Ethylene reaction with bromine

Ethylene bromohydrin has been prepared by the reaction between ethylene glycol and hydrobromic acid and phosphorus tribromide. It has also been prepared by the direct addition of hypobromous acid to ethylene, and by the reaction between ethylene and dilute bromine water. With ethylene oxide now available at a reasonable price, the method described is probably the best because of the high yields and the convenience of reaction. 

A"" -3-Ketones are more reactive than cross-conjugated A ""-3-ketones. A"" -3,3-CycIoethylenedioxy compounds can be easily prepared by acid-catalyzed reaction with ethylene glycol or by exchange dioxolanation. 3,3-Cycloethylenedioxy-A -dienes can be prepared from 3,3-cycloethy-lenedioxy-A -enes by allylic bromination and dehydrobromination. Acid hydrolysis yields A"" -3-ketosteroids. ... 

A recent example of a product that is demanding in terms of process chemistry is a new herbicide from BASF. The seven-step synthesis requires bromination, chlorination, carbonylation, oxydation (with H2O2), hydrogenation, and a reaction with ethylene. As no fine-chemical manufacturer was in a position to offer the whole range of process technologies, the manufacture will be split between two fine-chemical companies. 

Bromine adds readily to the alkenes to give dibromides. The reaction with ethylene is... 

Russel [142] developed a method based on the conversion of chlorine, bromine and iodine ions into the corresponding halogenated ethanols by reaction with ethylene oxide. Belcher et al. [143] offer a method for determining trace amounts of chloride ions, based on reaction with mercury phenylnitrate to give phenylmercury chloride, which is chromatographed with flame-ionization detection. 

Kinetic data on the reaction of oxygen atoms.with acetylenic compounds is reported in Table 25. It should be noted that the reaction with acetylene, for which there is considerable data, is much slower than the corresponding reaction with ethylene. The reactivity of ethylene is about five times greater than that of acetylene. This contrasts with bromine atom addition in which the reactivity of acetylene is slightly greater than that of... 

The transition state structure for the addition of molecular fluorine to ethylene VIIc was found by the 3-2IG calculations [17] to closely resemble that for the addition of HCl (IV). Of special interest are the computational results obtained on transition state structures Vlld, Vile for gas phase electrophilic addition reactions of molecular chlorine and bromine to ethylene. Whereas the four-centered structure VIIc for the fluorination of ethylene indicates concerted c/s-addition, which is in accord with experimental finding for this reaction [18], the transition state geometries for chlorination and bromination may be regarded as cyclic halonium ions backed by halogenide counter-ions. Noteworthy is that the calculations [17] predict the heterolysis to occur intrinsically without any assistance from polar solvents. The three-centered structures Vlld, Vile help to clarify the reason for trans-stereoselectivity of the chlorination and bromination reactions of ethylene [1, 19]. 

Bromine. Slip the glass cover of a jar momentarily aside, add 2-3 ml. of bromine water, replace the cover and shake the contents of the jar vigorously. Note that the bromine is absorbed only very slowly, in marked contrast to the rapid absorption by ethylene. This slow reaction with bromine water is also in marked contrast to the action of chlorine water, which unites with acetylene with explosive violence. (Therefore do not attempt this test with chlorine or chlorine water.)... 

Many of the features of the generally accepted mechanism for the addition of halogens to alkenes can be introduced by referring to the reaction of ethylene with bromine... 

Flame-Retardant Resins. Flame-retardant resins are formulated to conform to fire safety specifications developed for constmction as well as marine and electrical appHcations. Resins produced from halogenated intermediates (Table 5) are usually processed at lower temperatures (180°C) to prevent excessive discoloration. Dibromoneopentyl glycol [3296-90-0] (DBNPG) also requires glass-lined equipment due to its corrosive nature. Tetrabromophthahc anhydride (TBPA) and chlorendic anhydride (8) are formulated with ethylene glycols to maximize fiame-retardant properties reaction cycle times are about 12 h. Resins are also produced commercially by the in situ bromination of polyester resins derived from tetrahydrophthahc anhydride... 

