Purification, general procedures alcohols

N -Ethyl-jK-toluidine has been obtained by passing m-toluidine and ethyl alcohol over a catalyst at high temperatures,1 and by the use of ethyl />-toluenesulfonate 2 as an alkylating agent. The present method of purification is a modification of a general procedure for secondary amines developed by Diepolder.3... 

In terms of published practical applications, MEUF has been successfully employed to remove multivalent metal cations (such as Cu +) from wastewater (456), for removal of n-alcohols (457) as well as other organic substances (benzene, etc.) (454.455) from aqueous streams. The general procedure seems to offer an attractive means for purification of water streams containing organic substances or heavy metals. MEUF may prove to be useful in industrial applications as well (455). 

As a general procedure if the olefin is impure, the oxymercura-tion-reduction process may include an olefin purification step. Alternatively, this process may be used to purify the olefin for other purposes. - In such cases, acetone is substituted for ether and, after oxymercuration for the same length of time as suggested above, the solution is poured with stirring into two volumes of water containing one equivalent each of sodium bicarbonate and sodium chloride. The mercury derivative is filtered, recrystallized from ethanol-water, ether, dioxane, or ethyl acetate-heptane and then either reduced as described above (in 70-80% yield) to produce pure alcohol, or deoxy-mercurated with cold 6N HCl, with ethereal lithium aluminum hydride (added cautiously), or high concentrations of alkali halides - to produce the pure olefin. 

The procedure described below is quite general and uses finely, freshly machine--powdered KOH, which is added to a solution of the primary or secondary (acetylenic) alcohol and a 10-15% molar excess of tosyl chloride in Et20, kept around 0 C The excess of tosyl chloride is destroyed during the reaction of the excess of KOH. Side- and subsequent reactions ("saponification of the ester by KOH and 1,2-elimination of p-toluenesulfonic acid from thtfester) can be suppressed by keeping the temperature of the reaction mixture below 5 C. This procedure can be carried out within 2 h and generally gives excellent (often almost quantitative) yields of the tosylates. Purification of acetylenic tosylates by distillation, which is risky because of the limited thermal stability of the esters, is not necessary because the... 

Once cell wall breakage or enzymatic dissolution has occurred, a variety of procedures can be used for isolation and purification of the DNA. These generally rely on an initial deproteinization using phenol or a mixture of perchlorate, sarcosine, and chloroform-isoamyl alcohol.6 9 The crude DNA is further purified by enzyme treatments, alcohol precipitation and spooling, hydroxylapatite chromatography, cesium chloride gradient centrifugation, or any combination of these methods. 

Quinazoline-4(3//)-thiones 13 are prepared in a very simple, one-step synthesis by treatment of 2-[(ethoxymethylene)amino] derivatives 12 with alcoholic sodium hydrosulfide. Numerous other hetero-fused pyrimidinethiones are also available by this procedure (Method Cyclization proceeds uniformly in very high yields, generally in excess of 90%. In some cases, since isolation and purification of (ethoxymethylene)amino derivatives results in the lowering of the overall yield, the one-step procedure, consisting of treatment of a 2-aminonitrile 11, either with a 1 1 mixture of triethyl orthofoimate and acetic anhydride or with triethyl orthoformate alone, to give an intermediate ethoxymethyleneamino derivative which, without isolation, is treated with an ethanolic solution of sodium hydrosulfide, is preferred for preparative purposes (Method B). In a few cases, conversion of the 2-aminonitrile to a 2-aminothioamide followed by cyclization with triethyl orthoformate (see p 47) competes favorably with the above procedure. 

When treated with concentrated alkali, acetoacetic ester is converted into two moles of sodium acetate, (a) Outline all steps in a likely mechanism for this reaction. (Hint See Sec. 21.11 and Problem 5.8, p. 170.) (b) Substituted acetoacetic esters also undergo this reaction. Outline the steps in a general synthetic route from acetoacetic ester to carboxylic acids, (c) Outline the steps in the synthesis of 2-hexanone via acetoacetic ester. What acids will be formed as by-products Outline a procedure for purification of the desired ketone. (Remember that the alkylation is carried out in alcohol that NaBr is formed that aqueous base is used for hydrolysis and that ethyl alcohol is a product of the hydrolysis.)... 

The most common procedure for preparing bismuth alkoxides is the substitution reaction of bismuth halides with alkali metal alkoxides. The alternative is treatment of bismuth amides with alcohols. Bismuth alkoxides such as trimethoxide, triethoxide and triisopropoxide were first prepared in 80-93% yields by the reaction between BiCl3 and alkali metal alkoxides by Mehrotra et al. in 1966. Bismuth alkoxides are less soluble in organic solvents and the yields after purification by sublimation are generally very low (10-20%) [66IJC537]. Known aliphatic alkoxides include Bi(OEt)3... 

For example, reaction of methoxyallene with an allyHc alcohol under palladium catalysis yielded unsymmetrical mixed acetal 22a in 74% yield (Scheme 5(a)). Treatment of 22a with 10 mol% of Grubbs second generation catalyst 3, followed by add promoted aromatization yielded fiiran 12a in 79% isolated yield for the one-pot protocol. However, the nonpolar furan products were usually contaminated with (nonpolar) phosphine residues from the catalyst, which made the purification step problematic. Therefore, it was generally advantageous to purify the dihydrofuran intermediate prior to the aromatization step. In a similar manner to furans, allyftc sulfonamide 21a was converted to the N,0-acetal 23a in 63% yield under palladium catalysis. Then RCM followed by aromatization proceeded smoothly to provide the desired N-protected pyrrole 13a in 61% yield over two steps (Scheme 5(b)). This procedure can also be applied... 

Analytical procedures for foods are generally based on extraction with purified solvents following saponification with alcoholic potash. Purification of the extracts by chromatography on column or plates is followed by analysis of the purified extract using TLC, GLC or HPLC. Spectrophotometric or spectrofluorimetric methods may be used for quantitation of the hydrocarbons a collaborative study of a spectrophotometric method showed it to be applicable at the 2 fig/kg level. HPLC techniques using spectrofluorimetric detection have been described for which improved levels of detection are claimed. Benzo(a)pyrene produces substitution products with nucleic acids. Hydrocarbon deoxyribonucleoside adducts may be isolated from DNA by gel permeation chromatography, and the formation of hydrocarbon epoxides by mammalian enzyme reaction has also been demonstrated . The limit of detection of spectrophotometric and fluorimetric methods has been improved by three orders of magnitude by the use of laser-induced fluorescence procedures for the... 

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