Tri n-butylphosphine

Submitted by George B. Kauffman and Larry A. Teter Checked by E. O. BrimmI 

In contrast to the tertiary amines, trialkylphosphines have strong donor properties and form exceedingly stable coordination complexes with a wide variety of metal salts such as those of univalent copper and gold, and bivalent platinum, palladium, and mercury.1 Like phosphine itself, many of these tertiary alkylphosphines are highly flammable, toxic, and extremely susceptible to air oxidation. Ease of oxidation first decreases and then increases as the alkyl group becomes larger.2 3,4 5 The n-butyl compound is thus a convenient member of this group for preparation. 

Tertiary alkylphosphines can be prepared by reaction of phosphonium iodide with alcohols6 or by treatment of a 

three-necked round-bottomed flask is fitted with a Tru-bore paddle stirrer, a long water-cooled reflux condenser, a dropping funnel, and a gas inlet as shown in Fig. 11. The apparatus is dried by flaming with a Bunsen burner while being flushed with a stream of dry nitrogen. 

This gas is passed through the apparatus throughout the course of the entire reaction.  

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Complexes 79 show several types of chemical reactions (87CCR229). Nucleophilic addition may proceed at the C2 and S atoms. In excess potassium cyanide, 79 (R = R = R" = R = H) forms mainly the allyl sulfide complex 82 (R = H, Nu = CN) (84JA2901). The reaction of sodium methylate, phenyl-, and 2-thienyllithium with 79 (R = R = r" = R = H) follows the same route. The fragment consisting of three coplanar carbon atoms is described as the allyl system over which the Tr-electron density is delocalized. The sulfur atom may participate in delocalization to some extent. Complex 82 (R = H, Nu = CN) may be proto-nated by hydrochloric acid to yield the product where the 2-cyanothiophene has been converted into 2,3-dihydro-2-cyanothiophene. The initial thiophene complex 79 (R = R = r" = R = H) reacts reversibly with tri-n-butylphosphine followed by the formation of 82 [R = H, Nu = P(n-Bu)3]. Less basic phosphines, such as methyldiphenylphosphine, add with much greater difficulty. The reaction of 79 (r2 = r3 = r4 = r5 = h) with the hydride anion [BH4, HFe(CO)4, HW(CO)J] followed by the formation of 82 (R = Nu, H) has also been studied in detail. When the hydride anion originates from HFe(CO)4, the process is complicated by the formation of side products 83 and 84. The 2-methylthiophene complex 79... 

Darkowski and Cocivera [94] investigated trialkyl- or triarylphosphine tellurides, as low-valent tellurium sources, soluble in organic solvents. They reported the cathodic electrodeposition of thin film CdTe on titanium from a propylene carbonate solution of tri-n-butylphosphine telluride and Cd(II) salt, at about 100 °C. Amorphous, smooth gray films were obtained with thicknesses up to 5.4 p,m. The Te/Cd atomic ratio was seen to depend on applied potential and solution composition with values ranging between 0.63 and 1.1. Polycrystalline, cubic CdTe was obtained upon annealing at 400 C. The as-deposited films could be either p- or n-type, and heat treatment converts p to n (type conversion cf. Sect. 3.3.2). 

Sanders BW, Cocivera M (1987) Characterization of cadmium selenide electrodeposited from diethylene glycol solution containing tri-n-butylphosphine selenide. J Electrochem Soc 134 1075-1080... 

In 1989 Jutzi et al. reported the reaction of decamethylsilicocene 50 with tri-n-butylphosphine selenide in benzene at room temperature, leading to almost quantitative formation of a 1,3,2,4-diselenadisiletane derivative 52, a head-to-tail [2+2] cycloaddition reaction product of the initially formed silaneselone 51.35 The intermediacy of silaneselone 51 was experimentally supported by the reaction in the presence of 2,3-dimethyl-1,3-butadiene resulting in the formation of the corresponding [2+4] cycloaddition reaction product 53 (Scheme 14). 

Cotton treated with bis(2-isocyanatoethyl) disuphide in dimethylformamide at 80 °C, followed by reduction with tri-n-butylphosphine in methanol containing 10% water. This gives the 2-mercaptoethylcarbamyl ester, which is treated with methyl iodide to form sulphonium salts. (Scheme 10.66). 

The beneficial effect of added phosphine on the chemo- and stereoselectivity of the Sn2 substitution of propargyl oxiranes is demonstrated in the reaction of substrate 27 with lithium dimethylcyanocuprate in diethyl ether (Scheme 2.9). In the absence of the phosphine ligand, reduction of the substrate prevailed and attempts to shift the product ratio in favor of 29 by addition of methyl iodide (which should alkylate the presumable intermediate 24 [8k]) had almost no effect. In contrast, the desired substitution product 29 was formed with good chemo- and anti-stereoselectivity when tri-n-butylphosphine was present in the reaction mixture [25, 31]. Interestingly, this effect is strongly solvent dependent, since a complex product mixture was formed when THF was used instead of diethyl ether. With sulfur-containing copper sources such as copper bromide-dimethyl sulfide complex or copper 2-thiophenecarboxylate, however, addition of the phosphine caused the opposite effect, i.e. exclusive formation of the reduced allene 28. Hence the course and outcome of the SN2 substitution show a rather complex dependence on the reaction partners and conditions, which needs to be further elucidated. 

