Acetone aliphatic aldehydes

Physical Description Pyrolysis products of rosin core solder include acetone, aliphatic aldehydes, methyl alcohol, methane, ethane, various abietic acids (the major components of rosin), CO CO2. ... 

Reagent A is particularly useful for the treatment of the lower aliphatic aldehydes and ketones which are soluble in water cf. acetaldehyde, p. 342 acetone, p. 346). The Recent is a very dilute solution of the dinitrophenylhydrazine, and therefore is used more to detect the presence of a carbonyl group in a compound than to isolate sufficient of the hydrazone for effective recrystallisation and melting-point determination. 

Several improved methods for the preparation of known unsaturated azlactones as well as some interesting new compounds of this type have been reported. Crawford and Little observed that the direct use of 2-phenyl-5-oxazolone (1) in the Erlenmeyer reaction gave much improved yields (35-74%) of unsaturated azlactones with aliphatic aldehydes and with ketones such as acetone and cyclohexanone [Eq, (1)], The usual procedure of mixing a carbonyl compound, hippuric acid, acetic anhydride, and sodium (or lead) acetate affords poor yields in the aliphatic series. 

Ketones such as acetone, hydroxyacetone, and methoxyacetone can be condensed with both aromatic and aliphatic aldehydes.198... 

The two established Hnls, those from L. usitatissimum and P. amygdalus, have found biocatalytic applications for the production of (i )-cyanohydrins. The former of these Hnls is the least widely applied, the natural substrates being acetone cyanohydrin or (i )-2-butanone cyanohydrin (Table 1) [28]. Although an improved procedure for the purification of this enzyme has been reported [27] it is still only available in limited quantities (from 100 g of seedlings approximately 350 U of enzyme are obtained). It was found that this enzyme transforms a range of aliphatic aldehyde and ketone substrates [27], the latter of which included five-membered cyclic (e.g. 2-methylcyclopentanone) and chlorinated ketone substrates. In contrast, attempts to transform substituted cyclohexanones and 3-methylcyclopentanone failed and it was even found that benzaldehyde deactivated the enzyme. 

Other related reactions involve TV-fluorenylmethyloxycarbonyl (N-Fmoc) AAs and aliphatic aldehydes (83JOC77) or substituted /-butoxycarbonyl (N-Boc) Aas and 2,2-dimethyoxypropane (acetone dimethyl ketal) (84TL5855 87JOC2361 88TL2019), as well as A-(dimethylthio)methylene derivatives of an AA and aromatic aldehydes [89JCS(P1)1577]. 

This protocol complements Akiyama s method which provides P-amino carbonyl compounds as i yn-diastereomers [14], It tolerated aromatic, heteroaromatic, and aliphatic aldehydes. Cyclic ketones, acetone, as well as acetophenone derivatives could be employed. The use of aromatic ketones as Mannich donors was up to that time unprecedented in asymmetric organocatalysis. Rueping et al. independently expanded the scope of the asymmetric Brpnsted acid-catalyzed Mannich reaction of acetophenone [45]. 

The first step corresponds to a normal carbonyl addition, as is also observed with aliphatic aldehydes but here the equilibrium does not lie so far to the right. A strongly acidic medium is necessary for the next stage, the formation of a carbonium ion. For example, it is found that PH3 only reacts with acetone when the solution is more than 8-molar in hydrochloric acid. 

Variations on this theme include the use of acrolein/ammonia (72GEP2224160) and acrolein/acetaldehyde/ammonia (64BRP963887,69BRP1141526). Ketones can also be utilized. For example, 2,6-dimethylpyridine is obtained in 36% yield from combination of for-malin/acetone/ammonia (71GEP2064397) (Scheme 3). This general reaction has recently been extended to include the preparation of 2,6-disubstituted (78BEP858390) and 2,3-disubstituted (78GEP2712694) pyridines from aromatic or heteroaromatic ketones/aliphatic aldehydes and ammonia. 

The addition of aliphatic aldehydes and ketones to alkenes is less successful as a preparative procedure for oxetanes. An essential requirement for addition is that the triplet energy of the alkene must be considerably greater than that of the carbonyl. If this condition is not fulfilled, energy transfer to the alkene can occur,279 sensitizing, for example, dimerization of the alkene. This is clearly illustrated 280, 281 for norbornene (264) which on irradiation in the presence of benzophenone (ET 68.5 kcal/mole) forms the adduct 265 photolysis in acetone (ET 75 kcal/mole) affords only norbornene dimers (266 and 267), whereas acetophenone, which has intermediate triplet energy (Et 73.6 kcal/mole) forms both oxetanes and norbornene dimers. 

Cyanohydrin Synthesis. Another synthetically useful enzyme that catalyzes carbon—carbon bond formation is oxynitrilase (EC 4.1.2.10). This enzyme catalyzes the addition of cyanides to various aldehydes that may come either in the form of hydrogen cyanide or acetone cyanohydrin (152—158) (Fig. 7). The reaction constitutes a convenient route for the preparation of a-hydroxy acids and p-amino alcohols. Acetone cyanohydrin [75-86-5] can also be used as the cyanide carrier, and is considered to be superior since it does not involve hazardous gaseous HCN and also virtually eliminates the spontaneous nonenzymatic reaction. (R)-oxynitrilase accepts aromatic (97a,b), straight- (97c,e), and branched-chain aliphatic aldehydes, converting them to (R)-cyanohydrins in very good yields and high enantiomeric purity (Table 10). 

