- Interactive n→σ* delocalizations that control an aqueous organic equilibrium
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Hydrated acetaldehydes were condensed in D2O with substituted alcohols and thiols to determine ΔG of hemiacetalization by 1H NMR. Specific n→σ* delocalizalions in the alkoxy/alkylthio functionality of the product interact to influence n→σ* delocalization in the hemiacetal functionality. Delocalization in the latter functionality controls ΔG.
- Fan, Yun-Hua,Haseltine, John
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- Process for formylation of aromatic compounds
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A process for the preparation of a formylated aromatic compound comprising contacting an aromatic compound with (i) a halogenated compound in the presence of a Lewis acid, and (ii) a base, is described. The subject process provides an efficient and effect
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- Lewis Acid Catalysis of Ene Addition of Chloral and Bromal to Olefins; Product Studies
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The addition of chloral and bromal to a variety of alkyl-substituted alkenes has been investigated.The effect of the reaction of varying the Lewis acid catalyst and the structure of substrate have been studied.Anhydrous AlCl3 was found to be most effective catalyst, and ene-type adducts were the major products in most cases.Side reactions were observed with the less reactive systems leading, variously, to the formation of trihalogenoketones, hydrohalogenated ene adducts, and cyclic ethers.Conditions for optimising the yield of ene adducts were established in some cases.The trihalogenoketone by-products can be conveniently removed by a Grignard-type reaction.
- Benner, Jill P.,Gill, G. Bryon,Parrott, Stephen J.,Wallace, Brian
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p. 291 - 313
(2007/10/02)
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- Chlorine NQR on Hemiacetals of Chloral, Cl3CCH(OH)OR
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The 35Cl NQR spectra of 22 hemiacetals of chloral, Cl3CCH(OH)OR, were studied.Most of these hemiacetals with R = unbranched aliphatic group, show a three line 35Cl NQR spectrum having a regular splitting pattern; two lines around νL = 38.6 +/- 0.1 MHz and the third line at νH = 39.0 +/- 0.1 MHz.It is assumed that the difference between νL and νH is due to "chemical splitting".Completely irregular splitting pattern are found for the hemiacetals carrying bulky branched aliphatic groups.Moreover the magnitudes of these splittings are relatively large.A deformation of the molecules due to intramolecular steric hindrance seems to be responsible for this large splitting.The frequency shift in these compounds due to the steric effect is estimated to be 1 MHz or less.A peculiar temperature dependence of the 35Cl NQR line intensity was found for chloral n-butylhemiacetal.An intramolecular bifurcated hydrogen bond between CCl3 and OH groups is proposed to be responsible for the phenomenon.For p-chlorobenzylalcohol at ca. 226 K a phase transition was observed.
- Hashimoto, M.,Weiss, Alarich
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p. 134 - 141
(2007/10/02)
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