General acid decomposition

General acid Decomposition of acetaldehyde CH3CH(OH)2 = ch3cho + h2o... 

General acid Decomposition of acetaldehyde hydrate Hydrolysis of o-esters Formation of nitro componnd CH3CH(0H)2 = CH3CHO + H2O HC (0C2H5)3 -I- H2O = H COOC2H5 + 2C2H5OH CH2 N02 -I- acid = CH3-N02 + base ... 

Many problems have been reported (163), and the process has been abandoned because of the difficulty in handling sohds. Processes which are thought to have the best likelihood of success ate based on sulfuric acid decomposition. Three prominent cycles are based on this reaction the General Atomics iodine—sulfur cycle... 

The trialkyltrlazenes are essentially protected diazo-nlum ions. They decompose cleanly and quantitatively to the dlazonlum ions and the corresponding amines over a wide pH range (M). Good kinetic data were obtained over the range of pH 6.9 - 8.3. In more acid solutions, the reactions are too rapid to measure by conventional kinetics. The decomposition reaction is subject to general acid catalysis. Thus, the trialkyltrlazenes will be a useful tool for the study of the reactive intermediates produced by the metabolism of dialkyl-nitrosamines. 

For reactions in which the decomposition of the zwitterionic intermediate, ZH, is, at least partially, rate-limiting, two major mechanisms are now widely accepted. These are known as the specific base-general acid (SB-GA) and the rate-limiting proton transfer (RLPT) mechanisms and are shown in Scheme lla. 

Fig. 9.2. Simplified reaction mechanisms in the hydrolytic decomposition of organic nitrites. Pathway a Base-catalyzed hydrolysis with liberation of nitrite. Pathway b Reversible nitro-syl exchange between organic nitrites and alcohols. Pathway c General acid catalysis with concerted mechanism in the acid hydrolysis of organic nitrites.

Belke et al. (1971) reported general base and general acid catalysis in cyclization of 2-hydroxymethylbenzamide [equation (18)]. However, with 2-hydroxymethyl-6-aminobenzamide strict general base catalysis by buffer bases is observed with a Bronsted coefficient of O 39 (Fife and Benjamin, unpublished data). In contrast with the unsubstituted amide, the Bronsted plot is nicely linear. An amino-group in the 6-position might assist decomposition of a tetrahedral intermediate as in [37a, b] or a kinetic equivalent. The pH-rate constant profile for spontaneous cyclization at zero buffer concentra-... 

In oxidation studies it has usually been assumed that thermal decomposition of alkyl hydroperoxides leads to the formation of alcohols. However, carbonyl-forming eliminations of hydroperoxides, usually under the influence of base, are well known. Of more interest, nucleophlic rearrangements, generally acid-catalyzed, have been shown to produce a mixture of carbonyl and alcohol products by fission of the molecule (6). For l-butene-3-hydroperoxide it might have been expected that a rearrangement (Reaction 1) similar to that which occurs with cumene hydroperoxide could produce two molecules of acetaldehyde. 

Even more surprising is the finding that the reactivity picture exhibited by the various ethoxide species in the ethanolysis of phenyl acetate is very similar to that found in the ethanolysis of the activated amide N-methyl-2,2,2-trifluoroacetanilide [Eq. (3)], despite the different mechanisms of the two reactions [13]. Schowen ef al. [14] showed that C-N bond breaking in the rate-limiting decomposition of the tetrahedral intermediate is assisted by proton transfer from a general acid to the leaving group. 

At pH < 5 general acid catalysis of the decomposition of the adducts is observed and suggests, in agreement with analogous features of spiro... 

Transition state XIX involves the rate-determining formation of an anionic transition state and XX the rate-determining decomposition of the anionic transition state. General acid-catalysed process... 

An important point to note in figure 8.1 is that the same general acid or base that catalyzes the formation of the tetrahedral intermediate also can participate in the decomposition of the intermediate. When a general acid (HA) donates a proton to the ester oxygen it becomes a base (A ), which can retrieve the proton as the intermediate breaks down. When a general base (B ) removes a proton from water it becomes an acid (BH), which can provide a proton to the alcohol. Note also that general-acid and general-base catalysis are not mutually exclusive they can both occur in a concerted manner in the same step of a reaction. 

McClelland et al.221 have suggested that the general acid-catalyzed decomposition of a hemiacetal anion, Equation (63), proceeds through an imbalanced transition state where sp3 to sp2... 

Since general acid catalysis of reaction (19) had been observed8, the terms in [I-] and [I-]2, in equation (22) might be due to water-catalysed decompositions of the complexes CH2-CHCH2HgI2 and CH2 CHCH2HgI32. However, it was felt that the catalytic constants in equation (22) were much too large for this to... 

In general, there are two alternatives for coupling the S-I process to a VHTR. In the first, secondary helium is initially used to supply heat to the MT/HT1 sulphuric acid decomposition steps. LT helium heat is then consumed by the HI decomposition section before the helium return to the intermediate heat exchanger. In the second alternative, heat integration between the chemical process steps allows for helium heat supply solely to the MT/HT sulphuric acid decomposition steps. Residual process LT heat recovered there is utilised in the HI decomposition section. 

Use of PSA for design of emergency mitigation systems in a hydrogen production plant using General Atomics SI cycle technology. Section II Sulphuric acid decomposition... 

Thiazolyl sulfamic acids, rearrangement of sulfonic acid, 70 rearrangement to sulfonic acid, 75 by sulfonation, 75 2-Thiazolyl sulfenyl chloride, transformation to, thiazolyl disulfides. 412 2-Thiazolyl sulfide, in hydrocarbon synthesis, 406 oxidation of, with m-chloroperbenzoic acid, 415 with CrOj, 415 with Hj02,405,415 with KMn04,415 physical properties, infrared, 405 NMR, 404 pKa, 404 ultraviolet, 404 preparation of, from 2-halothiazoles and 5-Thiazolyl sulfides, bis-5-thiazolyl sulfide, oxidation of, 415 general, 418 5-(2-hydroxythiazolyl)phenyl sulfide case, 418 physical properties, 418 preparation of, 417-418 table of compounds, 493-496 uses of. 442 2-Thiazolyl sulfinic acid, decomposition of, 413 preparation of, from 2-acetamidothiazole sulfonyl chloride, 413 from A-4-thiazoline-2-thione and H, 0, 393,413 table of compounds, 472-473 5-Thiazolyl sulfinic add, preparation of,... 

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