Phosphoric halides

The important compounds of nitrogen with hydrogen are ammonia, Irydrazine, and hydrazoic acid, the parent of the shock-sensitive azides. Phosphine forms neutral solutions in water reaction of phosphorous halides with water produces oxoacids without change in oxidation number. 

A considerable number of examples will be found in the text in which halo-genated and other substituted olefins are produced. Their modes of formation do not usually differ in principle from the corresponding unsubstituted case. However, some special methods have been used, for example, the direct preparation of halo olefins from ketones with phosphorous halides, or via hydrazones. 

The traditional methods utilize sulfur or phosphorous halides to convert the acid to die acid chloride. Of these methods, thionyl chloride [often with a catalytic amount of dimethyl formamide (DMF)] is the most useful since the by-products of die reaction are gases (SO2, HC1) which can be easily purged from the reaction mixture with a stream of nitrogen. The acid chloride product can then be purified on a small scale by bulb-to-bulb distillation or crystallization. Because an excess of thionyl chloride is usually used, there must be a purification step to remove the excess reagent. 

Reaction of alcohols with sulfur and phosphorous halides... 

Alcohols can be converted to alkyl halides by reaction with thionyl chloride, SOCI phosphorous trichloride, PCI phosphorous pen-tachloride, PCI or phosphorous tribromide, PBr3. For example, ethyl chloride or ethyl bromide can be prepared from ethyl alcohol via reactions with sulfur and phosphorous halides. 

Ethylene may react vigorously with acids, acid chlorides, oxidizing agents, acid anhydrides, phosphorous halides, and perchlorates.2... 

Protonation of phosphine, phosphites or phosphorous halides in strong acid forms P—H bonds. Phosphine in cone H SO or HCl is converted" to [PHJ ... 

Phosphorous halides form ester groups which can be substituted by other nucleophiles (see Houben-Weyl, Vol. 5/3, p 870). 

A. From Carboxylic Acid Hydrazides and Phosphorous Halides... 

The multistep chemical conversion of penicillin G to 7-ADCA (Fig. 16) has recently been replaced by a 2-step biosynthesis (Fig. 18). This is a major step forward to shorten the industrial synthesis of cephalosporins and this has already been implemented. The 7-N-adipoyl-ADCA is obtained directly through fermentation with a modified Penicilium chrysogenum followed by a simple enzymatic removal of the amino substituent. Again, various reagents such as silylat-ing agents, phosphor halides, pyridine and DMF, and some halogenated solvents have been replaced by biocatalysts in aqueous medium. 

As implied by Equation 14b, a polymer with multiple hydroxyl groups will react with pentavalent or trivalent phosphorous electrophiles to crosslink the polymer if a molar excess of the phosphorus compound is present. This was verified by Doughty, who found that phosphorous halide or sulfide/lignin reactions with a greater than 1/1 mole ratio produced insoluble products (183). If the number of moles of phosphorous compound are equal or less than the moles oflignin in the reaction, the soluble reaction product can be further reacted with mono and polyhydroxy compounds to produce flame retardant resins with film- forming capacity (185). 

Keywords Hirshfeld Electron density Phosphorous halides Dipole moments... 

Phosphorous halides and thionyl chloride are preferred to hydrogen halides, as alcohols tend to undergo dehydration in the presence of acids. 

Aryl and alkyl phosphines are also important intermediates and ligands in organic synthesis. While traditionally they have been prepared by the reaction of carbon nucleophiles with phosphorous halides, their synthesis can also be accomplished by the cross-coupling of aryl halides and phosphorous derivatives having at least one P-H bond... 

Phosphorous acid is water soluble and may be removed by washing the alkyl halide with water or with dilute aqueous base... 

Alcohol Phosphorus trihalide Alkyl halide Phosphorous acid... 

Amongst heat stabilisers are copper salts, phosphoric acid esters,phenyl-3-naphthylamine, mercaptobenzothiazole and mercaptobenzimidazole. Of these, copper salts in conjunction with halides have been found particularly effective, and some automotive specifications require the use of copper for heat stabilisation. Light stabilisers include carbon black and various phenolic materials. 

The Arbuzov reaction,also called the Michaelis-Arbuzov reaction, allows for the synthesis of pentavalent alkyl phosphoric acid esters 4 from trivalent phosphoric acid esters 1 (Z,Z = R,OR) by treatment with alkyl halides 2. 

The reaction mechanism outlined below for phosphorous acid esters analogously applies for the other two cases. The first step is the addition of the alkyl halide 2 to the phosphite 1 to give a phosphonium salt 3 ... 

In the phosphor-photoelectric detector used as just described, the x-ray quanta strike the phosphor at a rate so great that the quanta of visible light are never resolved they are integrated into a beam of visible light the intensity of which is measured by the multiplier phototube. In the scintillation counters usual in analytical chemistry, on the other hand, individual x-ray quanta can be absorbed by a single crystal highly transparent to light (for example, an alkali halide crystal with thallium as activator), and the resultant visible scintillations can produce an output pulse of electrons from the multiplier phototube. The pulses can be counted as were the pulses-from the proportional counter. 

These compds are also formed during the prepn of nitriles, by heating aryl or arylalkyl halides, or alkyl sulfuric or phosphoric esters, or arylsulfonic esters with K or Na cyanide in ale... 

Diesters of phosphorous acid are in general neutral because the phosphorous acid exists mostly in the phosphonate form with one hydrogen directly attached to the phosphorus. But with alkali metals the H can be changed against the alkali and reactive intermediates formed. Such alkali metal derivatives of dialkyl phosphites react with alkyl halides to give dialkyl alkanephosphonates, according to Eqs. (45) and (46). 

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