Phosphorus generation

Processing wastes containing chlorine, sulfur, or phosphorus generates acids that must be neutralized in the reactor to prevent corrosion. 

Because removal of a proton from a carbon bonded to phosphorus generates a resonance-stabilized carbanion (the ylide), this proton is somewhat more acidic than other protons on an... 

Aromatic thioamides can be prepared as described in the literature by different ways, either by S -> O exchange between the corresponding benzamides and phosphorus pentasulfide in pyridine solution in the presence of triethylamine (65, 646) as strong base, or by action of H2S on the appropriate nitrile with pyridine and triethylamine solvents using the method of Fairfull et al. (34, 374, 503). In this reaction, thioacetamide in acidic medium can also be used as a H2S generator with dimethylform-amide as the solvent (485). 

Phosphorus [7723-14-0] is a nonmetaUic element having widespread occurrence in nature as phosphate compounds (see Phosphoric acid and phosphates). Fluorapatite [1306-03-4], Ca F(P0 2> is the primary mineral in phosphate rock ores from which useful phosphoms compounds (qv) ate produced. The recovery from the ore into commercial chemicals is accompHshed by two routes the electric furnace process, which yields elemental phosphoms and the wet acid process, which generates phosphoric acid. The former is discussed herein (see Furnaces, electric). Less than 10% of the phosphate rock mined in the world is processed in electric furnaces. Over 90% is processed by the wet process, used primarily to make fertilisers (qv). 

Additional n or p-type character may be added to the conduction properties by tire addition of small amounts of impurities such as boron to generate holes in Si and Ge, and phosphorus to generate free electrons. 

Fire Hazards - Flash Point (deg. F) 82 - 105 CC (solutions only pure liquid difficult to burn) Flammable Limits in Air (%) Not pertinent Fire Extinguishing Agents (for solutions) Foam, dry chemical, or carbon dioxide Fire Extinguishing Agents Not to be Used Water may be ineffective Special Hazards of Combustion Products Oxides of sulfur and phosphorus are generated in fires Behavior in Fire Not pertinent Igrution Temperature Not pertinent Electrical Hazard Data not available Burning Rate (for solutions) 4 mm/min. 

Difluorocarbene generated by the thermolysis of trimethyltnfluoromethylsilane reacts with disilanes by insertion into the silicon-silicon bond [S] (equation 9) Thermolysis of pentafluoroethyltnfluorosilane at 200 °C gives tetrafluoro ethylidene carbene, which reacts with phosphorus trifluonde to give trifluoro vinyltetrafluorophosphorane [9] (equation 10) and with perfluorotnmethylphos-phine to give perfluorodimethyhsopropylphosphine and perfluoro-2-butene [9] (equation 10)... 

Alcohol attack generates an unstable intermediate that undergoes nucleophilic attack by CL at carbon. Compare electrostatic potential maps of methanol, thionyl chloride intermediate, and phosphorus trichloride intermediate. What features of these maps are consistent with an electrophilic reactive intermediate ... 

Various other heteroatom-centered radicals have been generated as initiating species. These include silicon-, sulfur-, selenium- (see 3.4.3.1). nitrogen- and phosphorus-centered species (see 3.4.3.2). Kinetic data for reactions of these radicals with monomers is summarized in Table 3.10. 

Although phosphorus ylids are most commonly used to alkenylation reactions, nitrogen ylids can occasionally be used. As an example, the reaction of A-benzyl-A-phenylpiperidinium bromide with base generated a A-ylid, which reacted with benzaldehyde to form styrene. ... 

Another versatile approach, which nicely complements these Mannich-based procedures, incorporates a preformed symmetrical hexahydro-l,3,5-triazine (HHT) intermediate. In this case the phosphorus reagent reacts with HHT as a trimeric form of the normal aldimine species generated in situ between the amine or amino acid and formaldehyde. These HHT reagents can often be puritied and isolated prior to the reaction with phosphites. They are reasonably stable under neutral or slightly basic conditions, but they can readily revert back to the original amine and formaldehyde after heating with aqueous acid (25). Several can be purchased commercially. 

Phosphine-borane 63a (75% ee) was obtained by reduction of compound (Sp)-62a using LDBB at -60°C and nucleophilic substitution with iodomethane in 72 % yield. The observed loss of optical purity may be ascribed to stereomutation of the generated tricoordinated phosphorus species. Recrystallization afforded (S)-63a in > 99% ee. On the other hand, severe racemization was observed using the same method with (Rp)-62b. An alternative strategy consisted of deborana-tion of (Rp)-62b using ZSl-methylpyrrolidine, methylation with methyl triflate. 

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