Acid Catalysis in the Isomerization of 5α,6β-Dibromocholestane

Kwart, Harold; Weisfeld, L. B.

doi:10.1021/ja01584a032

Cited by 14 publications

(4 citation statements)

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“…Imidazole and hydroxylamine prove to be exceptional in the general base catalysis of the aminolysis of phenyl acetate (140), probably because functions other than base strength are involved. Similarly, carboxylic acids function as general acid catalysts in the isomerization of 4 <x,6 -dibromocholestane following the Br0nsted equation but phenols are not correlated, appearing in the kinetic expression as a second-order term (162).…”

Section: A the Br0nsted Catalysis Equationmentioning

confidence: 99%

Linear Free Energy Relationships.

Wells¹

1963

Chem. Rev.

531

313

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Section: A the Br0nsted Catalysis Equationmentioning

confidence: 99%

Linear Free Energy Relationships.

Wells¹

1963

Chem. Rev.

531

313

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“…Oxidation of Aldehyde 5. Ketones 6 and 7.-A mixture of 465 mg of aldehyde 5 and 200 mg of powdered KOH in 20 ml of tert-BuOH was vigorously stirred under an oxygen atmosphere for 0.5 hr.8 The product was isolated with hexane and distilled affording 213 mg (48%) of a nearly 1:1 mixture of ketones 6 and 7:12•13 bp 107°(bath temperature) (0.1 mm); Xj,1" 5.88, 8.61 pm;…”

Section: Experimental Section11mentioning

confidence: 99%

Selective degradation of guaiol. Synthesis of 7-epiguaiol

Marshall¹,

Ruden²

1971

J. Org. Chem.

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“…Bell uses his thermal maximum method in a study of the hydration of acetaldehyde, for which the catalytic constants of bases fail to obey the Bronsted relationship (103), and in measuring the rate of neutralization of nitroethane by metallic hydroxides, which leads to values of the dissociation constants of CaOH+, BaOH+ and TlOH (104). Kinetic studies on acid catalysis in aprotic solvents include the isomerization reactions of Sa, 6{J dibromocholestane in CaHa [Kwart (105)] and I-phenyl. allylchloride in CsHoCI [Braude (106)] and the dimerization of certain diaryl ethylenes in CaHa [Evans (107)].…”

Section: Inorganic Reactionsmentioning

confidence: 99%

Kinetics of Reactions in Solution

King¹

1957

Annu. Rev. Phys. Chem.

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This review deals with homogeneous reactions in liquid solution; studies in the areas of photochemistry, radiation chemistry, and polymerization kinetics are not reviewed. A short review of the past year's work in enzyme kinetics is included, and this inclusion has necessitated a somewhat ab breviated review of organic reactions. In a sense, the entire review is ab breviated since fewer than half of the worth-while papers published during the year are included.A short book by Dainton (1) on chain reactions, including those in solu tions, has appeared during the year as have reviews of the kinetic studies published in 1955 [Noyes (2); Ashmore et al. (3)]. Guggenheim (4) sets the record straight on the early history of kinetics and points out that the lack of correlation between the reaction order and the coefficients in the chemical equation was realized by the earliest workers in the field. If the teacher wishes to emphasize this point, a nice example is the reaction, 30 ROH + BloH14�10 B(OR)a+22 H2, which Beachell (5) finds to be first order in ROH and in B1oH14•The design of a four-channel stop flow mixing apparatus for use with the Beckman D.U. spectrophotometer is presented by Beers (6), and De Tar (7) describes apparatus for the precise manometric determination of rate data. Under the heading of neat tricks is Winstein's use of a tape recorder for not ing the time of quenching of reaction mixture aliquots (8); this technique should prove useful for the solitary researcher who is studying a relatively rapid reaction.Westman & De Lury (9) have considered the integrated rate equations for consecutive first order reactions, and Widequist (10) describes a method for the calculation of the rate constants for two competitive, consecutive reactions; this method is applicable to experiments in which the reactants are present in nonequivalent amounts.Harris & Weale (11) have measured the rates of several reactions as a function of pressure up to pressures of 5000 atm. The value of l:!. vt is often dramatically different at high pressures from what it is at one atmosphere, a point also stressed by Hamann (12).Noyes (13) has presented theoretical considerations pertaining to diffu sion controlled reactions and concludes that current data suggest "that dif fusion in liquids involves almost continuous motion and small individual displacements, and does not involve 'jumps' of the order of a molecular di ameter that are opposed by significant potential barriers." Other theoretical papers dealing with diffusion controlled reactions are by Schulz (14) and 1 The survey of literature pertaining to this review was completed in December, 1956. 273 Annu. Rev. Phys. Chem. 1957.8:273-298. Downloaded from www.annualreviews.org Access provided by McMaster University on 02/06/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS

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Acid Catalysis in the Isomerization of 5α,6β-Dibromocholestane

Cited by 14 publications

References 1 publication

Linear Free Energy Relationships.

Linear Free Energy Relationships.

Selective degradation of guaiol. Synthesis of 7-epiguaiol

Kinetics of Reactions in Solution

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