A Study of Superacid Solutions. I. The Use of the Chloranil Electrode in Glacial Acetic Acid and the Strength of Certain Weak Bases

Hall, Norris F.; Conant, James Β.

doi:10.1021/ja01411a010

Cited by 219 publications

(64 citation statements)

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“…2 the trends in basicity with ring size are quite similar. We believe the values reported in the present work are more reliable, partly because no specific Hammett type acidity function was used in arriving at these values and partly because most of the previous data were obtained in anhydrous acetic acid and the pK's corrected to the aqueous scale (19 Measured at ZS' C. "In these acids, the reaction is too fast to measure k$ accurately. However the estimated rates show that these are higher than the values at lower acidity.…”

Section: Basicity Constantsmentioning

confidence: 80%

The kinetics and mechanism of acid catalysed hydrolysis of lactams

Wan¹,

Modro²,

Yates³

1980

Can. J. Chem.

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This paper is dedicated to Prof. Raymond U . Lemieux on the occasion of his 60th birthday PETER WAN, TOMASZ A. KEITH YATES. Can. J. Chem. 58,2423 (1980). The acid-catalysed hydrolysis of lactams of ring size 4-7, and of N-ethylacetamide, has been studied at various temperatures in 0-70% aqueous sulfuric acids. The kinetics have been analysed by means of the r-hydration parameter treatment and the transition-state activity coefficient (TSAC) approach. Except for the (3-lactam, all substrates show a strongpos~tiverate dependence on water activity, indicating a tetrahedral intermediate type of mechanism (A82), similar to that found for simple (acyclic) amide hydrolyses; only the (3-lactam shows a negative rate -water activity dependence, which is interpreted in terms of a unimolecular (Aal) mechanism, involving rate-determining acylium ion formation. Similarly, all substrates except the (3-lactam show a pronounced destabilization of the transition-state as ac~dity is increased, typical of oxonium Ion specles. The behaviour of the (3-lactam resembles that of methyl mesitoate hydrolys~s. Basicity constants for lactams of ring size 4-9 show a definite dependence on ring s u e , with the 6-lactam being unusually basic. Both rate and pK dependence on ring size are discussed In terms of ring strain and steric effects. The activat~on parameters, particularly AS*, are fully consistent with the conclus~ons drawn concerning transitionstate hydration.

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Section: Basicity Constantsmentioning

confidence: 80%

The kinetics and mechanism of acid catalysed hydrolysis of lactams

Wan¹,

Modro²,

Yates³

1980

Can. J. Chem.

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“…Finally, it was filtered with the aid of suction and dried in a vacuum oven at 100 0 C. The yield was 77 p ercent. The product C mp , 232 0 to 236 0 0 )8 may be used without furt h er purification or reclystallized 8 All melting poin ts were determ ined witll a n ASTM t her mometer for 3-in . immersion, ca librated at t he National Bureau 01 Stanctards. l~ from n-butyl alcohol (about 50 ml of hot butyl alcohol to 10 g of phenolphthalin).…”

Section: Acid-base Reactions In Organic Solventsmentioning

confidence: 99%

Acid-base reactions in benzene and other organic solvents: Behavior of bromphthalein magenta with different classes of organic bases

Davis¹,

Schuhmann²

1947

J. RES. NATL. BUR. STAN.

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Practical and theoretica l aspects of acid-base reactions in benzene and other organic solvents al'e discussed . The synthesis of the indicators bromphtha lein magenta E and B (the ethyl and n-butyl esters of t etrabromopheno lph thale in ) an d of their t etraalkylammonium salts is descri bed. Qualitative and spectrophotometric data concern in g the color reactions of the indicators with primary, seconda ry, and t ertia ry a li phatic amines , s ubstituted guan idines, a nd other n itrogen bases in benz ene and other types of organic solvents are presen ted. An expla nati on off ered for the color phenom ena is also appli cable to ulfon ephthalcins and other indicators.Examples are given of the qu antitative m eas urement of the relative reactivity of bases with bromphthal ein magenta in benzene. Illust rations a re furnishe d of the app li cation of the ind icato rs to the quantitative estimation of acids and bases, to measu rem ents of the relative s trengt,h s of orga ni c acids, and to the differen tiation o f primary, secondary, and tertiary a liphatic a mines.During t he sp ectrophotometric inves t igations, it was necessar y to des ign new types of a bsorption cells s uitable fo r vo latile solvents a nd for th in laye rs of solu t ion. A desc ription of the e cells is given.

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“…Chlorosulfonique acid (Ho ¼ À13.80) and perchloric acid [19][20][21] (Ho ¼ À10.31) led to the desired product.…”

Section: Thiele-winter Reactionmentioning

confidence: 99%

Activated Zeolites and Heteropolyacids Have Efficient Catalysts for Synthesis Without Use of Organic Solvent at Room Temperature

Hammadi

Dokari

Villemin

et al. 2015

Progress in Clean Energy, Volume 1

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The Thiele-Winter reaction is of interest for synthesis of triacetoxyaromatic precursors of hydroquinones.Solid acids such as heteropolyacids and activated zeolites have an efficient catalyst in acetoxylation reaction of quinones without the use of organic solvent at room temperature. Hydroquinones and substituted hydroquinones was easily oxidized at room temperature in quinones by using (Pc[Co]/K10) and air (1 atm). We have also tested this type of reaction in naphthoquinone series. Many naphthoquinones are natural products with interesting biological properties. The catalytic system (Pc[Co]/K10) in the presence of pure oxygen easily oxidizes the 1,5-dihydroxynaphthalene in Juglone (yield 87 %).

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A Study of Superacid Solutions. I. The Use of the Chloranil Electrode in Glacial Acetic Acid and the Strength of Certain Weak Bases

Cited by 219 publications

References 0 publications

The kinetics and mechanism of acid catalysed hydrolysis of lactams

The kinetics and mechanism of acid catalysed hydrolysis of lactams

Acid-base reactions in benzene and other organic solvents: Behavior of bromphthalein magenta with different classes of organic bases

Activated Zeolites and Heteropolyacids Have Efficient Catalysts for Synthesis Without Use of Organic Solvent at Room Temperature

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