Acid-acceleration

Primary alkyl groups are more reactive than secondary and tertiary. PivaUc acid accelerates the rate of protonolysis of trialkylboranes with water and alcohols (207,208). The reaction can be controlled to give excellent yields of dialkylbotinic acids and esters. 

Zinc oxide, fatty acid, accelerator, sulfur... 

The principal mbbers, eg, natural, SBR, or polybutadiene, being unsaturated hydrocarbons, are subjected to sulfur vulcanization, and this process requires certain ingredients in the mbber compound, besides the sulfur, eg, accelerator, zinc oxide, and stearic acid. Accelerators are catalysts that accelerate the cross-linking reaction so that reaction time drops from many hours to perhaps 20—30 min at about 130°C. There are a large number of such accelerators, mainly organic compounds, but the most popular are of the thiol or disulfide type. Zinc oxide is required to activate the accelerator by forming zinc salts. Stearic acid, or another fatty acid, helps to solubilize the zinc compounds. 

Nitration vs side-chain oxidation of toluene in dilute MA was investigated by Namba et al (Ref 69). They found that addition of sulfuric acid accelerated both reactions but nitration more than oxidation. Addition of water to the MA favors oxidation as does an increase in reaction temp... 

Emulsion oxidation of alkylaromatic compounds appeared to be more efficient for the production of hydroperoxides. The first paper devoted to emulsion oxidation of cumene appeared in 1950 [1], The kinetics of emulsion oxidation of cumene was intensely studied by Kucher et al. [2-16], Autoxidation of cumene in the bulk and emulsion occurs with an induction period and autoacceleration. The simple addition of water inhibits the reaction [6], However, the addition of an aqueous solution of Na2C03 or NaOH in combination with vigorous agitation of this system accelerates the oxidation process [1-17]. The addition of an aqueous phase accelerates the oxidation and withdrawal of water retards it [6]. The addition of surfactants such as salts of fatty acids accelerates the oxidation of cumene in emulsion [3], The higher the surfactant concentration the faster the cumene autoxidation in emulsion [17]. The rates of cumene emulsion oxidation after an induction period are given below (T = 353 K, [RH] [H20] = 2 3 (v/v), p02 = 98 kPa [17]). 

Alkylsulfonic acids are active oxidative agents like other organic peracids. Several oxidative reactions of seodecylsulfonic peracid were studied by Safiullin et al. [41]. Peracid was found to oxidize benzene to phenol as the first intermediate product. The formed sulfonic acid accelerates the reaction. Oxidation occurs according to the stoichiometric equation... 

The presence of one or more heteroatoms in either the 4jt or In component allows the synthesis of six-memebered heterocycles via the Diels-Alder process. These strategies have been successfully developed (218) leading to a diverse array of natural products. Similar to the carbo-Diels-Alder reaction, many of these processes are amenable to Lewis acid acceleration, and several have been developed using chiral catalysts. 

Electron-donating groups in the ketone and electron-withdrawing groups in the per acid accelerate the reaction. The case of migration of some common groups decreases in the order. 

Amino acids accelerate and proteins retard the rate of Cu(II)-catalyzed oxidation of di-2-pyridyl ketone hydrazone (173) yielding fluorescent compounds. This has been applied for the analysis of amino acids and proteins378. 

The presence of low levels of acetic acid accelerated the initial rate of reaction, but levels above 30 % by volume inhibited the reaction. 

With the aid of density functional theory, the ZnCl2 acceleration of the Simmons-Smith reaction of ethylene and allyl alcohol has been investigated. A pathway involving direct Lewis acid acceleration of the leaving halogen atom (327) was found to be a more facile process than the more popular pathway involving 1,2-chlorine migration (328). 

Mixture of nitric and hydrochloric acids Accelerating rate calorimetry American Society for Testing and Materials Slow reaction with air... 

Tris(pentafluorophenyl)boron [(CgF5)3B], a triarylboron bearing electron-withdrawing perfluorinated phenyl rings, was found to be much more powerful than (05115)36 as a Lewis acid accelerator for the present polymerization. When (0565)36 was added at room temperature to the polymerization system at an equimolar ratio of (0565)36 to the growing species 2, the polymerization took place rapidly with considerable heat evolution, attaining 100% monomer conversion within only about 10 min [6ig. 13 ( )]. This polymerization was estimated to be 150-times faster than that in the absence of (0565)36, and 12.5-times faster than that with (05115)36 as a Lewis acid under similar conditions. 

The admixture of various substances acts in different ways bn the decomposition rate of fulminate inorganic acids accelerate decomposition organic acids... 

During other studies catalytic amounts of nitric acid accelerated the air oxidation of noble metals suspended in acetic acid. A similar effect might be anticipated in the oxidation of Co (II) to Co (III). 

It was further observed by Pamfilov, Shikher and Shikher [34] that the less the nitrocellulose had been stabilized the quicker the precipitation of gel. On this basis it was assumed that traces of acids accelerate the coagulation process. According to Vodiakov [35] the quantity of metal or metal oxide combined or absorbed in the gelatinized nitrocellulose is approximately proportional to its nitrogen content. 

Some insoluble organic macromolecules catalyze polar organic reactions (7). Asymmetric cyanohydrin formation is catalyzed by ami-nated cellulose with 22% optical yield and is an early example of this type of catalysis (8). Polypeptides that create a unique microenvironment through hydrogen bonding catalyze many organic reactions. Poly-[(S)-amino acids] accelerate the epoxidation of chalcone with alkaline... 

The activating energy of the replacement is calculated to be 28,000 2000 calories. It is estimated that the displacement of 1 per cent, of arsenic from a normal solution of arsenic trichloride at room temperature and 100 atm. of hydrogen would require 1140 years. Increase in the concentration of hydrochloric acid accelerates the reaction, which is inhibited by the presence of sodium chloride, and the reaction appears to be ionic rather than molecular.3... 

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