Hydroxyl reaction with alcohols

Hydroxypyridines are readily alkylated under a variety of conditions. Mitsunobu reaction with alcohols occurs selectively at oxygen in the presence of PPh3 and DEAD in THF at room temperature <2003TL725>. The 3-hydroxy group may be selectively alkylated in the presence of aliphatic hydroxyl groups. Pyridine 104 is alkylated at the aromatic position with dodecyl bromide in the presence of potassium carbonate in DMF at 95 °C <20030BC644> (Equation 70). 

Campbell, I.M., McLaughlin, D.F., Handy, B.J. (1976) Rate constants for reactions of hydroxyl radicals with alcohol vapours at 292 K. Chem. Phys. Lett. 38, 362-364. 

Esters.—(3) Reaction with alcohols. As the sulphonic acids are acid compounds still containing one acid hydroxyl they react with alcohols forming esters. 

To throw additional light on the relative reactivity of diisocyanates at higher temperatures Cunningham and Mastin [130] measured rates of reactions with alcohols at 115°C. To provide both primary and secondary hydroxyl groups, 1- and 2-octanol were used (Table 9). At 115°C the... 

Secondary hydroxyl reaction with nitric acid (secondary alcohols give nitroalkanes) -1- -1-... 

Substitution reactions. Replacement of the hydroxyl group of l-alkyn-3-ols on reaction with alcohols, thiols, and amines is accomplished at room temperature in the presence of binuclear complex 1 and NH4BF4. 

Monosaccharides can be modified by reaction with alcohols and amines to form adducts. For example, D-glucose will react with methanol in an acid-catalyzed process the anomeric carbon atom reacts with the hydroxyl group... 

Glucose is a six-carbon aldohexose. The straight chain hexose structures can become cyclic. When aldehydes and ketones undergo reactions with alcohols, hemiacetals or hemiketals are formed. In aldohexoses, the eyclic structure is formed when the hydroxyl group in the fifth carbon reacts (nucleophilic addition) with the carbonyl carbon of the aldehyde group. The product formed is a hemiacetal. The cyclization is represented in Figure 29-4. 

The rate data for reaction of NO3 with aliphatic esters show that the presence of the ester group in an organic molecule has little influence on the reactivity compared to the parent alkane. The reactivity trends exhibited by the nitrate radical for reactions with alcohols, ethers and esters are similar to those shown for the analogous reactions of hydroxyl radicals. The major products identified from the NO3 radical-initiated oxidation of alcohols, ethers and esters under atmospheric conditions were esters, carbonyls and alkyl nitrates. Similar products arise from the reactions of OH radicals with these molecules under atmospheric conditions. 

Hydrogen atom abstraction by thiyl radicals has also been shown to occur with various aliphatic and aromatic compounds [57]. Extensive studies have been conducted with respect to the thiyl reaction with alcohols and ethers in which the C-H bond of interest is activated by a-positioned hydroxyl or alkoxy groups. In these systems, an equilibrium is established, as formulated in equation (36) [9, 55] ... 

The hemlacetal nature of the anomeric hydroxyl group makes it the most reactive of that type. Direct oxidation can be carried out with several reagents, most classically, hypoiodite. This results in rapid oxidation to the aldono-lactone and is only exhibited by aldoses. Alternatively, reaction with alcohols results in the formation of full acetals (glycosides). A very large variety of such structures have been made. 

The alcohol groups of carbohydrates undergo chemical reactions typical of hydroxyl functions They are converted to esters by reaction with acyl chlorides and carboxylic acid anhydrides... 

Acetals are readily formed with alcohols and cycHc acetals with 1,2 and 1,3-diols (19). Furfural reacts with poly(vinyl alcohol) under acid catalysis to effect acetalization of the hydroxyl groups (20,21). Reaction with acetic anhydride under appropriate conditions gives the acylal, furfuryUdene diacetate... 

