[NewtoAtoms]

Which of the following reactions would not give an acceptable yield of the desired carboxylic acid?

Now I have done the leg work for this but am STUCK between #2 and #3 let me explain my reasoning:

1.  This would give an acceptable yield of the desired carboxylic acid.
2.  This would not give an acceptable yield because it is a tertiary carbon, and the preparation and hydrolysis of nitriles DO NOT work with aryl halides because they don't react with nucleophiles. 
3.  I think this also wouldn't give an acceptable yield because this reaction, is for the 'OXIDATION OF ALDEHYDES' but yet in the picture there is no aldehyde. 

Therefore I am stuck and would deeply appreciate some assistance.

My only options are:

a. 1 only -  NO
b. 2 only - MAYBE
c. 3 only - MAYBE
d. All would give an acceptable yield. - NO

[macman104]

For option 2, you mention part of your reasoning is because aryl halides do not work because there is no substution, but that is not an aryl halide you are working with.  Are you saying that since the tertiary carbon cannot undergo substitution, then just like an aryl halide it won't work?  What about Sn1 substitution?

[NewtoAtoms]

Hello macman104,

Yes please pardon me, I meant to say that tertiary carbons can't undergo substitution instead of 'aryl halide'..

Now having reviewed what you said I went back and looked at the 'synthesis of carboylic acids by the preparation and hydrolysis of nitriles' to learn that the reaction is of the S_N2 type and works best with primary and secondary alkyl halides.  It goes on to specifically state that elimination is the only reaction observed with tertiary alkyl halides. So I am torn....  because I just assumed that no substitution was possible in that situation. 

However if substitution were possible in a tertiary carbon via SN1 then this would be possible MAKING 3 not possible due to the lack of the aldehyde. 

However could you clarify if S_N1 would be possible here, I am feeling a bit lost

I am very grateful for your time and explanations!!

Newtoatoms

[macman104]

Partially correct, and I was only half-correct.  You can effect an S_N1 by using AgCN and diethyl ether, but then we get the N substitution (and form an isonitrile).

So!  My next thought was that you can chew off any alkyl groups on a benzene ring (and leave a carboxylic acid) using strong oxidizing conditions, but I have never seen it with K2Cr2O7, always with KMnO4 and strong base.

Which leaves me at a sort of "i dunno" phase, lol.

[NewtoAtoms]

Ha Ha Ha Ha... that's so funny macman! 

I was totally agreeing with what you were saying as I read, and when I came to the 'I dunno' part I had to laugh... because I really dunno either. 

Thank you for your help and I will take what you said and continue researching.

Have a great night!

[russellm72]

ok 1 would as I have done this many time with [14C] CO2.

2 looks a bit ropey

3 looks fine to me in principle.

I'd go with 1 and 3....

R.