1879.1 " *' [Greene. 



isolated dioxyethyl-methylene, the reaction between sodium ethylate and 

 methylene chloride taking place as indicated by theory. 



The chief difficulty lies in the preparation of pure methylene chloride ; 

 the process described by Perkin, and depending upon the reduction of 

 chloroform by zinc and ammonia, yields only small quantities of methy- 

 lene chloride, and the direct chlorination of methylchloride yields equally 

 unsatisfactory results. The method which, after numerous experiments, 

 I have found to answer best, consists in the reduction of an alcoholic so- 

 lution of chloroform by zinc and hydrochloric acid. 



The zinc and chloroform mixed with several times its volume of alcohol 

 are placed in a flask connected with a suitable condensing apparatus, and 

 hydrochloric acid is added in small portions. The reaction develops con- 

 siderable heat, and methylene chloride and chloroform distill over ; when 

 the reaction has somewhat subsided, and no more liquid distills, more 

 hydrochloric acid is added, and a moderate heat is'applied, if necessary. 

 In any case, the mixture is heated towards the close of the operation, until 

 alcohol begins to distill in quantity. The operation is then arrested, and 

 the product in the receiver is washed, dried and rectified, that portion 

 which passes below about 53° being retained. The residue is returned to the 

 flask and again submitted to the action of the zinc and hydrochloric acid. 

 By several careful rectifications of the product passing below 58°, pure 

 methylene chloride, boiling at 40-41°, is obtained. 



By several operations in this manner the yield of methylene chloride may 

 be brought up to about twenty per cent, of the chloroform employed. 



Little or no advantage is gained by attempting to fractionate the product 

 as it distills from the flask, so that the chloroform may flow back into the 

 reducing mixture, for such distillation necessarily takes place in a stream 

 of hydrogen which carries with it about as much chloroform as methylene 

 chloride. 



Dioxyethyl-methylene.— This compound was prepared by gradually 

 introducing one molecule of sodium into a mixture of one molecule of 

 methylene chloride and about four times the theoretical quantity of absolute 

 alcohol, contained in a flask connected with a reflux condenser. After all 

 of the sodium has been introduced, the mixture is heated on a water-bath 

 for about an hour, and is then distilled. The distillate is fractionated, and 

 the portion which passes belovv 78^ contains all of the diethyl ether. 

 It is agitated with a tolerably concentrated solution of calcium chloride, 

 and the light ethereal layer is separated, dried over calcium chloride and 

 carefully rectified, until a liquid is obtained which boils at 86-89°. 



Dioxyethyl-methylene so obtained is an ethereal liquid, having a pene- 

 trating, pleasant odor, somewhat recalling that of mint. Its specific gravity 

 at 0° is 0.851, and it boils at 89°, under a pressure of 769 millimetres. It 

 is slightly soluble in water, from which it may be separated by the addition 

 of calcium chloride ; it mixes in all proportions with ether and alcohol, 

 and it cannot readily be separated from its alcoholic solution if much 

 alcohol be present ; in such a case, fractional distillation and treatment of 

 the portion which passes below 78° with solution of calcium chloride, effect 

 the separation. 



