Catalytic influences

The reaction depends upon the catalytic influence of the cyanide ion, the mechanism being probably as follows ... 

Note 2. Propargyl bromide itself also reacts with ammonia and therefore the interval between the addition of this compound and its conversion with the enethiolate should be kept as short as possible. Inverse addition was applied if propargyl bromide is added to the enthiolate solution, the primary product partly isomerizes into H2C=C(5C2Hs)SCH=C=CH2 under the catalytic influence of the enethiolate. 

Condensation occurs most readily at a pH value equal to the piC of the participating silanol group. This representation becomes less vaUd at pH values above 10, where the rate constant of the depolymerization reaction k 2 ) becomes significant and at very low pH values where acids exert a catalytic influence on polymerization. The piC of monosilicic acid is 9.91 0.04 (51). The piC value of Si—OH decreases to 6.5 in higher order sihcate polymers (52), which is consistent with piC values of 6.8 0.2 reported for the surface silanol groups of sihca gel (53). Thus, the acidity of silanol functionahties increases as the degree of polymerization of the anion increases. However, the exact relationship between the connectivity of the silanol sihcon and SiOH acidity is not known. 

The oxidation proceeds rapidly under the catalytic influence of the oxides of nitrogen formed, but there is sometimes difhculty in starting the reaction using pure nitric acid. In this case the checkers found it convenient to oxidize a few drops of the chlorohydrin with nitric acid by heating in a test tube and to add this to the nitric acid in the flask without stirring. A small portion of the chlorohydrin is then added and allowed to react for a few minutes before starting the stirrer and continuing the oxidation of the main lot. 

This type of co-catalytic influence is well loiown in heterogeneous catalysis, in which for some reactions an acidic support will activate a metal catalyst more efficiently than a neutral support. In this respect, the acidic ionic liquid can be considered as a liquid acidic support for the transition metal catalysts dissolved in it. 

Gaylord et al. [49] reported the dilution and matrix effects in grafting of the styrene/AN binary mixture onto cellulose with K2S2O8 as the initiator. Titledman and coworkers [50] reported the effect of hydroxypro-pylmethyl cellulose on the course of (NH4)2S20 decomposition and claimed a route for grafting of vinyl monomers onto the polymer backbone. The decomposition of the peroxo salt, under the catalytic influence of the... 

Platinum phthalocyanine (PcPt) is prepared by the reaction of phthalonitrile286,288 or isoindolinediimine114,117,288 with platinum(ll) chloride in a solvent such as 2-(dimethyl-amino)ethanol under the catalytic influence of l,8-diazabicyclo[5.4.0Jundec-7-ene. Another possibility is the fusion of phthalonitrile and pialinum(II) chloride58,156,157 or dipotassium tet-rachloroplatinate(II) (K2PtCl4) in the presence of urea, ammonium molybdate(Vl) and sodium sulfate.289... 

Since the early days of using PVC separators in stationary batteries, there has been a discussion about the generation of harmful substances caused by elevated temperatures or other catalytic influences, a release of chloride ions could occur which, oxidized to perchlorate ions, form soluble lead salts resulting in enhanced positive grid corrosion. Since this effect proceeds by self-acceleration, the surrounding conditions such as temperature and the proneness of alloys to corrosion as well as the quality of the PVC have to be taken carefully into account. 

At elevated temperatures and possibly under the catalytic influence of the sorbent surface there is probably elimination of functional groups to yield aromatic ring systems that are excited to fluorescence under long-wavelength UV light (X = 365 nm). 

Peroxodisulfate ions oxidize aromatic amines md phenols to colored derivatives, paitic ularly under the catalytic influence of silver ions [1-4]. 

Heteroaromatic ring systems are formed presumably with loss of functional groups, elevated temperatures and probably under the catalytic influence of the aminopro groups on the sorbent surface. The compounds so formed are excited to fluorescei by long-wavelength UV light (A. = 365 nm). 

With such a diversity of N-nItrosatlon pathways theoretically possible. It Is comforting to note that only a few combinations of circumstances have been Implicated In environmental nitrosamlne formation thus far. Two of these are so facile and prevalent that, as of 20 years ago, they were the only recognized mechanisms of N-nItrosatlon. They Involve the Interaction of di-or trisubstituted ammonia derivatives with a nitrite Ion, as Illustrated In Figure 1 for the secondary amines, under the catalytic Influence of acid. Note the Important special cases of nucleophilic displacement of water from the nitrous acldlum Ion, H20-N0 , by a second nitrite Ion to yield NoOo (as in the reaction at the top of Figure 1), and by nitrate (bottom of Figure... 

