The Reactions of Alcohols

The nondissociative adsorption of methanol also decreased the work function, indicating that the molecule adsorbed with the negative end of 

Work Function Changes Following Methanol Adsorption on Clean Metals Monolayer Coverages) 

Binding Energies and Peak Temperatures for Species Desorbed from Cu(110) and Ag l 10) Surfaces/  

Only a small amount of methanol adsorbed on the Ag(llO) surface at 180 K in the absence of preadsorbed oxygen. In the presence of oxygen adatoms, however, methanol adsorbed both dissociatively and nondisso-ciatively. The TPRS product spectrum obtained for a low exposure of 

Reprinted with permission of North-Holland Publishing Company, Amsterdam, 1978. 

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Mechanism of the Reaction of Alcohols with Hydrogen Halides... 

MECHANISM OF THE REACTION OF ALCOHOLS WITH HYDROGEN HALIDES... 

The dehydration of alcohols resembles the reaction of alcohols with hydrogen halides (Section 4 7) m two important ways... 

These common features suggest that carbocations are key intermediates m alcohol dehydra tions just as they are m the reaction of alcohols with hydrogen halides Figure 5 6 portrays a three step mechanism for the acid catalyzed dehydration of tert butyl alcohol Steps 1 and 2 describe the generation of tert butyl cation by a process similar to that which led to its for matron as an intermediate m the reaction of tert butyl alcohol with hydrogen chloride... 

We have seen this situation before m the reaction of alcohols with hydrogen halides (8ection 4 11) m the acid catalyzed dehydration of alcohols (8ection 5 12) and m the conversion of alkyl halides to alkenes by the El mechanism (8ection 5 17) As m these other reactions an electronic effect specifically the stabilization of the carbocation intermediate by alkyl substituents is the decisive factor The more stable the carbo cation the faster it is formed... 

The principles developed in this chapter can be applied to a more detailed examination of the reaction of alcohols with hydrogen halides than was possible when this reaction was first introduced m Chapter 4... 

The reactions of alcohols with hydrogen halides to give alkyl halides (Chapter 4) are nucleophilic substitution reactions of alkyloxonium ions m which water is the leaving group Primary alcohols react by an 8 2 like displacement of water from the alkyloxonium ion by halide Sec ondary and tertiary alcohols give alkyloxonium ions which form carbo cations m an S l like process Rearrangements are possible with secondary alcohols and substitution takes place with predominant but not complete inversion of configuration... 

Esters are also formed by the reaction of alcohols with acyl chlorides... 

The mechanisms of the Fischer esterification and the reactions of alcohols with acyl chlorides and acid anhydrides will be discussed m detail m Chapters 19 and 20 after some fundamental principles of carbonyl group reactivity have been developed For the present it is sufficient to point out that most of the reactions that convert alcohols to esters leave the C—O bond of the alcohol intact... 

The reaction of alcohols with acyl chlorides is analogous to their reaction with p toluenesulfonyl chloride described earlier (Section 8 14 and Table 15 2) In those reactions a p toluene sulfonate ester was formed by displacement of chloride from the sulfonyl group by the oxygen of the alcohol Carboxylic esters arise by displacement of chlonde from a carbonyl group by the alcohol oxygen... 

Although the term ester used without a modifier is normally taken to mean an ester of a carboxylic acid alcohols can react with inorganic acids m a process similar to the Fis cher esterification The products are esters of inorganic acids For example alkyl nitrates are esters formed by the reaction of alcohols with nitric acid... 

Lower aHphatic amines can be prepared by a variety of methods, using many different types of raw materials. By far the largest commercial appHcations involve the reaction of alcohol with ammonia to form the corresponding amines. Other methods are employed depending on the particular amine desired, raw material availabiHty, plant economics, and the abiHty to seU co-products. The foUowing manufacturing methods are used commercially to produce the lower aLkylamines. Table 5 gives plant and capacity information for these methods. 

Reduction of Alcohols or Ketones. The reaction of alcohols and ketones with chlorine and base to give chloroform is well known (30). 

The reaction of alcohols and acid chlorides in the presence of magnesium has been described (68). With primary and secondary alcohols the reaction is very smooth, and affords high and sometimes quantitative yields. Difficulty esteritiable hydroxy compounds such as tertiary alcohols and phenols can be esteritied by this method. The reaction carried out in ether or benzene is usually very vigorous with evolution of hydrogen. 

Kinetic studies of the reaction of alcohols with acyl chlorides in polar solvents in the absence of basic catalysts generally reveal terms both first-order and second-order in alcohol. Transition states in which the second alcohol molecule acts as a proton acceptor have been proposed ... 

The radical X is formed by homolysis of the X—R bond either thermally or photolytically. In the reactions of alcohols with lead tetraacetate evidence suggests that the X—R bond (X = 0, R = Pb(OAc)3) has ionic character. In this case the oxy radical is formed by a one electron transfer (thermally or photochemically induced) from oxygen to lead. 

