Ethylene compound

Perbenzoic acid is used for the conversion of ethylenic compounds into oxides ... 

Ethylenic compounds when oxidised with perbenzoic acid or perphthalic acid in chloroform solution yield epoxides (or oxiranes). This Is sometimes known as the Prileschajew epoxidation reaction. Thus pyrene affords styrene oxide (or 2-plienyloxirane) ... 

Heating or steam distillation affords ethylenic compounds thus (I) yields pheuyl vinyl ketone (II) ... 

Reduction of the ethylenic compound gives a ketone, propiophenone (III), with one more methylene group than the ketone used in the original preparation ... 

It is essential to apply both tests, since some symmetrically substituted ethylenic compounds (e.g., ilbene C4H5CH=CHCjHj) react slowly under tbe conditions of the bromine test. With dilute permanganate solution the double bond is readily attacked, probably through the intermediate formation of a cis diol ... 

When fluorine is beta to siUcon, compounds undergo a facile elimination of an ethylenic compound and again form the stable silicon—fluorine bond... 

Xthyl at, n. ethylate, -atber, m. ethyl ether, >azetat, n, ethyl acetate, -blau, n, ethyl blue. AthyleQi n, ethylene, -bindung, /, ethylene linkage, double bond, -jodid, n. ethylene iodide, -oryd, n. ethylene oxide, -reihe, /. ethylene series, -verbindung, /. ethylene compound,... 

STEREO-, REGIO- AND CHEMOSELECTIVITY OF BROMINATION OF ETHYLENIC COMPOUNDS... 

Apart from information on stereochemistry, bromine bridging does not provide a priori any rule regarding regio- and chemoselectivity. Therefore, we systematically investigated (ref. 3) these two selectivities in the bromination of ethylenic compounds substituted by a variety of more or less branched alkyl groups (Scheme 4). 

Shimada T, Swanson AF, Leber P, et al. 1985. Activities of chlorinated ethane and ethylene compounds in the Salmonella microsome mutagenesis and rat hepatocyte/DNA repair assays under vapor phase exposure conditions. Cell Biol Toxicol 1 159-179. 

Saturated and ethylenic compounds have the same AIT averages on the other hand the presence of an aromatic cycle significantly increases this parameter. AIT averages for these groups are respectively 339 9 C, 347 14°c and 538 16°C. 

Excessive heating of ethylenic compounds, which caused their polymerisation. 

This reaction is characteristic of aromatic and ethylene compounds. The amine group does not play a direct role in it. 

The electrophilic bromination of ethylenic compounds, a reaction familiar to all chemists, is part of the basic knowledge of organic chemistry and is therefore included in every chemical textbook. It is still nowadays presented as a simple two-step, trans-addition involving the famous bromonium ion as the key intermediate. T]nis mechanism was postulated as early as the 1930s by Bartlett and Tarbell (1936) from the kinetics of bromination of trans-stilbene in methanol and by Roberts and Kimball (1937) from stereochemical results on cis- and trans-2-butene bromination. According to their scheme (Scheme 1), bromo-derivatives useful as intermediates in organic synthesis... 

The bromination of ethylenic compounds is in most cases a very fast reaction. Half-lives of typical olefins are given in Table 1. Most of them are very short. In order to obtain extended and meaningful kinetic data, it has been necessary to find suitable reaction conditions and to design specific kinetic techniques. This was not done until 1960-1970. As a consequence, kinetic approaches to the bromination mechanism are relatively recent as compared with those to solvolytic reactions, for example. 

Table 1 Bromination half-lives" of some ethylenic compounds at 10 3 m reagent concentration and at 25°C.

It is concluded that the selectivities of electrophilic additions are not directly related to the reactivities but to the transition-state positions. Extensive comparison with similar data on the bromination and hydration of other ethylenic compounds bearing a conjugated group shows that this unexpected reactivity-selectivity behaviour can arise from an imbalance between polar and resonance effects (Ruasse, 1985). Increasing resonance in the ground state would make the transition state earlier and attenuate the kinetic selectivity more strongly than it enhances the reactivity. Hydration and halogenation probably respond differently to this imbalance. 

In fact, the analogy between the mechanisms of heterolytic nucleophilic substitutions and electrophilic bromine additions, shown by the similarity of kinetic substituent and solvent effects (Ruasse and Motallebi, 1991), tends to support Brown s conclusion. If cationic intermediates are formed reversibly in solvolysis, analogous bromocations obtained from bromine and an ethylenic compound could also be formed reversibly. Nevertheless, return is a priori less favourable in bromination than in solvolysis because of the charge distribution in the bromocations. Return in bromination implies that the counter-ion, a bromide ion in protic solvents, attacks the bromine atom of the bromonium ion rather than a carbon atom (see [27]). Now, it is known (Galland et al, 1990) that the charge on this bromine atom is very small in bridged intermediates and obviously nil in /f-bromocarbocations [28]. 

In order to characterize electron acceptor (basic type) properties of the samples, tetracyano ethylene compound, known to be easily ionizable in TCNE radical anion, was introduced at room temperature in the samples outgassed at different temperatures up to 800°C. No ESR signal was observed. As steric hindrance could preclude the experiment, smaller molecules as SO and p-dinitro benzene were also introduced. Then too, no ESR spectrum could be detected although the ESR technique is extraordinarly sensitive. It may thus be concluded that the ZSM-5 and ZSM-11 materials did not exhibit electron donor (basic) properties as detectable by ESR. 

Type iii-b This reaction leads to products (67). The electrochemical oxidation of the sodium salts of acetic, propionic, and isovaleric acids in the presence of ethylenic compounds bearing electron-withdrawing substituents gives 1,2-dialkylated adducts as the main products. A methyl radical generated from an acetate ion reacts with diethyl fumarate to give diethyl 2,3-dimethylsuccinate in 80% yield [106]. 

Howard, C.J. Rate constants for the gas-phase reactions of OH radicals with ethylene and halogenated ethylene compounds, J. Chem. Phys., 65(ll) 4771-4777, 1976. 

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