Lithium methoxide

Other, even milder bases than LDA and LHS, such as lithium methoxide and lithium /-butoxide, may be used in organic syntheses (143,144). Lithium methoxide is available commercially as a 10% solution in methanol and lithium /-butoxide as an 18% solution in tetrahydrofuran (145). Lithium /-butoxide is also soluble in hydrocarbon solvents (146). Both lithium alkoxides are also available as soHds (147) (see Alkoxides, metal). 

Lithium methylate (lithium methoxide) [865-34-9] M 38.0. Most probable impurity is LiOH due to hydrolysis by moisture. It is important to keep the sample dry. It can be dried by keeping in a vacuum at 60-80° under dry N2 using an oil pump for a few hours. Store under N2 in the cold. It should not have bands above 3000cm-> IR has VKBr 1078, 2790, 2840 and 2930cm-. [JOrgChem 21 156 7956.]... 

The thermolabile, unsubstituted 3-benzothiepin (3) can be synthesized by a double Wittig reaction, in analogy to the Knoevenagel condensation (vide supra). This is achieved by condensation of phthalaldehyde with the bis(triphenylphosphonium) salt of bis(bromomethyl) sulfide in the presence of lithium methoxide as base at — 30"C.68... 

According to the depth profile of lithium passivated in LiAsF6 / dimethoxyethane (DME), the SEI has a bilayer structure containing lithium methoxide, LiOH, Li20, and LiF [21]. The oxide-hydroxide layer is close to the lithium surface and there are solvent-reduction species in the outer part of the film. The thickness of the surface film formed on lithium freshly immersed in LiAsF /DME solutions is of the order of 100 A. 

A suspension of lithium methoxide (prepared from 1.00 g (31.2 mmol) of methanol in 50 mL of THF and 17.7 mL (27.2 mmol) of 1.54 M butyllithium in hexane) is transferred via a cannula into a — 78 C sol ution of 5.86 g (27.1 mmol) of 2-[(/ )-(/T)-1-chloro-2-butenyl]-4,4,5,5-tctramethyl-l,3,2-dioxaborolane in 100 mL of THF. The solution is warmed, becoming homogeneous at 0 JC, and stirred for 1 h. Solvents arc removed in vacuo and the residue dissolved in 150 mL of petroleum ether (bp 40 -60 °C). This solution is washed with a citric acid/boric acid/phosphate buffer (pH 3) until the aqueous phase shows a pH of 4. The aqueous phase is extracted with 50 mL of petroleum ether (bp 40 - 60 rC). The combined organic extracts are dried over MgS04 and concentrated in vacuo to give a slightly tan oil yield 5.34 g (90%) ca. 90% ee. 

Synthesis of N,N -bis(p-carbomethoxybenzoyl) butanediamine (T4T-dimethyl). Dimethyl terephthalate (DMT) (275 g, 1.42 mol) is dissolved at 65°C in a mixture of 1100 mL anhydrous toluene and 85 mL anhydrous methanol in a 2-L flask equipped with a stirrer, condenser, calcium chloride tube, and nitrogen inlet. When all the DMT is dissolved, 15 mL lithium methoxide (1.25 M) is added. 1,4-Butanediamine (BDA) (34 mL, 0.34 mol), dissolved in 150 mL anhydrous toluene and 10 mL anhydrous methanol, is added dropwise in 4-6 h while the nitrogen flow is stopped. Three hours after the start of the BDA addition, the temperature is gradually increased up to 90°C (5°C/h) while the methanol is stripped off. After a total reaction time of 24 h the reaction is stopped. The white... 

Vollmer et al. [4] compared the Hg(II) acetate method described in the Code of Federal Regulations for the determination of penicillamine in bulk drug and formulations with (i) a nonaqueous lithium methoxide titration, (ii) a nonaqueous HCLO4 titration, and (iii) a colorimetric method with hydroxylamine. Method (ii) was unsatisfactory for bulk determinations. Method (i) was less precise than the Hg(II) acetate method, but gave satisfactory results for bulk drug and capsule samples. Method (iii) was the only method that gave satisfactory results in the presence of EDTA. 

The reduction of aldehydes to alcohols takes place under mild conditions upon treatment with a mixture of trimethoxysilane and lithium methoxide (20 mol%... 

The titration of nalidixic acid in DMF with lithium methoxide has been reported(1)(2) with thymolphthalein as the indicator. It has also been titrated with sodium methoxide in ethylene-diamine or DMF methanol 1 2 with thymol blue indicator.(31) An error for this titration was reported as + 0.7%. A titration with sodium borohydride followed potentiometrically or with thymol blue indicator has also been reported by Bachrata and co-workers. The standard deviation was reported as + 0.60%.(32)... 

