Magnesium cyclohexyl- bromid

Mercury dicyclohexyl.—This compound proved more difficult to isolate than the phenyl derivative, but has been obtained by the action of mercuric bromide on a large excess of magnesium cyclohexyl bromide. It is much less stable than mercury diphenyl, decomposing even in a few hours to a black oil when kept over phosphorus pentoxide in the dark in a vacuum desiccator. Mercury dicyciohexyl forms white, hard granules, M.pt. 78° to 79° C., which are more soluble than mercury diphenyl, and combines directly with mercuric halides or cyanide in any solvent to form cyclohexylmercuric salts. It has also been prepared by the sodium amalgam method, when it is said to form white needles, M.pt. 189° C., -which can be sublimed in small quantities in vacuo ... 

Tin triphenyl cyclohexyl is obtained from tin triphenyl chloride and an excess of magnesium cyclohexyl bromide. It forms bushy, colourless... 

Lead diphenyl dicyclohexyl may be prepared either by the interaction of magnesium cyclohexyl bromide and lead diphenyl dibromide or magnesium phenyl bromide and lead dicyclohexyl dibromide. It forms pale yellow needles, Mq t. 178° to 180° C., the yellow liquid soon depositing metallic lead. The compound is soluble in alcohol, benzene, carbon tetrachloride, or ethyl acetate. ... 

A 3-I. three-necked, round-bottom flask is fitted with a mechanical stirrer through a mercury seal, a reflux condenser and a i-l. separatory funnel. A mixture of 200 g. (r mole) of 2,3-dibromopropene (Org. Syn. 5, 49) and 200 cc. of dry ether is added. The flask is now cooled in an ice bath, the stirrer is started, and one molecular equivalent of cyclohexylmagnesium bromide, prepared from 31 g. of magnesium, 204 g. of cyclohexyl bromide and 400 cc. of dry ether (Note i) is added at such a rate that the mixture refluxes gently (Note 2). The addition takes about one-half to three-quarters of an hour. Two layers are formed and magnesium bromide may or may not separate. 

The preparation of cyclohexylmagnesium bromide is described on p. 22. The solution may be standardized by titrating against 0.5 N hydrochloric acid, and exactly one mole equivalent is used in the preparation. Five cubic centimeters of cyclohexylmagnesium bromide solution is slowly added to 20 cc. of water, an excess of the standard acid is added, and the excess acid titrated with sodium hydroxide. If 85 g. (3.5 moles) of magnesium, one liter of dry ether, and 571 g. of cyclohexyl bromide (3.5 moles) are used, a solution results which is about 2 molar. 

In a i-l. three-necked, round-bottom flask fitted with a mechanical stirrer through a mercury seal, a separatory funnel and an efficient reflux condenser to which a calcium chloride tube is attached, are placed 25 g. (1.03 moles) of magnesium turnings 140 cc. of dry ether, and a small crystal of iodine. The stirrei is started and a small portion (about 10 cc.) of a solution of 118.5 g. (i mole) of cyclohexyl bromide (Note i) in 120 cc. of dry ether is added through the separatory funnel. After the reaction starts, the remainder of the solution is run in at such a rate that the whole is added at the end of forty-five minutes. The mixture is stirred and refluxed for an additional thirty to forty-five minutes. 

N-Phenacyl-N -methylpiperazine Cyclohexyl bromide Magnesium Dimethyl sulfate... 

The phosphine is prepared according to the above procedure starting with 24.1 g (0.99 mole) of magnesium turnings in 350 mL of dry diethyl ether and 162 g (122 mL, 0.99 mole) of cyclohexyl bromide (bromocyclohexane) in 130 mL of dry diethyl ether. The resulting Grignard reagent is cooled in an ice-salt bath and treated dropwise (2 hr) with 81 g (61.4 mL, 0.45... 

Lead diphenyl cyclohexyl bromide occurs as fine groups of prismatic needles, M.pt. 185 C., decomposing at 100 C. Phenyl magnesium bromide converts it to lead triphenyl cyclohexyl. 

Lead diphenyl cyclohexyl methyl is isolated fronci pure lead diphenyl cyclohexyl bromide and an excess of methyl magnesium bromide. It is a liqxiid at ordinary temperatures, miscible with most organic solvents and aqueous alcohol. When brorainated it is converted into lead phenyl cyclohexyl methyl bromide. 

The manufacture of the cyclohexyl analog is as follows. Phenyl magnesium bromide was prepared from 48.5 g (0.308 mol) of bromobenzene, 7 g (0,29 mol) of magnesium, and 125 ml of dry ether. To it was added at 5°C over a period of A hour 40 g (0.18 mol) of cyclohexyl (3-(N-piperidyl)-ethyl ketone (BP 115° to 117°C/1 mm) in 125 ml of dry ether. The mixture was allowed slowly to come to room temperature, refluxed for one hour, and then poured into ice containing 80 ml of concentrated hydrochloric acid. Ammonium chloride (100 g) and 200 ml of concentrated ammonium hydroxide were added and the organic layer was separated. After drying and removing the solvent, the residue was distilled under reduced pressure. The base distilled at 158° to 170°C (1 mm) and solidified. Upon recrystallization from methanol it melted at 112° to 113°C. 

Holm determined the enthalpies of formation of a collection of hydrocarbyhnagnesium bromides by reaction calorimetry with HBr in diethyl ether . He also determined the enthalpies of formation in ethereal solution of the magnesium bromide salts of 20 Bronsted acids, HB, by measuring the enthalpies of reaction of the acid with pentylmag-nesium bromide. For those species that were reported in both studies (hydrocarbyl = phenylethynyl, phenyl, methyl, cyclopropyl, cyclopentyl, cyclohexyl), the enthalpies of formation were identical. The values are listed in Tables 3 and 4. 

There remain three Bronsted acids that have no liquid phase enthalpy of formation data that we know of dodecanethiol, cyclohexyl methyl amine and A-methyl dodecanamide. Although the enthalpy of formation of 1-dodecanethiol has not been measured, there are experimental values available for other members of its homologous series, C2-C7, Cjo. From a weighted least-squares analysis of the data from which a slope, —25.4, and an intercept, —23.3, are derived, the enthalpy of formation of dodecanethiol is —328.1 kJ moH The enthalpy of formation of dodecanethiolate magnesium bromide is thus estimated as —744.6 kJmoH. We can estimate the enthalpy of formation of cyclohexyl methyl amine by assuming equation 12 is thermoneutral. 

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