Alcohol, as byproduct

Vinyltrimethylstannanes react with xenon difluoride in dichloromethane at room temperature in the presence of equimolar (or a 50 Vo excess) of silver trifluoromethanesulfonate and a catalytical (0.1 equiv) quantity of 2,6-di-/e/7-butyl-4-methylpyridine to form the corresponding vinyl fluorides in high to moderate yields.54 57 The substitution reaction is tolerant to various functional groups, such as ketones, esters, carbamates, ketals, ethers, phenol rings and tertiary alcohols. As byproducts corresponding alkenes have been detected due to pro-tiodestannylation. 

Ketone synthesis. The synthesis of ketones by reaction of Grignarcj. reagents with esters is usually unsatisfactory because of formation of tertiary alcohols as byproducts. However, this secondary reaction is mainly prevented if triethylamine (large excess) is present, and reasonable yields of ketones can be obtained unless the ester is readily enolized.1... 

The synthesis of aldehydes [C5] can also be accomplished by controlled reduction of acylaziridines 3.178 [BK5] or of acylimidazoles 3.179 [W3] by LAH in Et20 at -10°C, by LTBA or by Red-A1 in [H3, M3] R can be aliphatic or aromatic (Figure 3.66). The N-methoxy-N-methylcarboxamides 3.180 are also cleanly reduced to aldehydes by LAH in excess in THF at low temperature or by DIBAH in THF at 0°C. In many cases, the latter reagent does not lead to formation of alcohols as byproducts resulting from a subsequent reduction of the aldehyde [NWl]. This behavior can be understood by the stabilization through chelation of the lithium or aluminum intermediate (Figure 3.66). a,p-Unsaturated aldehydes may also be prepared by this method, using DIBAH in THF [BS8, NBl]. 

For many years your plant on the Texas Gulf Coast has produced tetrahydrofuran (THF) for use as a synthetic fiber intermediate. The reaction is carried out in water solution, producing a crude THF which also contains lower aliphatic alcohols as byproducts plus some gamma-butyrolactone (GBL), which is an unreacted intermediate. The THF is purified in a three-column distillation train. The impurities have been incinerated or sent with the water to the biological effluent treatment system. 

Finally, it has to be remarked that, except for what concerns other equilibrium reactions that produce water (etherification reactions, Knoevenagel reactions, etc.), the real future challenge for PVMRs is to switch from water to alcohols. In fact, transes-teiification reactions, as an equilibrium reaction, produce alcohol as byproduct. In this... 

With the successful development of an isobutanol production pathway in E. coli, the a-keto-acid isobutanol production pathway was transferred to the traditional amino acid producer Corynebacterium glutamicum [89]. The native ilvCD and adhA genes were overexpressed, which led to 2.6 g 1 of isobutanol production with other alcohols as byproducts. By deleting the competing pathways, namely pyruvate carboxylase and lactate dehydrogenase, isobutanol production was increased to 4.9 g 1 . The work showed the potential of both the universality of the a-keto-acid isobutanol production pathway and the potential of utilization of C. glutamicum for higher chain alcohol production [89]. 

Af-Acyliminium ions are known to serve as electron-deficient 4n components and undergo [4+2] cycloaddition with alkenes and alkynes.15 The reaction has been utilized as a useftil method for the construction of heterocycles and acyclic amino alcohols. The reaction can be explained in terms of an inverse electron demand Diels-Alder type process that involves an electron-deficient hetero-diene with an electron-rich dienophile. Af-Acyliminium ions generated by the cation pool method were also found to undergo [4+2] cycloaddition reaction to give adduct 7 as shown in Scheme 7.16 The reaction with an aliphatic olefin seems to proceed by a concerted mechanism, whereas the reaction with styrene derivatives seems to proceed by a stepwise mechanism. In the latter case, significant amounts of polymeric products were obtained as byproducts. The formation of polymeric byproducts can be suppressed by micromixing. 

The direct conversion of alcohols and amines into carbamate esters by oxidative carbonylation is also an attractive process from an industrial point of view, since carbamates are useful intermediates for the production of polyurethanes. Many efforts have, therefore, been devoted to the development of efficient catalysts able to operate under relatively mild conditions. The reaction, when applied to amino alcohols, allows a convenient synthesis of cyclic urethanes. Several transition metal complexes, based on Pd [218— 239], Cu [240-242], Au [243,244], Os [245], Rh [237,238,246,247], Co [248], Mn [249], Ru [224,250-252], Pt [238] are able to promote the process. The formation of ureas, oxamates, or oxamides as byproducts can in some cases lower the selectivity towards carbamates. 

The PET polymer structure can also be generated from the reaction of ethylene glycol and dimethyl terephthalate, with methyl alcohol as the byproduct. A few producers still use this route. The aromatic rings coupled with short aliphatic chains are responsible for a relatively stiff polymer molecule, as compared with more aliphatic structures such as polyolefin or polyamide. The lack of segment mobility in the polymer chains results in relatively high thermal stability, as will be discussed later. 