Ditfural undergoes condensation to furoin under the catalytic influence of cyanide ions in aqueous alcohol soluticm (compare Benzoin, Section IV,125) ... 

Hosier H, Richter B, Behm RJ. 2004. Catalytic influence of Pt monolayer islands on the hydrogen electrochemistry of Ru(OOOl) studied by ultrahigh vacuum scanning tunneling microscopy and cychc voltammetry. J Phys Chem B 108 14780. 

In the course of studying the reactions of Si-H compounds with dialkyltitanocenes, with a view to the synthesis of new hydridosilyltitanocene complexes, we adventitiously discovered that phenylsilane undergoes facile, quantitative dehydrogenative coupling to a linear poly(phenylsilylene) under the catalytic influence of dimethyltitanocene. The ease with which this reaction proceeds initially induced us to underestimate the significance of the observation. 

Although the concepts of specific acid and specific base catalysis were useful in the analysis of some early kinetic data, it soon became apparent that any species that could effect a proton transfer with the substrate could exert a catalytic influence on the reaction rate. Consequently, it became desirable to employ the more general Br0nsted-Lowry definition of acids and bases and to write the reaction rate constant as... 

In a more complex type of reaction, propene reacts with methyl trichloro-acetate under the catalytic influence of cyclopentadienylmolybdenum tricarbonyl or cyclopentadienyliron dicarbonyl dimers to give 4-methyl-2,2 -... 

The kinetic study of antioxidant decay by the reaction with hydroperoxides produced by T-6 oxidation proved the catalytic influence of the copper surface. The rate of this reaction in the absence of dioxygen obeys the equation... 

Summarizing, it appears that D-mannitol with boiling hydrochloric acid first suffers dehydration between Cl and C4 (because when the treatment is interrupted after only a few hours duration, 1,4-anhydro-D-mannitol is obtained), then between C3 and C6. The dehydration is probably achieved by the catalytic influence of the chloride ion. Dehydration is accompanied by the formation of smaller amounts of other ring compounds and by substitution of secondary hydroxyl groups by chlorine. With fuming hydrochloric acid, D-mannitol gives mainly 1,6-dichloro-... 

For the replacement of oxygen by hydrogen in ketones and aldehydes the method of Kishner and Wolff is used as often as is that of Clemmensen. In the former method the hydrazone or semicarbazone of the carbonyl compound is heated for several hours—preferably in the presence of hydrazine hydrate—in a sealed tube or autoclave with sodium ethoxide at about 160°. The explanation of the reaction is that, under the catalytic influence of the ethoxide, the hydrazone is transformed into a diimine which then decomposes in the same way as does phenyldiimine (p. 286) ... 

The observed catalytic effect of the crown ether appears to be dependent on the nucleophile employed in both polymerization and corresponding model reactions. Not surprisingly, it appears that the stronger the nucleophile employed, the smaller the catalytic influence of the crown ether. For example, with potassium thiophen-oxide yields of polymer or model products were almost quantitative with or without catalyst. By contrast, the reaction of PFB with potassium phthalimide, a considerably weaker nucleophile, affords 6 in 50% with catalyst and in 2-3% without catalyst under identical conditions. However, it may be that this qualitative difference in rates is, in fact, an artifact of different solubilities of the crown complexed nucleophiles in the organic liquid phase. A careful kinetic study of nucleophilicity in catalyzed versus non-catalyzed reactions study is presently underway. 

A much more systematic approach involves the use of p-chlorides carrying non-participating groups at C-2 as is exemplified by the Wolfrom synthesis of p-isomaltose octa-acetate from 1,2,3,4-tetra-O-acetyl-p-D-glucopyranose and 3,4,6-tri-0-acetyl-2-0-nitro-p-D-glucopyranosyl chloride In this work silver carbonate was used as acid acceptor and soluble silver perchlorate was fmmd to exert valuable catalytic influence, but later the perchlorate itself was used in an application to a tiisacchar-ide s mthesis which incorporated the trityl ether modification 2 ). 

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