Dehydration to olefins, which sometimes accompanies the reaction of alcohols with DAST [95, 108], is seldom as extensive as with a-fluoroamines (FAR and 1,1,2,3,3,3 hexafluoropropyldiethylamine) but occurs in a few cases to the exclusion of fluonnation, thus, 9a-fluoro-11-hydroxysteroids give 9a fluoro-A -steroids [127, 128] Dehydration accompanied by Wagner-Meerwein rearrangement occurs during the fluonnation of testosterone [129] Intermolecular dehydration to form ethers in addition to fluorides is observed in the reaction of benzhydryl alcohols [104] (Table 6)... 

The intermediate formation of covalent inflates is assumed also in the reaction of alcohols with tnflic anhydride in the presence of nitriles to give the corresponding amides [96] (equation 47),... 

The order of reactivity of the hydrogen halides parallels their acidity HI > HBr > HCl >> HF. Hydrogen iodide is used infrequently, however, and the reaction of alcohols with hydrogen fluoride is not a useful method for the preparation of alkyl fluorides. 

We first encountered nucleophilic substitution in Chapter 4, in the reaction of alcohols with hydrogen halides to fonn alkyl halides. Now we ll see how alkyl halides can themselves be converted to other classes of organic compounds by nucleophilic substitution. 

In the presence of strong acid, formic acid decomposes to water and carbon monoxide. In the process, reactive intermediates form which are capable of direct carboxylation of carbonium ions. Since many carbonium ions are readily generated by the reaction of alcohols with strong acid, the process of elimination and carboxylation can be conveniently carried out in a single flask. The carbonium ions generated are subject to the... 

A review of the preparation, properties, the uses of surface-active anionic phosphate esters prepared by the reactions of alcohols or ethoxylates with tetra-phosphoric acid or P4O10 is given in Ref. 3. The preparation and industrial applications of phosphate esters as anionic surfactants were also discussed in Ref. 31. 

In the preparation of surfactants by the reaction of alcohols with P4Ol0 with subsequent neutralization of the partial phosphate esters with a base, the quality of the surfactants is improved by using RNEt3OH (R = Et or benzyl) in alcoholic solution as the base, by using C6 10 alcohol mixtures of hydroxyethylated C7 9 alcohols or equimolar mixtures of C6 I0 alcohols with polyethylene glycol (mol wt 200-1500) and by using a reaction temperature of 55-60°C [8]. 

The reaction of alcohols with arylbromides and nickel or copper catalysts, in presence of base, has been investigated comparatively in regard to the influence of the metals, of the ligands, of the base, of the primary or secondary alcohols and of the substituents on the arylbromide. The best conditions, with bipyNiBr2 in presence of KHCO3 at 125°C, afford quantitative yields in the phenylalkyl ethers from the primary alcohols. 

The example shown is the most important case of this mechanism yet discovered, since the reaction of alcohols with thionyl chloride to give alkyl halides usually proceeds in this way, with the first step in this case being ROH -I- SOCI2 ROSOCl (these alkyl chlorosulfites can be isolated). 

Alkyl esters are efficiently dealkylated to trimethylsilyl esters with high concentrations of iodotrimethylsilane either in chloroform or sulfolane solutions at 25-80° or without solvent at 100-110°.Hydrolysis of the trimethylsilyl esters serves to release the carboxylic acid. Amines may be recovered from O-methyl, O-ethyl, and O-benzyl carbamates after reaction with iodotrimethylsilane in chloroform or sulfolane at 50—60° and subsequent methanolysis. The conversion of dimethyl, diethyl, and ethylene acetals and ketals to the parent aldehydes and ketones under aprotic conditions has been accomplished with this reagent. The reactions of alcohols (or the corresponding trimethylsilyl ethers) and aldehydes with iodotrimethylsilane give alkyl iodides and a-iodosilyl ethers,respectively. lodomethyl methyl ether is obtained from cleavage of dimethoxymethane with iodotrimethylsilane. 

Esters from the reaction of alcohols with carboxylic acids, acid halides and anhydrides. 

Various acetals and ketals from the reaction of alcohols and diols with aldehydes and ketones can be advantageously obtained using ion-exchange resin catalysts. Batch reactive distillation or DCR can be employed to obtain these acetals at high selectivity at very high conversion levels. 

There was also a polymerisation reaction during the sulphuric treatment of benzyl alcohol. The reactor in which the reaction of alcohol dehydration was... 

Another general method for converting alcohols to halides involves reactions with halides of certain nonmetallic elements. Thionyl chloride, phosphorus trichloride, and phosphorus tribromide are the most common examples of this group of reagents. These reagents are suitable for alcohols that are neither acid sensitive nor prone to structural rearrangement. The reaction of alcohols with thionyl chloride initially results in the formation of a chlorosulfite ester. There are two mechanisms by which the chlorosulfite can be converted to a chloride. In aprotic nucleophilic solvents, such as dioxane, solvent participation can lead to overall retention of configuration.7... 

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