Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Compounds with acetone

The 9,11 olefin in the intermediate (25-4) is next converted to the 9a-fluoro-11(3-hydroxy derivative (26-1) by the customary scheme. The additional unsaturation in ring A is then introduced by means of selenium dioxide to afford triamcinolone (26-2). Reaction of that compound with acetone converts the 16,17 diol to an acetal to afford triamcinolone acetonide (26-3) [21]. The latter is approximately 50 times more potent than cortisone in animal models the free glycol interestingly shows only a 2.5-fold increase in potency over the cortisone in the same model. [Pg.180]

Cleavage of hydrazones, oximes, and semicarbazones. Amberlyst 15, an ion-exchange resin with sulfonic acid groups, is a superior reagent for exchange of nitrogeneous derivatives of carbonyl compounds with acetone. Yields are 85-95% with reactions that proceed at room temperature.1... [Pg.178]

Quite recently Gitis [42] isolated a number of coloured products formed by polynitro compounds with acetone in the presence of sodium hydroxide. The author, like Reitzenstein and Stamm, postulated that it was the enol form of acetone that reacted with a nitro compound, products of nucleophilic substitution of the type described by Meisenheimer [36-38] (p. 202), being formed ... [Pg.209]

Alkylation and nitration of malonic esters. Zaugg, using sodium hydride for conversion of n-butylmalonic ester into its sodio derivative, found that the rate of alkylation of this substance with -butyl bromide in dimethylformamide is 1,000 times the rate in benzene. Emmons and Freeman developed a procedure for the nitration of active methylene compounds with acetone cyanohydrin nitrate by conversion to the sodio derivative with sodium hydride. The reaction product (3)... [Pg.1272]

When berberine is the chief alkaloid in a plant extract its isolation is conveniently effected by making use of the sparing solubility of its sulfate in dilute sulfuric acid. The hydrochloride, hydriodide, and nitrate are easily recrystallized from water or precipitated from acetic acid solutions on the addition of the appropriate ions in the form of salts (182). The phosphate (183) is a bright yellow, non-deliquescent crystalline substance soluble in 14.3 parts of water at 16°. Berberine can be purified through its addition compound with acetone (184, 185, 186). [Pg.84]

For lipophilic toxins, the mouse bioassay is, therefore, the current method of use (rat fecal bioassay in also used in the Netherlands [10]). The advantages and problems of the bioassay are shown in Table 5.3, and a brief description is shown in Table 5.4. This method is based on the extraction of lipophilic toxin compounds with acetone followed... [Pg.143]

We chose benzyli dene acetone (4.39, Scheme 4.11) as a model dienophile for our studies. The uncatalysed Diels-Alder reaction of this compound with cyclopentadiene is slow, justifying a catalytic approach. Reaction of 4.39 with paraformaldehyde and dimethyl amine under acidic conditions in an aqueous ethanol solution, following a literature procedure, produced the HCl salt of 4.42 (Scheme 4.11). The dienophile was liberated in situ by adding one equivalent of base. [Pg.114]

The selective intermolecular addition of two different ketones or aldehydes can sometimes be achieved without protection of the enol, because different carbonyl compounds behave differently. For example, attempts to condense acetaldehyde with benzophenone fail. Only self-condensation of acetaldehyde is observed, because the carbonyl group of benzophenone is not sufficiently electrophilic. With acetone instead of benzophenone only fi-hydroxyketones are formed in good yield, if the aldehyde is slowly added to the basic ketone solution. Aldols are not produced. This result can be generalized in the following way aldehydes have more reactive carbonyl groups than ketones, but enolates from ketones have a more nucleophilic carbon atom than enolates from aldehydes (G. Wittig, 1968). [Pg.56]

Out first example is 2-hydroxy-2-methyl-3-octanone. 3-Octanone can be purchased, but it would be difficult to differentiate the two activated methylene groups in alkylation and oxidation reactions. Usual syntheses of acyloins are based upon addition of terminal alkynes to ketones (disconnection 1 see p. 52). For syntheses of unsymmetrical 1,2-difunctional compounds it is often advisable to look also for reactive starting materials, which do already contain the right substitution pattern. In the present case it turns out that 3-hydroxy-3-methyl-2-butanone is an inexpensive commercial product. This molecule dictates disconnection 3. Another practical synthesis starts with acetone cyanohydrin and pentylmagnesium bromide (disconnection 2). Many 1,2-difunctional compounds are accessible via oxidation of C—C multiple bonds. In this case the target molecule may be obtained by simple permanganate oxidation of 2-methyl-2-octene, which may be synthesized by Wittig reaction (disconnection 1). [Pg.201]

Polymer is separated from the polymerisation slurry and slurried with acetic anhydride and sodium acetate catalyst. Acetylation of polymer end groups is carried out in a series of stirred tank reactors at temperatures up to 140°C. End-capped polymer is separated by filtration and washed at least twice, once with acetone and then with water. Polymer is made ready for extmsion compounding and other finishing steps by drying in a steam-tube drier. [Pg.58]

