Alcohols etherification

Drastic conditions, 240 °C and 70 bar, using 1.7 wt% H2SO4, give 90% conversion in only 15 min. Under such conditions, highly acidic feedstocks (44% FFAs) could be easily transformed with continuous water removal, but side-reactions such as alcohol etherification can also take place [10]. 

Ethyl ether of orthosilicon acid (tetraethoxysilane) is most widely applied of all the ethers of orthosilicon acid because it is cheap, relatively easy to prepare and not toxic. Since the production of tetraethoxysilane uses the mixture of anhydrous and hydrous alcohol, etherification as a rule yields a mixture of tetraethoxysilane and ethylsilicates, the products of its partial hydrolysis and condensation. That is why we view below at the same time the technology to prepare tetraethoxysilane and ethylsilicate. 

To etherify methyltrichlorosilane or ethyltrichlorosilane with ethyl alcohol, etherificator 4 is continuously filled through batching device 3 with a corresponding alkyltrichlorosilane from batch box 1 and with alcohol from batch box 2,... 

Before the start all equipment is throroughly washed with butyl alcohol. Etherification is conducted in reactor 6 with a jacket and agitator. First, the reactor is loaded with butyl alcohol the agitator is switched on the jacket is filled with cooling salt solution. 

Aiouache F and Goto S. Reactive distillation-pervaporation hybrid column for tert-amyl alcohol etherification with ethanol. Chem Eng Sci 2003 58(12) 2465-2477. 

The pulse chromatographic method was also used to study the kinetics of the etherification of alcohols of various structures with acetic anhydride [74]. The reaction kinetics were studied for high-boiling alcohols the volatile reagent (acetic anhydride) was fed into the rdactor column in the form of a pulse, and the involatile one (alcohol) was present in the column reactor as the stationary phase. Unlike the pulse method used in studying the reactions involved in diene synthesis, in the etherification of an alcohol with acetic anhydride one of the reaction products (acetic acid) is eluted from the column reactor after the starting component (acetic anhydride). The reaction of alcohol etherification was examined at 80—130 C. The mixture of acetic anhydride with the standard (benzene) was pulsed into the reactor column in which the alcohol under study served as the stationary phase. Various extents of reaction were achieved by varying the carrier gas flow-rate. Table 2.6 summarizes the kinetic characteristics of the etherification of alcohols with acetic anhydrides [74]. The rate constants decrease in the order primary > secondary > tertiary. 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

Ether alcohols Ether formation Ether hydroperoxides Etherification... 

Substitution Reactions on Side Chains. Because the benzyl carbon is the most reactive site on the propanoid side chain, many substitution reactions occur at this position. Typically, substitution reactions occur by attack of a nucleophilic reagent on a benzyl carbon present in the form of a carbonium ion or a methine group in a quinonemethide stmeture. In a reversal of the ether cleavage reactions described, benzyl alcohols and ethers may be transformed to alkyl or aryl ethers by acid-catalyzed etherifications or transetherifications with alcohol or phenol. The conversion of a benzyl alcohol or ether to a sulfonic acid group is among the most important side chain modification reactions because it is essential to the solubilization of lignin in the sulfite pulping process (17). 

Etherification. Ethers of amyl alcohols have been prepared by reaction with ben2hydrol (63), activated aromatic haUdes (64), dehydration-addition reactions (65), addition to olefins (66—71), alkoxylation with olefin oxides (72,73) and displacement reactions involving thek alkah metal salts (74—76). 

Etherification. Isopropyl alcohol can be dehydrated ia either the Hquid phase over acidic catalysts, eg, sulfuric acid, or ia the vapor phase over acidic aluminas to give diisopropyl ether (DIPE) and propylene (qv). 

