Haloform Reaction

[budullewraagh]

i was reading my organic book the other day and i came across the haloform reaction, which intrigued me. for those not familiar, it involves the oxidation of a methyl ketone by a hypohalite to a carboxylic acid, liberating chloroform. in short:

 

R-C(O)CH3+3NaOCl---->R-C(O)CCl3+3NaOH----->R-COO- + Na+ + HCCl3

 

i was wondering if anyone knew of specific conditions for this reaction to occur under, the expected yield and perhaps some other notes that should be made concerning this reaction.

 

also, since acetone is a ketone with two methyl groups coming off from the carbonyl group, does anybody not think that one could do the following?

 

H3C-C(O)CH3+NaOCl---->Na+ -OC(O)O- Na+ + 2HCCl3

 

(pretty much the same reaction as above but the acetone oxidizing on both sides)

[raivo]

I have one organic chemistry book where making chloroform by distilling mix of calcium hypochlorite and acetone is described. It seems to be quite straightforward. They put mix of calcium hypochlorite and water into flask and added acetone by small amounts. Output was 60% or 30g when using 200g of hypochlorite and 25g acetone.

[Guest atarax]

The haloform reaction is just a regular carbonyl alpha-substitution. I believe it is usually done with Iodine, since CHI3 is a solid that precipitates out of solution, driving the reaction.

 

And, I suppose you could use it to make carbonic acid, but it's probably cheaper to just buy it than to make it this way.

[budullewraagh]

i think the point is to make the haloform; the carbonic acid is just a byproduct...

[BenSon]

This is from wiki

"Chloroform was first produced independently and simultaneously in 1831 by Justus von Liebig and the French chemist Eugene Soubeiran, who produced chloroform through the action of chlorine bleach powder (calcium hypochlorite) upon acetone (2-propanone) or ethanol (an application of the generic process known as the haloform reaction)."

So yeah your right it can be produced that way.

 

~Scott

[BenSon]

Alright i was bored so i had a stab at the reaction for ethanol and sodium hypochlorite is this right.

 

CH3CH2OH + NaOCl = CHCL3 + NaCH3COO + (H2O or H2)

 

I dont know much about organic chem but its just a guess (I know its not balanced).

 

~Scott

[budullewraagh]

i can see nucleophilic substitution...

CH3CH2OH+3NaOCl-->CHCl3+NaAc+H2O

[BenSon]

So i was right?!? Wow there's a first time for everything

 

~Scott

[budullewraagh]

congrats