2, H2O / NaBH4 ---> CH3CH2CH2OH

CH3CH2CH2OH +SOCl2 ---> CH3CH2CH2Cl

 

Separately,

 

propyne + LDA (lithium diisopropyl amide) ----> CH3CCLi

 

Now add the two together:

 

CH3CC- + CH3CH2CH2Cl ----> 2-hexyne (substitution rxn)

Ok...in part a), I was wrong. Hydroboration instead of oxymercuration.

 

In part b) I have got all the way to heptane, but I'm not sure how to get to 2,5 heptadiene.

 

In part c) I have to add propane (3C's) with ethyne (2C's) and get butanal (4C's). I have no idea how to break the ethyne in half....or even if that's how to do it.

 

In part d) Propane + propane gives me hexane....but then I'm not sure how to go to an internal diol.