Reaction of addition

Woodworth, based on the common reaction of addition of carbenes to double bonds to form cyclopropane derivatives (15-50). If the singlet species adds to cis-2-butene, the resulting cyclopropane should be the cis isomer since the movements of the two pairs of... 

Control of the bromine concentration is maintained by reaction (c) which is fast, though ionic, but can be activated only by HBr produced in the chain reaction (b). The alternative reaction of addition of Br-to the double bond to form (89) is reversible,... 

Tanaka et al.28 have synthesised a series of (S)-chiral Schiff bases as the highly active (yield 69-99%) and enatioselective (ee 50-96%) catalysts in the reaction of addition of dialkylzinc to aldehydes. The stereochemistry of the asymmetric addition was suggested. In a transition state when S-chiral Schiff base was used as chiral source, the alkyl nucleophile attacked Re face of the activated aldehyde and formed the R-configuration alkylated product [13]. 

Thermal initiation in the reaction of dichlorine with olefins proceeds via the bimolecular reaction of addition [4] ... 

The cleavage reaction is the reverse of the reaction of addition to unsaturated molecules which prevails at lower temperatures. 

Kamai, G. and Kukhtin, V.A., Reaction of addition of trialkyl phosphites to some unsaturated acids, Dokl. Akad. Nauk S.S.S.R., 109, 91, 1956. 

In this context, an avalanche of studies were devoted to acid-base reactions in their broadest sense (i.e., the Lewis picture), also involving complexation reactions, to the typical organic reactions of addition, substitution, and elimination types, involving nucleophilic and electrophilic reagents including the case of radicalar reactions and excited states (for a review see Ref. [11]) in which our group has... 

The reaction of additional tryptamine analogues (28) and EMME in boiling ethanol gave the appropriate aminomethylenemalonates (29) in 97-98% yields [85TL1769 87JCS(P 1)2079, 87T191]. 

Other examples of reactions of this type are the reactions of addition of hydrogen-halides to olefins, for example,... 

Heats of reactions. Starting with classic experiments by Kistiakowsky et al. (36JA146), the endothermicity of the first step, Eq. (36), of successive hydrogenation of benzene, namely, the transformation into cyclohexa-1,3-diene, unlike the exothermicity of the reactions of addition of the following hydrogen molecules, was thought to be largely associated with the loss... 

Modification of biological molecules (by reactions of addition or substitution), for instance, by alkylating agents or as a consequence of a coagulation of proteins... 

The two nonbonded electrons of a carbene can be either paired or unpaired. If they are paired, the species is spectrally a singlet, while, as we have seen (p. 193), two unpaired electrons appear as a triplet. An ingenious method of distinguishing between the two possibilities was developed by Skell,202 based on the common reaction of addition of carbenes to double bonds to form cyclopropane derivatives (5-50), If the singlet species adds to cis-2-butene, the resulting cyclopropane should be the cis isomer since the movements of... 

An interesting property of nitric esters, namely their ability to catalyse certain reactions of addition polymerization has been reported recently. Initially this observation was made by Rogovin and Tsaplina [66] while polymerizing styrene and methyl methacrylate in the presence of nitroglycerine. The latter amounted to 5-20 parts by weight corresponding to about 10% of the polymerized substance. As a result of the increased polymerization speed, the molecular weight of the polymer is smaller than if polymerization is carried out slowly. 

A summary of the major chemical reactions of free radicals is given in Table 4.3. Broadly speaking these can be classified as unimolecular reactions of dissociations and isomerizations, and bimolecular reactions of additions, disproportionations, substitutions, etc. The complexity of many photochemical reactions stems in fact from these free radical reactions, for a single species formed in a simple primary process can lead to a variety of final products. 

Interactions between the C=C double bond and halogens deserve particular attention. The importance of these interactions arises from the fact they are the first step of the reactions of addition of halogens to alkenes (and, in general, of the electrophilic addition to the carbon-carbon double bond68), which is a very useful functionalization reaction of the alkene double bond. 

The nature of the interaction between alkenes and halogens (complex 26 of Scheme 10) preceding the reactions of addition of the halogens to the C=C double bond is labelled according to Mulliken s classification71 as a CT complex. The nature of the carbonium... 

