Acetone secondary formation

As an example of this type of work. Fig. 1.13 indicates the care with which the initial values of [(CHsCOCHg) + (DMO)]/t/[/-C4H8] were obtained for a range of the mixtures used at 753 K. Typically the ratio was determined over the first 5-10% consumption. As can be seen, the change in the ratio is significant and arises from a complex mechanism often involving secondary formation of products and widely differing rates of removal of the intermediate products. Here, for example, acetone is... 

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. 

Ttinitroparaffins can be prepared from 1,1-dinitroparaffins by electrolytic nitration, ie, electrolysis in aqueous caustic sodium nitrate solution (57). Secondary nitroparaffins dimerize on electrolytic oxidation (58) for example, 2-nitropropane yields 2,3-dimethyl-2,3-dinitrobutane, as well as some 2,2-dinitropropane. Addition of sodium nitrate to the anolyte favors formation of the former. The oxidation of salts of i7k-2-nitropropane with either cationic or anionic oxidants generally gives both 2,2-dinitropropane and acetone (59) with ammonium peroxysulfate, for example, these products are formed in 53 and 14% yields, respectively. Ozone oxidation of nitroso groups gives nitro compounds 2-nitroso-2-nitropropane [5275-46-7] (propylpseudonitrole), for example, yields 2,2-dinitropropane (60). 

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). 

Oxidations usually proceed in the dark at or below room temperature in a variety of solvents ranging from aqueous bicarbonate to anhydrous benzene-pyridine. Base is quite commonly used to consume the hydrogen halide produced in the reaction, as this prevents the formation of high concentrations of bromine (or chlorine) by a secondary process. The reaction time varies from a few minutes to 24 hours or more depending on the nature of the reagent and the substrate. Thus one finds that NBS or NBA when used in aqueous acetone or dioxane are very mild, selective reagents. The rate of these oxidations is noticeably enhanced when Fbutyl alcohol is used as a solvent. In general, saturated, primary alcohols are inert and methanol is often used as a solvent. 

A number of diarylmethyl alkylpiperazines, such as, for example lidoflazine, have found use as coronary vasodilators for the treatment of angina. The most recent of these interestingly incorporates a 2,6-dichloroaniline moiety reminiscent of antiarrhythmic agents. Treatment of the piperazine carboxamide 124 with acetone leads to formation of the nitrogen analogue of an acetal, the aminal 125. Alkylation of the remaining secondary nitrogen with chloroamide 126 leads to the intermediate 127. Exposure to aqueous acid leads to hydrolysis of the aminal function... 

Contained within intermediate 25 is an acid-labile mixed acetal group and it was found that treatment of 25 with camphorsulfonic acid (CSA) results in the formation of dioxabicyclo[3.3.0]octane 26 in 77 % yield. Acid-induced cleavage of the mixed cyclic acetal function in 25, with loss of acetone, followed by intramolecular interception of the resultant oxonium ion by the secondary hydroxyl group appended to C leads to the observed product. Intermediate 26 clearly has much in common with the ultimate target molecule. Indeed, the constitution and relative stereochemistry of the dioxabicyclo[3.3.0]octane framework in 26 are identical to the corresponding portion of asteltoxin. 

Although acetone was a major product, it was not observed by infrared spectroscopy. Flowing helium/acetone over the catalyst at room temperature gave a prominent carbonyl band at 1723 cm 1 (not show here). In this study, a DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) cell was placed in front of a fixed reactor DRIFTS only monitored the adsorbed and gaseous species in the front end of the catalyst bed. The absence of acetone s carbonyl IR band in Figure 3 and its presence in the reactor effluent suggest the following possibilities (i) acetone formation from partial oxidation is slower than epoxidation to form PO and/or (ii) acetone is produced from a secondary reaction of PO. 

Yeast alcohol dehydrogenase (YADH), catalysis of reduction by NADH of acetone formate dehydrogenase (FDH), oxidation by NAD of formate horse-liver alcohol dehydrogenase (HLAD), catalysis of reduction by NADH of cyclohexanone With label in NADH, the secondary KIE is 1.38 for reduction of acetone (YADH) with label in NAD, the secondary KIE is 1.22 for oxidation of formate (FDH) with label in NADH, the secondary KIE is 1.50 for reduction of cyclohexanone (HLAD). The exalted secondary isotope effects were suggested to originate in reaction-coordinate motion of the secondary center. 

