SUBSTITUTION OF ACYCLIC SUGAR ACETALS: RATE OF PERCHLORIC ACID CATALYZED ACETOLYSIS OF 2,3,4,5,6-PENTA-O-ACETYL-D-GLUCOSE DIETHYL DITHIOACETAL AND 1,2,3,4,5,6-HEXA-O-ACETYL-D-GLUCOSE S-ETHYL MONOTHIOACETAL

1966 ◽  
Vol 44 (15) ◽  
pp. 1773-1782 ◽  
Author(s):  
Norman H. Kurihara ◽  
Edgar Page Painter
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Perchloric Acid ◽  
Rate Constants ◽  
Acetoxy Group ◽  
Rate Determining Step ◽  
Conjugate Acid ◽  
Acid Catalyzed ◽  
Sugar Derivatives

The rate constants for the perchloric acid catalyzed substitution of one ethylthio group of 2,3,4,5,6-penta-O-acetyl-D-glucose diethyl dithioacetal (Va) and the acetoxy group bonded to C1 of 1,2,3,4,5,6-hexa-O-acetyl-D-glucose S-ethyl monothioacetal (VIa) have been measured when the substrates were dissolved in solutions of acetic acid and acetic anhydride. The rate-determining step is interpreted to be the dissociation of the substrate conjugate acid to give a carbonium–sulfonium cation. The rate constants indicate that acyclic sugar derivatives are substituted faster than cyclic (pyranose) derivatives, and that an acetoxy group is substituted faster than an ethylthio group.

Substitution of acyclic sugar acetals. Perchloric acid catalyzed acetolysis of poly-O-acetyl acyclic oxygen and sulfur acetals and epimerization of monothioacetals

1967 ◽  
Vol 45 (13) ◽  
pp. 1467-1473 ◽  
Author(s):  
Norman H. Kurihara ◽  
Edgar Page Painter
Keyword(s):  
Acetic Acid ◽  
Perchloric Acid ◽  
Rate Constants ◽  
First Order ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Sugar Derivatives

The rate constants are reported for the substitution of acyclic sugar poly-O-acetyl diethyl dithioacetals, poly-O-acetyl diethyl acetals, and poly-O-acetyl dimethyl acetals and for the epimerization of poly-O-acetyl S-ethyl monothioacetals when catalyzed by perchloric acid in acetic acid. All the reactions are pseudo first order. Monothioacetals substitute faster than oxygen acetals, and oxygen acetals substitute faster than sulfur acetals. A group bonded to C1 of these acyclic sugar derivatives is substituted faster than when the group is bonded to C1 of poly-O-acetyl pyranose derivatives.

Substitution of acyclic sugar acetals. Is the acid-catalyzed substitution of erythro and threo l,2,3,4,5-penta-O-acetyl-l-arabinose S-ethyl monothioacetals anchimerically assisted?

1967 ◽  
Vol 45 (13) ◽  
pp. 1475-1483 ◽  
Author(s):  
Edgar Page Painter ◽  
Norman H. Kurihara
Keyword(s):  
Rate Constants ◽  
Acetoxy Group ◽  
Rate Determining Step ◽  
Acid Catalyzed

The rate constants for the inversion and for the 14C-acetoxy exchange of the diastereomeric 1,2,3,4,5-penta-O-acetyl S-ethyl monothioacetals show that the substitution is not anchimerically assisted by the C2-acetoxy group. The substitution of acyclic poly-O-acetyl sugar monoacetals is best explained by the formation of the acyclic intermediate [Formula: see text] (X = S or O) in the rate-determining step.