A wide range of donor ketones, including acetone, butanone, 2-pentanone, cyclopentanone, cyclohexanone, hydroxyacetone, and fluoroacetone with an equally wide range of acceptor aromatic and aliphatic aldehydes were shown to serve as substrates for the antibody-catalyzed aldol addition reactions (Chart 2, Table 8B2.6). It is interesting to note that the aldol addition reactions of functionalized ketones such as hydroxyacetone occurs regioselectively at the site of functionaliztion to give a-substitutcd-fi-hydroxy ketones. The nature of the electrophilic and nucleophilic substrates utilized in this process as well as the reaction conditions complement those that are used in transition-metal and enzymatic catalysis. 

AMJnsubstituted and 4-alkylthiosemicarbazones of aliphatic aldehydes 88 (R1 = R3 = H R2 = Me, Et, i-Pr R4 = H, Me, PhCH2, Ph) exhibit only the three-component (or four-component when R4 H) equilibrium 89B( and Z, when R4 H) 89A 89C in trifluoroacetic acid solution (93T5327). The tautomer 89B (70-90%) prevails in the equilibrium, particularly at higher dilution. The contents of the tautomers 89A and 89C are roughly equal, ca. 5-10%. Replacement of an alkyl substituent R2 by an aryl group (R2 = 4-MeOC6H4) leads to total disappearance of the tautomer 89C. Change from an aliphatic aldehyde to an acetone thiosemicarbazone or introduction of an alkyl substituent at N(2) (R3 = alkyl) stabilizes the... 

Not only does acetone undergo a highly enantioselective aldol reaction, but hydroxy acetone exhibits excellent stereoselectivity to produce the anti-aldol products 75 (Scheme 2.3d). For example, L-proline catalyzed the aldol reaction between hydroxy acetone and cyclohexanecarbaldehyde to furnish the anti -diol in 60% yield with a greater than 20 1 diastereomeric ratio. The enantiofacial selectivity of the anti-isomer was higher than >99%. Diastereoselectivities are very high with a-substituted aldehydes, whereas low selectivities are recorded in reactions with aromatic aldehydes and with a-unsubstituted aliphatic aldehydes. It is noteworthy that the levels of enantiofacial selectivity for the anti -aldol products... 

In the Claisen-Schmidt reaction, aliphatic aldehydes and ketones are the sources of the carbanion and the products are unsaturated aldehydes and ketones. In the reaction with acetaldehyde (ethanal), cinnamaldehyde (3-phenylpropenal) is formed. With acetone, 4-phenylbut-3-enone (benzyli-deneacetone) is the product (Scheme 6.18). The reaction is generally applicable and a large variety of products have been obtained in this way, some of which are used in perfumery. 

The yields of nitro alcohols from simple nitroparaffins and aliphatic aldehydes or benzaldehyde are usually above 60%. The condensations are generally carried out with aqueous ethanolic sodium hydroxide, although weaker bases are sometimes desirable to prevent polymerization of the aldehyde. Sodium bisulfite addition compounds of the aldehydes are sometimes used. Better results are obtained with sodium methoxide than with alkali hydroxides in the condensation of nitroethane with formaldehyde. Sodium alkoxides are also used to effect the condensation of nitroethane with acetone and cyclohexanone. Condensation proceeds to the nitroalkanediol stage in certain cases with both nitromethane and with formaldehyde. ... 

Hydrolysis by Emmons path 2 has been suggested" as a method for converting amines to ketones, the acid counterpart of a base-catalyzed procedure cited previously. The oxaziridines were obtained by oxidation of the product from amines and acetone, and hydrolyzed with 2M hydrochloric acid at room temperature for 40 hours. The only aliphatic aldehyde produced was not stable under these conditions. This reaction has received further study. ... 

It was stated that aliphatic aldehydes or aldoses reduced mercuric acetate, but no such reduction is noticed with ketones or ketoses. Ne ertheles.s most investigators differ as to the products derived from ketones, and it is very difficult to say -svhether many of the compounds described are truly organometallic or merely complex addition products of the ketones. For the sake of readers interested in these derivatives, the following table is inserted to summarise these compounds of doubtful structure. The ketone used in these investigations was acetone. 

Aromatic and aliphatic aldehydes in the presence of dialkylamines and an equivalent of acid such as hydrochloric, perchloric or p-toluenesulfonic acid give iminium salts, which add cyanide ion to form a-(dialkylamino)nitriles. An alternative preparation involves the reaction of the aldehyde with dialkylamines in the presence of acetone-cyanohydrin, a-(A, -dialkylamino)isobutyronitiiles, diethyl phosphorocyanidate or TMS-CN. Another route to a-aminonitrile starts with an aldehyde, the salt of an amine and KCN in organic solvents under solid-liquid two-phase conditions by combined use of alumina and ultrasound. Chiral a-aminonitriles were prepared by Strecker-type reactions, cyano-silylation of Schiffs bases, amination of a-siloxynitriles or from an A -cyanomethyl-l,3-oxazolidine synthon. Reaction of tertiary amines with CIO2 in the presence of 5.1 mol equiv. of aqueous NaCN as an external nucleophile affords a-aminonitrile. °... 

Uranium. Ephritikhine has reported a UC -catalyzed variant of the TiC -cata-lyzed process illustrated in Fig. 3-7 [63]. Both aliphatic aldehydes and aliphatic ketones are coupled by UCI4 (cat.)/Li/Hg/AlCl3 (reaction of acetone 97% yield). 

KJass" found that aliphatic aldehydes react with the complex in refluxing ethylene dichloride to give betaine salts in good yield. Acetone and benzaldehyde did not react under the same conditions. 

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