[mjb5676]

I am not the best when it comes to explaining a electron-pushing mechanism, so any criticism or corrections would be appreciated.



In the first step, the nitrite ion, which lost the sodium due to it being aqueous in water, undergoes protonation on the single bonded oxygen. This is due to the acidic conditions. The oxygen is protonated again creating a positively charged oxygen on the nitrite ion.  Dehydration occurs, turning the nitrite ion into a nitrosonium ion. Next, the lone pair of electrons on the primary amine of phenylalanine attacks the nitrosonium ion. This causes the electrons to shift, breaking a bond and making the positively charges oxygen neutral. Water then deprotonates one hydrogen on the positively charged, primary amine. The hydronium ion protonates the oxygen attached to nitrogen. The lone pair of electrons on the now secondary amine attacks the nitrogen, which breaks a bond with the positively charged oxygen, creating a neutral charge oxygen and positively charged secondary amine. The secondary amine is deprotonated again neutralizing the nitrogen. Oxygen is again protonated by a hydronium ion creating a positively charged oxygen. This leads to the lone pair of the nitrogen coming down and attacking the other nitrogen, causing dehydration to occur. The alcohol oxygen’s lone pair of electron then attach the carbon kicking out the nitrogen bond in the form of N2 gas. The carbon is then hydrated, breaking the oxygen’s bond. The final step is deprotonating the oxygen forming an alcohol.

[orgopete]

Its pretty good and I presume it gets you there. However, is neighboring group chemistry being discussed with this problem? If so, then you may need to use the carboxyl group.