ALBERTL. HENNEAND PAUL T~orr
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 % 2.18calcd. 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. RECENBDFBBRUARY 7, 1947
C O L U ~ UOrno S,
[CONTRIBUTION FROM THEDEPARTIKENT OF CHEMISTRY AT T H E OHIO %ATE
UNIVERSITY]
Improved Preparation of Trifluoroacetic Acid BY ALBERTL. HENNEAND PAUL TROIT 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 to about a80 , where the distillate is practically all antimony chloride. The organic material is steam-didled, to give crude CFaCCkCCICFa (886 g. or 95% ykM). 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 to be CF&F=CQCFI. In a five-liter, three-ncckulround-bottom flask equipped with a mercury d e d stirrer, a 12-krlb rrrlhrr.&mdanwr 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 to 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 %anmaCial antimony t d u o r i d e (1225 g. or 6.76 dropping funnel is replaced by a thamometer dipping in m-) is placed in a steel vessel equipped with an as- the liquid p d the sdution is heated until its t a n p a a t m e sembly W i g a needle valve and 300 p. s. i. steel gage. reaches 95 The time required isofromeight to ten hours. The vessd, maintained at 135" by an electric jacket, is The solution is cooled to 40 A stream of sulfur strappad to a machpnical shaker, and flexibly connected dioxide is bubbled through, with stirring and cooling to a chlorioe tank. Chlorine (480 g. or 6.76 moles) is below 60' until the permanganate color just fades. The allow+ to be &sorbed,, with continued shaking. The solution is acidified with just en& 60% mxlfwic a d d to is completed m one and one-half hours and neutralize the potassium hydroxide und. and sulfur attention, as -tion stops a u t o m a t i d y dioxide is again passed through until the soluriOn clears. whrm the foqmtipn of SbFaCh is completed. Con'tinuous extraction with ether is then plied, or else "he v u d ~9 duaxmected from the tank and cooled to the solution is extracted three times with B &e.portion room tunpemture; the ~ ~ b s o r b echlorine d is vented of ether tumbled for two hours. of the ether e valve; the vessel is opened; extract yields 480 g. of the into a hood through the d aosoCro$c mixture of more antimony t d u o r i d e (305 g. or 1.7 mole) is added, CFaCOsH and water boiling at 103-105 (745 mm.) then percklombutadiene, CCh, (1044g. or 4 moles) is This is a 87y0yield for the oxidation. pamd in. The vessel is closed, then heated in a steamThe net over-all yield of t d u o r ~ a c c t i cacid from combath to 96-100" for half an hour, a time-saving step due mercial material is therefore 83%. to betta heat trpnsfa; it is then strapped in the heating jacket d the shober and rocked at 155" for two hours. summary At thL temperature, the working pressure is about 90 Practical directions for mating triibmacetic p. s. I. After cooling, the gage and valve assembly is replaced acid from conhnercial C,Cb with an 83% over-all
A practical preparation of trifluoroacetic acid based on the 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.
.
.
(am)
+
xapsc, Alderson 8nd Ncwmna. THIS JOURNAL. a?, 918 (lM6). (2) Hcnnc .nd Zimmarhied, ibid., a?, 1908 (1945). (1)
yield are described.
COLUMBUS, Okro
RECEIVEDARCH 14,1947
