July, 1947
ALKALINECONDENSATION OF FLUORINATED ESTERSWITH KETONES
and the solvent removed in mu0 at 35". The dark, sirupy residue was dissolved in ether (150 ml.) and decoloritstion cclmpletcd by filtration again through Norit and Celite. Removal of the ether left 8.1 g.. (55%) 'of clear, amber sirup having a high, positive rotation, [a]% 130.6" (c, 6.530; chiaoform). This compound was UUstable oq standing, but did not decompose as rapidly as the corresponding bromide. Anal. Calcd. for C,SH~OQCI:C1, 8.41. Found". c1, 8.66.
summary
Crystalline 2,3,4,6-tetrapropionyl-8- D - glucose (14) Analyzed by the procedure of Vaughn and Nieurland. Ird En#.Chcm., And. Ed.. 8 , 294 (1981).
[CONTRIBUTION FROM THE
1819
has been prepared by controlled hydrolysis of tetrapropionyl-a-Dglucosyl bromide. The crystalline nature is striking, since Dglucose penta' propionate and others are sirups. The mutarotation of 2,3,4,6-tetrapropionyl8-D-glucosehas been studied a t two temperatures, the sum of the rate cqnstants for these mutarotations calculated, and these data compared with the corresponding values for 2,3,4,6-tetraacetyl-8-D-glucose. STANFORD UNIVERSITY,CALIFORNLI EVANSTON, ILLINOIS ARGO,ILLINOIS RECENED.APRIL 9, 194;
DEPARTMENT OF CHEMISTRY OF
THE OHIO STATE UP&VERSITY]
The AJknline Condensation of Fluorinated Esters with Esters and Ketones1 BY ALBERT L. HENNE,MELVINS. NEWMAN, LAURENCE L. QUILLAND ROBERTA. STANTFORTH A series of dkaline condensations have beeo performed, linking a fluorinated ester with, another ester, a ketone or a fluorinated ketone. At that time (1942-1943) the only known condensation of this kind was the preparation of a trifluoroacetoacetate, CFKOCH*CGR, by Swarts," who also obtained Muomacetone, CFaCOCH,, from it by decomposition with 10% sulfuric acid; recently a similar work has been reported.2 First, Swarts' work was repeated, Using an proved technique. Next, ethyl &fluoroacetate was successfully condensed with ethyl acetate to yield the difluoroamtoacetate. In contrast it was not found possible to condense a trifluoro- with a difluoroacetate, nor was it found possible to condense a difiuoroaretate with itself. With ketones, twocondensations were tried, which both succeeded well: a trifluoroacetate and acetone yielded trifluoroacetylacetone, CFICOCH~COCH~, while a trifluoroacetate and trifluoroacetone yielded hexafluoroacetylacetone, CFsCOCHnCOCS. In all cases, the condensed qmpounds gave stable chelated derivatives with such ease, that it became advantageous to separate the condensates lrom the reaction mixtures as their crystalline copper derivatives. These chelated derivatives were easily recrystallized from paraffin hydrocarbons or from alcohol; they proved more stable, lower melting and more volatile than their unfluorinated analogs. A number of metal derivatives were prepared which will be reporfed separately.*
