RESEARCH
GC Profiles Sugars G a s c h r o m a t o g r a p h y sep arates methylated carbohy d r a t e s , aids structure studies VT-\s chromatography may offer a newroute to carbohydrate structure analy sis. Now C C can be used to separate methylated sugars. Dr. Henry W. Kircher, d. oartment of agricultural bio chemistry. University of Arizona, told Division of Carbohydrate Chemistry. When analyzing polysaccharides that contain more than one sugar, it is often hard to determine whether or not cer tain methylated sugars are present in the hydrolyzate of the methylated poly mer, Dr. Kircher says. If these sugars occur in very small amounts, the usual methods—paper chromatography, for example—are either not sensitive enough to detect the sugars or else they will not separate thein from others in the mixture, he adds. Example: glucomannans, galactomannans, and galactoglucomannans that occur in woody tissue. T h e meth ylated and hydrolyzed polymers yield tetramethyl derivatives of glucose, gal actose, and mannose. Often, xylan is an impurity in the original polymer, and trimethx lxylose is obtained. Separating these methylglycosides is extremely dif ficult by conventional techniques. Dr. Kircher says. However, he does it us ing vapor phase chromatography. In his chromatographic system, Dr. Kircher uses helium as the carrier gas at 5 to 30 p.s.i. inlet pressure and tem peratures near 2 0 0 ' C. H e makes col umns from methylated c a r b o h y d r a t e s such as methylated starch, hydroxyethyl cellulose, guar gum, and the like—and finds that they work better than the conventional ones. A number of com mercially available gas-liquid partition columns can separate the alpha and beta methylglycosides of glucose, mannose, and xylose. However, these col umns do not separate the pentamethvl hexoses efficiently and some do not separate the glucose and arabinose de rivatives, Dr. Kircher says. Gas chromatography may separate other sugar alcohols, such as sorbitol, dill ci toi, xylitol, arabitol, rhamnitol, and the like, Dr. Kircher says. Other possi bilities: Nlake pure derivatives, analvze mixtures quantitatively, study the equi librium in acidic methanol between the methyl alpha and beta furanosides and pyranosides of certain sugars. 44
C&EN
OCT.
5,
1959
"»*»•- ACS fftec t i n g B r i e f s . ·
••ΗΗΗΒΗΒΗΗΜΗΜΙ
• I m p r o v e d route to a - c y a n o k e t o n e s ,
• Some
valuable synthetic intermediates for a host of medicinal compounds (steroids, alkaloids, and the like) has been devel oped by Ciba Pharmaceutical Products. T h e new scheme: conversion of alicyclic ketones to the corresponding cxcyanoketones via an enamine-cyanogen chloride sequence. Ciba has already tried out the new synthesis successfully with the ketones cyclopentanone through cyclononanone and various 2and 4-substituted cyclohexanones. Pro cedure: Alicyclic ketones are refluxed with pyrrolidine to give their pyrrol idine enamines. Cyanogen chloride treatment then converts the enamine to the corresponding a-cyanoketones with yields around 70'i- or better.
standard hypotensive agents are more potent than the parent compounds. T h e analog of pentolinium dibromide, for example, has three times the hypo tensive potency and duration of the parent compound. Of the hydrazine derivatives, the bisquaternar\ ammo nium compounds are comparable to, or better than the parent; monoquaternary and acid addition salts are inac tive as hypotensives.
Or. Martin E. Kuchne Ciba Pharmaceutical Products Organic Chemistry
• Rapid adsorption means strong ad sorption. A gold electrode vibrating 1 mm. in the air above an oil-covered metal electrode forms a condenser which registers electrical potentials across the oil-metal interface to measure adsorption rates on the test metal of fatty-acid compounds dissolved in the oil. Depending upon the compound and the metal, rates of adsorption are as much as several thousand times slower than the rates calculated for diffusion-eon trolled adsorption. Poten tials of tight-packed monolayers are the same as for film-balance measure ments of insoluble monolayers of the same compounds at the air water inter face. Conclusion: Adsorption is strong where rates are rapid and where equi librium potentials are independent of concentration. Dr. Frederick M. Fowkes Shell Development Co. Colloid Chemistry
• A large number of allyloxybenzoic acids and derivatives arc potent central nervous system depressants. Com pounds studied include 2-allyloxy- and 4 - allyloxy - 3,5 - dialkylbenzoic acids. Most active compounds are 2-allyloxy3,5-dipropylbenzoic acid and 4-allyloxy3,5-dipropylbenzoic acid. Several of the compounds are slated for clinical study. Robert Bruce Moffett William Bradlev Reid Patrick H. Seay Upjohn Co. Medicinal Chemistry
hydrazine
derivatives
of
John H. Biel Alexander E. Drnkker Lakeside Laboratories Medicinal Chemistry
• Chromatographic
separation of six
and seven carbon isomers in crude oil is now possible through a new tech nique. Developed by Standard Oil (Ind.) researchers, the method has two steps: prefractionation of components through seven carbons from the crude, and separation of this fraction into its components. A specially designed gas chromatographic prefractionator col umn, containing 18''
C&EN
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