Alkyl group in alcohols

The application of the HSAB concept to solutions leads to the rule that hard solutes dissolve in hard solvents and soft solutes dissolve in soft solvents (Pearson, 1987). For example, benzene is considered a very soft solvent since it contains only a basic function. Contrary to benzene, water is a very hard solvent, with respect to both its basic and acidic properties, ft is the ideal solvent for hard bases and hard acids. The hardness of water is reduced by the introduction of alkyl substituents in proportion to the size of the alkyl group. In alcohols, therefore, softer solutes become soluble. 

Ester has a fruity note. When the initial alkyl group in alcohol or acid or both is relatively large in molecular size or with its own characteristic note, the resulting ester maintains this note in addition to the fruity note. Examples include citronellyl acetate, having a fresh rosy-fruity odor, which inherits the rosy note from citronellol and bomyl acetate, having a sweet herbaceous-piney odor with a balsamic undertone, which maintains the odor of bomeol. 

It IS convenient m equations such as this to represent generic alcohols and alkyl halides as ROH and RX respectively where R stands for an alkyl group In addition to con venience this notation lets us focus more clearly on the functional group transformation that occurs the OH functional group of an alcohol is replaced as a substituent on car bon by a halogen usually chlorine (X = Cl) or bromine (X = Br)... 

Like aldehydes, ketone functions take precedence over alcohol functions, double bonds, halogens, and alkyl groups in determining the parent name and direction of numbering. Aldehydes outrank ketones, however, and a compound that contains both an aldehyde and a ketone carbonyl group is nfflned as an aldehyde. In such cases, the carbonyl oxygen of the ketone is considered an oxo-substituent on the main chain. 

Nitro groups attached to a primary and secondary alkyl group in a highly basic (pH > 13) medium exist as the nitronate (enolate) anions. These anions must be very difficult to reduce by electron transfer and are surely much more difficult to reduce than water. Since the electrohydrogenation of such nitro compounds to the corresponding amines is veiy efficient at Raney metal cathodes in 0.1 to 0.15 M KOH (or NaOH) aqueous alcohol (pH > 13) (12), as... 

In parallel to the asymmetric catalytic isomerization of allylamines, [Rh(BINAP) (solvent)2]C104 is a very efficient catalyst for the isomerization of allylic alcohols.9,11 By employing 0.5mol% of the catalyst, good to excellent conversions were achieved even in the case of substrates that are more difficult to isomerize, such as allylic alcohols having two alkyl groups in the terminal position (R1 = R2 = Me) and 2-cyclohexen-l-ol (Scheme 19). 

The presence of the OH group in alcohols makes alcohol combustion chemistry an interesting variation of the analogous paraffin hydrocarbon. Two fundamental pathways can exist in the initial attack on alcohols. In one, the OH group can be displaced while an alkyl radical also remains as a product. In the other, the alcohol is attacked at a different site and forms an intermediate oxygenated species, typically an aldehyde. The dominant pathway depends on the bond strengths in the particular alcohol molecule and on the overall stoichiometry that determines the relative abundance of the reactive radicals. 

Iodide is a good nucleophile. It attacks the least substituted carbon of the oxonlum ion formed in step 1 and displaces an alcohol molecule by S 2 mechanism. Thus, in the cleavage of mixed ethers with two different alkyl groups, the alcohol and alkyl Iodide formed, depend on the nature of alkyl groups. When primary or secondary alkyl groups are present. It Is the lower alkyl group that forms kyl Iodide (Sn2 reaction). 

Esters are reduced to alcohols, the products depending upon alkyl groups in the ester ... 

As is to be expected, an alkynic ketone undergoes a Michael addition with a carbanion, leading eventually to a pyranone (50JA1022). Using malonic esters, a 3-alkoxycarbonyl derivative results, which is hydrolyzed to the 2-oxopyran-3-carboxylic acid under alkaline conditions, but to the pyranone by sulfuric acid. Rapid ester exchange is observed with the initial products, the alcohol used as solvent determining the nature of the alkyl group in the 3-carboxylic esters (Scheme 90). 

An ester group trans to an aryl or alkyl group in epoxides of type 1 is reduced by NaBH4 in ethanol to an alcohol. These reductions do not occur in ethyl acetate, and therefore involve a hydroxy- or alkoxyborohydride. 

Rearrangement of the alkyl groups of alcohols is very common in dehydration, particularly in the presence of strong acids, which are conducive to carbocation... 

Ferles et al. have studied the crossed hydrocoupling of acetone and cyclopentanone with pyridinium salts.167 The products were similar to those found for hydrocoupling of ketones with the pyridine free bases except for the Af-alkyl group. In the case of cyclopentanone, the tertiary alcohol product eliminated water in some cases to form an olefin. 

The preparation and properties of the oxonium salts have been considered here in some detail because of their great importance in the polymerization of cyclic ethers by Friedel Crafts catalysts. From the point of view of this review the most important reactions of these salts are those with ethers and alcohols with ethers they exchange alkyl groups in an equilibrium process,... 

Judging by their appearance, monoclinching alcohols resemble j8-diketonate ligands (Fig. 13). Bulky (tBu) or fluorinated (CF3) alkyl groups in R1 and R3 position ensure volatility of /J-diketonate complexes [107]. 

Friedman and Krishnan (1973c) using the HNC method (p. 245) calculate that Ay for the hydrophobic interaction between the alkyl groups of alcohols ROH in water (R = Me to t-Bu) is around —418 J mol-1. In general, for overlap between solvent co-spheres of methylene groups, 4Xx — —360 J mol-1, which characterizes hydrophobic association. 

Primary and secondary alcohols may serve as the source of alkyl groups in the preparation of aryl phenyl tellurium compounds. Phenyl tellurium cyanide, conveniently obtained from diphenyl ditellurium (p. 368), reacted smoothly with alcohols in dichloromethane in the presence of tributylphosphane. The alkyl phenyl telluriums were obtained in yields ranging from 32 to 78%. Triphenylphosphane or triethyl phosphite did not catalyze these reactions2. 

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