Tertiary phosphites

Phosphites. Tertiary phosphites are also commonly used and are particularly effective ia most mixed metal stabilizers at a use level of 0.25—1.0 phr. They can take part ia a number of different reactions duting PVC processing they can react with HCl, displace activated chlorine atoms on the polymer, provide antioxidant functionaHty, and coordinate with the metals to alter the Lewis acidity of the chloride salts. Typical examples of phosphites are triphenyl phosphite [101 -02-0], diphenyl decyl phosphite [3287-06-7], tridecyl phosphite [2929-86-4], and polyphosphites made by reaction of PCl with polyols and capping alcohols. The phosphites are often included in commercial stabilizer packages. 

As with secondary phosphites, tertiary phosphites add to ethyl thio-acetylene to give the /S-ethylthioalkenylphosphonate (26) rather than the a-analogue. ... 

The observed order of ease of rearrangement of the acetylenic phosphites, tertiary > secondary > primary, appears to be consistent with the postulated SN/ mechanism. 

Phosphorus trichloride reacts readily with three equivalents of an alcohol e.g, ethanol, in the presence of a tertiary amine such as pyridine, dimethyl-aniline, or diethylaniline, to form triethyl phosphite and hydrogen chloride, the latter being immediately neutralised by the tertiary amine. 

In the absence of a tertiary amine, the initial reaction is again the formatfon of a trialkyl phosphite and hydrogen chloride. The latter now reacts rapidly with the trialkyl phosphite to give the alkyl chloride and the dialkyl hydrogen... 

The following preparation of triethyl phosphite illustrates the interaction of phosphorus trichloride and ethanol in the presence of dimethylaniline the preparation of di-isopropyl hydrogen phosphite illustrates that of phosphorus trichloride and isopropanol in the absence of a tertiary amine. 

Unlike simple, unhindered carbonyl compounds, the quinones do not yield bisulfite addition products, but undergo ring addition. Another significant carbonyl reaction is the addition of tertiary phosphites under anhydrous conditions (98). The ester product (99) is easily hydroly2ed, and the overall sequence produces excellent yields of hydroquinone monoethers. 

P-coupling occurs in the formation of azophosphonic esters [ArN2PO(OCH3)2] from diazonium salts and dimethyl phosphite [HPO(OCH3)2] (Suckfull and Hau-brich, 1958). P-coupled intermediates are formed in the reaction between diazonium salts and tertiary phosphines, studied by Horner and Stohr (1953), and by Horner and Hoffmann (1956). The P-azo compound is hydrolyzed to triphenylphosphine oxide, but if a second equivalent of the tertiary phosphine is available, phenyl-hydrazine is finally obtained along with the phosphine oxide (Scheme 6-26 Horner and Hoffmann, 1958). It is likely that an aryldiazene (ArN = NH) is an intermediate in the hydrolysis step of the P-azo compounds. 

A number of ruthenium(II) complexes have been prepared. Cole-Hamilton and Stephenson isolated cts-[Ru(Me2dtc)2L2] (L = PPhj, PMe2, Ph, PPhMe2, or P(OPh)3) from Ru(II) and Ru(III) tertiary phosphine and phosphite complexes with NaMe2dtc, and found that they undergo rearrangements (288). 

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. ... 

The mechanism of the reaction of tertiary phosphites with halogeno-acetylenes has been investigated by two groups of workers. - Initial attack of phosphite could be on carbon to give the anion (78), which can eliminate halide, or on halogen to give the ion pair (79) which leads to the same intermediate (80). In both cases an Arbusov reaction would give the isolated product (81). 

Kellum [115] has described a class-selective oxidation chemistry procedure for the quantitative determination of secondary antioxidants in extracts of PE and PP with great precision (better than 1 %). Diorgano sulfides and tertiary phosphites can be quantitatively oxidised with /-chloropcroxybenzoic acid to the corresponding sulfones and phosphates with no interference from other stabilisers or additives. Hindered phenols, benzophenones, triazoles, fatty acid amides, and stearate... 

The first examples of five-coordinate platinum(II) complexes of the type [Pt(PR3)L]2+ (L = tris(2-(diphenylphosphino)ethyl)phosphine R = Et, OMe, OEt) (104) containing only P-donor atoms have been prepared by the reaction of [PtClL]+ with an appropriate monodentate tertiary phosphine or phosphite ligand.284 Triaryl phosphines and phosphites do not react with the precursor complex, even at elevated temperatures, most probably due to the considerable steric interactions that would occur upon the approach of the P-donor ligand to the platinum(II) center. 

The cationic complexes Rh(diene)L >+ (L is a tertiary phosphine, phosphite, or arsine) were reported by several groups in 1969- 1970 (7, p. 270), but Osborn et al. 129-132) first reported on their potential for hydrogenation of olefins, acetylenes, and ketones. Full details on these systems have now appeared 133-135), and the important equilibria governing the active catalysts are given in Eqs. (23)-(25). An important difference from... 

The very unusual selective hydrogenation of ,/3-unsaturated aldehydes to the unsaturated alcohols, Eq. (30), has been accomplished using [RhCl(CO)2]2 in the presence of tertiary amines under oxo conditions (162). RhCl(PPh3)3 systems under similar conditions reduce the olefinic bond (162), as do Co2(CO)8 systems in the presence of amines or phosphites (163). Further details on the versatile Rh(BH4)(amide)py2Cl2 systems (/, p. 280) have appeared (164, 165) ketones are also slowly hydrogenated (166), and 1,5,9-cyclododecatriene has been selectively reduced to cyclododecene (167). 

Preparation of diethyl phenylphosphonate — Reaction of an aryl halide with a dialkyl phosphite in the presence of a Pd(0) catalyst and a tertiary amine... 

The closely related Todd reaction, useful for the preparation of dialkyl phosphorochloridates and phosphoramidates, also involves the use of amines with dialkyl phosphites.146152 180-182 Although the reaction proceeds using preformed salts of the dialkyl phosphites,183 the use of tertiary amines facilitates the reaction by allowing all reagent materials to be in solution. Biphasic reaction systems utilizing phase-transfer catalysts and crown ethers have also been successful for this reaction.158-161... 

Walsh, E.N., Conversion of tertiary phosphites to secondary phosphonates. Diethyl phosphonate, /. Am. Chem. Soc., 81, 3023, 1959. 

In the tetranuclear clusters significant steric control of substitution with tertiary phosphines and phosphites is generally only observed in the fourth substitution step. The synthesis of tetra-substituted derivatives, therefore, requires more severe conditions22,46,86,248 and then breaking of the cluster can become important. 

With tertiary phosphines, phosphites and iso-nitriles, the substitution of the carbonyl groups in Co4(CO)i2 and Rh4(CO)i2 occurs very easily up to the tri-substituted complex. It is sufficient to add slowly at room temperature a solution of the ligand to a solution of the dodecacarbonyl ... 

---