Trichloroacetyl chloride, with

Tri-n-butylcarbinol, 52, 22 TRI-tert-BUTYLCYCLOPROPENYL FLUOROBORATE, 54, 97 Trichloroacetyl chloride, with pyrrole to give pyrrol-2-yl trichloromethyl ketone, 51, 100... 

Figure 15.33 is based on the first and most common method for the preparation of dichloroketene, i.e., the reductive /3-elimination of chlorine from trichloroacetyl chloride with zinc (for the mechanism see Sections 4.7.1 and 17.4.1). Upon addition of the dichloroketene to the isomerically pure 2-butenes perfect stereoselectivity (and hence overall stereospecificity) occurs /ra .v-2-butene reacts to give frans-dichlorodimethylcyclobutanone and cis-2-butene to furnish its cw-isomer. 

Allyl ethers, sulfides and selenides can react with dichloroketene to yield a.a -dichloro-y,<5-un-saturated esters together with cyclobutanones as byproducts25. Dichloroketene is prepared in situ by dehalogenation of trichloroacetyl chloride with zinc dust in absolute diethyl ether. The rearrangement usually proceeds at 25-30°C. 

Cycloaddition. An improved method for in situ generation of dichloroketene involves treatment of trichloroacetyl chloride with zinc activated with CuSOi and with POCI3. The role of POCI3 seems to be that of complexing the ZnCl2 formed in the reaction. Under these conditions adducts were obtained even from tri- and tetrasubstituted olefins. ... 

Chloroacetyl chloride is manufactured by reaction of chloroacetic acid with chlorinating agents such as phosphoms oxychloride, phosphoms trichloride, sulfuryl chloride, or phosgene (42—44). Various catalysts have been used to promote the reaction. Chloroacetyl chloride is also produced by chlorination of acetyl chloride (45—47), the oxidation of 1,1-dichloroethene (48,49), and the addition of chlorine to ketene (50,51). Dichloroacetyl and trichloroacetyl chloride are produced by oxidation of trichloroethylene or tetrachloroethylene, respectively. 

Trichloroacetanilide has been prepared from hexachloroacetone and aniline, from trichloroacetyl chloride and aniline, by the action of aniline magnesium iodide on ethyl trichloroacetate, by heating N-phenyltrichloroacetimidyl chloride with dilute methanol, and from trichloroacetic acid and aniline in the presence of phosphorus oxychloride. ... 

It is of interest to note that 2,4,6-trinitrochlorobenzene reacts similarly with 49 to give the cation of 138 isolated as the perchlorate. In the reaction of the enamino ketone (50) with trichloroacetyl chloride (77) the chloro-... 

In the reaction with enamino ketones derived from dimedone (e.g., 49) p-toluenesulfonyl chloride gives the chloroiminium cation (138) isolated as the perchlorate. This indicates that initial O sulfonation is followed by addition of chloride ion and subsequent expulsion of tosylate (42) in a manner similar to the trichloroacetyl chloride reaction with 49 (Section IV.A). 

Acylation of the vinylogous pyrrolidine amide of dimedone with acetic anhydride or acetyl chloride led (possibly indirectly) to the carbon acylation product, whereas trichloroacetyl chloride gave rise to products derived from attack of chloride at the oxygenated double bond position in an initial 0-acylation product (401-404). 

Symmetrical piperazines 364 have been obtained from the corresponding 4,5-dihydrazinofurazano[3,4- ]pyraz ne 363 in good yield on reaction with acetic anhydride in the presence of a Lewis acid (Equation 98) <1999CHE499>. When formaldehyde was used, the yield was slightly reduced at 76%. Acid chlorides can also be used in this reaction although the yield drops to 23% when trichloroacetyl chloride is used. 

Derivatives of 269 are formed either via acylation of 291 or by treatment of293 with trichloroacetyl chloride (cf. 291-292 and 293-294) (78LA1491 85JAP6006688). 

A. Pyrrol-2-yl trichloromethyl ketone. In a 3-1. three-necked round-bottomed flask equipped with a sealed mechanical stirrer, a dropping funnel, and an efficient reflux condenser with a calcium chloride drying tube are placed 225 g. (1.23 moles) of trichloroacetyl chloride and 200 ml. of anhydrous ether. The solution is stirred while 77 g. (1.15 moles) of freshly distilled pyrrole in 640 ml. of anhydrous ether is added over 3 hours (Note 1). The heat of reaction causes the mixture to reflux during the addition. Following the addition, the mixture is stirred for 1 hour, and then 100 g. (0.72 mole) of potassium... 

Dihydro-1,2,4-oxadiazol-5-ones (74) cannot be 7V-acylated by either chlorocarbonyl isocyanate or trichloroacetyl chloride. However, preparation of 4-chlorocarbonyl compounds (73) can be achieved by cycloaddition of stable nitrile oxides to the C=N double bond of chlorocarbonyl isocyanate <888994, 90ZOR339). Compounds (73) decompose with ammonia, primary amines, or primary amides to isocyanates and (74) (Scheme 26). 

A. N,N-Diethyl-2,2,2-trichloroacetamide. A 1-1. three-necked flask equipped with a stirrer and dropping funnel is charged with 73 g. (1.00 mole) of diethylamine, 500 ml. of ether, and a solution of 40 g. (1.00 mole) of sodium hydroxide in 160 ml. of water. The mixture is stirred and maintained at a temperature of —10° to — 15° by a bath of Dry Ice and acetone while 200 g. (1.10 moles) of trichloroacetyl chloride is added in the course of 1 hour. The cooling bath is removed, the temperature is allowed to rise to 10°, and the organic layer is separated. The aqueous layer is extracted with two 50-ml. portions of ether. The ether extracts are combined, washed with 50 ml. of 5% hydrochloric acid, two 50-ml. portions of 5% sodium bicarbonate solution, and 50 ml. of water, and dried over magnesium sulfate. The ether is removed by distillation at atmospheric pressure. The residue is distilled through a short indented Claisen still head at reduced pressure. N,N-Diethyl-2,2,2-trichloroacetamide is collected at 77-79°/1.5 mm. 1.4902-1.4912 weight 183-200 g. (84-92%). 

In this experiment, no carbon tetrachloride was detected but, on the basis of the mechanism proposed, carbon tetrachloride would have been an important reaction product, arising by the combination of chlorine atoms and trichloj-omethyl radicals. Further, the production of octachloropropane by the secondary photolysis of octachlorobutanone would involve the formation of decachlorobutane. In the presence of chlorine, only carbon tetrachloride was formed, whereas by interaction of the postulated CCI3CO- radical with chlorine, substantial amounts of trichloroacetyl chloride should have been observed. In the presence of oxygen, only carbon dioxide and phosgene were found and the yield of the latter was far too small to account for the loss of the radical products. 

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