Acetone dimerization

ED 1,3-Dihydroxy Acetone Dimer S Pyruvaldehyde El Lactic Acid Glyceraldehyde... 

Remarkable differences are found between the results for MOX or DAA and other ketones. With these acetone dimers, no macrocyclic product was obtained. In the case of S-apip and S-ahaz, the yield of other products (B and C) are also very low. This probably indicates the effects of some steric factors, which reduce the reactivity. The steric factor will be due chiefly to repulsions brought about by two methyl groups in ketones. The repulsion works in the transition state for formation of both B and C, so that the yield of each for S-apip and S-ahaz is lowered. 

The formation of type C products for S-apip and S-ahaz is rather surprising, because these substances should be generated through the four-coordinated-copper(II) complexes. The four-coordinated species are considered to be present in only a small ratio compared with the five-coordinated species, as disscussed earlier. Therefore, the formation of C for these diamines (S-apip and S-ahaz) seems to suggest the low reactivity of acetone dimers towards their five-coordination complexes. 

The advantages of the procedure we have developed include the relatively few steps from a convenient starting material (dihydroxy acetone dimer), the use of low-tech conditions throughout,... 

Certain solvents should be avoided with alumina or silica gel, especially with the acidic, basic, and highly active forms. For instance, with any of these adsorbents, acetone dimerizes via an aldol condensation to give diacetone alcohol. Mixtures of esters transesterify (exchange their alcoholic portions) when ethyl acetate or an alcohol is the eluent. Finally, the most active solvents (pyridine, methanol, water, and acetic acid) dissolve and elute some of the adsorbent itself. Generally, try to avoid going to solvents more polar than diethyl ether or methylene chloride in the eluent series (Table 19.2). 

Figure 3.172 Diacetone aicohoi CgH jOj, M 116, CAS 123-42-2. Occurrence acetone dimer, forms from the soivent under basic conditions.

Acrolein is produced according to the specifications in Table 3. Acetaldehyde and acetone are the principal carbonyl impurities in freshly distilled acrolein. Acrolein dimer accumulates at 0.50% in 30 days at 25°C. Analysis by two gas chromatographic methods with thermal conductivity detectors can determine all significant impurities in acrolein. The analysis with Porapak Q, 175—300 p.m (50—80 mesh), programmed from 60 to 250°C at 10°C/min, does not separate acetone, propionaldehyde, and propylene oxide from acrolein. These separations are made with 20% Tergitol E-35 on 250—350 p.m (45—60 mesh) Chromosorb W, kept at 40°C until acrolein elutes and then programmed rapidly to 190°C to elute the remaining components. 

Ketene Process. The ketene process based on acetic acid or acetone as the raw material was developed by B. F. Goodrich (81) and Celanese (82). It is no longer used commercially because the intermediate P-propiolactone is suspected to be a carcinogen (83). In addition, it cannot compete with the improved propylene oxidation process (see Ketenes, ketene dimers, and related substances). 

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). 

Squalane [111-01-3] (fully saturated squalene) is produced synthetically by the coupling of two molecules of geranyl acetone with diacetylene, followed by dehydration and complete hydrogenation (205). Squalane can also be made by dimerization of dehydroneroHdol, followed by dehydrogenation and hydrogenation (206). 

Photodimers of IV-methylisoindole and isobenzofuran have been isolated [8+8] dimers are the major products. The [8 + 8] dimer (30) obtained by UV irradiation of an acetone solution of isobenzofuran at -60 °C has anti stereochemistry (78HCA444, 82CC1195). 

Analogously, pyrazolyl-aluminate and -indate ligands have been prepared <75JCS(D)749) and their chelating properties evaluated with cobalt, nickel, copper and zinc. Gallyl derivatives of pyrazoles and indazoles have been extensively studied by Storr and Trotter e.g. 75CJC2944) who determined several X-ray structures of these compounds. These derivatives exist in the solid state as dimers, such as (212) and (288). A NMR study in acetone solution showed the existence of a slow equilibrium between the dimer (212) and two identical tautomers (289) and (290) (Section 4.04.1.5.1) (81JOM(215)157). 

