# Acetic acid reaction sequence

Can anyone tell me where I am doing it wrong for the following reaction?

In the first step, Br should be attached to the alpha carbon.

In second step, the bromide is replaced by cyanide.

I am able to get the third product that is final compound.

• Heating a carboxylic acid often leads to decarboxylation. So decarboxylate your product from step 2 (well actually the product formed following acidification in step 3!) Jul 21, 2016 at 12:26
• @Leeser can you tell me the products formed
– user32086
Jul 21, 2016 at 12:31

Step 1: $\alpha$-bromination $$\ce{CH3-COOH + Br2/P -> Br-CH2-COOH}$$

Step 2: Nucleophilic Substitution by Sodium Cyanide $$\ce{Br-CH2-COOH + NaCN -> NaBr + NC-CH2-COOH}$$

Step 3: Acid-catalyzed Conversion of Nitrile to Amide or Acid

(1) First hydration... $$\ce{NC-CH2-COOH + H2O -> H2N-CO-CH2-COOH}$$ (2) Further heating... $$\ce{H2N-CO-CH2-COOH -> HOOC-CH2-COOH + NH4+}$$

Special Notes

Be VERY CAREFUL with Step 2 as you are potentially forming $\ce{HCN}$ which could get everyone in the lab killed if you're not careful.

• But @sixtytrees has made different products
– user32086
Jul 21, 2016 at 12:41
• @user123733 No, he only went step further with decarboxylation, without any good reason. Jul 21, 2016 at 13:43

There are two possibilities. You will have a two step reaction

NC-CH2COOH -> HOOC-CH2-COOH This is malonic acid. It can be further decarboxylated to

HOOC-CH2-COOH + H$^+$ + heat -> CO2 + CH3COOH

the final product is acetic acid.