Crystalline derivatives preparation alcohols

Triiodobenzoates. The derivatives enumerated above are unsatisfactory for alcohol - ethers, e.g., the mono-ethers of ethyleneglycol ( cellosolves ) and the mono-ethers of diethyleneglycol ( car-bitols ) (see Table 111,27). Crystalline derivatives of alcohol - ethers are readily obtained with 3 4 5-triiodobenzoyl chloride (for preparation, see Section VII,21), for example ... 

A crystalline derivative of benzyl alcohol cannot be obtained by using benzoyl chloride, because the benzyl benzoate, C HiCOOCHiCaHj, so obtained has m.p. 18°, and is thus usually liquid the present preparation illustrates therefore the use of a substituted benzoyl chloride (p-nitrobenzoyl chloride, m.p. 75°) in order to obtain a crystalline derivative of suitably high m.p. 

B. Boil 2 g of the ester with 30 ml of 10 per cent sodium or potassium hydroxide solution under reflux for at least 1 hour. If the alcohol formed is water (or alkali) soluble, the completion of the hydrolysis will be indicated by the disappearance of the ester layer. Distil off the liquid through the same condenser and collect the first 3-5 ml of distillate. If a distinct layer separates on standing (or upon saturation of half the distillate with potassium carbonate), remove this layer with a capillary dropper, dry it with a little anhydrous potassium carbonate or anhydrous calcium sulphate and determine the b.p. by the Siwoloboff method (Section 2.34). Whether an insoluble alcohol separates out or not, prepare a crystalline derivative (e.g. the 3,5-dinitrobenzoate, Section 9.6.4, p. 1241) and determine its m.p. 

One of the best ways of purifying the product is to convert it to a crystalline derivative, the 3,5-dinitrobenzoate. 3,5-Dinitrobenzoates are common alcohol derivatives (see Chapter 71) they are easily prepared, the two nitro groups add considerably to the molecular weight, and they are easily crystallized. 

Levene and Sobotka repeated Dale s experiments using crystalline acetylmannosyl bromide as the starting material. Their product was identical with the y-form of Dale s new methyl mannoside acetates. Deacetylation by alkali led to a dry, hygroscopic mass, which gave the correct analysis for D-mannose methyl 1,2-orthoacetate. From the crystalline acetylmannosyl bromide, on treatment with ethyl alcohol and silver carbonate, they prepared the analogous ethyl orthoacetate (Illb) with m. p. 81-82° and C ]d —28°. On saponification, it behaved in a manner analogous to the methyl derivative prepared from the same source. For the deacetylation of the triacetyl-n-mannose methyl 1,2-orthoacetate, Bott, Haworth and Hirst employed 0.5 N sodium hydroxide in ethanol at 0°. 

Dimethylamino-l,3-diphenyl-l,3,2-diazaphospholane (102) reacts with primary and secondary alcohols to give crystalline derivatives (103) useful for characterization purposes more interesting is their use to convert alcohols to alkyl halides. Several new ligands for catalysts in asymmetric redox reactions have been prepared. These include (104) and (105), the Rh complexes of which have been used successfully in asymmetric hydrogenations, and (106), which however was inferior to diop in hydrogenation and hydroformylation reactions. ... 

Picrates are usually prepared by mixing solutions of equivalent quantities of the two components in the minimum volume of rectified spirit and allowing to cool the derivative separates in a crystalline condition. It is filtered off, washed with a little ether, and pressed on a porous tUe. If the picrate is stable, it is recrystaUised from alcohol, ethyl acetate or ether. 

Here, as in every other case, the only difference between the derivatives of the two limonenes is that they are equally active optically in the opposite directions, and differ in the usual way in crystalline form. The nitrosochlorides, on boiling with alcoholic potash, yield nitroso-limonenes, CjdHjjNO. These are identical with the two carvoximes, and their constitution is probably Cj Hj. NOH. They both melt at 72° The carvoxime prepared from deicfro-limonene-nitrosochloride is faew-rotatory, whilst that from faew-limonene-nitrosochloride is dextro-rotatory. 

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