PRESSURE EFFECT AND MECHANISM IN ACID CATALYSIS: V. THE HYDROLYSIS OF ACETIC ANHYDRIDE

1959 ◽  
Vol 37 (8) ◽  
pp. 1360-1366 ◽  
Author(s):  
J. Koskikallio ◽  
D. Pouli ◽  
E. Whalley
Keyword(s):  
Acetic Anhydride ◽  
Acid Catalysis ◽  
Pressure Effect ◽  
Valid Method ◽  
Acetone Water ◽  
Entropy Of Activation ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The spontaneous and the acid-catalyzed hydrolyses of acetic anhydride have been measured as a function of temperature over the range 0 to 40 °C, as a function of pressure over the range 0 to 3 kb at 0 °C, and as a function of solvent over the range 0 to 70.3% w/w acetone–water at 0 °C. The results are discussed with reference to the mechanisms of the hydrolyses. The volume and entropy of activation of the acid-catalyzed hydrolysis are −17.1 ± ~1.3 cm3 mole−1 and ~ −20 cal deg−1 mole−1, showing that the mechanism[Formula: see text]suggested because the rate was proportional to Hammett's h0, is not correct. It follows that the Zucker–Hammett hypothesis is invalid for this reaction, as we have shown previously for other reactions, and hence that it does not provide a valid method of distinguishing between the A-1 and A-2 mechanisms.

PRESSURE EFFECT AND MECHANISM IN ACID CATALYSIS: IV. THE HYDROLYSIS OF DIETHYL ETHER

1959 ◽  
Vol 37 (4) ◽  
pp. 788-794 ◽  
Author(s):  
J. Koskikallio ◽  
E. Whalley
Keyword(s):  
Diethyl Ether ◽  
Acid Catalysis ◽  
Pressure Effect ◽  
Slow Step ◽  
Acidity Function ◽  
Temperature Range ◽  
Entropy Of Activation ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of diethyl ether has been measured in the temperature range 120–160 °C at low acid concentrations; the entropy of activation is −9.0 ± ~2.5 cal deg−1 mole−1. The effect of pressures up to 3000 atm has been measured at 161.2 °C; the volume of activation at 1 atm is −8.5 ± ~2 cm3 mole−1. These two results show that the slow step is bimolecular. The rate in concentrated acids was measured at 119 °C; the rate was much more nearly proportional to the acidity function h0 than to concentration of acid. This is contrary to the predictions of the Zucker–Hammett hypothesis, which is therefore not valid for the hydrolysis of diethyl ether.

PRESSURE EFFECT AND MECHANISM IN ACID CATALYSIS: VIII. HYDROLYSIS OF ACETAMIDE AND BENZAMIDE

1961 ◽  
Vol 39 (5) ◽  
pp. 1101-1108 ◽  
Author(s):  
A. R. Osborn ◽  
T. C-W. Mak ◽  
E. Whalley
Keyword(s):  
Water Molecule ◽  
Transition State ◽  
Perchloric Acid ◽  
Acid Catalysis ◽  
Pressure Effect ◽  
Protonated Form ◽  
Dilute Acid ◽  
Additional Information ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The effect of pressures up to 3 kbar on the rate of the acid-catalyzed hydrolysis of acetamide and benzamide in both dilute and concentrated perchloric acid has been measured. The volumes of activation in dilute acid are consistent with a transition state that is not highly polar. It follows from this that if the attacking water molecule adds to the amidium ion then the reactive amidium ion is the O-protonated form, and if the attacking water molecule substitutes then the reactive amidium ion is the N-protonated form.The volume of activation for acetamide in concentrated acid provides no additional information about the mechanism. That for benzamide in concentrated acid is tentatively interpreted as favoring the O-protonated benzamidium ion as the reactive ion.

Acid-catalyzed Solvolysis of Isonitriles. I

1971 ◽  
Vol 49 (14) ◽  
pp. 2455-2459 ◽  
Author(s):  
Y. Y. Lim ◽  
A. R. Stein
Keyword(s):  
Formic Acid ◽  
Acid Catalysis ◽  
Hydrolysis Product ◽  
Rate Dependence ◽  
Linear Rate ◽  
First Order ◽  
Methyl Amine ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of methyl isonitrile has been examined. The initial hydrolysis product is N-methylformamide which is further hydrolyzed to methyl amine and formic acid at a much slower rate. The hydrolysis to N-methylformamide is pseudo-first order in methyl isonitrile and shows a linear rate dependence on concentration of general (buffer) acid at fixed pH. The significance of general acid-catalysis in terms of the mechanism of the hydrolysis is considered and taken as evidence for carbon protonation rather than nitrogen protonation as the initiating step.

