Alcohols open-chain alkyl

The efficiency of oxidation of open-chain alkyl, cycloalkyl, and unsaturated alcohols in acetonitrile by 9-phenylxanthylium ion (PhXn+) was dependent on the alcohol stmc-tures. Structure-reactivity relationship was discussed with relation to formation of a carbocationic transition state (C +-OH). Kinetic isotope effects determined at a-D, p-D3, and OD positions for the reaction of 1-phenylethanol suggested a hydride-proton sequential transfer mechanism that involved a rate-limiting formation of the a-hydroxy carbocation intermediate. Unhindered secondary alkyl alcohols were selectively oxidized in the presence of primary and hindered secondary alkyl alcohols. Strained C(7)-C(ll) cycloalkyl alcohols reacted faster than cyclohexyl alcohol, whereas the strained C(5) and C(12) alcohols reacted slower. Aromatic alcohols were oxidized efficiently and selectively in the presence of aliphatic alcohols of comparable steric requirements. ... 

Asymmetric reduction of a,fi-enon s. This combination of reagents (1 1) in conjunction with N-cthylaniline (2 equivalents) reduces alkyl aryl ketones to alcohols with high stereoselectivity.1 Under these conditions 2,/1-unsaturated ketones arc reduced to optically active (S)-allylic alcohols. Optical yields of 80 98% have been reported for open-chain enones. Reduction of cyclic enones is somewhat less efficient. The method was used to reduce 1 to 2, which has been used as an intermediate in an anthracyclinone synthesis.2... 

Monocyclic Phosphoranide Anion. The intramolecular oxidative addition of hydroxyalkyl phosphites, which gives P-H phosphoranes, is well known (10). Some P-H phosphoranes are so stable that the open-chain P(III) tautomers cannot be detected spectroscopically or even by attempted H2O2 oxidation (8). Thus, it is surprising to find no evidence for an equilibrium between phosphine alcohol 1 and its closed-ring tautomer phosphorane 2. Phosphine 1 is quaternized by alkyl halides giving phosphonium halides such as 3. These in turn are converted to alkoxyphosphor-anes, such as 4 by NaH (Scheme I). 

Alcohols are compounds of the general formula ROH, where R is any alkyl or subsiituled alkyl group. The group may be primary, secondary, or tertiary It may be open-chain or cyclic it may contain a double bond, a halogen atom, or an aromatic ring. For example ... 

Unlike carboxylic esters, open-chained S-alkyl thiocarboxylates cannot be obtained by direct proton-catalyzed esterification. Whereas thiocarboxylic acids react with alcohols to form esters as expected, thiol esters are formed on reaction of carboxylic acids with thiols, but the equilibrium is shifted towards the educts and the reaction is not useful for synthetic purposes. Therefore, activation is necessary and several methods have been developed to meet this requirement. 

Ethers are compounds that have two organic groups bonded to the same oxygen atom, ROR. The organic groups can be alkyl, vinylic, or aryl, and the oxygen atom can be in a ring or in an open chain. Ethers are prepared by either the Williamson ether synthesis, which involves Sf t2 reaction of an alkoxide ion with a primary alkyl halide, or the alkoxymercuration reaction, which involves Markovnikov addition of an alcohol to an alkene. 

The hydrolysis (or alcoholysis) of furans involves nucleophilic addition of water (or an alcohol) to an initially formed cation, giving rise to open-chain 1,4-dicarbonyl-compounds or derivatives thereof. This is in effect the reverse of one of the general methods for the construction of furan rings (18.13.1.1). Suc-cindialdehyde cannot be obtained from furan itself, presumably because this dialdehyde is too reactive under conditions for hydrolysis, but some alkyl-furans can be converted into 1,4-dicarbonyl products quite efficiently, and this can be viewed as a good method for their synthesis, and of cyclopentenones derived from them. ° Other routes from furans to 1,4-dicarbonyl compounds are the hydrolysis of 2,5-dialkoxy-tetrahydro-furans (18.1.1.4) and by various oxidative procedures (18.2). 

The ability of polyether ligands to activate alkoxyde anions was checked in the etherification of primary alcohols with alkyl bromides, by using solid potassium hydroxide as a base. Results showed that the efficiency of the open-chain PEG2000 dimethylether 1 is similar to that of cr ptand 9 and DCH18C5. ... 

Branching of the alkyl chain attached to the O H group opens up a variety of perspectives. It increases the bulkiness of the alcohol with consequences for aggregation [234, 235], it allows for the introduction of permanent chirality [117], and it can help to introduce larger energy differences among conformations. 

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