The numerous combinations of functional groups occurring in the steroid hormones render difficult the development of a specific test for individual compounds. However, reactions which reveal certain groupings are available and may be applied singly or in combination to elucidate the characteristics of pure steroids or of compounds in a mixture. The ketol side chain, located at carbon atom 17 in...

1. A method is described for the differentiation and determination of as little as 0.2mug. of vitamins D(2) and D(3) by gas-liquid chromatography. 2. The vitamins are converted by treatment with antimony trichloride into isovitamins D(2) and D(3), which show single, separate peaks on gas-liquid chromatography, unlike the unmodified vitamins, which give twin peaks due to the formation of pyro an...

An efficient and simple one-pot approach for the synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives using antimony trichloride (SbCl3) as a mild catalyst by means of three-component Biginelli reaction between β-keto esters, aldehyde derivatives and urea/thiourea under thermal and solvent-free conditions with excellent yields and short reaction times is reported. This m...

Retinal extracts have been prepared from dark-adapted mudsuckers by treatment of retinal tissue or of isolated outer segments of the visual cells with digitonin solution. The extracts were examined spectrophotometrically and found to absorb light maximally between the wave lengths of 488 and 510 mmicro, depending on the proportion of yellow impurities and light-sensitive pigment present. This p...

This paper deals with a new calorimetric reaction of vitamin A with glycerol 1,3-dichlorohydrin (which we henceforth will refer to as GDH) that appears to be suitable for the quantitative estimation of this vitamin. The estimation of vitamin A in vitro has been the subject of many reviews in recent years (l-6). The two widely used methods at present are the ultraviolet absorption at 325 to 328 ...