- Preparative synthesis of 2,2-dimethyl-5-(trifluoroacetyl)-1,3-dioxane-4,6-dione (2-trifluoroacetyl Meldrum's acid) and 2,2-dimethyl-6-(trifluoromethyl)-4H-1,3-dioxin-4-one and their synthetic usefulness as (trifluoroacetyl)ketene precursors
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A simple and reliable method for the preparation of 2,2-dimethyl-5-(trifluoroacetyl)-1,3-dioxane-4,6-dione and 2,2-dimethyl-6-(trifluoromethyl)-4H-1,3-dioxin-4-one on a multigram scale was developed. These (trifluoroacetyl)ketene precursors were used in the hetero-Diels-Alder reaction with dialkylcyanamides and 1-ethoxyprop-1-yne, as well as in some reactions with nucleophiles.
- Sevenard, Dmitri V.,Didenko, Andrey V.,Lorenz, Denis,Vorobiev, Michael,Stelten, Johannes,Dülcks, Thomas,Sosnovskikh, Vyacheslav Ya.
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p. 1495 - 1502
(2017/02/18)
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- METHOD FOR PREPARATION OF TRIFLUOROACETYLACETIC ACID
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The invention discloses a method for the preparation of trifluoroacetylacetic acid in its dehydrated form with a low content of the hydrate of trifluoroacetoacetic acid.
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Page/Page column 12
(2016/02/29)
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- METHOD FOR PREPARATION OF 4-ALKOXY-1,1,1-TRIFLUOROBUT-3-EN-2-ONES FROM TRIFLUOROACETYLACETIC ACID
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The invention discloses a method for the preparation of 4-alkoxy and 4-aryloxy-1,1,1-trifluorobut-3-en-2-ones from trifluoroacetylacetic acid and orthoesters. Such compound can be used for the preparation of pharmaceutical, chemical or agro-chemical products.
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Page/Page column 15
(2015/02/02)
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- Synthesis of low-fluoride organic compounds
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Organic compounds, e.g. fluorinated organic compounds such as fluorinated carboxylic acids or fluorinated carboxylic acid chlorides, may contain small amounts of carboxylic acid fluorides, hydrogen fluoride or hydrolyzable fluoride, which during the preparation of derivatives of the fluorinated organic compounds, for example by esterification, may yield corrosive fluorides or hydrogen fluoride. The invention is a method for the synthesis and/or purification of preferably fluorinated organic compounds such as carboxylic acids, carboxylic acid chlorides and derivatives such as esters thereof, starting from corresponding carboxylic acid chlorides containing acid fluorides or hydrolyzable fluoride, and alcohols under the catalytic action of “onium” salts of carboxylic acids, to obtain products which have a low fluoride content. Alternatively, an inorganic oxide adsorbent is utilized. The method is especially suitable for the synthesis of esters of trifluoroacetic acid, chlorodifluoroacetic acid, trifluoroacetoacetic acid and/or difluoroacetoacetic acid.
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- The 4,4,4-trifluoroacetoacetic acid keto-enol system in aqueous solution. Generation of the enol by hydration of trifluoroacetylketene
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Trifluoroacetylketene was generated in aqueous solution by flash photolysis of 2,2-dimethyl-6-trifluoromethyl-4H-1,3-dioxin-4-one and its spiro analogue, 4-trifluoromethyl-1,5-dioxaspiro[5.5]undec-3-en-2-one, and rates of hydration of the ketene to 4,4,4-trifluoroacetoacetic acid enol as well as subsequent ketonization of the enol were measured in this solvent across the acidity range [H+] = 10-1-10-12 M. Analysis of the rate profile produced by these data provides the acidity constants pQa,E = 1.85 for the carboxylic acid group of the enol and pQEa = 9.95 for its enolic hydroxyl group, which make these groups 2 and 3 orders of magnitude more acidic, respectively, than the corresponding groups in the parent unfluorinated acetoacetic acid enol. Rates of enolization of the keto group of 4,4,4-trifluoroacetoacetic acid were also measured, by bromine scavenging, and these, together with a value of the equilibrium constant for hydration of the keto group to its gem-diol derivative based upon a free energy relationship, Kh = 2900, provide an estimate of the keto-enol equilibrium constant for this system: pKE = 0.28. This is greater, by 2 orders of magnitude, than the keto-enol equilibrium constant for the unfluorinated acetoacetic acid.
- Chiang,Kresge,Meng,Morita,Yamamoto
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p. 8345 - 8351
(2007/10/03)
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