The number of reactions of addition of fluorine to the C=C double bond is not as large as that of addition of chlorine or bromine, and few examples of practical application of reactions of elemental fluorine are available. However, there is wide scope for development106 of these reactions for preparative purposes. 

Cristol and co-workers (4) found that cis-p-nitrostyryl bromide 22, in the presence of ethanolic sodium ethoxide, undergoes elimination (yielding Jl ) 2300 times faster than the trans-isomer 12 which undergoes an alternative reaction of addition (- 13). 

Tratnyek and Hoigne (1994) investigated 25 substituted phenoxide anions for QSARs that can be used to predict rate constants for the reaction of additional phenolic compounds oxidized by chlorine dioxide (OCIO). Correlating oxidation rates of phenols in aqueous solution is complicated by the dissociation of the phenolic hydroxyl group. The undissociated phenol and the phenoxide anion react as independent species and exhibit very different properties. The correlation analysis should be performed on the two sets of rate constants separately. 

Two different classes of chemical reactions are singled out, namely the reactions of addition of formaldehyde to the aromatic ring, which introduce a methylol group as a substituent, and the reactions of condensation, which produce components with higher molecular weight. In the presence of an alkaline catalyst, the reactions of addition are strongly oriented in the -orto and -para positions of the aromatic ring, whereas the reactions of condensation occur both between two substituted positions... 

Fig. 2.9 Reactions of addition to the phenolic ting (1-MPh = o-methylolphenol, 3-MPh = p-methylolphenol, 1,5-MPh = 1,5-methylolphenol, 1,3-MPh = 1,3-methylolphenol, TMPh = 1,3,5-methylolphenol)...

The studies of Schmidbaur et at. are also of interest in considering the possible mechanism of reaction of addition compounds (123). In this work... 

Results of recent study, however, have been interpreted in terms of a homo-lytic process. Schechter and Conrad [49] have observed that the production of methyl-3-nitroacrylate and methyl-2-hydroxy-3-nitropropionate in the reaction between N204 and methyl acrylate could not be explained on the basis of heterolytic addition, but was to be expected if a homolytic process were occurring. Brown [80] has shown that olefin nitration under circumstances in which the nitronium ion (N02+) is the reactant has characteristics entirely different from those of the N204-olefin reaction. Brand and I. D. R. Stevens [81] also believed the reaction of addition of nitrogen dioxide to olefins to involve radicals. According to these authors the following experimental facts provide evidence for this ... 

The kinetics and mechanism of Meisenheimer s reaction has been studied by Caldin and Ainscough [43] who utilized the reactions of addition of sodium etho-xylate to trinitroanisole, trinitrobenzene and trinitrotoluene. By using temperatures in the range from -70°C to -100°C they were able to reduce the reaction rate to a measurable value. On treating the addition product with acetic acid at temperatures ranging from -50°C to -80°C they obtained the starting product. Thus, the reaction was proved to be reversible, as for example in the case of trinitroanisole (TNA) ... 

In [17], two approaches were taken to assess the role of each reaction pathway quantum-chemical calculations and parabolic simulation of the reaction of addition (semiempirical method of intercrossing parabolas, MIP) [34-36]. Using these approaches in combination, the authors could evaluate independently the reaction rate constants for each pathway and compare their contributions to the total ozonation of olefins of different structures. The comparison results are listed in Table 8. We note a good agreement between the calculated and experimental constants values. 

Interesting possibilities for the synthesis of new types of polysaccharide derivatives are offered by the reaction of addition to double bonds, which proceeds by a free-radical mechanism. The presence of initiators of free-radical polymerization (benzoyl peroxide, tert-butyl peroxide, dicumyl peroxide, dinitrile of azodiisobutyric acid), also irradiation with ultraviolet light, has effected the addition to 5,6-cellulosene of chloroform, carbon tetrachloride, methylmonochloroacetate, dimethyl-phosphite and other compounds that decompc under the conditions of a reaction with the formation of free radicals (45,46). The reaction proceeds as follows ... 

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