Dimethyl 2-bromosuccinate

Olson and Cunningham (6) found that the specific conductance of 0.01m lithium bromide in acetone was increased by 30% when sufficient bromosuccinic acid, was added to make the solution 0.2m with respect to the acid. When dimethyl bromosuccinate was added in lieu of bromosuccinic acid, the specific conductance was diminished by 6% and when lithium perchlorate was substituted for lithium bromide, the specific conductance decreased linearly as bromosuccinic acid was added. These observations motivated Cunningham and his co-workers to continue work in the field. 

Dimethyl bromosuccinate was prepared from bromosuccinic acid by the diazomethane method (26) using the procedure of Eisenbraun, Morris, and Adolphen (27). It was distilled under vacuum (0.08-0.1 Torr) at 45°-49°C to yield a clear colorless oil. Thin layer chromatography with benzene as the solvent on SiC>2 yielded a symmetrical single spot, indicating either a pure compound or no separation with this particular solvent. Its mass spectrum had a very small peak corresponding to the parent compound, but none to a dibromo compound. The mass spectrum for dimethyl bromosuccinate was not found in the literature, but that for dimethyl succinate also has a small peak corresponding to the parent compound (25). 

Procedure. Equation 1 indicates that it is necessary to determine the concentration, resistance, dielectric constant, viscosity, and temperature of the system. These data were acquired for five different solvent systems. A series of measurements, in which the concentration of lithium bromide was varied from about 10 5N to 10 3N, was made on each system. The solvents used were acetone (I), 0.02063m bromosuccinic acid in acetone (II), 0.05009m bromosuccinic acid in acetone (III), 0.09958m bromosuccinic acid in acetone (IV), and 0.05047m dimethyl bromosuccinate in acetone(V). Each solvent was used to prepare stock solutions of 10-2 and 10 3m lithium bromide. All mixed solvents and solutions were prepared in the dry box. 

Bjornson also measured the specific conductance of a solution of 0.01m lithium bromide in acetone with various amounts of dimethyl bromosuccinate added and found a slight linear decrease in specific conductance with addition of dimethyl bromosuccinate. These results, along with those of Olson and Cunningham, lent support to Bjornson s postulate, in that when the acidic hydrogens of bromosuccinic acid were replaced with methyl groups, or the bromide ions of lithium bromide were replaced with perchlorate ions, the increase in specific conductance was not observed. 

Series V consisted of runs in which lithium bromide was added to a fixed amount of dimethyl bromosuccinate in acetone. Table I shows that the solvent correction is greater than for Series I, but less than for Series II—IV. The specific conductance of lithium bromide in dimethyl bromosuccinate-acetone is only slightly less than in acetone. This is in contrast to Series II—IV. Table II shows that both Ao and K are less than for Series I but greater than for Series II—IV. Table I indicates that for Series V the trends in each column are the same as for Series I. The results of Series V are in agreement with those of Bjornson and those of Olson and Cunningham. 

In any event, it can be concluded that in acetone there are strong associations between bromosuccinic acid and lithium bromide ions. The largest concentration of bromosuccinic acid studied (Series IV) is approximately equal to the lowest concentration studied for the acetone-water and acetone-methanol systems. As expected, the data show the association with the acid to be much greater than with either the methanol or the water. From the K and a values it is evident that the association between the salt and dimethyl bromosuccinate is much less than the association of the salt with bromosuccinic acid but greater than the salt-acetone association. In view of this, it is concluded that the association between the bromide ion and the second solvent accounts for the change in K. Knowledge of the precise nature of the association will have to await further investigations. 

Halohydrin formation with subsequent reductive dehalogcnation represents an interesting variation on the theme. For example, when the enone rac-1 was treated with A -bromosuccin-imide in aqueous dimethyl sulfoxide, the bromohydrin roc-2 was formed, predominantly as one diastereomer (the relative configuration at C-3 was not established)23. Reduction with tri-butyltin hydride gave the diastereomeric products exo-3 and endo-3 in 27% and 63% yield, respectively. Here, the product distribution can be explained by the preferred attack of the hydride reagent on the exo-face of the intermediate bicyclic carbon radical, i.e., by kinetic control. Thus, the predominant endo-orientation of the 2-(2-hydroxypropyl) substituent at C-3 was achieved, in contrast to what may be expected from a reversible, i.e., thermodynamically controlled, hydration of the enone rac-1. 

Diarylacetylenes are converted in 55-90% yields into a-diketones by refluxing for 2-7 h with thallium trinitrate in glyme solutions containing perchloric acid [413. Other oxidants capable of achieving the same oxidation are ozone [84], selenium dioxide [509], zinc dichromate [660], molybdenum peroxo complex with HMPA [534], potassium permanganate in buffered solutions [848, 856, 864,1117], zinc permanganate [898], osmium tetroxide with potassium chlorate [717], ruthenium tetroxide and sodium hypochlorite or periodate [938], dimethyl sulfoxide and iV-bromosuccin-imide [997], and iodosobenzene in the presence of a ruthenium catalyst [787] (equation 143). 

Problem 7.6 When an unsymmetrical alkene such as propene is treated with iV-bromosuccin-imide in aqueous dimethyl sulfoxide, the major product has the bromine atom bonded to the less highly substituted carbon atom. Is this Markovnikov or non-Markovnikov orientation Explain. 

Related Reagents. N-Bromosuccinimide-Dimethylform-amide N-Bromosuccinimide-dimethyl sulfide N-Bromosuccin-imide-hydrogen fluoride N-Bromosuccinimide-sodium azide Triphenylphosphine-Al-Bromosuccinitnide. 

The structure of the condensation products of thioureas and dimethyl acetylenedicarboxylate had not been assigned with certainty. This problem has now been resolved, in one case, by 2f-ray analysis. Thus the addition of iV-thiocarbamoylpiperidine to the acetylenic reagent, which may theoretically give rise to six isomeric products, yields in fact 5-methoxy-carbonylmethylene-2-piperidino-2-thiazolin-4-one, having the geometrical configuration shown in (166). Confirmation has also been provided that the reaction of thiourea with bromosuccinic, maleic, fumaric, or acetylenedicarboxylic acids yields, in each case, a 2-thiazoIine, e.g. (167). ... 

Related Reagents. A-Bromosuccinimide-dimethylform-amide A-bromosuccinimide-dimethyl sulfide A-bromosuccin-imide-hydrogen fluoride A-bromosuccinimide-sodium azide triphenylphosphine-A-bromosuccinimide. 

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