Alcohols 2-propanol oxidation

Generally, primary aliphatic alcohols are oxidized to their respective aldehydes, secondary aliphatic and aromatic alcohols to the corresponding ketones, and allyl and benzyl alcohols to their carboxylic acid or carboxylate ions. For instance, 2-propanol, acetaldehyde, and methyl-benzoate ions are oxidized quantitatively to acetone, acetate, and terephtalate ion respectively, while toluene is converted into benzoate ion with an 86% yield. Controlling the number of coulombs passed through the solution allows oxidation in good yield of benzyl alcohol to its aldehyde. For diols,502 some excellent selectivity has been reached by changing the experimental conditions such as pH, number of coulombs, and temperature. 

Izumi and Urabe [105] found first that POM compounds could be entrapped strongly on active carbons. The supported POMs catalyzed etherization of ferf-butanol and n-butanol, esterification of acetic acid with ethanol, alkylation of benzene, and dehydration of 2-propanol [105], In 1991, Neumann and Levin [108] reported the oxidation of benzylic alcohols and amines catalyzed by the neutral salt of Na5[PV2Mo10O40] impregnated on active carbon. Benzyl alcohols were oxidized efficiently to the corresponding benzaldehydes without overoxidation ... 

The quantum yield for formation of 20, R=6-C(CH3)3, from 14, R=4-C(CH3)3, via photolysis in fer -butyl alcohol and oxidative workup, has been determined as (1.2 0.1) X 10 2 4 ). Quantum yields for formation of various other N-hydroxy-2-indolinones from appropriately substituted 2-nitro-fer -butylben-zenes fall into the range 1.1 X 10 to 2.2 X 10 and thus are of the same order of magnitude as the disappearance quantum yield reported for nitrobenzene in 2-propanol... 

Propanol oxidation under mild conditions takes place with high selectivity. No products other than acetone were observed in the ATR spectra recorded in situ. The situation is more complex for the oxidation of primary alcohols such as ethanol. The first oxidation step produces acetaldehyde, which is prone to further reactions, as is apparent in the ATR spectra. Figure 20, left, shows ATR spectra recorded in situ during ethanol oxidation. Figure 20, right, shows some signals as a function of time. The experiment was performed in a manner similar to that of the one... 

Another method to hydrogenate butadiene occurs during an oxidation—reduction reaction in which an alcohol is oxidized and butadiene is reduced. Thus copper—chromia or copper—zinc oxide catalyzes the transfer of hydrogen from 2-butanol or 2-propanol to butadiene at 90—130°C (87,88). 

Methanol is oxidized to formaldehyde and dimethyl formate. Under the experimental conditions, neither formic acid nor its esters were detected. The other primary alcohols are oxidized to give aldehydes and, in a subsequent reaction, carboxylic acids. Acetals and esters are also formed. Profiles of the reaction products in the oxidation of l-propanol are shown in Fig. 19. 

The secondary alcohols are oxidized to ketones by refluxing with aluminium isopropoxide, A1[0CH(CH3)2]3 [or Al(0-iPr)3], or potassium t-butoxide, KOC(CH3)3 [or KO-t-Bu]. A ketone such as acetone used in the reaction as refluxing agent is reduced to alcohol, 2-propanol. The reaction is known as the Oppenauer oxidation. The reverse reaction known as the Meerwein-Ponndorf-Verly reduction is the reduction of ketones to alcohols in the presence of alcohol such as 2-propanol. Potassium fert-butoxide can be used for the oxidation of primary alcohols. Aluminium isopropoxide in acetone is particularly used for... 

Primary Alcohols Yield Aldehydes.—Now methyl alcohol and ethyl alcohol which yield the two aldehydes that have been studied are both of them primary alcohols, and it has been found to be true that only primary alcohols yield aldehydes on oxidation. Normal propyl alcohol, propanol-1, and other primary alcohols thus yield aldehydes. 

Secondary Alcohols Yield Ketones.—The isomeric propyl alcohol, viz., the secondary alcohol propanol-2, on oxidation yields a compound the composition of which is CaHeO, but which is not an aldehyde. It is known as a ketone specifically as acetone, and is isomeric with propanal the aldehyde obtained from normal propyl alcohol. 

The rates of 2-propanol oxidation were measured for reactions run over an 8% Pt/Si02 catalyst in water at 20°C. The initial rates of oxygen uptake (about 10% conversion) were determined at three fixed partial pressures of oxygen over a range of alcohol concentrations. The resulting data are listed in Table 7.1. 

