Phosphorus halides synthesis

The action of phosphorus halides on pyrrolinones and related compounds offers an alternative route to chloropyrroles. Yields of around 60% of 2,5-dichloropyrroles were obtained in this way from N-substituted succinimides (82ZC126). Vilsmeier reaction of N-alkylsuccinimidals formed chlorinated pyrrole aldehydes in modest yields (90CJC791), and there are other examples [66YZ158 81H(15)547]. A useful synthesis of chloropyrrole-2-carboxylates employed the action of phosphorus pentachloride on pyrrolidin-2-one-5-carboxylates (40) (87CB45) (Scheme 15), and in a Pummerer-type reaction pyrrol-3-yl sulfoxides were transformed by thionyl chloride into chloropyrroles. Yields were increased to >80% by the use of oxalyl chloride (88JOC2634) (Scheme 15). 

Phenols resemble aryl halides in that the functional group resists displacement. Unlike ROH, phenols do not react with HX, SOCI2, or phosphorus halides. Phenols are reduced to hydrocarbons, but the reaction is used for structure proof and not for synthesis. 

Most of the conventional reagents for the synthesis of acid chlorides from carboxylic acids are unsatisfactory for the preparation of a-keto acid chlorides. For example, the reaction of pyruvic acid with phosphorus halides does not give pyruvoyl chloride7 whereas the use of phosgene8 or oxalyl chloride9,10 affords ether solutions of the acid chloride in low yield. Recently a useful preparation of pyruvoyl chloride from trimeth-ylsilyl pyruvate and oxalyl chloride has been described.11... 

Secondary phosphines can be prepared by three main routes. The first method, reduction of a phosphinous halide, R2PCI with UAIH4 (Scheme 12) requires an efficient synthesis of the starting phosphorus halide, as both the starting material and the product may be difficult to purify. 

Conant, J.B.. and Coyne, B.B., Addition reactions of the phosphorus halides. Part 5. The foimation of an unsaturated phosphonic acid, J. Am. Chem. Soc., 44, 2530, 1922 Chem. Abstr., 17, 273a. 1923. Gajda. T.. A convenient synthesis of diethyl 1-chloroalkylphosphonates, Synthesis, 111, 1990. Pudovik, A.N.. Zimin, M.G., and Sobanov, A.A., Reactions of dialkyl phosphites withketones activated by electronegative groups, Zh. Obshch. Khim., 42, 2174. 1972 Chem. Abstr., 78, 58543, 1973. Johnson. R.A.. Aryhnethylphosphonates and phosphonic acids useful as anti-inflammatory agents, their preparation, and their activity, Upjohn, U.S. Patent Appl. US 5500417, 1996 Chem. Abstr. 124. 307587. 1996. 

Amino groups can also serve to block a position on phosphorus (29, 49). To avoid nitrogen-phosphorus bond cleavage in the synthesis of 41, the lithium reagent was added to the phosphorus halide at —60° yield of 41 was 48% (49).. ... 

Tetravalent phosphorus halides are known to react with lithium reagents, but data is scarce. Aryllithium reagents easily displace chloride ion from phosphoryl chloride in the synthesis of tertiary phosphine oxides (143,144,174). A small quantity of the corresponding phosphinic acid (42) was isolated in the preparation of tris(p-dimethylamino-phenyl)phosphine oxide (43) (174). Choice of conditions and concentrations of reactants may well favor either the single or the double dis-... 

The reduced phospholes are never made directly by hydrogenation of phospholes most commonly, the ring is created in the desired state of reduction while phosphorus is in the oxide or sulfide form, and the process is completed by removal of these atoms. For the synthesis of 2- and 3-phospholenes, the McCormack cycloaddition of trivalent phosphorus halides with dienes, followed by hydrolysis, is the method of choice for obtaining the requisite P-oxides. This process, first described in US patents <53USP2663737,53USP2663738) by W. B. McCormack of the duPont Co., has... 

The reaction of thioamides with suitable chlorinating agents, such as phosphorus halides, thionyl chloride, carbonyl chloride, etc., is perhaps the most general method of synthesis of imidoyl chlorides. However, this method has been used only in very few instances because thioamides are less readily available than amides. 

Reactive impurities are substances that can react with the monomers, the growing chain-ends, or the acid acceptor to terminate the polymerization prematurely. They can be introduced with the solvent or with the intermediates. The acid chloride may contain impurities originating in its synthesis or storage such as hydrogen chloride, thionyl chloride, phosphorus halides, or monoacid halides. The diamine may contain monoamines, water, or carbonates. It may degrade oxidatively in air or absorb moisture and carbon dioxide. The degree of interference caused by these impurities depends on both the quantity of the impurities as well the relative reaction rates of the desired polymerization vs. those of the impurities. 

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