Trialkyl phosphites preparation

Triethyl phosphite is a colourless mobile liquid, insoluble in water. Trialkyl phosphites are valuable intermediates in the preparation of many organophosphorus compounds they readily form dialkyl esters of alkylphosphonic acids by the Arbusov reaction (p. 311). 

Monoesters of the phosphonic acids are Httle used in industry. The diesters, 0=PR(0R)2, of phosphonic acid are commonly prepared in industry from trialkyl phosphites in a MichaeUs-Arbusov reaction ... 

Formation of esters of inorganic acids (Section 15.9) Alkyl nitrates, dialkyl sulfates, trialkyl phosphites, and trialkyl phosphates are examples of alkyl esters of inorganic acids. In some cases, these compounds are prepared by the direct reaction of an alcohol and the inorganic acid. 

All the trialkyl phosphites required for the preparations listed are available from the suppliers mentioned in Note 1. 

Sulfonic esters are most frequently prepared by treatment of the corresponding halides with alcohols in the presence of a base. The method is much used for the conversion of alcohols to tosylates, brosylates, and similar sulfonic esters. Both R and R may be alkyl or aryl. The base is often pyridine, which functions as a nucleophilic catalyst, as in the similar alcoholysis of carboxylic acyl halides (10-21). Primary alcohols react the most rapidly, and it is often possible to sulfonate selectively a primary OH group in a molecule that also contains secondary or tertiary OH groups. The reaction with sulfonamides has been much less frequently used and is limited to N,N-disubstituted sulfonamides that is, R" may not be hydrogen. However, within these limits it is a useful reaction. The nucleophile in this case is actually R 0 . However, R" may be hydrogen (as well as alkyl) if the nucleophile is a phenol, so that the product is RS020Ar. Acidic catalysts are used in this case. Sulfonic acids have been converted directly to sulfonates by treatment with triethyl or trimethyl orthoformate HC(OR)3, without catalyst or solvent and with a trialkyl phosphite P(OR)3. ... 

A useful new method of preparing arylphosphonates (123) involves the reaction of trialkyl phosphites with aryl halides in the presence of a nickel catalyst.The suggested mechanism is via the nickel complex (124), and is non-radical. 

Pyridylphosphonic acid derivatives (68) have been prepared by addition of dialkyl phosphite anion to A-alkoxypyridinium salts. Similar compounds, it is reported, are formed from trialkyl phosphites with... 

Preparation of trisodium phosphonoformate — Reaction of a chloroformate with a trialkyl phosphite and cleavage of the ester linkages... 

Preparation of dimethyl (4-methoxybenzyl)phosphonate — Reaction of a benzyl halide with a trialkyl phosphite... 

Preparation of diethyl isobutyrylphosphonate — Reaction of a trialkyl phosphite with a carboxylic acid chloride... 

Preparation of [l-(diethoxyphosphinyl)ethoxy]dimethyl-silane — Reaction of an aldehyde with a trialkyl phosphite in the presence of a silyl halide... 

Preparation of 2-chloromethyl-2-ethyl-l,3-propanediol phosphorochloridate — Preparation of a dialkyl phosphorochloridate by reaction of a trialkyl phosphite with chlorine... 

Preparation of 2,2,2-trimethoxy-3-phenyl-4-acetyl-5-methyl-A4-oxaphospholene — Preparation of an oxyphosphorane by reaction of a trialkyl phosphite with an a,(l-unsaturated carbonyl compound... 

Hall, N. and Proce, R., The copper-promoted reaction of o-halogenodiaryl-azocompounds with nucleophiles. Part I. The copper-promoted reaction of o-bromodiarylazo-compounds with trialkyl phosphites. A novel method for the preparation of dialkyl arylphosphonates, /. Chem. Soc., Perkin I, 2634, 1979. 

The carbanions take up 02 and these take up protons to give hydroperoxides in good yields. But because they are explosive in nature, they are not usually isolated and on reduction with sodium sulphite on trialkyl phosphite give alcohols. Alcohols can also be prepared via hydroperoxy molybdenum complexes and alkyl boranes. These reactions are summarized as follows ... 

As regards methods of synthesis, one of our early attempts consisted in preparing the trialkyl phosphite, (-RO)3P, by the action of phosphorus trichloride on an alcohol in the presence of a tertiary base such as pyridine or dimethylaniline ... 

These compounds can be prepared by the action of bromine on a trialkyl phosphite,2 but a more satisfactory method recently worked out by Goldwhite and Saunders3 consists in treating the dialkyl hydrogen phosphite with iV-bromosuccinimide. In this way dimethyl, diethyl w-propyl and isopropyl phosphoro-bromidates have been obtained as pure liquids by distillation at very low temperature. When kept at ordinary temperatures, they gradually decompose with the evolution of the corresponding alkyl bromide. 

Fourth, the present procedure bears a resemblance to the photochemical reaction of aryl iodides with trialkyl phosphites, by means of which several dialkyl arylphosphonates have been prepared.13 However, prolonged irradiation (>24 hours) in quartz vessels was employed. 

It was later found that dialkyl(dialkylamino) phosphites (phosphoramidites, (RO)2PNR2 [114]), which are stable towards air and water and can be stored for longer, can readily be converted into the phosphinic chlorides (RO)2PCl by treatment with dimethylaniline hydrochloride, or into the corresponding tetrazolides by treatment with tetrazole. Tetrazolides (RO)2P-(l-tetrazolyl) had proven excellent reagents for the phosphorylation of nucleosides [113], and the treatment of phosphoramidites with alcohols in the presence of tetrazole was found to be a satisfactory method for the rapid preparation of trialkyl phosphites [115,116]. 

The complex of tartaric acid and antimony (emetic) was described three centuries ago. Nevertheless, the structure of this compound has been elucidated these last fifteen years by X-ray diffraction ( 1 ). In fact, emetic presents a binuclear cyclic structure. Many authors mentioned similar complex with transition metals (vanadium (2), chromium (3)) or metalloids (arsenic (4), bismuth (5)). Emetic with phosphorus was not mentioned. Nevertheless, tartaric acid or alkyl tartrates has been utilized in phosphorus chemistry tartaric acid reacts with trialkyl phosphites giving heterocyclic phosphites (6). Starting from alkyl tartrates, we prepared spirophosphoranes with a P-H bond and sixco-ordinated compounds (7). With unprotected tartaric acid, many possibilities appear condensation as a diol, as a di(oc-hydro-xyacid), or even as a 8-hydroxyacid. 

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