The procedure described is essentially that of Belleau and Weinberg and represents the only known way of obtaining the title compound. One other quinone acetal, 1,4,9,12-t6traoxadispiro[4.2.4.2]tetradeea-6,13-diene, has been synthesized by a conventional method (reaction of 1,4-cyclohexanedione with ethylene glycol followed by bromination and dehydrobromination ) as well as by an electrochemical method (anodic oxidation of 2,2-(l,4-phenylenedioxy)diethanol ). Quinone acetals have been used as intermediates in the synthesis of 4,4-dimethoxy-2,5-cyclohexadienone,. syw-bishomoquinone, - and compounds related to natural products. ... 

Figure 3.1 The reactions of ethylene and menthene with bromine. In both molecules, the carbon-carbon doublebond functional group has a similar polarity pattern, so both molecules react with Br2 in the same way. The size and complexity of the remainders of the molecules are not important.

Benzene shows neither the typical reactivity nor the usual addition reaction of ethylene. Benzene does react with bromine, Brs, but in a different type of reaction ... 

An alternative synthesis of a thermally stable cyclopentadienyl functionalized polymer involved ring bromination of poly(oxy-2,6-diphenyl-l,4-phenylene), followed by lithiation with butyl lithium to produce an aryllithium polymer. Arylation of 2-norbornen-7-one with the metalated polymer yielded the corresponding 2-norbornen-7-ol derivative. Conversion of the 7-ol to 7-chloro followed by treatment with butyl lithium generated the benzyl anion which undergoes a retro Diels-Alder reaction with the evolution of ethylene to produce the desired aryl cyclopentadiene polymer, 6. 

If ethylene is treated with nitrating acid, nitroethyl nitrate, N02.CH2.CH20N02 is produced, as has already been mentioned. The nitroethyl alcohol which is first formed by addition of nitric acid is fixed by esterification, whereas the addition compound with HNOs which is first formed at the double bond of benzene is decomposed with elimination of H20 for reasons which have been mentioned repeatedly. This case is therefore analogous to the reactions of bromine with ethylene and with benzene (p. 106). 

A rather more complex tertracyclic indole based compound lowers blood pressure by selective blockade of a 1-adrenergic receptors. Reaction of the anion from indole (72-1) with butyrolactone (72-2) leads to the scission of the carbon-oxygen bond in the reagent and the formation of the alkylated product (72-3). The acid is then cyclized onto the adjacent 2 position to give the ketone (72-4) by treatment with a Lewis acid such as polyphosphoric acid. Reaction with bromine then leads to the brominated ketone (72-5). This is subjected to reductive alkylation with ethylene... 

Sugar derivatives of phosphanes can be made by reaction of ethylene glycol derivatives with sugar diacetonides to form monoallyl ethers, which can be brominated at the double bond. These compounds react with phenyl-and diphenylphosphanes to yield ligands with a sugar function in the side chain (57). Phosphinated glucopyranosides were prepared by Oehme and... 

The halogenation reaction of ethylene has been modeled by many researchers [170, 172-176], For chlorination in apolar solvents (or in the gas phase), the formation of two radical species requires the use of flexible CASSCF and MRCI electronic structure methods, and such calculations have been reported by Kurosaki [172], In aqueous solution, Kurosaki has used a mixed discrete-continuum model to show that the reaction proceeds through an ionic mechanism [174], The bromination reaction has also received attention [169,170], However, only very recently was a reliable theoretical study of the ionic transition state using PCM/MP2 liquid-phase optimization reported by Cammi et al. [176], These authors calculated that the free energy of activation for the ionic bromination of the ethylene in aqueous solution is 8.2 kcalmol-1, in good agreement with the experimental value of 10 kcalmol-1. 

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