| 摘要 |
<p>Optically active title cpd. (I) is prepd. by dissolving the racemate in aq. benzene sulphonic acid soln. (pref. 5-30%) to give a supersaturated soln. (pref. degree of supersaturation 105-150%), the adding seed crystals of D or L isomer to induce selective crystallisation of the corresp. isomer contained in soln. and recovering the crystals so formed before crystallisation of the second isomer has started. The seed may be dry, wet or a soln. or mixt. thereof. The D isomer is splite to give D-alpha-phenylglycine an intermediate for semi-synthetic penicillins. The residual L isomer is racemised by heating in aq. benzene sulphonic acid soln. at 110-200 degrees C in a sealed reactor.</p> |
