Phosphinous acid, esters

Most common is the preparation of alkyl phosphonic acid esters (phospho-nates) 4 (Z,Z = OR) from phosphorous acid esters (phosphites) 1 (Z,Z = OR). The preparation of phosphinic acid esters (Z = R, Z = OR) from phosphonous acid esters, as well as phosphine oxides (Z,Z = R) from phosphinous acid esters is also possible. 

The cyclic 4-hydroxy-phosphinic acid esters yield diastereoisomers which show remarkable differences in H-NMR, in some cases also in IR or in mass spectra. 

Trisubstituted X -phosphorins or X -phosphorins can be isolated unchanged even after long periods of irradiation when oxygen is excluded. Stade discovered that cyclic phosphinic acid esters 208 a-c which contain a cyclic butadiene (1.3)-moiety, photochemically rearrange smoothly to the tricyclic compounds 214 a-c. 

At the alkyl group of the 0-alkyl substituent (cleavage of an alkyl cation and formation of an unsaturated phosphinic acid ester). 

In both cations 221 and 225 the alkyl groups are easily split off by halide ions. Whereas addition to the carbenium ion leads in a kinetically controlled reaction to the addition products 226 and 227, this type of reaction leads to the thermodynamic stable unsaturated phosphinic acid esters 228 and 229. 

Depending on the substituents, different product distributions of phos-phonic 36d-f and phosphoric acid esters 33d-f have been found in the reaction of HFA and phosphinic acid esters (752). 

Pudovik, A.N., Samitov, Y.Y., Gur yanova, I.V, and Banderova, L.V., Reaction of phosphonic and phosphinic acid esters with the nitriles of a-keto carboxylic acids, Khim. Org. Soedin. Eosfora., Akad. Nauk SSSR, 45, 1967 Chem. Abstr., 69, 67489j, 1968. 

Different routes leading to the formation of silyl esters of phosphinic acids R2P(0)0SiMe3 have been investigated and the products characterized, and novel bis(phosphinic acid esters) can be prepared as shown in equation (50). The... 

Phosphonous acids have been alkylated with chloroacetic esters to give the phosphinic acid esters (136). The appropriately catalyzed reaction between trimethyl 1-phosphono-acrylate and methyl phenylphosphonite yields an intermediate... 

Several possible reactions may give rise to impurities in the preparation of phosphonic or phosphinic acid esters by the Michaelis-Arbuzov reaction, and it is possible that, in some cases, such reactions become preponderant. Triethyl phosphite, for instance, has been successfully used as a dehalogenating agent, in particular, for debrominations. Isomerization of allylic groups may occur through S T-type processes (reaction 5) or be induced thermally (reactions 6 and 7) 25,126... 

Reactions between haloketones and phosphonite esters, R P(OR)2, produce enol esters of phosphonic acids or esters of the phosphinic acids, R (R C0CH2)P(0)0R, depending on the halogen involved whilst phosphinite esters, R2POR yield the phosphinic acid esters R2P(0)0CPh=CHBr when treated with a,a-dibromoacetophenone . ... 

Attack on Saturated Carbon.—The kinetics and mechanism of Arbuzov reactions of several phosphonous and phosphinous acid esters have been studied with the use of and n.m.r. The nucleophile of the dealkylation step is either X" or (1), depending on X (Scheme 1). Tetraphenyl methylenebis(phosphonate)... 

Esters of orthophosphoric acid have been used extensively as plasticizers and lubricant additives. Others have been used as flame retardants. Many sulfur analogues find use as insecticides, while the introduction of P—C bonds give phosphonic and phosphinic acids. Esters of pyrophosphoric acid (H4P2O7) are also of interest as are amide derivatives. 

Phosphinic acid anhydrides and aldehydes from phosphinic acid esters and 1,1-dihalides... 

Ar. phosphonic and phosphinic acid esters from halides... 

Triethyl phosphite added dropwise during 2 hrs. at 160° to a suspension of NiClg in bromobenzene with distillation of the resulting ethyl bromide, and heating continued ca. 0.5 hr. -> diethyl benzenephosphonate. Y 91%. - Similarly with diethyl benzenephosphonite and 2-bromothiophene, after subsequent 3 hrs. reflux with NaOH in methanol -> phenyl-2-thienylphosphonic acid. Y 82%. F. e., also phosphinic acid esters, and with NiBrg, limitations, s. P. Tavs, B. 103, 2428 (1970) Tetrahedron 26, 5529 (1970). 

Without additional reagents Phosphinic acid esters from phosphinic acid chlorides... 

Ethylene derivatives from phosphinic acid esters... 

---