A new strategy for the synthesis of heterocyclic a-amino acids utilizing the Hantzsch dihydropyridine synthesis was developed in the laboratory of A. Dondoni." ° The enantiopure oxazolidinyl keto ester was condensed with benzaldehyde and fert-butyl amino crotonate in the presence of molecular sieves in 2-methyl-2-propanol to give a 85% yield of diastereomeric 1,4-dihydropyridines. The acetonide protecting group was removed and the resulting amino alcohol was oxidized to the target 2-pyridyl a-alanine derivative. 

Certain features of alcohol photo-oxidation are connected with the presence of sensitizers. As found by Backstrom [60], the rate of photooxidation of 2-propanol (with benzophenone as sensitizer) is inversely proportional the oxygen pressure. Dependence of the 2-propanol oxidation rate on alcohol concentration and on light intensity, /, (with anthraquinone as sensitizer) is expressed as... 

If >>c(oo-)o-h = 75 kcal mole-1, then q = 30 kcal mole-1. Therefore, hyroxyperoxy radicals, in contrast to alkylperoxy radicals, display a dual reactivity. They can take part both in oxidation and in reduction reactions and they would be expected to react not only with radicals but with molecules of the oxidizing agent, with quinones for example. The kinetics of 2-propanol oxidation in the presence of benzoquinone has been studied [80], Quinones are known to terminate chains in hydrocarbon oxidation only by reactions with alkyl radicals [1]. In alcohol oxidation, quinone terminates chains by reaction with hydroxyalkyl as well as with hydroxyperoxy radicals [80]. At 71°C and PQl = 760 torr, 86% of chain termination is due to the reaction >C)0H)00- + quinone. The rate coefficient is M>C(0H)00- + quinone) = 3.2 X 1031 mole-1 s-1 and kQ/kp = 1.0 X 104. Just as in the case of aromatic amines, f> 2 f= 23 for quinone, i.e. quinone is regenerated in the reactions... 

Br" ions inhibit the oxidation of alcohols if the latter do not contain H202. However, in the presence of H202, 2-propanol oxidation is accelerated by Br" [89], as the latter induces decomposition of H202 leading to free radical formation. The rate of initiation by reaction of Br" with H202 is [89]... 

Secondary alcohols are oxidized to give ketones. The oxidation of 2-propanol (isopropyl alcohol) gives acetone, a ketone widely used as an organic solvent. 

In the Absence of Oxygen Methanol, Ethanol, 2-Propanol, and t-Butyl Alcohol Alcohols such as methanol, ethanol, and 2-propanol are converted with Pt/Ti02 to the corresponding dehydrogenation products such as formaldehyde, acetaldehyde, and acetone, respectively, with the formation of equimolar H2. t-Butyl alcohol is converted into 2,5-dimethyl-2,5-hexanediol with the formation of H2 through intermolecular dimerization since t-butyl alcohol has no alpha-hydrogen. In these oxidative reactions, alcohols are oxidized by photoformed holes, while photoexcited electrons reduce water (or H" ) to form H2 [4]. 

Recently, Chu and Shul [128] have applied combinatorial chemistry to the screening of 66 PtRuSn-anode arrays for investigation of methanol, ethanol, and 2-propanol oxidation. The screening was performed by employing quinine as indicator of the catalytic activity, which allowed for selection of the optimum composition of electrocatalysts for DAFCs (Direct Alcohol Fuel Cells). PtRuSn (80 20 0), PtRuSn (50 0 50), and PtRuSn (50 30 20) furnished the lowest onset potential for methanol, ethanol, and 2-propanol electro-oxidation according to the CV results, respectively. The active area/composition for ethanol electro-oxidation is represented in Figure 15.8 as adapted from Ref. [128]. 

Allyl alcohol is oxidized by aqueous [PdClJ to jS-hydroxypropanol, a-hydroxyacetone, and acrolein (CH2 = CHCHO), or propanol. Deuterium labeling was used to show that acrolein does not result from dehydration of HOCH2CHCHO, but is a direct oxidation product. Most probably the C=C bond as well as the OH group are coordinated to the metal.The... 

Isobutyl alcohol, isobutanol, 2-methyl-propanol, isopropyl carbinol, Me2CHCH20H. B.p. 108°C. Occurs in fusel-oil. Oxidized by potassium permanganate to 2-methyl-propanoic acid dehydrated by strong sulphuric acid to 2-methylpropene. 

Glycerol -dichlorohydrin, 2.3-dichloro-propanol, CH2CI CHC1 CH2 0H. Colourless liquid, b.p. 182 C. Prepared by the chlorination of propenyl alcohol. Oxidized by nitric acid to 1,2-dichloropropionic acid. Reacts with NaOH to give epichlorohydrin. 

