NUCLEsR 31AGNETIC RESONANCE O F Sy?Z-anti ISOMERISM IN KETOXIMES 49 1 of P(O), however, as it is reasonable to expect much of Ihe effects of correlation to cancel. In any case the entire polymer chain would collapse to within A' of the surface as P(0,t') for the polymer given by Fig. 2 approaches unity.A significant point with regard to equation 15 and the curves of Fig. 2 is that P(0) may bevery sensitive to 8 over a certain range of 8. In considering the thermodynamics of chain adsorption*J the number of anchoring segments v = P(O)t is an important factor. It is seen that for e going from 0 to 0.9, v may vary over a wide range (-a factor of ten) if, say K-10 a t 0 = 0 (or K-1 a t 8 = 0.9 if K O remains constant). Any isotherm equation should take this variation of v into account if agreement with experiments is to he expected. Comparison of Calculations with DataRecently Fontana and Thomas13 have carried out some very interesting experiments bearing on the problem of the configuration of adsorbed polymers. They were able to directly determine P(0) for poly-(alkyl methacrylate), PLMA, adsorbed onto silica by infrared spectrometry.Their investigation showed that, for this system, P(0) is relatively independent of 8 over a wide range of e. Since it is clear from their work that the mechanism of adsorption involves hydrogen bonding between the surface hydroxyl groups on (13) E. J. I'ontana and J. R. Thomas, J . Phys. Chem., 66, 480 (1961).the silica and the carbonyl groups on the polymer, e is very likely relatively large (>5kT) for this case. Thus, their data is consistent with the idea that this system is operating a t the upper regions of the curves in Fig. 2 where P(0) is relatively insensitive to 8.These investigators found, however, that the relatively constant value for P(0) was not unity but instead about 0.4. This, as the authors point out, most probably is a result of the combination of polymer backbone inflexibility and availability of properly spaced adsorption sites. It is to be expected that as P(0) approaches a value as high as 0.4 the chain becomes relatively rigid (as compared to the solution configuration) and surface site spacing and surface uniformity requirements become more critical. Furthermore, under these conditions both intermolecular and intramolecular overlapping of portions of the chains will lead to smaller P(0) because of steric effects. Alternatively it may be stated that at P(0) = 0.4 the entire PLMA chain is collapsed t o the surface to the extent that equation 18 might be more appropriate.Acknowledgments.-The author wishes to acknowledge the very helpful suggestions and discussions concerning the problem with Drs. 0. L. Isomerism of the syn-anti kind has been detected for the first time in several aliphatic ketoxinies and ketoxime ethers and is indicated by the presence of two resonance lines for the protons on carbon atoms next to the >C=KOH or >C=SOR group. The separation of these two lines depends on (a) the presence of aromatic compounds, acids or bases in the oxime solution, ...
This study confirms the chemical nature of the major organic extractable metabolite of carbaryl in milk and urine. The data obtained with the aid of ultraviolet, infrared, mass, and nuclear magnetic resonance spectroscopy are consistent with the structure of the methylcarbamate of 5,6-dihydro-5,6dihydroxy-1-naphthol. The compound exhibits a lower degree of toxicological hazard than carbaryl, as evidenced by anticholinesterase and fly bioassay tests, and has a very low potential as a microbial mutagenic agent. The presence of this metabolite may be qualitatively confirmed by colorimetric analysis, but no quantitative assay is available. The
SELECTIVE CARBAMYLATION WITH METHYL ISOCYANATE 3635 was allowed to stand at room temperature overnight. The reaction mixture was diluted with 5 ml of ethylene glycol, allowed to stand for 5 min, and concentrated on the steam bath to about 20 ml. The mixture was taken up in 600 ml of ether and 200 ml of ice-cold water, the layers were separated, and the aqueous phase was extracted first with 600 ml of ether and then with 300 ml of ether. The organic extracts were washed with three 200-ml portions of water, three 200-ml portions of ice-cold saturated sodium bicarbonate solution, and again with water to neutrality. The organic extracts were dried over anhydrous magnesium sulfate, filtered, and evaporated to leave 0.835 g of an oily residue.Chromatographic purification of this product on 100 g of silica gel gave rise to 0.739 g of the desired formate 9a which was obtained in the eluateri with benzene-ethyl acetate (4: 1). The compound could not be obtained in crystalline form. A typical chromatographic fraction contained, in addition to the formate 9a, three trace impurities as shown by thin layer chromatographic analysis (silica gel, benzene-methanol 9: 1). The compound Pa had [cY]*~D --4 O ( c 0.972); I , , , 3605, 1720, 1170 cm-I. Anal. Calcd for ClsHzsOa: C, 71.22; H, 8.81. Found: C, 71.92; H, 9.01.Ja, 17~-Dihydroxy-13a-C-nor-5p-androstan-ll-one (9b) .-A solution of 0.729 g of the above-obtained product 9a and 0.320 g of potassium carbonate in 25 ml of methanol and 3.5 ml of water was allowed to stand at room temperature for 5 days.The solution was diluted with 100 ml of distilled water and the methanol was removed under reduced pressure. The resulting crystalline suspension was cooled ; the crystals were collected on a filter, washed with several small amounts of water, and dried to yield 0.466 g of compound. The turbid, aqueous filtrate was acidified with 2 N hydrochloric acid and extracted with ether. The ether extract was washed with water, dried over anhydrous magnesium sulfate, filtered, and evaporated to leave 0.198 g of a solid residue. This material was shown to be identical with the above 0.466 g of product by infrared and nmr spectra and thin layer chromatography.Chromatography of the above combined reaction product on 70 g of silica gel and two recrystallizations of the residues from the benzene-ethyl acetate (1 : 1) eluates from acetone-heptane gave rise to a first crop of 0.370 g of the desired C-nor ketone 9b, of mp 184.5-185'. A second crop amounted to 0.156 g, mp 180-183'. The over-all yield of the ketone 9b (both crops) from the lactone 6a was 60%.A part of the above first crop was recrystallized twice for analysis: mp 185-185.5'; [~] * S D +5" ( c 1.01); Q , , , 3600, 1720 cm-I.Reactions of methyl isocyanate (CHaN=C=O), a fundamental decomposition product of some K-methylcarbamates, have been investigated. Nuclear magnetic resonance (nmr) was used to measure the end of the reaction in a sealed system. Reaction of CHsN=C=O with water proceeds slowly enough to be followed by nmr; n o evidence was...
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