An example of a photolabile mask for alcohols and thiols employing o-benzoylbenzoate esters is reported by Porter and co-workers [100], Primary and secondary alcohols as well as thiols can be easily masked via the formation of the corresponding 2-benzoylbenzoate esters and converted back into alcohols/ thiols under PET-reductive conditions. Irradiation in isopropanol/benzene 1 1 leads to 3-phenylphthalide dimers as the coproduct (together with acetone), whereas more potent electron donors (e.g., amines) result in the monomers and the corresponding imine. Yields generally range from 60% to 90% (Scheme 55) [100]. 

By analogy, the formation of a double bond between carbon and phosphorus, which in our opinion, however is improbable, is assumed to be the third stage. Finally, this is followed by the addition of water and tautomeric rearrangement to the primary phosphine. In this way, phosphine, which is present in technical acetylene, and because of its good solubility in actone concentrates in the commercial steel cylinders, forms with acetone, isopropylphosphine oxide and possibly, secondary products... 

The oxidation is first order with respect to catalyst and alcohol, while the order with respect to NMO is fractional. A rate expression was derived and formation of a catalyst snbstrate complex proposed [500]. Oxidation of 2-propanol to acetone (and other secondary alcohols) by stoich. TPAP/CH Cl may be anto-catalytic the initial redaction product (RuO ) may form an adduct [Ru0. nRu02] with [RuO ]. The initially slow rate of oxidation by TRAP accelerated sharply as the concentration of product built up and then decreased near the end of the reaction because of the lower concentration of reactants, giving a bell-shaped curve typical of autocatalytic reactions [501]. 

Diaryl- and tetraaryl-substituted furans such as tetraphenylfuran (384) for example, yield generally cw-diaroylethylenes such as 380, probably via intermediate ozonide formation.257 Secondary reactions seem to depend very much on the nature of the solvents. Thus, cis-dibenzoylstilbene (380) has been observed by direct photooxygenation of 384 in CS2 as well as by methylene blue-sensitized photooxygenation of 384 in methanol.257,258 However, when the latter reaction was carried out in acetone, epoxide 386 and the enolbenzoate 387 were obtained.258... 

It is noticeable that over the nickel catalysts, isophorone was a major product. The production of isophorone and the small quantities of other byproducts once again revealed formation of the three intermediate aldol products of the reaction between MO and acetone. However it is clear that hydrogenation was not as facile over the nickel catalysts as it was over the palladium catalysts. Hence there was more secondary and tertiary aldol condensation. To further investigate this a reaction was performed at 573 K using the Ni-KOH/silica catalyst with nitrogen as the carrier gas rather than hydrogen. The results are shown in Table 1. 

The metabolism of isopropanol is via oxidation by aldehyde dehydrogenase (ADH) to acetone. In common with other a-substituted (secondary) alcohols, isopropanol is a relatively poor substrate for ADH (WHO, 1990 Light et al., 1992). The primary metabolite, acetone, is eliminated in the expired air and in the urine and also undergoes further oxidation to acetate, formate and, ultimately, CO,. 

In the case of cationic complexes with unsaturated macrocycles two molecules of nucleophile, such as ammonia, amines and alkoxides, add to carbon atoms of two inline groups. For example, the reaction of [Ni(Bzo[16]octaeneN4)](C104)2 (Table 106) with sodium methoxide or ethoxide yields the compounds (395),2860 while with secondary amines and diamines complexes of type (396) are obtained.28 1 The reaction of (396) with acetone at room temperature yields complex (397) where the enolate anion of acetone, MeC(0)CH2, replaces the diethylamide group (Scheme 58). 2862 The addition of molecules such as bis(2-hydroxyethyl)methylamine and bis(2-hydroxyethyl) sulfide, HOCH2CH2YCH2CH2OH (Y = NMe, S) results in the formation of derivatives which possess one more coordination site just above the plane of the macrocyclic donors (398).2863... 

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