Trialkyl compounds

Trialkyl- and triarylarsine sulfides have been prepared by several different methods. The reaction of sulfur with a tertiary arsine, with or without a solvent, gives the sulfides in almost quantitative yields. Another method involves the reaction of hydrogen sulfide with a tertiary arsine oxide, hydroxyhahde, or dihaloarsorane. X-ray diffraction studies of triphenylarsine sulfide [3937-40-4], C gH AsS, show the arsenic to be tetrahedral the arsenic—sulfur bond is a tme double bond (137). Triphenylarsine sulfide and trimethylarsine sulfide [38859-90-4], C H AsS, form a number of coordination compounds with salts of transition elements (138,139). Both trialkyl- and triarylarsine selenides have been reported. The trialkyl compounds have been prepared by refluxing trialkylarsines with selenium powder (140). The preparation of triphenylarsine selenide [65374-39-2], C gH AsSe, from dichlorotriphenylarsorane and hydrogen selenide has been reported (141), but other workers could not dupHcate this work (140). 

The alkylation of benzenes having electron withdrawing groups, such as chlorobenzene and anisole, with 3 gave only monoalkylated, dialkylated. and trialkylated compounds.but no peralkylated products were obtained even upon heating of... 

If a higher ratio of alkylating agent to PX3 is used, the dialkyl and trialkyl compounds can also be obtained. At high temperature, the reaction of benzene and PC13 produces phenyldichlorophosphine, CsH5PC12, an intermediate in the preparation of parathion. 

Trialkyltin and triaryltin compounds possess powerful biocidal properties. These are manifested to a high degree only when the tin atom is combined directly with three carbon atoms, as in trialkyl compounds (R3SnX) biocidal effects are at a maximum when the total number of carbon atoms attached to Sn is 12. These compounds are used as fungicides, insecticides and as pest control in agricultural applications29. 

In the polyalkylation reaction of benzene with allylchlorosilanes, trialkylated compounds are the most substituted products obtained in appreciable amount due to increased steric interactions with additional allyltrichlorosilane. This is the case even when more than a four-fold excess of allyltrichlorosilane is used. In addition, multi-step alkylation reactions give the trialkylated products in higher yields than the one-step reaction. 

In these compounds the metal-carbon bonds are highly covalent and chemically rather stable. The chemical reactivity of the trivalent compounds, in particular those of the type R3M is associated with an easy oxidizability to the pentavalent state rather than with rupture of metal-carbon bonds. Thus, the vigorous reaction of the trialkyl compounds R3M with air depends on the following oxidative transformation ... 

The dialkyl and trialkyl compounds can also be obtained by using different ratios of the alkylating agent to PC13. At high temperatures (600-700 °C), PC13 reacts with benzene to produce phenyl dichlorophosphine ... 

Organobismuth(III) halides may be prepared by elimination of aryl halide from triarylbismuth(V) dichlorides or dibromides upon heating (equation 4). Presumably, a bis-muth(V) compound is the intermediate when triarylbismuth compounds are treated with iodine or when trialkylbis-muth complexes are treated with chlorine, bromine, or iodine, but the intermediates have not been isolated and organobismuth halides are obtained directly (equation 5). The tris(trifluoromethyl)bismuth behaves like the trialkyl compounds without the observation of a bismuth(V) intermediate. ... 

How can we assess the thermochemical data presented in Table 1 Many were obtained by static-bomb calorimetry. Regrettably, this technique is clearly unsuitable to deal with these substances due to the ill-defined composition of the combustion products (see the discussion in References 13 and 28). The formation of nonstoichiometric oxides upon combustion all but precludes the experimental rigor demanded of the combustion calorimetrist. This fact, by itself, allows us to question the reliability of the values shown for all of the trialkyl compounds and for triphenylantimony. Although the results for triphenylbismuth found by static and rotating-bomb calorimetry overlap within their error bars, this has been suggested to be fortuitous ... 

Differing from this course of reaction, in the case of the analogous trialkyl compounds the P atom may be incorporated into the ring system (equation 63). ... 

The reactivity of trialkylated compounds is lower than that of dialkylated ones. 

Because of the steric hindrance, trialkylated compounds hardly undergo further alkylation on the surface of catalysts. 

Thus the lower trialkyl compounds inflame spontaneously in the air. However, in contrast to the behavior of other alkylmetals, the reaction with oxygen does not occur first at the metal-carbon bond cautious oxidation gives instead oxides of composition R3MO. The triaryl compounds are stable to atmospheric oxygen and yield their oxides only when subjected to strong oxidizing agents. 

Trialkyl phosphorothioates can be made to isomerize to the 0,0,5 -trialkyl compounds in a process which can be thermally initiated and which may occur during distillation. A similar rearrangement, coupled (evidently) with an allylic rearrangement, occurs... 

The p(SnF) for terminal bonds are at 650-625 cm whereas those for bridging bonds are at 425-335 cm. in the solid state, the coordination number of tin is five or six. Dialkyl compounds prefer six-coordinate structures, while trialkyl compounds tend to form five-coordinate structures. In both cases, the favored positions of the alkyl groups are those shown in the above diagrams. Normal coordinate calculations have been made on the tra .s-t(CH3)2SnX4] " (X = F, Cl, and Br) series. " ... 

The trialkyl compounds, AlkgArPX, are obtained from dialkylaryl-phosphines and alkyl halides ... 

Alkyl aluminum compound n. Any of a family of organo-aluminum compounds widely used as catalysts in the Ziegler-process polymerization of olefins. Members include trialkyl compounds such as triethyl-, tripropyl-, and triisobutyl aluminums alkyl aluminum hydrides such as diisobutyl aluminum hydride and diethyl aluminum hydride and alkyl aluminum halides such as diethyl aluminum chloride. 

Organoaluminum sonochemistry is not yet well developed despite the synthetic and economic interest. Aluminum, a ductile metal, is easily activated by sonication, as evidenced by the use of foils to determine the energy of cleaning baths. Alkyl halides react with aluminum at room temperature in THF to give the sesquihalide, reduced to the trialkyl compound in the presence of magnesium. Examples are known with bromomethane or -ethane.1 2,183 reaction occurs with stirring under similar conditions. Triethylaluminum was used in sonochemical transmetallation reactions leading to zinc and boron alkyls (Eq. 38). 

The SiH group. Numbers of tri-substituted silanes with three identical substituents have been studied by Smith and Angelotti [40] in connection with their electronegativity relationships, and many additional data are available from studies on siloxanes and similar materials. Triaryl silanes absorb between 2132—2112 cm" and trialkyl compounds between 2100—2095 cm". Mixed alkyl/aryl materials have corresponding intermediate values. The effects of the electronegativity of the substituents is well shown by the values of trifluro (2282 cm" ), tribromo (2236 cm ) and trimethoxy (2203 cm" ) silanes. Compounds with mixed groups have the appropriate intermediate values. 

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