Butane-, lithium

In order to determine if the tacticity is maintained in changing from a monfunctional lithium initiator to a bifunctional lithium initiator, DMA, TrMA, and MMA were all homopolymerized using 1,1,4,4-tetraphenyl butane lithium dianion (DPE Li" )2. 

Scheme 10.54. The reaction of triphenylphosphine, (C6Hs)3P, with bromomethane (CHsBr) to form the phosphonium bromide salt and its subsequent treatment with n-butyltithium (written here in quotation marks since it should be realized now that n-butylUthium is used in solution and it may actually not be the monomeric species shown) to produce butane, lithium bromide, and the phosphorane.

The product described here, 4-(4-chlorophenyl)butan-2-one, was previously prepared in the following ways a) by reduction of the corresponding benzalacetone, b) by catalyzed decarbonylation of 4-chlorophenylacetaldehyde by HFeiCO) in the presence of 2,4-pentanedione, - c) by reaction of 4-chlorobenzyl chloride with 2,4-pentanedione under basic catalysis (K2CO3 in EtOH), d) by reaction of 4-chlorobenzyl chloride with ethyl 3-oxobutanoate under basic catalysis (LiOH), - and e) by reaction of 3-(4-chlorophenyl )-propanoic acid with methyl lithium. - ... 

The central C—C bond in bicyclo[ 1.1.0] butane has a high -character and is known to behave as an olefin. Thus, 1-arylsulfonylbicyclobutanes 312 reacted with Grignard reagents in the presence of lithium dialkylcuprates or cuprous salts (Me2S, CuBr or CuCl) giving 3-alkyl-1-arylsulfonylcyclobutanes 313406. 

The oxidation of n-butanal by CUCI2 in dimethylformamide showed simple second-order kinetics in the presence of lithium chloride . At 83 °C, 2 s 2x10 1.mole". sec". a-Monohalogenation occurs in 97% yield. Cu(Il)-catalysed enolisation followed by ligand-transfer is proposed. a-Halogenation of acetone is accomplished by CUCI2, viz. 

The next step in this study is to test this control algorithm on the actual laboratory reactor. The major difficulty is the direct measurement of the state variables in the reactor (T, M, I, W). Proposed strategy is to measure total mols of polymer (T) with visible light absorption and monomer concentration (M) with IR absorption. Initiator concentration (I) can be monitored by titrating the n-butyl lithium with water and detecting the resultant butane gas in a thermal conductivity cell. Finally W can be obtained by refractive index measurements in conjuction with the other three measurements. Preliminary experiments indicate that this strategy will result in fast and accurate measurements of the state vector x. 

Irradiation causes ring closure by valence isomerization of 1,3-diphosphacyclobutane-2,4-diyl 42 (R = 2,4,6-tri(tert-butyl)phenyl) to 2,4-diphosphabicyclo[1.1.0]butane 43 which on thermolysis yielded the gauche-1,4-diphosphabutadiene 44 <99AG(E)3028>. The same group of workers have isolated the carbene 45 (R as above) as the lithium salt of a trimethylalane complex 46 <99AG(E)3031>. 

Generation in situ. Butyllithium (primary, secondary, or tertiary) can be generated by sonication of a mixture of lithium wire and a butyl chloride at 15° in dry THF. The corresponding butane is evolved under these conditions and LiCl precipitates the reaction is generally complete within 15 min. The highly useful lithium diisopropylamide can be prepared by sonication of a mixture of diisopropylamine, lithium, and butyl chloride in dry THF or ether. The yield is 91% and the solution can be used directly for deprotonation. Other lithium amides, even LiTMP, can be prepared in the same way. 

Geurink and Klumpp used 2-butanol as the proton source in benzene solvent. They found an exothermic protodelithiation of —221 4 kJmoP for w-butyl lithium and —240 5 kJmol for the isomeric iec-butyl lithium to form the same w-butane product. The difference between the protodelithiation enthalpies is 19 6 kJmoP, the same as the difference between the enthalpies of formation of the two alkyl lithiums. From Table 1, the difference is ca 21 kJmoR, in complete agreement. 

The protodelithiation enthalpy of n-propyl lithium is very nearly the same as for the n-butyl species, —219 2 kJmoP. From reaction 10 with w-butyl lithium as the benchmark species and the enthalpies of formation of the hydrocarbons in their gaseous reference states, the enthalpy of formation of n-propyl lithium is calculated as ca —91 klmoP, a value consistent with that of —86 kJ moP derived from w-PrMgBr in an earlier section. If the reference state of n-butane is taken as the liquid instead, the enthalpy of formation of n-propyl lithium is ca —70 kJ moP, a value consistent with another previous derivation of ca —73 kJmoP. At least with respect to consistency with the enthalpies of formation in Table 1, the best reference state for ethane and propene is the gas it is not yet clear which is better for butane. 

