Mass spectra of halogenated esters 5—Chloromethyl esters of aliphatic C 2 C 12 n ‐carboxylic acids and their monochlorinated derivatives

A study has been made of the mass spectral fragmentation upon electron impact of aliphatic C 2 C 12 chloromethyl esters and all their 66 monochlorinated derivatives. The fragmentation pathways of the parent chloromethyl esters were elucidated with the aid of the 1st FFR metastable ions. A McLafferty rearrangement gives the base peak in the C 6 C 11 parent esters and in almost all the 4‐chloro and ω‐chloro isomers. The subsequent loss of HCl gives a very characteristic peak of the chloromethyl esters and their (3‐ω)‐chloro derivatives at m / z 72, [C 3 H 4 O 2 ] + . The 2‐chloro isomers have the corresponding chlorine‐containing fragment ion at m / z 106/108. The mass spectra of 2‐, 3‐, 4‐, 5‐ and ω‐chloro isomers give the characteristic fragment ions, the mass spectra of the other isomers being very similar.