Hine studies

Table 24.4 summarizes the features of selected methods for the LC determination of carbamates in environmental samples. As can be seen, the most used reversed-phase chromatography is with Ci8 or Cg columns and aqueous mobile phases. Other reversed-phase chromatography such as with phenyl has also been used. Some methods use normal-phase silica or diol and nitrile." Sparcino and Hines studied the retention and resolution of 30 A-methylcarbamates in the normal (e.g., silica, cyanopropyl, and propylamine) and reversed-phase mode (Cig). The authors concluded that the reversed-phase columns generally provided better results and acetonitrile-water gave the best overall results on a Cig column. 

During the next fifty years the interest in derivatives of divalent carbon was mainly confined to methylene (CHg) and substituted methylenes obtained by decomposition of the corresponding diazo compounds this phase has been fully reviewed by Huisgen. The first convincing evidence for the formation of dichlorocarbene from chloroform was presented by Hine in 1950. Kinetic studies of the basic hydrolysis of chloroform in aqueous dioxane led to the suggestion that the rate-determining step was loss of chloride ion from the tri-chloromethyl anion which is formed in a rapid pre-equilibrium with hydroxide ions ... 

As was noted previously, Hine and Bailey (16, 17) have obtained correlation of rate data for the reaction of tra s-3-substituted acrylic acids and diphenyl-diazomethane with the Hammett equation. Bowden has reported correlation of rate data for the reaction of tra s-3-substituted acrylic acids with diphenyl-diazomethane (59) and the alkaline hydrolysis of trans-3-substituted methyl acrylates (69) with the Hammett equation. Sufficient data are available for nine sets of rate studies. The sets studied are reported in Table VIII. The results of the correlations are given in Table IX. Of the nine sets studied, seven gave... 

The opinions expressed in this chapter are solely those of the author and do not necessarily reflect those of the Department of Veterans Affairs (DVA), the VA Cooperative Studies Program (VACSP), or the Hines VA Cooperative Studies Program... 

Mazen Abdellatif, Hines VA Cooperative Studies Program Coordinating Center (151K), P.O. Box 5000, 5th Ave. and Roosevelt Rd. Bldg. 1, Rm. B240, Hines, IL 60141-5000, USA. (mazen.abdellatif med.va.gov). 

The initiating nucleophile in the vast majority of these studies is the hydroxide anion. However, in principle, any nucleophile can add to the keto or formyl group to give rise to an anionic intermediate, which then could act as an intramolecular nucleophile and effect hydrolysis of the ester. Their relative effectiveness will depend on two factors the relative extent of formation and the nucleophilicity of the adduct. The nucleophiles that have been investigated are hydroxide, cyanide, morpholine and piperazine. The only quantitative comparison available is that of hydroxide, morpholine and piperazine, which are effective in the order of ca. 102 10-3 1 (Bender et al., 1965 Dahlgren and Schell, 1967). For morpholine and piperazine this is as expected on the basis of their relative basicities. However, the expected order of increasing formation of the adducts would be cyanide > nitrogen bases > hydroxide (Hine, 1971). At this time, these results cannot be analysed further, but more work on the systems could enable the structural dependence and reactivity to be elucidated. 

Neurological Effects. The major public health concern regarding -hexane exposure is the potential for the development of neurotoxicity. Occupational studies have documented that human exposure to -hexane can result in a peripheral neuropathy that in severe cases can lead to paralysis (Altenkirch et al. 1977 Yamamura 1969 Wang et al. 1986). The dose-duration relationship has not been well characterized in humans, but concentrations of 500 ppm and above, and exposure for 2 months or more have been associated with human neurotoxicity. Brief exposure to extremely high concentrations of w-hexane may cause signs of narcosis in humans prostration and coma have been observed in animals exposed to a mixture of hexanes at concentrations of 70,000-80,000 ppm (Hine and Zuidema 1970). At these levels, however, explosion and fire would be the main concern. 

Eisenlord G, Loquvam GS, Leung S. 1968. Results of reproduction study of rats fed diets containing endrin over three generations. Prepared by Hine Laboratories for Shell Chemical Co. and Velsicol Chemical Corp. 