The Mechanism of Decay of the Radical HO—CH—CH2—OCOCH3 in Aqueous Solutions. A Conductometric Pulse Radiolysis Study

1976 ◽  
Vol 31 (7) ◽  
pp. 960-964 ◽  
Author(s):  
G. Koltzenburg ◽  
T. Matsushige ◽  
D. Schulte-Frohlinde
Keyword(s):  
Acetic Acid ◽  
Aqueous Solutions ◽  
Rate Constants ◽  
Pulse Radiolysis ◽  
Electron Pulse ◽  
Rate Determining Step ◽  
A Value

From conductivity changes following a 1 µs electron pulse applied to Ν2Ο saturated H2O or D2Ο solutions of acetic acid 2-hydroxyethyl esterthe rate constants of the monomolecular decay of the radical HO-ĊH-CH2-OCOCH3 (1) in H2O and of DO-ĊH-CH2-OCOCH3 in D2O were derived, reaction (1).A value of k1 of 5.5 · 105 s-1 ± 25%, at 22 to 24°C, independent of the above solvents and of pH (or pD) was obtained. It is concluded that the rate determining step of reaction (1) is the heterolytic fragmentation of the carbon acetate bond in 1 followed by formation of H+.

Kinetics and Mechanism of Acid Catalyzed Decomposition of 1-Phenyl-3,3-dialkyltriazenes

1994 ◽  
Vol 59 (2) ◽  
pp. 401-411 ◽  
Author(s):  
Miroslav Ludwig ◽  
Pavla Valášková ◽  
Oldřich Pytela
Keyword(s):  
Rate Constants ◽  
Steric Effect ◽  
Aqueous Ethanol ◽  
Pivalic Acid ◽  
Decomposition Kinetics ◽  
Methyl Ethyl ◽  
Rate Determining Step ◽  
Alkyl Groups ◽  
Acid Catalyzed ◽  
Catalytic Rate

Five model 1-phenyl-3,3-dialkyltriazenes (methyl, ethyl, 2-propyl, butyl, cyclohexyl) have been synthesized and their acid-catalyzed decomposition kinetics have been investigated spectrophotometrically in aqueous ethanol (40 vol.%) with pivalic acid as the catalyst. The results show that the rate-determining step is catalyzed by the proton. The decrease in the observed rate constant at higher concentrations of pivalic acid is explained by the formation of an unreactive complex of the nondissociated acid and respective triazene. The steric effect of alkyl groups on the catalytic rate constants is discussed.

Perchloric Acid Catalyzed Aromatic Mercuration in Acetic Acid Solution. I. Electrophilic Reagents

1967 ◽  
Vol 32 (3) ◽  
pp. 745-752 ◽  
Author(s):  
A Kresge ◽  
M Dubeck ◽  
Herbert Brown
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Perchloric Acid ◽  
Acetic Acid Solution ◽  
Electrophilic Reagents ◽  
Acid Catalyzed

scholarly journals Titration of bases of strong acid salts with perchloric acid in acetic anhydride and glacial acetic acid.

1986 ◽  
Vol 35 (3) ◽  
pp. 147-150 ◽  
Author(s):  
Yutaka ASAHI ◽  
Masami TANAKA ◽  
Kazuko MIMA
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Perchloric Acid ◽  
Glacial Acetic Acid ◽  
Strong Acid ◽  
Acid Salts

Perchloric acid-catalyzed acetic anhydride enol acetylation of steroidal .DELTA.-3-ketones

1968 ◽  
Vol 33 (8) ◽  
pp. 3109-3113 ◽  
Author(s):  
A. J. Liston ◽  
P. Toft
Keyword(s):  
Acetic Anhydride ◽  
Perchloric Acid ◽  
Acid Catalyzed

ELECTROPHILIC REACTIONS OF STEROIDAL AND OTHER α-PHENYL DIENES

1966 ◽  
Vol 44 (19) ◽  
pp. 2233-2239
Author(s):  
Maurice Douek ◽  
George Just
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Perchloric Acid ◽  
Electrophilic Substitution ◽  
Aluminium Chloride ◽  
Substitution Reactions ◽  
Electrophilic Reactions ◽  
Electrophilic Substitution Reactions

3-Phenylcholesta-3,5-diene (I) is shown to undergo electrophilic substitution reactions exclusively at the 6 position with formaldehyde – perchloric acid, acetic anhydride – aluminium chloride, and the Vilsmeier reagent.In the case of formaldehyde, the final product is "dimmer" II. The reaction is specific for formaldehyde and can be used to detect trace amounts of formaldehyde in, for example, commercial acetic acid and acetic anhydride.

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