The syntheses of L(+) and D(−) enantiomers of α-amino acids, norvaline, norleucine, and leucine, as their hydrochloride salts have been achieved in almost 100% optical purity and 40–60% overall yield.

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sion is valid. T h e red t o purple colors provide sufficient shows u p best through t h e green color of chromic ion if contrast t o t h e green of t h e chromic ion t o m a k e t h e color t h e solutions are examined in light from a tungsten change very pronounced, although as m u c h as 1 m l of 1% source. indicator might be necessary when large quantities of Currently, solvent extractions by toluene or carbon tetrachloride using standard Soxhlet apparatus, a n d a densit y method are t h e three analytical procedures described in t h e literature for t h e determination of b i t u m e n content of bituminous sands ( I ) . T h e toluene-extraction method yields t h e most accurate results a n d is widely used in laboratory determinations.In the toluene-extraction procedure, the water a n d bitumen are simultaneously extracted with toluene. T h e a m o u n t of silt t h a t passes through t h e extraction thimble is determined by ashing, a n d applied as a correction to t h e bitumen. Bitumen content is calculated on a dry weight basis from loss in weight. T h e procedure requires four to six hours for extraction a n d several extra hours for residual solids determination; for routine analyses, this is very time-consuming a n d laborious. T h e purpose of this present investigation was t o develop a rapid a n d simple analytical procedure for determining bitumen content of bituminous sands.In t h e present method, extracting solvent (toluene) is p u m p e d through a column of bituminous s a n d of known moisture content. B i t u m e n content of the extract is then determined by absorbance measurement a n d calculation from a per cent b i t u m e n us. absorbance plot of a standard bitumen. EXPERIMENTALThe extraction column consisted of a stainless steel tube (4-in. X 5b-in. i.d.) with threaded caps at each end for inlet and outlet of the extraction fluid. The caps were fitted with metal filter disks (Yg-in. coarse-grade porous bronze) and rubber O-rings (Buna-N or Viton A). . 4 Milton Roy Minipump, Model 196-47. with 240 ml per hour volume capacity and discharge pressure of 1000 psi, was used to pump the extraction solvent. Absorbance measurements were made at 530 nm. using toluene (ACS grade) as the solvent and blank, on a Bauch and Lomb Spectronic-20 colorimeter with a square silica cell of 10-mm path length. A gas chromatograph equipped with a flame ionization detector was used for toluene determination. A stainless steel column (6-in. X Yg-in. i.d.) packed with 5% SE-30 on Chromosorb G (AW 100-120 mesh) was used at a helium flow rate of 40 ml/minute and column and injection port temperatures of 60 and 75 "C, respectively.The samples used for this study were collected at the Great Canadian Oil Sands mining site in the Fort Mcxlurray, Alberta, area of the Athabasca bituminous sand deposit.Procedure. The extraction column was assembled as shown in Figure 1. A cap was placed at the bottom end of the extraction tube. A bed of clean sand 5-to 10-mm thick was deposited on top of the metal filter and the tube wa...

Durch Reaktion der D(+)‐ oder L(‐)‐Form des Amins (I) mit den Aldehyden (II) werden die Schiffschen Basen (III) erhalten, die HCN addieren unter Bil‐ L dung von nur einem Diastereomeren der Aminonitrile (IV).

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