Direct Borohydride Reduction of Alcohols to Alkanes with Phosphonium Anhydride Activation N-Proovlbenzene. To a solution of 5.56 g (20 mmol) of triphenylphosphine oxide in 30mL of dry methylene chloride at CfC was added dropwise a solution of 1.57 mL (10 mmol) of triflic anhydride in 30mL of dry methylene chloride. After 15 min when the precipitate appeared, a solution of 1.36g (10 mmol) of 3-phenyl-1-propanol in 10 mL of dry methylene chloride was added and the precipitate vanished in 5 min. An amount of 1.5g (40 mmol) of sodium borohydride was added as a solid all at once and the slurry was stirred at room temperature for... 

Synthesis of (A) started with the combination of 2,4,6-trimethylphenol and allyl bromide to give the or/Ao-allyl dienone. Acid-catalyzed rearrangement and oxidative bydroboration yielded the dienone with a propanol group in porlactone ring were irons in the product as expected (see p. 275). Treatment with aqueous potassium hydroxide gave the epoxy acid, which formed a crystalline salt with (R)-l-(or-naphthyl)ethylamine. This was recrystallized to constant rotation. 

PMMA is not affected by most inorganic solutions, mineral oils, animal oils, low concentrations of alcohols paraffins, olefins, amines, alkyl monohahdes and ahphatic hydrocarbons and higher esters, ie, >10 carbon atoms. However, PMMA is attacked by lower esters, eg, ethyl acetate, isopropyl acetate aromatic hydrocarbons, eg, benzene, toluene, xylene phenols, eg, cresol, carboHc acid aryl hahdes, eg, chlorobenzene, bromobenzene ahphatic acids, eg, butyric acid, acetic acid alkyl polyhaHdes, eg, ethylene dichloride, methylene chloride high concentrations of alcohols, eg, methanol, ethanol 2-propanol and high concentrations of alkahes and oxidizing agents. 

In this process, the fine powder of lithium phosphate used as catalyst is dispersed, and propylene oxide is fed at 300°C to the reactor, and the product, ahyl alcohol, together with unreacted propylene oxide is removed by distihation (25). By-products such as acetone and propionaldehyde, which are isomers of propylene oxide, are formed, but the conversion of propylene oxide is 40% and the selectivity to ahyl alcohol reaches more than 90% (25). However, ahyl alcohol obtained by this process contains approximately 0.6% of propanol. Until 1984, ah ahyl alcohol manufacturers were using this process. Since 1985 Showa Denko K.K. has produced ahyl alcohol industriahy by a new process which they developed (6,7). This process, which was developed partiy for the purpose of producing epichlorohydrin via ahyl alcohol as the intermediate, has the potential to be the main process for production of ahyl alcohol. The reaction scheme is as fohows ... 

Propjiene [115-07-17, CH2CH=CH2, is perhaps the oldest petrochemical feedstock and is one of the principal light olefins (1) (see Feedstocks). It is used widely as an alkylation (qv) or polymer—ga soline feedstock for octane improvement (see Gasoline and other motor fuels). In addition, large quantities of propylene are used ia plastics as polypropylene, and ia chemicals, eg, acrylonitrile (qv), propylene oxide (qv), 2-propanol, and cumene (qv) (see Olefin POLYMERS,polypropylene Propyl ALCOHOLS). Propylene is produced primarily as a by-product of petroleum (qv) refining and of ethylene (qv) production by steam pyrolysis. 

Isopropyl Alcohol. Propylene may be easily hydrolyzed to isopropyl alcohol. Eady commercial processes involved the use of sulfuric acid in an indirect process (100). The disadvantage was the need to reconcentrate the sulfuric acid after hydrolysis. Direct catalytic hydration of propylene to 2-propanol followed commercialization of the sulfuric acid process and eliniinated the need for acid reconcentration, thus reducing corrosion problems, energy use, and air pollution by SO2 and organic sulfur compounds. Gas-phase hydration takes place over supported oxides of tungsten at 540 K and 25... 

Hydrogen Sulfide andMercaptans. Hydrogen sulfide and propylene oxide react to produce l-mercapto-2-propanol and bis(2-hydroxypropyl) sulfide (69,70). Reaction of the epoxide with mercaptans yields 1-aLkylthio- or l-arylthio-2-propanol when basic catalysis is used (71). Acid catalysts produce a mixture of primary and secondary hydroxy products, but ia low yield (72). Suitable catalysts iaclude sodium hydroxide, sodium salts of the mercaptan, tetraaLkylammonium hydroxide, acidic 2eohtes, and sodium salts of an alkoxylated alcohol or mercaptan (26,69,70,73,74). 

Hydrogenolysis of propylene oxide yields primary and secondary alcohols as well as the isomeri2ation products of acetone and propionaldehyde. Pd and Pt catalysts favor acetone and 2-propanol formation (83—85). Ni and Cu catalysts favor propionaldehyde and 1-propanol formation (86,87). 

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