derivative.' They were esterified either by treatment of their sodium salt with ethyl sulfate, or by heating their salt in an excess of alcohol with a small amount of sulfuric acid, distilling the a m t r o p i c mixture of ester and alcohol as formed, and ultimately washing off the alcohol by means of calcium chloride. I t was noted that an appreciable amount of ether was formed when triiluoroacetic acid reacted with ethanol or with butanol but that the amount of ether formed in the case of diiluoroacetic acid was s m d . This is well in line with the known strength of these acids. Properties observed were: CF'COIGH,: b. p. 60.5", nD 1.3093 a t 15" and CHFICOICIH,: b. p. 99", n~ 1.3453 at.20". The meld of pure ester was 75 to 809; and additional impure fractions were .obtained which accounted for all o h h e materid used. Condensation and Iaolrtion Procedurer.-AU condensations were performed in ether, with sodium ethylate freshly prepared by treating one equivalent of absobte ethanol with one equivalent of finely dispersed sodium. To the resulting suspension was added one equivalent of dry fluorinated ester, whereupon solution took place with a slight evolution of heat. The second compound (ester or ketone) was then added, and the mixture refluxed for about fifty hours, a period of time which may be unnecessarily long. On account of the avidity of the condensates for water, the following procedure of isolation was adopted. The reaction mixture was treated with a concentrated solution of sodium bisulfate in very slight excess o w neutralization requirements, then with a clear aqueous solution of cupric acetate. The organic layer was distilled off, then the aystalline copper derivative was filtered and recrystallized from a suitable solvent. The dry copper dezivative was suspended in dry ether, in which it partly dissolved, and was subjected to a stream of hydrogen sulfide. Afterremoval of thecupricsulfide, thecondensed compound was separated from the ether by fractional distillation, with rigorous precautions to avoid losses by volatility. CFaCOCHnC&Et, b. p. 131.8"; over& yield 64%; copper chelate as green crystals from alcohol, m. p. lao, Cu % 33.4 found, 33.5:aIcd. CFaCOCHs, b. p. 21 , 75% yield by rduxing the preceding compound for two hours with 10% sulfuric acid, collecting the vapors on phosphoric anhydride t o destroy the hydrate, and distgling therefrom; 2,4dinitrophenylhydrazone, m. p. -139 , N l o 19.06 found, 18.98calcd. CHFICOCHnCOIEt, b. p. 72" a t 30 mm., no 1.4018 a t 20", 35% over-all yield. F % found 22.3, calcd. 22.90; copper chelate as blue crystalline prisms m. p. 183-184 . Low yield attributed to faulty technique.
e-
Experimental Reparation of Fluorinated Bstere.-Trifiuoroacetic
and difluoroacetic acids were obtained by oxidation of a prppene (1) Thin paper u bucd on work performed under Contract W74QCHng-96 for the Manhattan Project and the information therein r i l l appear in Division V I 1 of the Manhattan Project Technical Series. a~ pnrt of the contribution of the Department of Chemistry. Ohio State U n i v d t y . (In) Swmrts, Bull. class tci. Acad. my. Belt., 151 1%692 (1920) (2) B r a l o w and rcr-workers, THISJ O ~ A L U, . 100 (1940). (3) Quill and Stanifath. private communication.
(4) Henne. Nderson and Nermao, Tras JOURNAL, 6T, 818-919 (llU6); Henne, U S. Patent 2.371.767. March 20, 1946.
ALBERTL. HENNEAND PAUL TRorr
1820
CFICOCHKCOCHI, b. P. 107', 70% net yidd. copper chelate 89 u u e - d e m frm ~ Mc P32-52, H % 2.W found, C % 32.48, H % 2.18 calcd. CF&!OCH,COCFI, b. p. 63-65', 72% net yield, F % 54.0 found, 54.9 44.; copper chelate as bright green aystals m. p. 113-115" with sublimation.
