Butane bromination

Chlorination or bromination of methane, ethylene, etc Maleic anhydride (from butane)... 

In the presence of catalysts, trichloroethylene is readily chlorinated to pentachloro- and hexachloroethane. Bromination yields l,2-dibromo-l,l,2-trichloroethane [13749-38-7]. The analogous iodine derivative has not been reported. Fluorination with hydrogen fluoride in the presence of antimony trifluoride produces 2-chloro-l,l,l-trifluoroethane [75-88-7] (8). Elemental fluorine gives a mixture of chlorofluoro derivatives of ethane, ethylene, and butane. 

Four-membered rings also exhibit angle strain, but much less, and are less easily opened. Cyclobutane is riiore resistant than cyclopropane to bromination, and though it can be hydrogenated to butane, more strenuous conditions are required. Nevertheless, pyrolysis at 420°C gives two molecules of ethylene. As mentioned earlier (page 177), cyclobutane is not planar. 

A base-induced bromination has been reported. 2-Methyl butane reacts with 50% aqueous NaOH and CBr4, in a phase-transfer catalyst, to give a modest yields of 2-bromo-2-methylbutane. ... 

Bromine Ammonia, acetylene, butadiene, butane or other petroleum gases, sodium carbide, turpentine, benzene, or finely-divided metals... 

Hydrocarbons (benzene, butane, Fluorine, chlorine, bromine, chromic acid, peroxide... 

Chlorine dioxide Copper Fluorine Hydrazine Hydrocarbons (benzene, butane, propane, gasoline, turpentine, etc) Hydrocyanic acid Hydrofluoric acid, anhydrous (hydrogen fluoride) Hydrogen peroxide Ammonia, methane, phosphine or hydrogen sulphide Acetylene, hydrogen peroxide Isolate from everything Hydrogen peroxide, nitric acid, or any other oxidant Fluorine, chlorine, bromine, chromic acid, peroxide Nitric acid, alkalis Ammonia, aqueous or anhydrous Copper, chromium, iron, most metals or their salts, any flammable liquid, combustible materials, aniline, nitromethane... 

Mercuric oxide, use in oxidation of hydrazones, 50, 28 with 3-chlorocyclobutanecar-boxylic acid and bromine to give l-bromo-3-chlorocyclo-butane, 51, 106 MERCURIC OXIDE-MODIFIED HUNS-DIECKER REACTION 1-BRQMO-... 

Bromination of alkanes follows the same mechanism as chlorination. The only difference is the reactivity of the radical i.e., the chlorine radical is much more reactive than the bromine radical. Thus, the chlorine radical is much less selective than the bromine radical, and it is a useful reaction when there is only one kind of hydrogen in the molecule. If a radical substitution reaction yields a product with a chiral centre, the major product is a racemic mixture. For example, radical chlorination of n-butane produces a 71% racemic mixture of 2-chlorobutane, and bromination of n-butane produces a 98% racemic mixture of 2-bromobutane. 

Likewise, a study on the bromination of these compounds also indicated that the 1,3-addition was 100% syn stercospecific.10 Interestingly, 3-phenylbicyclo[1.1.0]butane-l-carbonitrile, from which a relatively stable benzylic cation can be formed, yielded a mixture of cis- and /ram-products.10 An electron-transfer mechanism has been proposed for these reactions.10 A recent investigation on perchloric acid catalyzed methanol addition to 3-methylbicyclo[1.1.0]butane-1-carbonitrile and methyl 3-mcthylbicyclo[1.1.0]butane-l-carboxylate, however, showed that mixtures of irons- and cA-cyclobutanes were generated, with the m-isomers predominating.11... 

Dibromobutane (from butane-1,4-diol). Use 45 g (0.5 mol) of redistilled butane-1,4-diol, 6.84g (0.22mol) of purified red phosphorus and 80g (26 ml, 0.5 mol) of bromine. Heat the glycol-phosphorus mixture to 100-150 °C and add the bromine slowly continue heating at 100-150 °C for 1 hour after all the bromine has been introduced. Allow to cool, dilute with water, add 100 ml of ether and remove the excess of red phosphorus by filtration. Separate the ethereal solution of the dibromide, wash it successively with 10 per cent sodium thiosulphate solution and water, then dry over the anhydrous potassium carbonate. Remove the ether on a water bath and distil the residue under diminished pressure. Collect the 1,4-dibromobutane at 83-84 °C/ 12mmHg the yield is 73 g (67%). 

When the sodium derivative of butane tetra-carboxylic ester is acted upon by bromine, the resulting product is tetramethylene-1 2-tetracarboxylic ester ... 

Most butynediol produced is consumed in the manufacture of butane-diol and butenediol. Butynediol is also used for conversion to ethers with ethylene oxide and in the manufacture of brominated derivatives that are useful as flame retardants. Butynediol was formerly used in a wild oat herbicide, Carbyne (Barban), 4-chloro-2-butynyl-A-(3-chlorophenyl)carba-mate (CnH9Cl2N02). 

Peterson reactions. Reaction of Li in THF with 1 leads to the 1,4-dianion (2) of l,l,4,4-tetrakis(trimethylsilyl)butane in 96% yield. This dianion reacts with paraformaldehyde to form 1,5-diene 3, which can be converted to 4 by bromination-bromodesilylation. 

The recombination of bromine atoms can not occur except on collision with a third body but reaction between the more complicated ethyl radicals might be expected without the aid of walls or triple collisions. In any reaction involving the production of free ethyl radicals one might expect to find butane, ethane, etc., but actually very little of these products is found. Apparently in this case radicals of this type are not likely to combine with each other. 

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