A more recent study for estimating Henry s law constants using the bond contribution method was provided by Meylan and Howard (1991). In this study, the authors updated and revised the method developed by Hine and Mookeijee (1975) based on new experimental data that have become available since 1975. Bond contribution values were determined for 59 chemical bonds based on known Henry s law constants for 345 organic compounds. A good statistical fit [correlation coefficient (r ) = 0.94] was obtained when the bond contribution values were regressed against known Henry s law constants for all compounds. For selected chemicals classes, r increased slightly to 0.97. 

Russell et al. (1992) conducted a similar study using the same data set from Hine and Mookeijee (1975). They developed a computer-assisted model based on five molecular descriptors which was related to the compound s bulk, lipophilicity, and polarity. They found that 63 molecular stmctures were highly correlative with the log of Henry s law constants (r = 0.96). 

Hine CH, Unger H, Anderson HH, et al Toxicological studies on p-tertiary-butyl-toluene. Arch Ind Hyg Occup Health 9 227-244, 1954... 

The Marian Diamond studies are not without controversy. For example. Dr. Lucy Rorke, a neuropathologist in Philadelphia, feels that the number of glial cells was in fact normal, but she was impressed that the brain showed none of the usual degenerative changes one sees in older people. Rorke said it looks like the brain of a young person. Terence Hines of Pace University has also pointed out that the Diamond work may have statistical flaws in its analysis of Einstein s brain, so the debate continues. 

The evaluation of these basic fractionation parameters provides a basis for the study of dioxan-H20-D20 mixtures with a constant proportion of dioxan but varying relative amounts of the isotopic waters. No significant measurements in such systems or on systems with a non-aqueous component other than dioxan appear as yet to have been reported. Hine and Haworth (1958) have successfully studied the... 

Nong A, McCarver DG, Hines RN, Krishnan K (2006) Modelling interchild differences in pharmacokinetics on the basis of subject-specific data on physiology and hepatic CYP2E1 levels A case study with toluene. Toxicol Appl Pharmacol, 214(1) 78-87. 

Catalysis of D—H exchange in ketones and aldehydes by bi- and polyfunctional compounds [a>aminoalkanoic acids [82], cu-dimethylamino-alkylamines [83] and poly(ethylenimines)] has been extensively studied by Hine and coworkers as a model of various enzyme-catalysed transformations entailing analogous steps (see below). The main goal of this work lies in the determination of the steric requirements of intramolecular catalysis. Since the principal results have been recently reviewed (Hine, 1978), only a short survey will be presented here. 

For [2-2H]isobutyraldehyde, it was observed that neither compound [82] nor [83] is a more effective catalyst than simple monofunctional bases of comparable basicity (Hine et al., 1973). In contrast, studies of the dedeuteriation of [2H6]acetone using [83] as catalysts have shown that intramolecular base catalysis by the tertiary amino group occurs for n = 2 and... 

Agamanolis DP, Victor M, Harris JW, Hines JD, Chester EM, Kark JA (1978) An ultrastructural study of subacute combined degeneration of the spinal cord in vitamin B12-deficient rhesus monkeys. J Neuropathol Exp Neurol 37(3) 273-299... 

Information about the acidities or relative acidities of the haloforms has been obtained from kinetic studies under conditions where low concentrations of the carbanion are present and decomposition is unimportant. Extensive studies of this type have been carried out by Hine et al. [164]. Exchange of deuterium from CDX3 in aqueous buffer solutions (98)... 

Although an intermediate endpoint is associated with clinical benefit/ this benefit may be more than offset by the adverse effects of drug therapy when the ultimate outcome is considered. For example/ ventricular fibrillation is associated with increased mortality in the setting of acute myocardial infarction. The demonstration that lidocaine effectively prevents ventricular fibrillation in myocardial infarction patients at first provided a rationale for treating these patients prophylactically with this drug (7). However/ subsequent meta-analyses of several studies by MacMahon (8) and Hine (9) indicated that this use of lidocaine therapy actually worsens patient... 

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