Pressure effect and mechanism in acid catalysis. Part 2.—Hydrolysis of formals, acetals, and ethyl orthoformate

1959 ◽  
Vol 55 (0) ◽  
pp. 809-814 ◽  
Author(s):  
J. Koskikallio ◽  
E. Whalley
Keyword(s):  
Acid Catalysis ◽  
Pressure Effect ◽  
Ethyl Orthoformate ◽  
Hydrolysis Of

Solvolysis of Sulphonyl Halides. I. The Hydrolysis of Aromatic Sulphonyl Chlorides in Aqueous Dioxan and Aqueous Acetone

1961 ◽  
Vol 14 (2) ◽  
pp. 190 ◽  
Author(s):  
FE Jenkins ◽  
AN Hambly
Keyword(s):  
Dielectric Constant ◽  
Reaction Rate ◽  
Acid Catalysis ◽  
Salt Effect ◽  
Aqueous Acetone ◽  
Low Dielectric Constant ◽  
Low Dielectric ◽  
Enthalpy Of Activation ◽  
Entropy Of Activation ◽  
Hydrolysis Of

The hydrolysis of benzene, p-toluene, p-bromobenzene, and p-nitrobenzene sulphonyl chlorides in 10-60 wt. % water-dioxan and water-acetone has been shown to follow an SN2 mechanism. The reaction does not show acid catalysis or any " salt " effect. Hammett?s equation does not describe fully the effects of substituents on the reaction rate. For solutions in which water has the same molarity, aqueous acetone gives lower rates than aqueous dioxan when the molarity of water is high but higher rates when the molarity of water is low. Change in the water content of the solvent produces only small changes in the enthalpy of activation except in solutions of low dielectric constant. The reduction in rate as solutions become less aqueous is mainly determined by the entropy of activation becoming more strongly negative.

Kinetics and mechanism of hydrolysis of 3-diazobenzofuran-2-one and its hydrolysis product (3-hydroxybenzofuran-2-one)

2002 ◽  
Vol 80 (1) ◽  
pp. 82-88
Author(s):  
Y Chiang ◽  
A J Kresge ◽  
Q Meng
Keyword(s):  
Acid Catalysis ◽  
Hydrolysis Product ◽  
Diazo Compound ◽  
Acidity Function ◽  
Hydroxide Ion ◽  
Mechanism Of Hydrolysis ◽  
Acid Catalyzed ◽  
Catalyzed Reactions ◽  
Rate Profile ◽  
Hydrolysis Of

Rates of acid-catalyzed hydrolysis of 3-diazobenzofuran-2-one, measured in concentrated aqueous perchloric acid and hydrochloric acid solutions, were found to correlate well with the Cox–Yates Xo excess acidity function, giving kH+ = 1.66 × 10–4 M–1 s–1, m‡ = 0.86 and kH+ /kD+ = 2.04. The normal direction (kH/kD > 1) of this isotope effect indicates that hydrolysis occurs by rate-determining protonation of the substrate on its diazo-carbon atom. It was found previously that the next higher homolog of the present substrate, 4-diazoisochroman-3-one, also undergoes hydrolysis by this reaction mechanism but with a rate constant 15 times greater than that for the present substrate; this difference in reactivity can be understood in terms of the various resonance forms that contribute to the structures of these substrates. The product of the present hydrolysis reaction is 3-hydroxybenzofuran-2-one, which itself quickly undergoes subsequent acid-catalyzed hydrolysis to 2-hydroxymandelic acid. The acidity dependence of this subsequent hydrolysis is much shallower than that of the diazo compound precursor, and rates of reaction correlate as well with [H+] as with Xo. This is due in part to incursion of a nonproductive protonation on the hydroxy group of 3-hydroxy benzo furan-2-one that impedes hydrolysis and produces saturation of acid catalysis. Rates of hydrolysis of the hydroxy compound were also measured in dilute HClO4 and NaOH solutions as well as in CH3CO2H, H2PO4–, (CH2OH)3CNH3+, and NH4+ buffers, and the rate profile constructed from these data showed the presence of uncatalyzed and hydroxide ion-catalyzed reactions. This hydroxide-ion catalysis became saturated at [NaOH] [Formula: see text] 0.05 M, implying occurrence of yet another nonproductive substrate ionization. Key words: diazo compound hydrolysis, lactone hydrolysis, Cox–Yates excess acidity, acid catalysis, alcohol protonation.