With aldehydes, primary alcohols readily form acetals, RCH(OR )2. Acetone also forms acetals (often called ketals), (CH2)2C(OR)2, in an exothermic reaction, but the equiUbrium concentration is small at ambient temperature. However, the methyl acetal of acetone, 2,2-dimethoxypropane [77-76-9] was once made commercially by reaction with methanol at low temperature for use as a gasoline additive (5). Isopropenyl methyl ether [116-11-OJ, useful as a hydroxyl blocking agent in urethane and epoxy polymer chemistry (6), is obtained in good yield by thermal pyrolysis of 2,2-dimethoxypropane. With other primary, secondary, and tertiary alcohols, the equiUbrium is progressively less favorable to the formation of ketals, in that order. However, acetals of acetone with other primary and secondary alcohols, and of other ketones, can be made from 2,2-dimethoxypropane by transacetalation procedures (7,8). Because they hydroly2e extensively, ketals of primary and especially secondary alcohols are effective water scavengers. 

The primary and secondary alcohol functionahties have different reactivities, as exemplified by the slower reaction rate for secondary hydroxyls in the formation of esters from acids and alcohols (8). 1,2-Propylene glycol undergoes most of the typical alcohol reactions, such as reaction with a free acid, acyl hahde, or acid anhydride to form an ester reaction with alkaU metal hydroxide to form metal salts and reaction with aldehydes or ketones to form acetals and ketals (9,10). The most important commercial appHcation of propylene glycol is in the manufacture of polyesters by reaction with a dibasic or polybasic acid. 

The resihency and dyeabihty of poly(vinyl alcohol) fibers is improved by a process incorporating -hydroxybenzaldehyde to provide a site for the formation of a stable Mannich base. Hydroxyl groups on the fiber are converted to acetal groups by -hydroxybenzaldehyde. Subsequent reaction with formaldehyde and ammonia or an alkylamine is rapid and forms a stable Mannich base that is attached to the polymer backbone (94). 

With active methylene compounds, the carbanion substitutes for the hydroxyl group of aHyl alcohol (17,20). Reaction of aHyl alcohol with acetylacetone at 85°C for 3 h yields 70% monoaHyl compound and 26% diaHyl compound. Malonic acid ester in which the hydrogen atom of its active methylene is substituted by A/-acetyl, undergoes the same substitution reaction with aHyl alcohol and subsequendy yields a-amino acid by decarboxylation (21). 

Halogenation. Normally, 2-halopropane derivatives are prepared from isopropyl alcohol most economically by reaction with the corresponding acid haUde. However, under appropriate conditions, other reagents, eg, phosphoms haUdes and elemental halogen, also react by replacement of the hydroxyl group to give the haUde (46). 

The reactions of thionyl chloride with organic compounds having hydroxyl groups are important. Alkyl chlorides, alkyl sulfites, or alkyl chlorosulfites form from its reaction with aUphatic alcohols, depending on reaction conditions, stoichiometry, and the alcohol stmcture ... 

Zirconium tetrachloride is instantly hydrolyzed in water to zirconium oxide dichloride octahydrate [13520-92-8]. Zirconium tetrachloride exchanges chlorine for 0x0 bonds in the reaction with hydroxylic ligands, forming alkoxides from alcohols (see Alkoxides, METAl). Zirconium tetrachloride combines with many Lewis bases such as dimethyl sulfoxide, phosphoms oxychloride and amines including ammonia, ethers, and ketones. The zirconium organometalLic compounds ate all derived from zirconium tetrachloride. 

The other analytical methods necessary to control the typical specification given in Table 5 are, for the most part, common quality-control procedures. When a chemical analysis for purity is desired, acetylation or phthalation procedures are commonly employed. In these cases, the alcohol reacts with a measured volume of either acetic or phthalic anhydride in pyridine solution. The loss in titratable acidity in the anhydride solution is a direct measure of the hydroxyl groups reacting in the sample. These procedures are generally free from interference by other functional groups, but both are affected adversely by the presence of excessive water, as this depletes the anhydride reagent strength to a level below that necessary to ensure complete reaction with the alcohol. Both procedures can be adapted to a semimicro- or even microscale deterrnination. 

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