N-Acetyl-DL-alanine

Resolution of DL-alanine (1) is accomplished by heating the N-acetyl derivative (2) in weakly alkaline solution with acylase, a proteinoid preparation from porcine kidney containing an enzyme that promotes rapid hydrolysis of N-acyl derivatives of natural L-amino acids but acts only immeasurably slowly on the unnatural o-isomers. N-Acetyl-DL-alanine (2) can thus be converted into a mixture of l-( + )-alanine (3) and N-acetyl-o-alanine (4). The mixture is easily separable into the components, because the free amino acid (3) is insoluble in ethanol and the N-acetyl derivative (4) is readily soluble in this solvent. Note that, in contrast to the weakly levorotatory o-( - )-alanine (a 14.4°), its acetyl derivative is strongly dextrorotatory. 

The melting point of N-acetyl-DL-alanine is 137°C and that of N-acetyl-D-alanine is 125°C. What would you expect the melting point of N-acetyl-L-alanine to be, or is this impossible to predict ... 

Acetyl-DL-alanine-N-methylamide, 40B, 438 -Acetyl-L-alanine-N-methylamide, 40B, 438 -Alanyl-L-alanine, 37B, 267 -Alanyl-L-serine, 44B, 433... 

C]-DL-Phenylalanin5 [3- 11C]-L-Phenylalanina [.3-l C]-D-(2-Naphthyl)-alanin-Hydrochlorid4 N-Acetyl-2,3-ditntio-o- ( 2-naphthyl) -alanin9... 

A 5 L, 3-neck round bottom flask equipped with a mechanical stirrer was charged with the N-acetyl-3-(4-thiazolyl)-DL-alanine ethyl ester (210.0 g, 0.87 mol), distilled water (1.6 L), and 1 M aqueous KCI (0.8 L). The homogeneous solution was adjusted to pH 7.0 with 0.1 M NaOH and then was treated with Subtilisin Carlsberg (1.8 g) dissolved in 0.1 M aqueous KCI (25 ml). The reaction mixture was stirred at room temperature with 1.0 M NaOH added as required to maintain the pH at 6.25-7.25. After 4 h, 430 ml of base had been consumed and the reaction was judged to be complete. The reaction mixture was then extracted with chloroform (4x1.5 L), the aqueous phase was carefully acidified to pH 4 with 2 M HCI and then was concentrated under reduced pressure. Residual water was removed by consecutive evaporation... 

APRON 2E APRON FL CG 117 CGA 48988 D,L-N-(2,6-DIMETHYLPHENYL)-N-(2 -METHOXYACET-YL)ALANINATE de METHYLE N-(2,6-DIMETHYL-PHENYL)-N-(METHOXYACETYL)-ALANINE METHYL ESTER N-(2,6-DIMETHYLPHENYL)-N-(METHOXY-ACETYL)-DL-AL, NINE METHYL ESTER METALAXIL... 

A mixture of acrylic acid and acetonitrile added dropwise with stirring and ice-salt cooling under anhydrous conditions to oleum (33% SO3), the cooling bath removed, stirred 0.5 hr. at room temp., heated 0.5 hr. on a steam bath, stored 3 days at room temp., water added cautiously, and boiled 24 hrs. to hydrolyze the intermediate N-acetyl group -> DL-a-sulfo-j -alanine. Y 89.3%. F. e. s. D. Wagner, D. Gertner, and A. Zilkha, Tetrah. Let. 1968, 4875. 

DL-Alanine has been prepared by racemizing L-alanine with Ba(OH)] (296) and with a mixture of glacial acetic acid and acetyl chloride (852) or acetic anhydride (178). N-Benzoyl-DL-alanylchloride has been prepared by racemizing N-benzoyl-L-alanylchloride with PClj (444). 

Diethyl 2-thenylacetamidomalonate suspended in an aq. soln. of an equal weight of Na2G03, refluxed 18 hrs., cautiously acidified with coned. HGl to pH 2, and boiled a few min. N-acetyl-j -2-thienyl-DL-alanine. Y 77-85%. F. W. Dunn, Biochem. Prep. 10, 159 (1963). 

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