Benzal-acetone

Benzal acetone Me-cirrrrarnyi ketorre C5H5CH CHCOCHt... 

Recently a related brominating agent, pyrrolidone hydrobromide tribromide has been described. This reagent, also in tetrahydrofuran, gives co-bromobenzalacetone from benzal-acetone.13... 

Formation of Benzal- Acetone Structures. Formation of a peroxy group at C-5 (oxidation of structure lid) leads to ring opening between C-4 and C-5 and to formation of benzal acetone structures, which are assumed to be the possible source of the obtained degradation products (acetone and acid V, respectively, w-propyl methyl ketone and acid VI). 

In order to gain some information on the degradation mechanisms, experiments with substances assumed to represent essential intermediates were undertaken. 2-Hydroxy-3-methoxy-5-methylbenzal acetone (XVII) is considered to play a dominant role in the proposed degradation mechanism when 6,6 -bicreosol is oxidized in alkaline solution although it could not be detected among the degradation products. The benzal acetone (XVII) was oxidized and underwent alkaline hydrolysis under our standard conditions. Alkaline hydrolysis in nitrogen atmosphere yielded rather small amounts of acetone (about 10% of theoretical amount). Oxidation yielded... 

Benzal acetones, in general, are readily oxidized by alkaline peroxide solution via epoxides (see XXI, XXII in Figure 14) which might even be isolated in some cases when mild conditions are used. Under more drastic conditions, however, the oxidation proceeds to the corresponding benzoic acids. Since active oxygen compounds (peroxides) are formed when 6,6 -bicreosol is oxidized, the proposed benzal acetone intermediate (XVII) seems to be oxidatively split into the corresponding salicylic acid (V) and acetone. 

Alkaline hydrolysis of benzal acetone structures to the corresponding aldehyde (XIX) and acetone and subsequent oxidation of the aldehyde (XIX) to the corresponding benzoic acid (V) do not seem to represent an actual degradation stage since oxidizing the aldehyde (XIX) under our mild standard conditions yielded only traces of the corresponding benzoic acid (V). The aldehyde (XIX) was rapidly decomposed via Dakin reaction to formic acid and 3-methoxy-S-methyl-o-benzoquinone, which is immediately degraded to phenolic humic compounds. 

Chloro anthranilic acid pyrithiobac p-Chloro benzal acetone coumachlor o-Chloro benzaldehyde dimethazone... 

Disappearance of benzal acetone and appearance of product can be readily monitored by thin layer or gas chromatographic analysis on a 1-m column packed with 20% Silicone SE-30 at 180°C. The reaction should be stopped as soon as disappearance of benzalacetone is confirmed. 

Benzal acetone Me-cinnamyl ketone C6H5CH CHC0CH3 146,18... 

SYNS BENZALACETON (GERMAN) BENZAL-ACETONE BENZYUDENE ACETONE 4-PHENYL-3-BUTEN-2-ONE... 

Hydrolysis of 2-alkoxy-3,4-dihydro-l,2-pytans with dilute hydrochloric acid furnishes a convenient synthesis of glutaraldehyde (R = H) and other l,5 dicarbonyl compounds. The starting materials are obtained by the 1,4-addition of vinyl ethers to a,/3-unsaturated carbonyl compounds. The wide selection of diene systems includes acrolein, crotonaldehyde, meth-acrolein, cinnamaldehyde, /3-furylacrolein, methyl vinyl ketone, benzal-acetone, and benzalacetophenone. Ethyl vinyl ether is preferred as the dienophile. The yields in the cyclization step are in the range of 25 87% and in the subsequent hydrolysis Step, 55 85%. ... 

Give the structures of the organic products expected from the reaction of benzal-acetone, C6HsCH=CHCOCH3, with each of the following ... 

Dehydrohalogenation. a-Bromobenzalacetone has been prepared from benzal-acetone by addition of bromine and elimination of HBr by reaction with sodium... 

Prepared by alkali catalyzed condensation of the alkali salt of p-hydroxybenzaldehyde and acetone followed by selective hydrogenation of the double bond of 4-hydroxy benzal acetone. 

Anisal-acetone (p-j MeO-benzal acetone CH3OC6H4CH CHCOCH3... 

These dihydride complexes readily catalyze the hydrogenation of neat ketones to the alcohols under 1 atm of H2 gas at 20°. For example neat acetophenone (4.1 g, 34 mmol) was quantitatively hydrogenated to 5-phenethyl alcohol (60% e.e.) in less than 8 h by use of catalyst containing the chiral diamine (5 mg, 0.0068 mmol). Benzene was used as the solvent for the a,p-unsaturated ketone, benzal-acetone, and the product was exclusively the allylalcohol. The hydrogenation of an aldimine and a ketimine in benzene also proceeded under notably mild conditions [111]. 

Benzal acetone Me-cinnamyl ketone C6H5CH CHC0CH3 146.18 pi. 103520 0 41-2 260-2 i. s. s. 

Other ketones, used to investigate the reactivity in this modified Re-formatsky reaction with tert-hutyl bromoethanoate were acetone (69% yield), cyclohexanone (80% yield), 3-methyl-2-butanone (78% yield), benzophenone (74% yield), 4-phenyl-4-phenylbut-3-en-2-one (benzal-acetone 42% yield) and l,4-diphenylbut-3-en-2-one (40% yield). The conclusion was made by the author that the... 

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