%
SummqIV
Alkaline condensations of a fluorinated ester
Vol. 69
with another ester or a ketone were used to synthesize CF,C''H,CO,Et, Cm,C'&"lCaEt, C F & m H g m H s and C F g m H m F s in 70-75y0 net yields. All form chelated metal derivatives which are very stable and can be distilled. C O L U ~ UOrno S, RECENBDFBBRUARY 7, 1947
[CONTRIBUTION FROM THEDEPARTIKENT OF CHEMISTRY AT T H E OHIO %ATE
UNIVERSITY]
Improved Preparation of Trifluoroacetic Acid BY ALBERTL. HENNEAND PAUL TROIT
A practical preparation of trifluoroacetic acid CCbCCI=CCl, to C F r CCl=CCln to C F C G H has been described in a preceding article.' The last step of this sequence consumes an oxidizing agent not only to cut the double bond, but also to burn off the one-carbon fragment. To correct this waste, it would be better to start from a butene derivative CFr CCl=GClCF*, the oxidation of which supplies two moles a€triftuoroacetic acid per mole without loss of catbon,m we have shown before.' We are now describing a very simple and economical synthesis of this butene. Stmtingfrom a cheap commercial product CC+CClCCl=CClt, a single fast operation bfings about the 1,4addition of one mole of chlorine to make CCtcCl=CClCCl~and the substitution of the six end-atoms of chlorine to make CF&Cl=CCICF;. Our preferred procedure follows. %anmaCial antimony t d u o r i d e (1225 g. or 6.76
based on the
m-) is placed in a steel vessel equipped with an assembly W i g a needle valve and 300 p. s. i. steel gage. The vessd, maintained at 135" by an electric jacket, is strappad to a machpnical shaker, and flexibly connected to a chlorioe tank. Chlorine (480 g. or 6.76 moles) is allow+ to be &sorbed,, with continued shaking. The is completed m one and one-half hours and attention, as -tion stops a u t o m a t i d y whrm the foqmtipn of SbFaCh is completed. "he v u d ~9 duaxmected from the tank and cooled t o room tunpemture; the ~ ~ b s o r b echlorine d is vented e valve; the vessel is opened; into a hood through the d more antimony t d u o r i d e (305g. or 1.7 mole) is added, then percklombutadiene, CCh, (1044g. or 4 moles) is pamd in. The vessel is closed, then heated in a steambath to 96-100" for half an hour, a time-saving step due to betta heat transfu; it is then strapped in the heating jacket d the shober and rocked at 155" for two hours. At t h L temperature, the working pressure is about 90 p. s. I. After cooling, the gage and valve assembly is replaced
+
xapsc, Alderson 8nd Ncwmna. THIS JOURNAL. a?, 918 (lM6). (2) Hcnnc .nd Zimmarhied, ibid., a?, 1908 (1945). (1)
by a 0.5-inch vertical pipe 45 an. long which acts as a dephlegmator. This pipe is to a d d e n d i n g metal condenser which delivers the distilIate into a receiver half filled with water. Loss of volatile material is prevented by a tail trap cooled with Dry Ice. Distillation can be performed by heating directly with a gas burner and is pursued t o about a80 , where the distillate is practically all antimony chloride. The organic material is steam-didled, to give crude CFaCCkCCICFa (886 g. or 95% -1. Fractional 85 mde per cent. distillation with a ten plate cohunn of good mataial b d h g 66-86' at 748 mm.and 8.5 male per cent. of a heptduaaobutane b. p. 32-36' (745mm.) presumed t o be CF&F=CQCFI. In a five-liter, three-ncckulround-bottom flask equipped with a mercury d e d stirrer, a 12-krlb rrrlhrr.&mdenser protected by a tail Dry Ice trap, and a dreppmg funnel are placed potassium permanganate (480g. or 2.6 mdes), commatiat potassium hydroxide (315 g. or 5.5 moles) and water (3500e.). The solids are dissdved by heating t o 60" with constant stirring. Crude cF&~-CcICFa is dropped continuously into the reaction mtxture as fast as the capacity of the reflux condenser will permit. After completing the addition of the organic halide, the dropping funnel is replaced by a thamometer dipping in the liquid p d the sdution is heated until its t a n p a a t m e The time required isofromeight to ten hours. reaches 95 The solution is cooled t o 40 A stream of sulfur dioxide is bubbled through, with stirring and cooling below 60' until the permanganate color just fades. The solution is acidified with just en& 60% wlfwic a d d t o neutralize the potassium hydroxide und. and sulfur dioxide is again passed through until the solution clears. Con'tinuous extraction with ether is then plied, or else the solution is extracted three times with B &e.portion of ether tumbled for two hours. of the ether aosoCro$c mixture of extract yields 480 g. of the CFaCOsH and water boiling at 103-105 (745 mm.) This is a 87y0yield for the oxidation. The net over-all yield of t d u o r ~ a c c t i cacid from commercial material is therefore 83%.
.
.
(am)
summary Practical directions for mating triibmacetic acid from conhnercial C,Cb with an 83% over-all yield are described. COLUMBUS, Okro
RECEIVED U u i 14,1947
