Phosphonium compound

The reaction of higher alkyl chlorides with tin metal at 235°C is not practical because of the thermal decomposition which occurs before the products can be removed from the reaction zone. The reaction temperature necessary for the formation of dimethyl tin dichloride can be lowered considerably by the use of certain catalysts. Quaternary ammonium and phosphonium iodides allow the reaction to proceed in good yield at 150—160°C (109). An improvement in the process involves the use of amine—stannic chloride complexes or mixtures of stannic chloride and a quaternary ammonium or phosphonium compound (110). Use of these catalysts is claimed to yield dimethyl tin dichloride containing less than 0.1 wt % trimethyl tin chloride. Catalyzed direct reactions under pressure are used commercially to manufacture dimethyl tin dichloride. 

The Tetrahedral Carbon Atom.—We have thus derived the result that an atom in which only s and p eigenfunctions contribute to bond formation and in which the quantization in polar coordinates is broken can form one, two, three, or four equivalent bonds, which are directed toward the corners of a regular tetrahedron (Fig. 4). This calculation provides the quantum mechanical justification of the chemist s tetrahedral carbon atom, present in diamond and all aliphatic carbon compounds, and for the tetrahedral quadrivalent nitrogen atom, the tetrahedral phosphorus atom, as in phosphonium compounds, the tetrahedral boron atom in B2H6 (involving single-electron bonds), and many other such atoms. 

There do not appear to be any simple phosphines that bear a CH2F group. However, fluorine NMR spectra of phosphonates, phosphane oxides, and phosphonium compounds with CH2F and —CHF- bound to phosphorous have been reported. Examples are given in Scheme 3.26, including spectral data for the useful Horner-Wadsworth-Emmons reagent, triethyl 2-fluoro-2-phosphonoacetate. 

The fluoromethyl phosphonium compound is unique. Analogous CHF2 or CF3 phosphonium compounds do not appear to have been reported. 

In the Arbusov reaction using a triaryl phosphite both the stages (a) and (b) (above, p. 95) are slow, and it is possible to isolate the intermediate phosphonium compound.1... 

The phosphonium compounds (2) normally give the phosphonates (3) quite readily on heating. However, when R = Ph the salts are thermally stable but will rearrange under the influence of u.v. radiation.7... 

As stated in the footnote on p. 5, phosphonium compounds afford a better example of chemical shifts which are essentially governed by inductive factors thus giving better correlations. 

Solvent and temperature effects have been especially studied in simple compounds—white phosphorus,(1969 180) PH3, (1967>43> PFS, (1968,51) phosphorus acid, phosphines, phosphonium compounds etc. (1965> 39 1967,169 1968,155 1969,53) phosphorus chemical shifts or line-widths,... 

The pKa values of a series of conjugated acids of the arsonium ylides have been determined by potentiometric titration (73). A decrease in the basicity of the ylides with an increase in substituent electronegativity was observed. The effect of the substituents agrees well with the Hammett equation. Arsonium ylides are more basic (200-230 times) than the corresponding phosphonium compounds. 

Although the methods reviewed above have been most widely used for synthesis of conducting polymers, there are many other organic reactions capable of producing conjugated structures. One example is the Wittig condensation of bis-triphenyl-phosphonium compounds with dialdehydes in the presence of a strong base, typified by the synthesis of poly(p-phenylene-vinylene) 102). 

The reactions of picryl fluoride with (2,3-dihydroxypropyl)-ammonium or -phosphonium compounds have been found120 to yield zwitterionic spiro-cr-adducts such as (31). Aromatic diazonium cations have been shown to add to the 9-position of cr-adducts of 9-nitroanthracene to yield neutral derivatives.121 A study has been reported of the effects of ion pairing and change of solvent on the kinetics of decomposition of some anionic cr-adducts.122... 

Phosphine, as remarked on p. 66, combines with hydrogen iodide, forming a salt, PH4I, phosphonium iodide, resembling ammonium chloride. But as it is decomposed by water into phosphine, PH3, and hydrogen iodide, an attempt to convert it into phosphonium hydroxide, PH4OH. cannot be made. Substituted phosphonium compounds,... 

Third, reaction products of acid azo dyes acid 1 1 metal-complex azo dyes, or 1 2 metal complex azo dyes without acid groups with organic bases or cationic dyes. Cyclohexylamine, dodecylamine, and sulfonium or phosphonium compounds serve as bases, and derivatives of the xanthene range (rhodamines) are mainly used as cationic dyes. Example C.I. Solvent Red 109 [53802-03-2] is composed of Solvent Yellow 19, 13900 1 [10343-55-2] (3) and Solvent Red 49, 45170 1 [81-88-9] (4). These dyes are saltlike compounds of a metal-complex azo dye acid and a base. 

For the most part, the similar stereochemical results in the SN reactions of ordinary sulfoxides, phosphoryl, sulfoxonium and phosphonium compounds is remarkable. Evidently the lone pair on sulfur is equivalent to one substituent (Gillespie, 1967). For this reason, the isolation of racemic product in (125) was unexpected (Andersen and Papanikolaou,... 

Carboxyalkyl phosphonium compounds can be prepared by the following reaction. 

Tables I and II list some of the many phosphonium compounds studied and indicate their effectiveness. Many of our evaluations were halted by limited supplies of the phosphonium halides.

No phosphonium compound was formed when either the phosphorus or the... 

Phosphorus is almost exclusively tervalent in its organo-eompounds and lower halides, etc., and quinquevalent in the compounds PX5, phosphonium compounds and the phosphoric acids according to modem theory, however, this quinquevalency is really quadricovalency. Compounds showing other valencies are not common, and sometimes are of doubtful individuality. 

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