Pyrazolones show a great variety of reactions with carbonyl compounds (B-76MI40402). For instance, antipyrine is 4-hydroxymethylated by formaldehyde and it also undergoes the Mannich reaction. Tautomerizable 2-pyrazolin-5-ones react with aldehydes to yield compound (324) and with acetone to form 4-isopropylidene derivatives or dimers (Scheme 8 Section 4.02.1.4.10). 

Dimethyl peroxide Diethyl peroxide Di-t-butyl-di-peroxyphthalate Difuroyl peroxide Dibenzoyl peroxide Dimeric ethylidene peroxide Dimeric acetone peroxide Dimeric cyclohexanone peroxide Diozonide of phorone Dimethyl ketone peroxide Ethyl hydroperoxide Ethylene ozonide Hydroxymethyl methyl peroxide Hydroxymethyl hydroperoxide... 

Enamines containing one -hydrogen atom react with the lactone dimer of dimethylketene to form aminocyclohexanediones 116). Polycondensation of acetone diethyl ketal takes place by treating it with morpholine and a catalytic amount of p-toluenesulfonic acid while distilling off the ethanol formed 117-119). The resulting spiran, bicyclo, and cyclooctadienone products differ from the known polycondensation products of acetone, and hence their formation probably involves enamine intermediates 119). 

The required vicinal diols are in general accessible by standard methods. Pinacol itself can be obtained by dimerization of acetone. For the rearrangement reaction concentrated or dilute sulfuric acid is often used as catalyst. 

DNA sequencing and. 1113 Electrospray ionization (ESI) mass spectrometry, 417-418 Electrostatic potential map, 37 acetaldehyde, 688 acetamide, 791,922 acetate ion. 43. 53, 56, 757 acetic acid. 53. 55 acetic acid dimer, 755 acetic anhydride, 791 acetone, 55, 56. 78 acetone anion, 56 acetyl azide, 830 acetyl chloride, 791 acetylene. 262 acetylide anion, 271 acid anhydride, 791 acid chloride, 791 acyl cation, 558 adenine, 1104 alanine, 1017 alanine zwitterion, 1017 alcohol. 75 alkene, 74, 147 alkyl halide, 75 alkyne. 74... 

A general preparation of 2-acetonyl-2,4,6-triaryl-2//-thiopyrans 58 was discovered in the reaction of corresponding 2,4,6-triarylthiopyrylium perchlorates with ethanolic acetone catalyzed with various dialkylammonium salts (86GEP235455, 86JPR573). This preparative procedure was successfully extended to cyclohexane- and cyclopentane- 1,2-diones as the carbonyl components (89JPR853 90GEP280324). The action of bases on thiopyrylium salts may caused their dimerization to thiopyranyl derivatives under suitable conditions (89KGS479). 

Electrophile trapping of simple metalated epoxides (i. e., those not possessing an anion-stabilizing group) is possible. Treatment of epoxystannane 217 with n-BuLi (1 equiv.) in the presence of TMEDA gave epoxy alcohol 218 in 77% yield after trapping with acetone (Scheme 5.51) [76], In the absence of TMEDA, the non-stabilized epoxides underwent dimerization to give mixtures of enediols. 

The rapid fabrication of covalently bonded ID functional molecular lines with predefined location, direction, and length provides a means to make a predesigned interconnection of molecular lines running along and across the dimer rows. Indeed, the perpendicularly connected allyl mercaptan and styrene lines or allyl mercaptan and acetone lines have been fabricated on the H-Si(l 00)-2 X 1 surface. °° 2 ... 

The TI species abstracts hydrogen from the alcohol (p. 321), and then dimerizes. The t-PrO radical, which is formed by this process, donates H- to another molecule of ground-state benzophenone, producing acetone and... 

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