E-Benzoyllysine

A) dl-t-Benzoyllysine.—A solution of 180 g. (0.57 mole) of e-benzoylamino-a-bromocaproic acid (p. 18) in 2 1. of aqueous ammonia (sp. gr. 0.9) is filtered into a 5-I. flask and allowed to stand for two days. The crystals formed at the end of this time are filtered (Note 1) and the filtrate evaporated on a steam bath at reduced pressure to about 1 1. The crystals are filtered, combined with the first crop, and washed with 100 cc. of alcohol and finally with 100 cc. of ether. The aqueous filtrate is evaporated under reduced pressure to dryness and the residue washed with two 100-cc. portions of water to remove the ammonium bromide, and then with 50 cc. of alcohol followed by 50 cc. of ether. The total yield of e-benzoyllysine, melting at 265-270°, is 100-116 g. (70-81 per cent of the calculated amount). 

Changes in charge, e.g., due to proton dissociation from nearby groups, can affect the absorption spectrum of a chromophore as already discussed. Such effects are shown as difference spectra in Figs. 116-121 for 0-methyl-tyrosine, histidine, phenylalanine, tryptophan, glycyltryptophan, and a-benzoyllysine, and corresponding data are given in Table XXV. 

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