Non-aqueous titration of tablet extracts with sodium methoxide(27) or lithium methoxide(l)(2) has been reported. 

Lithium-magnesium alloys, 15 135 Lithium manganate(V), 15 592 Lithium-manganese dioxide cells, 3 461 characteristics, 3 462t Lithium metaborate, 15 137 Lithium metaborate octahydrate, 4 277 Lithium metal, 15 132 uses for, 15 134 Lithium metal films, 15 128 Lithium methoxide, 15 148 Lithium nickelate, 15 142 Lithium niobate, 15 141 17 153... 

Materials Required Dimethylformamide (DMF) 10 ml thymol blue (0.3% in MeOH) 0.1 N lithium methoxide in toluene-methanol benzoic acid 0.6 g. 

Procedure The apparatus shown in Figure 5.1, is employed for the standardization of 0.1 N methoxide solution. Transfer 10 ml of DMF in a conical flask and add to it 3 to 4 drops of thymol blue and first neutralize the acidic impurities present in DMF by titrating with 0.1 N lithium methoxide in toluene-methanol. Quickly introduce 0.06 g of benzoic acid and titrate immediately with methoxide in toluene-methanol. 

Table 5.4 Alkalimetric Assays Non-Aqueous Titrations using Lithium Methoxide/Sodium Methoxide either Potentiometrically or Titrimetrically...

Consider figure 2.5, which is a thermochemical scheme involving crystalline lithium methoxide (LiOCI I3) as the starting substance. The lattice energy, Aiati/°(LiOCI I3), is the internal energy associated to the following process, at 298.15 K ... 

Figure 2.5 The Born-Flaber cycle for lithium methoxide and the hydration enthalpies of the ions.

Example 49 fluorophosphoroamidites in particular cases can be exchanged for a fluoride group. For example 3 -0-thymidine-0-methyl-]V,Ar-di-isopropylphosphoroamidite has been prepared by the condensation of lithium methoxide with the corresponding fluorophosphoroamidite [30]. 

The mineralized core of ferritin can be modeled by mixed valence species such as [Fe 4-Fe g02(0Me)i8(02CMe)6]-4.67MeCN, whose 3D close-packed layer structure mimics ferritin. This compound can be prepared by oxidizing a methanolic solution of iron(II) acetate and lithium methoxide with a slow stream of dioxygen it can be reduced to give [Fe 2Fe o02-(0Me)i8(02CMe)g]2-.i ... 

The a-azidoesters 197-Me are not only precursors for a,)3-diamino acids 198 but could also be used to prepare 2 -substituted aminocyclopropanecarboxylic acid (ACC) derivatives 203 [10b, c, 62] (Scheme 60). Upon treatment with freshly prepared lithium methoxide in THF and subsequent hydrolysis (HCI), the a-... 

The study also suggests that the reaction proceeds via S/ 2-type displacement with retention of configuration of the silicon in the nncleophilic part bnt with inversion of configuration of the silicon in the electrophihc part. However, the final products, [2-(alkoxy)disilanyl]lithium and lithium methoxide, were in good agreement with experimental results. The verification of the stereochemistry is of future interest. 

Lithium isopropoxide [2388-10-5] Lithium methoxide [845-34-9] Flammable solid, SR(2)3057A ... 

For the non-aqueous titration of weak acids a solvent such as an alcohol or an aprotic, solvent is used that does not compete strongly with the weak acid for proton donation. Typical titrants are lithium methoxide in methanol or tetrabutyl ammonium hydroxide in dimethylformamide. End-point detection may be carried out with thymol blue as an indicator or potentiomctrically (see p. 65). 

Ring opening of a l//-2,3-benzothiazin (3//)-one 2,2-dioxide 118 with lithium methoxide has been accomplished in good yield to afford sulfonamide ester 119 (Equation 16) <1998BML3683>. 

In the polymerization designed to detect the amount of lithium methoxide formed, the reaction was terminated with a small amount of acetic acid, and the reaction mixture was analyzed for methanol by gas-liquid chromatography. It was assumed that the methoxide formed during the polymerization was converted quantitatively to methanol (10). 

Formation of Lithium Methoxide and Butane in the polymerization of MMA with BuLi(7c,14). Pndeuterated MMA was polymerized in toluene with BuLi and the reaction was terminated by a small amount of acetic acid. The reaction mixture was analyzed for methanol and butane by gas-liquid chromatography (Table V). The amount of... 

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