Sec-butyl lithium

Lithium ethoxide Ethyl alcohol, lithium salt (8) Ethanol, lithium salt (9) (2388-07-0) sec-Butyllithium Lithium, sec-butyl- (8) Lithium, (1-methylpropyl)- (9) (598-30-1) Acetyl chloride (8,9) (75-36-5)... 

Butyl lithium, sec-butyl lithium, tert-butyl lithium, and phenyl lithium cleave Te-phenyl and Te-alkyl bonds in tetrahydrofuran at — 78°. These reactions, in which on organic group bonded to tellurium is exchanged for the organic group associated with the organic lithium compound, are useful for the preparation of organic lithium compounds that are otherwise available only with difficulty or not at all. 

Initiating polymerisation of styrene with sec-butyl-lithium. 

When the styrene has been consumed, to give living polymers of narrow molecular mass distribution, more styrene and more catalyst is added. The styrene adds to the existing chains and also forms new polymer molecules initiated by the additional sec-butyl-lithium. 

Diethyl-sec-butyl methyl malonate Lithium aluminum hydride Ethyl urethane... 

The formation of 2-(t-butyl)-2-trimethylsilyl-2//-thiopyran has recently been reported from 1-substituted 1,3-butadienes with /-BuCSSiMe3 (92MI1) (see Scheme 2). An unusual product with proposed structure 47b has been reported (84JOC5143) from benzothiopyrone 46 on reaction with sec-butyl lithium (46 - 47a — 47b, Scheme 3) on the basis of spectroscopic data. 6-Methylthio-2//-thiopyran was isolated after the flash vacuum thermolysis of more complex starting precursors (93TL2605). 

Enantiomerically pure 3-tolyl-2-sulfinyl-2-cyclopentenone 37 undergoes smooth, mild and diastereoselective conjugate hydride addition with lithium tri(sec-butyl)borohydride to afford ultimately 3-tolylcyclopentanone 38 in 93% enantiomeric purity (equation 35)78. The absolute stereochemistry of product 38 is consistent with a chelated intermediate directing hydride addition from that diastereoface containing the sulfoxide lone pair. 

The observation of Tsuji et al. 148) concerned with copolymerization of 1- or 2-phenyl butadiene with styrene or butadiene illustrates again the importance of the distinction between the classic, direct monomer addition to the carbanion, and the addition involving coordination with Li4. The living polymer of 1- or 2-phenyl butadiene initiated by sec-butyl lithium forms a block polymer on subsequent addition of styrene or butadiene provided that the reaction proceeds in toluene. However, these block polymers are not formed when the reaction takes place in THF. The relatively unreactive anions derived from phenyl butadienes do not add styrene or butadiene, while the addition eventually takes place in hydrocarbons on coordination of the monomers with Li4. The addition through the coordination route is more facile than the classic one. 

Polymer Synthesis and Characterization. This topic has been extensively discussed in preceeding papers.(2,23,24) However, we will briefly outline the preparative route. The block copolymers were synthesized via the sequential addition method. "Living" anionic polymerization of butadiene, followed by isoprene and more butadiene, was conducted using sec-butyl lithium as the initiator in hydrocarbon solvents under high vacuum. Under these conditions, the mode of addition of butadiene is predominantly 1,4, with between 5-8 mole percent of 1,2 structure.(18) Exhaustive hydrogenation of polymers were carried out in the presence of p-toluenesulfonylhydrazide (19,25) in refluxing xylene. The relative block composition of the polymers were determined via NMR. 

N-( 1-butyl-lithium, 1,1,3,3-tetramethylbutyl isonitrile, and deuterium oxide,... 

Replacement of hydrogen by alkyl groups gives compounds like lithium triethylborohydride (Super-Hydride ) [100], lithium tris sec-butyl)borohydride [101] (L-Selectride ) and potassium tris sec-butyl)borohydride (K-Selectride ) [702], Replacement by a cyano group yields sodium cyanoborohydride [103], a compound stable even at low pH (down to 3), and tetrabutylammonium cyanoborohydride [93],... 

Other reagents used for the preparation of lactones from acid anhydrides are lithium borohydride [1019], lithium triethylborohydride (Superhydride ) [1019] and lithium tris sec-butyl)borohydride (L-Selectride ) [1019]. Of the three complex borohydrides the last one is most stereoselective in the reduction of 3-methylphthalic anhydride, 3-methoxyphthalic anhydride, and 1-methoxynaphthalene-2,3-dicarboxylic anhydride. It reduces the less sterically hindered carbonyl group with 85-90% stereoselectivity and is 83-91% yield [1019]. 

The dependence of the counterion and of the solvent99 was studied in the addition of sec-butyl and tert-butyl mercaptide to methyl 4-bromocrotonate (3). The highest yield of the Michael addition induced cyclopropane product 10 was observed with lithium as counterion in dichloromethane or pentane as solvent. 

The initiator was purified, by distillation (19), sec-butyl-lithium (Lithco). The ethers and 1,1-diphenylethylene were purified by sequential exposure to , dibutyl magnesium (Lithco)... 

Polymerizations were carried out at 30°C in all glass, sealed reactors using breakseals and standard high vacuum techniques (3). For the calorimetric measurements, a 1 liter sample of a 0.03M solution of each polymeric lithium compound with M of ca. 4,000 was prepared in benzene solution using sec-butyl-lithium as initiator and transferred to the glove box. 

Uraneck and Smith (45) recently have described that the product of 2,4-pentadiene-l-ol and sec-butyl-lithium can be used to synthesize polymers with hydroxyl end groups. However, some of the sec-butyl-lithium ( - 137 ) remains unreacted. 

In homopolymerization initiated by sec-butyl-lithium in hexane, isoprene is a more active monomer than butadiene (with kj 5.53 x 10-5 sec l vs. ki 0.98 x 10 sec- at 20eC). This is also true for reactions at 30° and 40°C. The apparent activation energy for both monomers has been found to be roughly the same,... 

Some information is available on other acrylates. N,N-disubstituted acrylamides form isotactic polymers with lithium alkyls in hydrocarbons (12). t-Butylacrylate forms crystallizable polymers with lithium-based catalysts in non-polar solvents (65) whereas the methyl, n-butyl, sec-butyl and isobutyl esters do not. Isopropylacrylate also gives isotactic polymer with lithium compounds in non-polar solvents (34). The inability of n-alkylacrylates to form crystallizable polymers may result from a requirement for a branched alkyl group for stereospecific polymerization. On the other hand lack of crystallizability cannot be taken as definite evidence of a lack of stereoregulating influence, as sometimes quite highly regular polymer fails to crystallize. The butyllithium-initiated polymers of methylmethacrylate for instance cannot be crystallized. The presence of a small amount of more random structure appears to inhibit the crystallization process1. 

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