Butyllithium properties

Organometallics Commercial Product Data, FMC Lithium Division, Gastonia, N.C. Butyllithium—Properties and Uses, Chemetad GmbH Lithium Division, Frankfurt, Germany t-Butyllithium in Heptane, FMC Lithium Division, Gastonia, N.C. 

Benzylthiazole reacts with n-butyllithium to give 2- and 5-substituted products, but as expected from the particular properties of the 2-methyiene group, the proportion of 2-lithium derivatives is much more important (223). 

A variable pressure oil pump was used in this distillation. Approximately 10 g of a volatile component, consisting mostly of hexamethyl-disiloxane, was obtained at room temperature (15 (in) before the forerun. The forerun contained the desired product and mineral oil from the n-butyllithium solution. The pot residue was about 5 g. The submitters find the disilyl compound thus obtained is contaminated with a trace amount of mineral oil and 4-6% of a vinylsilane, probably 2-methyl-l-trimethylsiloxy-3-trimethylsilyl-2-propene. This impurity becomes quite significant if the reaction medium is less polar than the one described (e.g., too much hexane from n-butyllithium is allowed to remain behind). The spectral properties of the desired product... 

The nucleophilic properties of phosphorus in phosphaferrocene were demonstrated by reaction with n-butyllithium occurring at the phosphorus atom (81IC3252 820M312). 

Currently, more SBR is produced by copolymerizing the two monomers with anionic or coordination catalysts. The formed copolymer has better mechanical properties and a narrower molecular weight distribution. A random copolymer with ordered sequence can also be made in solution using butyllithium, provided that the two monomers are charged slowly. Block copolymers of butadiene and styrene may be produced in solution using coordination or anionic catalysts. Butadiene polymerizes first until it is consumed, then styrene starts to polymerize. SBR produced by coordinaton catalysts has better tensile strength than that produced by free radical initiators. 

This section is completed with a brief review of the synthesis and properties of this epimer (20) of the precursor of thiazole in bacteria. This pentulose is conveniently accessible by an unconventional route (Scheme 19). Methyl 2,3 4,6-di-O-isopropylidene-a-D-mannopyranoside, readily available from methyl ot-D-mannopyranoside, is converted to the ketonic glycoside by butyllithium in 91% yield, following a method first published by Klemer and Rodemeyer43 and scaled up by Horton and Weckerle.44 This was converted by means of lithium hydroxide in a water-ether mixture into 3,5-0-benzylidene-l-deoxy-D-eryf/iro-2-pen-tulose in 55% yield. Hydrolysis to the free pentulose (20) proceeded in 73% yield in aqueous acetic acid. This product was obtained as a syrup with a characteristic absorption band at 1705 cm 1 as a film. Thus, there is a fair proportion of the open-chain ketone under these conditions, as with the D-threo epimer.45... 

The effect of media viscosity on polymerization rates and polymer properties is well known. Analysis of kinetic rate data generally is constrained to propagation rate constant invarient of media viscosity. The current research developes an experimental design that allows for the evaluation of viscosity dependence on uncoupled rate constants including initiation, propagation and macromolecular association. The system styrene, toluene n-butyllithium is utilized. 

The formation and properties of octafluorodibenzothiophene (85) have been the subject of a series of papers by Chambers et al. Ullman coupling of bis(2-bromotetrafluorophenyl)sulfide gives 85 in quantitative yield [Eq. (6)]. An alternative route to 85 involves treating 2,2 -dihydrooctafluorobiphenyl with butyllithium and reacting the... 

N-Unsubstituted azomethine ylides may be generated thermally (79), and the N-metalated, 2-azaallyl anion versions may be generated by action of nonmetalhc bases such as l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on certain imines (80). Although they are assumed to show similar chemical properties, these two species usually show different reaction patterns, as shown in Scheme 11.7, where the regio-and stereoselectivities of the cycloadditions are quite different (24,78-80). Metala-tion of (alkylideneamino)acetonitriles can be performed with metallic bases other than LDA. Thus, butyllithium, ethylmagnesium bromide, and magnesium bromide-diisopropylamide are also effective (78). The N-magnesioazomethine... 

Okamura and Katz31 prepared the azapentalenyl ion 246 in solution by treatment of the dihydro compound 245 with n butyllithium at —78° (cf. Section III,A,5). The spectroscopic properties and chemistry of this ion have been extensively explored, and the UV spectrum closely resembles that of the pentalenyl dianion2 (Section I). 

The properties of lithium metal are well known, but the properties of its alkyls have until recently received much less attention. The lowest member of the series, methyllithium, is a non-volatile microcrystalline powder insoluble in hydrocarbons. Ethyllithium is a colourless crystalline compound melting at 95°. n-Propyl and n-butyllithium are almost colourless fairly viscous non-volatile oils soluble in hydrocarbons and ethers. These properties are to be compared with those of the corresponding sodium alkyls which are all colourless, non-volatile crystalline solids, insoluble in hydrocarbons. The difference in properties is usually attributed to differences in the type of bond between lithium and sodium alkyls, the former being considered covalent and the latter ionic compounds. Thus Coates (17) distinguishes between two types of compounds ... 

Standstrom [3] improved the elongation at break properties of tires by blending 70% di-poly(l,4-isoprene) with 30% poly(butadiene) containing a high trans content. The latter was prepared using barium di(ethylene glycol) ethyl ether, tri-octyl aluminum, and n-butyllithium as the reaction catalyst mixture. 

To achieve optimal properties in an AB block copolymer, it is important to control the molecular weight of the blocks, and minimize the amount of A homopolymer produced on addition of the second monomer. Termination reactions do occur in these systems [20], but the rate is fairly slow, particularly at temperatures below about 100 °C. In a practical sense, protic impurities present a much greater challenge. In a two-reactor system it is common practice to prepare the first block in one reactor, titrate out impurities in the B monomer charge in a second reactor by adding small increments of butyllithium to a solution of the B monomer until the first sign of color or exotherm, and then the transfer poly(A)Li solution to the second reactor. 

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