Scheme 2.20 Enantiomerically enriched or pure vinylallenes formed by 1,5-substitution of chiral enyne acetates in the presence of tri-n-butylphosphine (53-56) or triethyl phosphite (57).

Tri-n-butylphosphine is also an effective catalyst for acylations by anhydrides. It is thought to act as a nucleophilic catalyst by generating an acylphosphonium ion.102... 

Compared with the variety of existing carbon or nitrogen nucleophiles that were subjected to nucleophilic addition to there are few examples for phosphorus nucleophiles. Neutral trialkylphosphines turn out to be to less reactive for an effective addihon to Cjq even at elevated temperatures [114], Trialkylphosphine oxides show an increased reactivity. They form stable fullerene-substituted phosphine oxides [115] it is not yet clear if the reaction proceeds via a nucleophilic mechanism or a cycloaddition mechanism. Phosphine oxide addition takes place in refluxing toluene [115], At room temperature the charge-transfer complexes of with phosphine oxides such as tri-n-octylphosphine oxide or tri-n-butylphosphine oxide are verifiable and stable in soluhon [116],... 

The deoxygenative ring expansion of nitrobenzene with tri-n-butylphosphine in butanol (77BCJ2013), or with phosphorus trichloride and di-n-butylamine in hexane, followed by catalytic reduction and hydrolysis of the resulting 2-butoxy- or 2-butylamino-3//-azepines have been patented as methods for the production of caprolactam (78JAP(K)78132586, 77GEP2647936 respectively). 

The method described here is based on two reactions first, the reduction of the disulphide bond between Hey and other thiols or the cysteine residue of proteins by the reducing compound tri-n-butylphosphine (Fig. 2.2.2a) followed by the reaction of Hey and other thiols with the flourogenic thiol-specific reagent ammonium... 

Fig. 2.2.2 a Reaction of tri-n-butylphosphine as a reducing agent, b Reaction of the derivatisa-tion of Hey with ammonium 7-fluorobenzo-2-oxa-l,3-diazole-4-sulfonate (SBDF), which is a fluorescent derivatising reagent... 

Tri-n-butylphosphine, 10% one volume of tri-n-butylphosphine (Sigma P-6918) is added to nine volumes of N,N-dimethylformamide (Aldrich 31,993-7). This solution must always be freshly prepared. 

The reduction reaction is carried out in 1.5-ml Eppendorf tubes. Frozen samples are thawed out, thoroughly mixed and, if necessary, centrifuged to remove particulate material. For samples and the pooled plasma blank, 150 pi plasma and 50 pi internal standard in 0.1 mol/1 borate buffer are added to 20 pi of 10% tri-n-butylphosphine. For each Hey standard, 150 pi of pooled plasma and 50 pi of Hey standard (internal standard is included) are mixed with 20 pi of tri-n-butylphosphine. Tubes are left to stand on ice for 30 min. Samples are deproteinised by the addition of 125 pi of... 

OH - Br. A primary or secondary alcohol can be converted to the alkyl phenyl selenide by reaction with phenyl selenocyanate and tri-n-butylphosphine (7, 252-253). Reaction with Br2 and triethylamine (7, 34-35) replaces the SeC6H5 group by Br. 

CH2OH - —CHiCN.1 This transformation is possible by treatment of a primary alcohol with tri-n-butylphosphine, carbon tetrachloride, potassium cyanide, and 18-crown-6 at room temperature. No reaction occurs in the absence of the crown ether. Yields of nitriles are 70-85%. 

The monomers dealt with can be polymerized by various mechanisms, not only by ROMP. For example, a rapid polymerization of norbornadiene occurs using a homogeneous catalytic system consisting of nickel acetylacetonate or a nickel-phosphine complex, such as nickel bis-(tri-n-butylphosphine) dichloride (NiCl2(TBP)2) or nickel bis-(tricyclohexylphosphine) dichloride (NiCl2(TBP)2). Nickel acetylacetonate as catalyst is known to initiate rather a classical vinyl polymerization (7). The classical vinyl polymerization... 

Trimerization of methyl isocyanate (MeNCO) in the presence of tri-n-butylphosphine gives a... 

To the Co complex (1.28 g, 2.32 mmol) in heptane (23 mL, purged with carbon monoxide for 3 h before use) was added tri-n-butylphosphine oxide (506 mg, 2.32 mmol). The solution was sealed in a screw-cap resealable tub under an atmosphere of CO and heated to 85°C (over glyme heated at reflux) for 71 h. After cooling, the solution was applied directly to a bed of Fluorisil and eluted with ethyl acetate-petroleum ether 95 5 to 50 50) giving the tricyclic enone 304 mg, 45%) as a colorless oil [a]D 22 +116° (c 2.47, CHC13). 

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