Diethyl phenylphosphonite

The kinetics of formation of phosphonates by reaction of o-dinitrobenzene with phosphites have been examined. The energy of activation for the reaction increases as the nucleophilicity of the phosphite decreases, e.g. ethyl diphenylphosphinite 14kcalmol"S diethyl phenylphosphonite 16 kcalmol S and triethyl phosphite 21kcalmol . An intermediate of the type (61), formed by nucleophilic attack of the phosphite, was proposed. In (61) there is a particularly favourable electrostatic interaction. That p-dinitrobenzene is unreactive, is thought to stem from the fact that this compound cannot form an intermediate with such a stabilizing factor. 

Anhydrous nickel(II) chloride (1.30 g., 0.01 mole) is dissolved in 100 ml. of absolute ethanol in a 200-ml. round-bottomed flask fitted with a reflux condenser and nitrogen inlet and outlet. Diethyl phenylphosphonite (10 g., 0.05 mole) is added, and the solution is heated to reflux. After 3 hours, the heat is removed and the solution is allowed to cool slowly to room temperature. The product separates as yellow crystals from the solution. With a stream of nitrogen passing through the flask, the mother liquor is transferred by syringe to another 200-ml. flask the crystals are washed with two 20-ml. portions of absolute ethanol, and dried in vacuo. Concentration of the mother liquor to 30 ml. yields additional product. Yield is 8.2 g. (97%). Anal. Calcd. for C HeoOsNiP C, 56.51 H, 7.11 P, 14.60. Found C, 56.27 H, 7.17 P, 14.54. 

In an apparatus identical to that used for the preparation of the cobalt complex are combined 1.27 g. anhydrous iron(II) chloride (0.01 mole), 10 g. diethyl phenylphosphonite (0.05 mole), and 40 ml. absolute ethanol. The mixture is heated to reflux under a slow stream of nitrogen. After 3 hours the heat is removed and a solution of sodium tetrahydroborate in abso-... 

The yellow diethyl phenylphosphonite complex is also known. It can be prepared directly from hydrated rhodium trichloride (equation 71).195... 

An interesting mixed-ligand complex is [Tc(dppe)2(ox)j, prepared by the reduction of TCO4 by dppe in hot ethanol in the presence of oxalic acid. The average Tc-0 bond distances of 2.13(1) and 2.12(1) A in two independent molecules are somewhat longer than those found in other oxalato complexes (197). Reaction of (NH4)2[Tc Clg] with diethyl phenylphosphonite in the presence of BH4" yields the yellow octahedral rans-[Tc HPhP(OEt)2 4Cl2l, with Tc-P and Tc-Cl bond distances both 2.41(1) A. The low measured magnetic moment of 1.4 BM has been ascribed to partial decomposition (198). 

Fragmentation of phosphoranes.3 3-Methyl-1 -phenyl-3-phospholene (1) reacts with diethyl peroxide to give the phosphorane (2), which fragments spontaneously at room temperature to give isoprene (3) and diethyl phenylphosphonite (4). 

The order of reactivity MeOPCla > (63) > (EtO)2PCl > (MeO)3P has been found for addition to isoprene. This diene and the phosphites (75) gave only the phospholens (76). If phosphoranes are intermediates in these reactions, then the fate of the aromatic nucleus is of some interest. The phospholens (77) with diethyl peroxide gave isoprene and diethyl phenylphosphonite, presumably via the phosphorane. ... 

Analogous reactions occur with trimethyl phosphite and diethyl phenylphosphonite. It is uncertain whether the nitro compound is first reduced to the nitroso compound which reacts with additional phosphite, or whether the nitro compound forms an intermediate with the phosphite which is then reduced by additional phosphite. In support of the former explanation, compound 2 (R = R = Me) was synthesized from... 

R = O-alkyl, n= 1) in the same way, diethyl phenylphosphonite affords 11 (R = Ph, R = Et, = 1, X = I). Bromoform and iodoform, although reactive to trialkyl phosphites, tend to yield alkyl halide, dialkyl hydrogenphosphonate and dialkyl phosphorohalidate, but (halomethyl)phosphonate esters are not obtained. With tetrahalomethanes, particularly those based on two or more different halogens, a more interesting picture is presented. Triethyl phosphite and tetrabromomethane are reported to yield EtBr quantitatively but... 

A. The Co-O distances of 1.871(7) and 1.902(7) A are not significantly different and the 0-0 distance is 1,420(10) A. Distorted trigonal-bipyramidal co-ordination at the cobalt atom is found in the molecular structure of hydridotetrakis(diethyl phenylphosphonite)cobalt(i), HCo[PhP-(OEt)2l4. The cobalt atom is displaced by 0.492 A from the plane of the three equatorial phosphorus atoms towards the axial phosphorus atom the Co-P(axial) distance of 2.128(1) A agrees well with the Co-P(equatorial) distances of 2.126(1), 2.103(2), and 2.115(2) A. The hydridic hydrogen atom was located at 1.54 A from the metal in a difference map after least-squares refinement the Co-H distance was 1.38(54) A. ... 

CuoHe 2Pe08Pn, cis-Dihydridotetrakis(diethyl phenylphosphonite)iron-(II), 38B, 1047... 

The addition of secondary phosphites to arynes is an attractive procedure for the formation of arylphosphonates (Schemes 4.211 and 4.212) [332]. The resulting arylphosphonates were formed in moderate to excellent yields, and a range of substrates were compatible with the reaction chemistry with the provision that they possessed a TMS group adjacent to a triflate. In addition to the tertiary phosphites, diethyl phenylphosphonite was successfully added to the arynes to generate arylphosphinates. This approach is a potentially valuable way to generate arylphosphonates or phosphinates under mild conditions without the addition of transition metals. 

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