Compounds with active hydrogen add to the carbonyl group of acetone, often followed by the condensation of another molecule of the addend or loss of water. Hydrogen sulfide forms hexamethyl-l,3,5-trithiane probably through the transitory intermediate thioacetone which readily trimerizes. Hydrogen cyanide forms acetone cyanohydrin [75-86-5] (CH2)2C(OH)CN, which is further processed to methacrylates. Ammonia and hydrogen cyanide give (CH2)2C(NH2)CN [19355-69-2] ix.orn. 6<55i the widely used polymerization initiator, azobisisobutyronitrile [78-67-1] is made (4). [Pg.93]

Acetalation. As polyhydroxy compounds, carbohydrates react with aldehydes and ketones to form cycHc acetals (1,13). Examples are the reaction of D-glucose with acetone and a protic or Lewis acid catalyst to form l,2 5,6-di-0-isoprop5lidene-a-D-glucofuranose [582-52-5] and its reaction with benzaldehyde to form 4,6-0-benzyhdene-D-glucopyranose [25152-90-3]. The 4,6-0-(l-carboxyethyhdine) group (related to pymvic acid) occurs naturally in some polysaccharides. [Pg.481]

In the presence of an alkali metal hydroxide at about 50°C, chloroform condenses with acetone to give l,l,l-trichloro-2-methyl-2-propanol, [57-15-8] ie, chlorobutanol, chloretone, or acetone—chloroform (9,10). Chlorobutanol is a white crystalline substance with a campborlike odor its sedative, anesthetic, and antiseptic properties have given the compound some importance in the pharmaceutical industry. [Pg.524]

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). [Pg.242]

Compounds with low flash points (below room temperature). Examples are acetaldehyde, acetone, acetonitrile, benzene, carbon disulfide, cyclohexane, diethyl ether, ethyl acetate and -hexane. [Pg.4]

The unsaturated tetraoxaquaterene (accompanied by linear condensation products) was first synthesized in 18.5% yield by the acid-catalyzed condensation of furan with acetone in the absence of added lithium salts. Other ketones also condensed with furan to give analogous products in 6-12% yield.A corresponding macrocycle was also prepared in 9% yield from pyrrole and cyclohexanone. The macrocyclic ether products have also been obtained by condensation of short linear condensation products having 2, 3, or 4 furan rings with a carbonyl compound. ... [Pg.77]

Meerwein-Pondorff reduction is the synthesis of alcohols by heating carbonyl compounds with aluminium isopropoxide in isopropanol and distilling off acetone by-product... [Pg.256]

Participation of fluorocarbocations, derived from carboxylic acids and from halo acetones, in reactions of carbonyl compounds with sulfur tetrafluoride has been directly evidenced by trapping them with aromatic hydrocarbons [207, 20S],... [Pg.243]

However, the cyclic structure of "hydrocotarnine acetic acid (20e) and the two condensation products of cotarnine with acetone (20f, 21) were even unambiguously determined by chemical methods alone. These compounds were not reduced either catalytically nor by sodium amalgam, although acetylhydrocotarnine acetic acid (22b) is easily reduced by both these methods. If even a small pro-... [Pg.184]

The synthesis of tropinone 14, a precursor of atropine and related compounds, is a classical example. In 1917 Robinson has prepared tropinone 14 by a Mannich reaction of succindialdehyde 11 and methylamine 12 with acetone 13 better yields of tropinone were obtained when he used the calcium salt of acetonedicar-boxylic acid instead of acetone. Modern variants are aimed at control of regio-and stereoselectivity of the Mannich reaction. ... [Pg.196]

Condensation of ethyl acetoacetate with phenyl hydrazine gives the pyrazolone, 58. Methylation by means of methyl iodide affords the prototype of this series, antipyrine (59). Reaction of that compound with nitrous acid gives the product of substitution at the only available position, the nitroso derivative (60) reduction affords another antiinflammatory agent, aminopyrine (61). Reductive alkylation of 61 with acetone in the presence of hydrogen and platinum gives isopyrine (62). Acylation of 61 with the acid chloride from nicotinic acid affords nifenazone (63). Acylation of 61 with 2-chloropropionyl chloride gives the amide, 64 displacement of the halogen with dimethylamine leads to aminopropylon (65). ... [Pg.234]

Reaction of p-chloroaniline with dicyanamide affords the biguan-ide, 182. This is condensed immediately with acetone to form the aminal cycloguanil (183). The compound is usually used as a salt with pamoic acid (184). [Pg.281]


See other pages where Compounds with acetone is mentioned: [Pg.19]    [Pg.107]    [Pg.2623]    [Pg.168]    [Pg.107]    [Pg.3561]    [Pg.19]    [Pg.107]    [Pg.2623]    [Pg.168]    [Pg.107]    [Pg.3561]    [Pg.11]    [Pg.270]    [Pg.172]    [Pg.133]    [Pg.208]    [Pg.242]    [Pg.307]    [Pg.72]    [Pg.73]    [Pg.467]    [Pg.66]    [Pg.104]    [Pg.573]    [Pg.289]    [Pg.670]    [Pg.376]    [Pg.299]    [Pg.389]    [Pg.201]    [Pg.183]   
See also in sourсe #XX -- [ Pg.19 , Pg.21 ]




SEARCH



Acetone compounds

© 2024 chempedia.info