The Grob fragmentation of N-halo-alpha-amino acids in aqueous solution
has been studied, being first order in N-halo-alpha-amino acid and pH
-independent. The substituents on the C-2 and N atoms strongly affect
the reaction rate. Structure reactivity correlations for C-2 substitue
nts provide rho values of -3.9 and -4.1 for N-Cl and N-Br compounds,
respectively. The same correlations for N substituents lead to rho va
lues of -2.1 and -1.9 for N-Cl and N-Br compounds. The transition stat
e (TS) can be generally described as product-like, its structure and c
haracteristics being significantly affected by the substituents on the
C-2 and an the N atoms. In conclusion, the reaction is a DEDN concert
ed and slightly nonsynchronous two-stage process.