Alcohols acetates

As regards reaetions other than nitration brought about by some of these systems, especially noteworthy are the addition processes undergone by eertain indole derivatives when treated with solutions of nitrie aeid in aeetie aeid. Produets inelude glycols, nitro-alcohols, and nitro-alcohol acetates. Such additions might well be encountered with some polynuclear aromatie eompounds, and with sueh eompounds the possibility of nitration by addition-elimination must always be borne in mind. 

This reaction is simply the reverse of the reaction by which acetals are formed—acetal formation is favored by excess alcohol acetal hydrolysis by excess water Acetal for matron and acetal hydrolysis share the same mechanistic pathway but travel along that pathway m opposite directions In the following section you 11 see a clever way m which acetal formation and hydrolysis have been applied to synthetic organic chemistry... 

Typical specifications for commercially available amyl alcohols (104) are given in Table 4. The impurities typically present are other monomeric alcohols, dimeric alcohols, acetals, and several miscellaneous substances. The alcohols are substantially free of suspended matter. 

The reactions of oxiranes with thiocyanate ion or with thiourea are usually done in homogeneous solution in water, alcohols or alcohol-acetic acid. The use of silica gel as a support for potassium thiocyanate in toluene solvent is advantageous for the simple work-up (filtration and evaporation of solvent) (80JOC4254). A crown ether has been used to catalyze reactions of potassium thiocyanate. 

The following set of conditions will selectively remove a phenolic acetate in the presence of an alcoholic acetate. 

Miscible/soluble organic materials Acetone Alcohol Acetic acid... 

Diols yield acetonides, even in the presence of a 17oc-hydroxylgroup. Reaction with acetone in the presence of zinc chloride as catalyst leads to the formation of diacetone alcohol acetal as a by-product. ... 

EtMgBr, Et20, it, 1 h, 90-100% yield. These conditions were used to prevent a neighboring silyl ether from migrating. Ethylmagnesium chloride is much more reactive thus, the reaction can be run at —42°, giving a 90% yield of the alcohol. Acetates and pivaloates are also cleaved. 

The procedure given above is applied to norbornene. However, the formation of the alcohol is accompanied by formation of moderate amounts of the acetate. Therefore, the dried tetrahydrofuran solution of the alcohol-acetate mixture is treated with 0.4 g (O.OI mole) of lithium aluminum hydride dissolved in 10 ml ofTHF. The excess hydride is decomposed by careful addition of water, followed by filtration, drying of the organic solution, and evaporation of the solvent. The residue is almost pure (>99.8%) exo-1-norborneol. It may be purified by direct distillation, bp 178-17971 atm, crystallizing slowly on cooling, mp 127-128°. 

CaHjOH + HOOC. CHg = C2H5OOC. CH, + H O Alcohol. Acetic Acid. Ethyl Acetate. Water. 

Acetaldehyde, methanol, ethanol (major), ethyl acetate, n-pro-pyl alcohol, isobutyl alcohol, acetic acid, amyl alcohol, and isoamyl alcohol... 

In the case of alcohols, acetic acid, and water, a > 3 2, indicating polymerisation in the liquid state. 

Carboxylic acids with an electron donating substituent in the a-position decarboxylate in a two-electron oxidation to carbocations (see chap. 7). These can react with the solvent (alcohol, acetic acid, water) or the unreacted carboxylate to ethers, esters, or alcohols (Eq, 14). In some cases the carbon skeleton rearranges, which is a clear indication of the cationic pathway. 

Hydrobromic acid Hydrochloric acid Hydrofluoric acid Nitric acid Sulphuric acid Acetone Alcohol Acetic acid Arsenic Selenium Lubricating oil Animal fat Chlorinated solvents... 

IV Glycols, benzyl alcohol, acetic acid, formamide... 

To be of maximum synthetic value, the generation of the cationic site that initiates cyclization must involve mild reaction conditions. Formic acid and stannic chloride are effective reagents for cyclization of polyunsaturated allylic alcohols. Acetals generate oxonium ions in acidic solution and can also be used to initiate the cyclization of... 

Organic solvent(s) Partition coefficients Insoluble Soluble in glycerol, very slight in alcohol Acetic acid6 Insoluble in alcohol... 

Leptogenys peuqueti W-PG Trail following Series of 14 related methyl-branched secondary alcohols acetates 136 137 [178]... 

Another detectable example of internal return is afforded by the solvolysis of xo-norborriylbromobenzenesulfonate (XL) it racemizes from 40 to 240% faster than it produces bromobenzenesulfonic acid, yet both reactions are strictly first order. The racemization reaction is kinetically independent of bulk bromobenzenesulfonate concentration but its rate is dependent on the nature of the solvent, pyridine being less effective than alcohol, acetic acid, or aqueous acetone.238 The behavior of 3-phenyl-2-butyl- -toluenesulfonate is similar.250... 

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