Phosphine oxides dehydration

Tetrakishydroxymethyl phosphonium chloride (THPC) is well established as a flame retardant agent with textiles (3). Collins (2) has suggested that THPC and urea break down to produce phosphoric acid via a phosphine oxide, phosphinic acid, and phosphonic acid. For cellulose, Collins concludes flameproofing is essentially caused by the dehydrating action of the phosphoric acid formed. 

The final stages follow the mechanism of the Wittig reaction you met in Chapter 14 you see them as a special case of dehydration made favourable by the formation of a phosphine oxide as well as an unsaturated carbonyl compound. 

The silver-catalyzed reaction of 2-allqmylbenzaldoximes with secondaiy phosphine oxides led eventually to 1-phosphinoyl-isoquinolines after tandem addition, cyclization and dehydration steps (Scheme 35)/ ... 

Poly(styryldiphenylphosphine) (8) in carbon tetrachloride converts alcohols to alkyl chlorides up to 20 times faster than does triphenylphosphine, as shown in equation (5). The phosphine oxide by-product is easily separated by filtration, but it cannot be recycled due to concurrent formation of a dichloromethylidinephosphorane. Yields are about 90% from primary and 40-70% from secondary alcohols. Reagent (8) in carbon tetrachloride also dehydrates primary carboxamides and oximes to amines, and secondary carboxamides and oximes to imidoyl chlorides. ... 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

It is often said that the property of acidity is manifest only in the presence of a base, and NMR studies of probe molecules became common following studies of amines by Ellis [4] and Maciel [5, 6] and phosphines by Lunsford [7] in the early to mid 80s. More recently, the maturation of variable temperature MAS NMR has permitted the study of reactive probe molecules which are revealing not only in themselves but also in the intermediates and products that they form on the solid acid. We carried out detailed studies of aldol reactions in zeolites beginning with the early 1993 report of the synthesis of crotonaldehyde from acetaldehyde in HZSM-5 [8] and continuing through investigations of acetone, cyclopentanone [9] and propanal [10], The formation of mesityl oxide 1, from dimerization and dehydration of... 

Nickel(II) complexes containing up to four molecules of trialkylphosphines have been prepared by the direct reaction of a nickel(II) salt with the appropriate phosphine in either aprotic or protic solvents. Anaerobic conditions have sometimes been employed in order to avoid oxidation of unstable phosphines whereas dimethoxypropane has occasionally been employed as a dehydrating agent when using hydrated nickel(II) salts. 

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