Early epidemiological studies suggested an association between the manufacture of isopropyl alcohol and paranasal sinus cancer/ The risk for laryngeal cancer may also have been elevated in these workers. The increased cancer incidence, however, appears to be associated with some aspect of the strong-acid manufacturing process rather than the isopropyl alcohol itself It is unclear whether the cancer risk is due to the presence of diisopropyl sulfate, which is an intermediate in the process, to isopropyl oils, which are formed as byproducts, or to other agents, such as sulfuric acid. ... 

In contrast to the active site of galactose oxidase, to pre-catalyst 13, and to the system reported by Stack et al., the proposed catalytic species 15 does not imdergo reduction to Cu intermediates, as the oxidation equivalents needed for the catalysis are provided for solely by the phenoxyl radical Hgands. Since the conversion of alcohols into aldehydes is a two-electron oxidation process, only a dinuclear Cu species with two phenoxyl ligands is thought to be active. Furthermore, concentrated H2O2 is formed as byproduct in the reaction instead of H2O, as in the system described by Marko et al. [159]. 

Firstly, various side reactions result from impurities left in the diazonium tetrafluoroborate (water, sodium nitrite, washing solvents). As already discussed, residual water or alcohols (often used to wash the solid diazonium tetrafluoroborate after filtration) substitute the diazo group in an ionic process to produce phenols or alkoxyarenes as byproducts. Residual alcohol can also lead to arenes through a radical hydrodediazoniation process, especially when electron-withdrawing groups are present, as in 3-fluoro-2-methoxy-5-(methoxyearbonyl)benzenediazo-nium tetrafluoroborate (ArF/ArH 4 1)227 or in 2-methyl-5-nitrobenzenediazonium tetrafluoroborate.240 Such radical phenomena increase when sodium nitrite is present as impurity... 

When olefins are used as alkylating agents, the catalytic activity of Nafion-H slowly decreases, most probably due to some polymerization on the surface, which deactivates the catalytic sites. The activity decreases faster when more reactive branched alkenes are used. The use of alcohols instead of olefins as the alkylating agents improves the lifetime of the catalyst. With alcohols, no ready polymerization takes place, since water formed as byproduct inhibits polymerization of any olefin formed (by dehydration) but does not affect the acidity of the catalyst at the reaction temperatures. 

In gas-phase methylation reactions over Nafion-H using methyl alcohol as the alkylating agent, the consumption of methyl alcohol was higher than that calculated by product analysis.207,208 This is due to the formation of dimethyl ether as the byproduct [Eq. (5.82)]. Indeed, when neat methyl alcohol is passed over Nafion-H catalyst at temperatures over 150°C, dimethyl ether is the only product formed quantitatively with water as the byproduct.218... 

Olah and co-workers219 have applied Nafion-H in the benzylation of benzene with benzyl alcohols [Eq. (5.83)] and also reported the reaction of benzyl alcohol with substituted aromatics (toluene, xylenes, mesitylene) to yield diphenylmethanes. The reaction is performed under mild conditions and produces the corresponding dibenzyl ethers as byproducts (2-22%). The substrate and positional selectivity in competitive benzylation of benzene and toluene (1 1 molar ratio) was found to be almost the same as observed in solution-phase Friedel-Crafts benzylation with benzyl chloride (AICI3-CH3NO2). Cyclic products 56 and 57 resulting from cyclialkylation were isolated when Nafion-H-catalyzed benzylation was applied to 2-(hydroxymethyl) diphenylmethane and 3,4-dimethoxybenzyl alcohol, respectively. 

A remarkable solvent effect on the chemoselectivity was discovered by Agarwala and Bandyopadhyay (Scheme 3.24, B) [114]. When cyclohexene la was oxidized with tBuOOH in the presence of an electronegative substituted iron(III) porphyrin complex in CH2Cl2-MeOH, epoxide 4a was the predominant product (69% yield) in addition to alcohol 2a and ketone 3a as byproducts in 20% and 11% yields,... 

This reaction is rapid and produces few side reaction products. In addition, the sulfur dioxide and hydrogen chloride formed as byproducts are gasses and therefore easily removed from the reaction. Mechanistically, the alcohol initially reacts to form an inorganic ester. 

NAD is a biochemical oxidizing agent that converts alcohols to aldehydes or ketones, yielding NADH and H+ as byproducts. 

The present procedure is based on the use of fluoroalkyl alcohols as solvents in oxidation reactions. The method is efficient and versatile, and produces disulfides and sulfoxides under mild conditions. These reactions have also been developed using hexafluoroisopropyl alcohol (HFIP) as solvent with a large variety of substrates (alkyl sulfides, alkyl thiols, vinyl sulfides, fiuorinated vinyl sulfides, thioglucosides) by Begue et al."> Replacement of HFIP with trifluoroethanol, a more common and less expensive solvent, also allows the use of mild conditions and affords high yields of disulfides and sulfoxides without contamination. 30% Aqueous hydrogen peroxide is inexpensive and, since water is the sole byproduct, this method is environmentally friendly. 

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