Sodium organometallic compounds

The properties of organometallic compounds are much different from those of the other classes we have studied to this point Most important many organometallic com pounds are powerful sources of nucleophilic carbon something that makes them espe cially valuable to the synthetic organic chemist For example the preparation of alkynes by the reaction of sodium acetylide with alkyl halides (Section 9 6) depends on the presence of a negatively charged nucleophilic carbon m acetylide ion... 

The first organometallic compounds we encountered were compounds of the type RC=CNa obtained by treatment of terminal alkynes with sodium amide m liquid ammo nia (Section 9 6)... 

Mechanistically the reaction can be divided into two steps. Initially the alkyl halide 1 reacts with sodium to give an organometallic species 3, that can be isolated in many cases. In a second step the carbanionic R of the organometallic compound 3 acts as nucleophile in a substitution reaction with alkyl halide 1 to replace the halide ... 

Many metals occur in crude oils. Some of the more abundant are sodium, calcium, magnesium, aluminium, iron, vanadium, and nickel. They are present either as inorganic salts, such as sodium and magnesium chlorides, or in the form of organometallic compounds, such as those of nickel and vanadium (as in porphyrins). Calcium and magnesium can form salts or soaps with carboxylic acids. These compounds act as emulsifiers, and their presence is undesirable. 

Other organometallic compounds that are hydrolyzed by water are those of sodium, potassium, lithium, zinc, and so on, the ones high in the electromotive series. Enantioselective protonation of lithium enolates and cyclopropyllithium compounds have been reported. When the metal is less active, stronger acids are required. For example, R2Zn compounds react explosively with water, R2Cd slowly, and R2Hg not at all, though the latter can be cleaved with concentrated HCl. How-... 

Many organometallic compounds are best prepared by this reaction, which involves replacement of a metal in an organometallic compound by another metal. The compound RM can be successfully prepared only when M is above M in the electromotive series, unless some other way is found to shift the equilibrium. That is, RM is usually an unreactive compound and M is a metal more active than M. Most often, RM is R2Hg, since mercury alkyls are easy to prepare and mercury is far down in the electromotive series." Alkyls of Li, Na, K, Be, Mg, Al, Ga, Zn, Cd, Te, Sn, and so on have been prepared this way. An important advantage of this method over 12-36 is that it ensures that the organometallic compound will be prepared free of any possible halide. This method can be used for the isolation of solid sodium and potassium alkyls." If the metals lie too close together in the series, it may not be... 

In the reaction of 3-( 1 -imidazolyl)-2-alkene-1 -ones with organometallic compounds or sodium borohydride (NaBIti), only the route leading to a 2-alkene-l-one via a 1,4-addition reflects azolide chemistry. 

The carbonates, sulfates, nitrates, and phosphates of the group IA and IIA metals are important materials in inorganic chemistry. Some of the most important compounds of the group IA and IIA elements are organometallic compounds, particularly for lithium, sodium, and magnesium, and Chapter 12 will be devoted to this area of chemistry. 

Merox [Mercaptan oxidation] A process for removing mercaptans from petroleum fractions by extracting them into aqueous sodium hydroxide and then catalytically oxidizing them to disulfides using air. The catalyst is an organometallic compound, either a vanadium phthalocyanine supported on charcoal, or a sulfonated cobalt phthalocyanine. Developed by UOP in 1958 and widely licensed by 1994, more than 1,500 units had been built, worldwide. Unzelman, G. H. and Wolf, C. J., in Petroleum Processing Handbook, Bland, W. F. and Davidson, R. L., Eds., McGraw-Hill, New York, 1967, 3-128. 

Organometallic compounds, 14 550-551 25 71. See also Organometallics carbides contrasted, 4 648 as initiators, 14 256-257 iridium, 19 649-650 molybdenum(III), 17 27 osmium, 19 642-643 palladium, 19 652 platinum, 19 656-657 reaction with carbonyl groups, 10 505-506 rhodium, 19 645-646 ruthenium, 19 639 sodium in manufacture of, 22 777 titanium(IV), 25 105-120 Organometallic fullerene derivatives,... 

The first weU-characterized organometallic compounds of the lanthanides or actinides were the tricyclopentadienides of various lanthanide ions S3mthesized by Birmingham and Wilkinson in 1954 (97—98). Anhydrous metal chlorides were reacted with sodium cyclopentadienide in tetrahydrofuran as follows ... 

Complex hydrides were used for reductions of organometallic compounds with good results. Trimethyllead chloride was reduced with lithium aluminum hydride in dimethyl ether at —78° to trimethylplumbane in 95% yield [1174, and 2-methoxycyclohexylmercury chloride with sodium borohydride in 0.5 n sodium hydroxide to methyl cyclohexyl ether in 86% yield [1175]. 

Less electronegative metals, such as sodium, tend to form ionic organometallic compounds. These compounds have limited use in synthesis. One example of using a different organometallic in a synthesis is... 

Isoxazolo[5,4-3]pyridine 95 reacted in the dark to give different addition products 96-98 (Equation 9 Table 16), depending on the number of equivalents of organometallic compound and on the reaction temperature <2002TL9527>. The same authors found that sodium malonate, thermally unreactive toward the isoxazolo[5,4-/ ]-pyridine 95, can be used as a photochemical trapping agent <2002TL9527>. 

Alkali-metal ate compounds are among the first organometallic compounds reported. Already in 1858 the formation of a crystalline material formulated as Na[Et3Zn] , obtaiued from the reaction of metallic sodium with EtaZn, was reported by Wanklyn . It then took almost a century before the first organomagnesiate was reported. In 1951 Wittig and coworkers realized that organometallic compounds with anionic formulations, for which he coined the term ate , could be made. In this paper the formation of LilPhsMg] and other ate -type compounds from its homometallic components was described (equation 4). 

Organometallic compounds that exhibit Lewis acidity on the metal centre are susceptible towards nucleophilic attack by alkali metal compounds, thus forming the so-called ate compounds in which the Lewis acidic metal is often coordinatively saturated. Already in 1858 Wanklyn reported the formation of a crystalline compound formulated as [EtsZnJNa which he obtained from the reaction of diethylzinc with metallic sodium (equation l). i5. is. 

---