Arnett and Moe studied the protodelithiation of organolithiums with isopropyl alcohol in hexane/ether mixtures. These authors found protodelithiation enthalpies for n- and iec-butyl lithium of —209.2 4.2 and —220.9 2.9, respectively. The difference between their enthalpies of reaction, and so of the enthalpies of formation of the two organolithiums, is 11.7 5.1 kJmor, about half the difference between these species as found in Table 1. The protodelithiation enthalpy of terf-butyl lithium is —237.7 7.5 kJmoP. From equation 10 with n-butyl lithium as the benchmark species, and the butane hydrocarbons in their liquid reference states, the derived enthalpy of formation of ferf-butyl lithium is —87.5 kJmoP, in good agreement with that found before by Hohn . 

The derived enthalpies of formation of the n-propyl and ec-butyl lithiated methoxy ethers are —260 and —275 kJmon, respectively, from equation 16, the enthalpies of protodelithiation, the enthalpy of formation of n-butyl lithium from Table 1 and of liquid n-butane, and the measured enthalpies of formation of methyl n-propyl ether (Iq, —266.0 ... 

The reduction of l,l-bis(diphenylphosphanyl) ethylene (248) with an excess of metallic lithium, activated by ultrasonic irradiation, leads to C—C coupling under the formation of a l,l,4,4-tetrakis(diphenylphosphanyl)butane (249) (Scheme 88)". Surprisingly, the lithium centres in the resulting dilithium compound do not form any lithium-carbon contacts, being coordinated by two diphenylphosphanyl groups and two TFIF molecules each. With this strucmral motif, the molecular structure is similar to the one of tris(phosphaneoxide) 20 (Section n. A), also obtained by Izod and coworkers upon deprotonation. ... 

The chelate formation in lithium complexes 17 or 20 contributes to stabilization. Enhancement of kinetic acidity arises from the formation of pre-complexes 16 and 19, respectively. Here, already a dipole is induced and, in addition, proton exchange can proceed intramolecularly via a five- or six-membered ring. Despite these favourable features, the acidity of alkyl carbamates 15 is lower than those of the 1-proton in butane n-BuLi does not lead to deprotonation. In order to suppress carbonyl attack, a branched amino residue NR2 such as diisopropylamino (in Cb) or 2,2,4,4-tetramethyl-l,3-oxazolidin-3-yl (in Cby) is essential. A study on the carbenoid nature of compounds 17 was undertaken by Boche and coworkers. ... 

A suspension of 1.5 mol of lithium acetylide in 600 ml of THF (p. 21) is cooled to -10 C. Acetylene is then introduced at a rate of 500 ml/min with vigorous agitation. After 10 min the rate is adjusted to -300 ml/min and 1.5 mol of fleshly distilled butanal is added dropwise over 30 min, while keeping the temperature between -10 and 0 C. The bath is then removed and stirring and introduction of acetylene are continued for an additional 10 min. The equipment is removed and two stoppers are placed on the outer necks. The greater pan of the THF is... 

The enantiomerically pure a-stannyl ether, (R)-l-benzyloxymethoxy-l-tributylstannyl-propane, can be obtained by resolution of the precursor compound. The tin - lithium exchange reaction, as well as the electrophilic substitution, occurred with retention of configuration to give (I )-2-(benzyloxymethoxy) butane only28. A later study examined more examples and also confirmed this result27. 

Die hier beschriebenc Art der Oxyaminierung ist hoch stereospezifisch so erhalt man z. B. aus ( )- bzw. (Z)-2-Buten mit Dimethylamin als Amin-Komponente (nach reduktiver Deacetylierung des primar gebildeten 3-Acetoxy-2-amino-butans mit Lithium-alanat) threo- bzw- erythro-2-Dimethylconino-3-hydroxy-butan in jeweils 99%iger Reinheit2. 

Hohe optische Ausbeuten an 2-Amino-alkanen [z.B. (S)-2-Amino-butan, (S)-l-Amino-1-cyclohexyl-ethan] und Amino-ary 1-alkanen [z.B. (S)-i- und (S)-2-Amino-1-phenyl-propan] erhalt man auch bei der Reduktion der entsprechenden Ketoxime mit einem aus Lithium-alanat und 3-0-Cyclohexylmethyl-l,2-0-cyclohexyliden-a-D-glucofuranose ge-bildeten Komplex in Ether3. 

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