Etherification. The reaction of alkyl haUdes with sugar polyols in the presence of aqueous alkaline reagents generally results in partial etherification. Thus, a tetraaHyl ether is formed on reaction of D-mannitol with aHyl bromide in the presence of 20% sodium hydroxide at 75°C (124). Treatment of this partial ether with metallic sodium to form an alcoholate, followed by reaction with additional aHyl bromide, leads to hexaaHyl D-mannitol (125). Complete methylation of D-mannitol occurs, however, by the action of dimethyl sulfate and sodium hydroxide (126). A mixture of tetra- and pentabutyloxymethyl ethers of D-mannitol results from the action of butyl chloromethyl ether (127). Completely substituted trimethylsilyl derivatives of polyols, distillable in vacuo, are prepared by interaction with trim ethyl chi oro s il an e in the presence of pyridine (128). Hexavinylmannitol is obtained from D-mannitol and acetylene at 25.31 MPa (250 atm) and 160°C (129). 

Etherification. Ethers of poly(vinyl alcohol) are easily formed. Insoluble internal ethers are formed by the elimination of water, a reaction cataly2ed by mineral acids and alkaU. 

Modification of urea-formaldehyde resins with other reagents gives rise to a number of useful materials. For example, co-condensation of urea-formaldehyde and a monohydric alcohol in the presence of small quantities of an acidic catalyst will involve simultaneous etherification and resinification. n-Propanol, n-butanol and isobutanol are commonly used for this purpose. As an example n-butanol will react with the methylol urea as shown in Figure 24.4. 

Cross-conjugated dienones are quite inert to nucleophilic reactions at C-3, and the susceptibility of these systems to dienone-phenol rearrangement precludes the use of strong acid conditions. In spite of previous statements, A " -3-ketones do not form ketals, thioketals or enamines, and therefore no convenient protecting groups are available for this chromophore. Enol ethers are not formed by the orthoformate procedure, but preparation of A -trienol ethers from A -3-ketones has been claimed. Another route to A -trien-3-ol ethers involves conjugate addition of alcohol, enol etherification and then alcohol removal from la-alkoxy compounds. 

Nucleophilic trans-etherification of alkoxy-s-triazines occurs in a few minutes at the boiling point of various alcohols, either molar or catalytic amounts of alkoxide or triethylamine being used. This reaction occurs during attempts to prepare unsymmetrical polyalkoxy compounds e.g., 333 is formed from 332. 

Commercial alkylation is the reaction of isobutane with C3 through Cg olefins in the presence of either sulfuric acid or hydrofluoric acid (see Example 10-1). Etherification is the reaction of a tertiary olefin with an alcohol or water in the presence of an acidic catalyst (see Example 10-2). 

Oriyama and coworkers reported an iron-catalyzed reductive etherification of carbonyl compounds with triethylsilane and alkoxytriaUcylsilane [149, 150] and alcohols (Scheme 48) [151]. 

Although some methods for reductive etherifications of carbonyl compounds have been reported [152-162], the iron-catalyzed version possesses several advantages (1) fairly short reaction times are needed, (2) not only trimethylsilyl ether but also triethylsilyl and butyldimethylsilyl ethers and alcohols are adaptable, and (3) a broad substrate scope. 

Clay-supported heteropoly acids such as H3PW12O40 are more active and selective heterogeneous catalysts for the synthesis of MTBE from methanol and tert-butanol, etherification of phenethyl alcohols with alkanols, and alkylation of hydroquinone with MTBE and tert-butanoi (Yadav and Kirthivasan, 1995 Yadav and Bokade, 1996 Yadav and Doshi, 2000), and synthesis of bisphenol-A (Yadav and Kirthivasan, 1997). 

Fig. 5.5.15 Spatially resolved 13C DEPT spectra recorded for the competitive etherification and hydration reactions of 2-methyl-2-butene (2M2B) to 2-methoxy-2-methylbutane (tert-amyl methyl ether, TAME) and 2-methyl-butan-2-ol (tert-amyl alcohol, TAOH), respectively. The molar composition of the feed was in the ratio 2 10 1 for 2M2B methanol water. The...

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