The acid-catalyzed hydrolysis of methyl 2-chloro-2-deoxy-β-D-glucopyranoside

1967 ◽  
Vol 45 (5) ◽  
pp. 515-519 ◽  
Author(s):  
E. Buncel ◽  
P. R. Bradley
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solutions ◽  
Hydrochloric Acid Solutions ◽  
Mechanism Of Hydrolysis ◽  
Entropy Of Activation ◽  
Acid Catalyzed ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the hydrolysis of methyl 2-chloro-2-deoxy-β-D-glucopyranoside have been determined in hydrochloric acid solutions over a range of acid concentrations and temperatures. Chloro substitution reduces the rate by a factor of 35 compared with the hydroxy analogue. Application of the Hammett criterion indicates a unimolecular (A-1) mechanism of hydrolysis, as does application of the Bunnett criterion. The entropy of activation, however, is considerably smaller than that observed for the hydrolysis of methyl β-d-glucopyranoside. This is interpreted as being indicative of partial A-2 character.

Kinetic effects induced by cellulose on water-catalyzed reactions. Hydrolysis of 2,4-dinitrophenyl cellulose xanthate and some sugar xanthate ester analogues

1998 ◽  
Vol 76 (6) ◽  
pp. 960-965 ◽  
Author(s):  
Eduardo Humeres ◽  
Luiz Fernando Sequinel ◽  
Mauricéa Nunes ◽  
Célia MS Oliveira ◽  
Patrick J Barrie
Keyword(s):  
Cellulose Xanthate ◽  
First Order Kinetics ◽  
Acetone Water ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Of Cellulose ◽  
Entropy Of Activation ◽  
Kinetic Effects ◽  
Catalyzed Reactions ◽  
Parallel Reactions ◽  
Hydrolysis Of

The hydrolysis of 2,4-dinitrophenyl cellulose xanthate (CelXDNP) was studied in 10% v/v aqueous ethanol at 25°C and μ = 0.1 (KCl). The water-catalyzed hydrolysis showed that, as for p-nitrobenzyl cellulose xanthate, it occurs through two parallel reactions with rate constants k'H2O = 4.40 x 10-3 s-1 for the fast hydrolysis, and k''H2O = 6.90 x 10-5 s-1 for the slow hydrolysis. The entropy of activation of the fast hydrolysis was 0.7 ± 1.8 cal K-1 mol-1. External nucleophiles such as hydroxide and simple amines show simple first-order kinetics. The spontaneous hydrolysis of CelXDNP in acetone-water mixtures indicates that the fast reaction does not occur through water polymers and that for water molarity higher than 30 M there are no acetone molecules (or very few) in the highly ordered cybotactic region of cellulose. The spontaneous hydrolysis of methyl 4,6-O-benzylidene- α -D-glucopyranoside 3-(S-p-nitrobenzyl-xanthate) although is faster than the 6-isomer, it is slower than the fast hydrolysis of p-nitrobenzyl cellulose xanthate (CelXNB). Also Δ Sdouble dagger is highly negative (-41.0 cal K-1 mol-1), as it is for alkyl and sugar analogues. Only for the fast hydrolyses of CelXDNP and CelXNB is the entropy of activation almost zero. It is concluded that there is no neighbouring OH effect on the fast hydrolysis of cellulose xanthate esters. Key words: hydrolysis, water catalysis, cellulose xanthate esters, methyl glucose, xanthate esters, neighbouring OH effect.

Analyses of reaction rate data for the simple hydrolysis of acetic anhydride in the acetonitrile/water and acetone/water cosolvent systems using recently developed thermodynamic rate equations

2019 ◽  
Vol 52 (1) ◽  
pp. 52-60 ◽  
Author(s):  
F. L. Wiseman ◽  
D. W. Scott ◽  
J. Tamine ◽  
R. O'Connell ◽  
A. Smarra ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Reaction Rate ◽  
Rate Equations ◽  
Rate Data ◽  
Acetone Water ◽  
Hydrolysis Of
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