Reactivity with phosphorus halides

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). 

The most important derivatives of the amino acids are halides and esters. The most reactive are the halides, which, as described by Emil Fischer, can be obtained by shaking dry amino acids with phosphorus pentachloride in acetyl chloride. 

Several methods for the preparation of the parent compound in this system, tris(trimethylsilyl)phosphite, have been reported.114 118 The application of this and related reagents in reaction with alkyl halides has been reported and used for the preparation of a variety of phosphonic acid analogues of phospholipids.114119-124 Interestingly, alkyl chlorides appear to be more reactive with the silyl reagents than do alkyl iodides, a reversal of the normally observed trend with alkyl esters of the phosphorus acids. (The particular use of silyl phosphorus reagents for the synthesis of biologically significant compounds has... 

The reactive 3-carbonyl group in compounds of type (279) undergoes aldol condensation with active methylene compounds such reactions of isatin with indoxyl, oxindole (Section 3.3.2.5.4) and with thiophenes (Section 3.3.1.5.7.ii) have already been mentioned. These compounds also react with Grignard reagents and phosphorus halides as expected, e.g. isatin (279 Z = NH) with MeMgBr and PC13 yields (285) and (286), respectively. 

In contrast to the inertness of carbon halides, the halides of silicon and phosphorus are extremely reactive with water, to the extent that they must be protected from atmospheric moisture. A clue to the reactivity of these halides is provided hy the somewhat Similar reactivity of acid halides which readily react with water... 

Sterically hindered compounds have been of interest in view of their protecting nature of reactive sites or molecules (1, 2, 3). During the course of our studies of phosphorus-containing reactive intermediates ( -8) we have found the following interesting reactions of 2,4,6-tri-t-butylphenyllithium (I) with some phosphorus halides. 

To get a broader concept of the nucleophilic reactivity of phosphorus acid derivatives towards organosilanes we studied mechanism of reactions of triorganosilyl halides with esters of tricoordinate and tetracoordinate phosphorus having the general formulae ... 

Ethane occurs in natural gas, from which it is isolated. Ethane is among the chemically less reactive organic substances. However, ethane reacts with chlorine and bromine to form substitution compounds. Ethyl iodide, bromide, or chlorides are preferably made by reaction with ethyl alcohol and the appropriate phosphorus halide. Important ethane derivatives, by successive oxidation, are ethyl alcohol, acetaldehyde, and acetic acid. Ethane can also be used for the production of aromatics by pyrolysis (Fig. 1). 

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