?atented eh. 6, 1795i 2,540,998

UNITED STATES PATENT OFFICE

2,540,998 . AZEOTROPIO DEHYDRATION 0F 1,1'-OXY BIS-(Z-CHLOROETHANOL) ' Stephen C. Stowe, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Application July 15, 1948, Serial No. 38,947 ‘ ‘ 8 Claims. (01. 260-601)

. This invention concerns an improved method of is so small as to render the process impractical dehydrating 1,1’-oxybis-(Z-chloroethanol) to for industrial use. Apparently, such solution form chloroacetaldehyde. It relates more par contains little, if any, chloroacetaldehyde as‘ ticularly to the production of anhydrous chloro such, but instead contains its derivative, l,1’-' acetaldehyde by dehydration of concentrated oxybis-(2~chloroethanol). For convenience, such aqueous chloroacetaldehyde and 1,l'-oxybis-(2 solution will be referred to herein as a chloroé chloroethanol) solutions. acetaldehyde solution, it being understood, how It is known to prepare chloroacetaldehyde by ever, that the organic solute is present principally introducing chlorine and vinyl chloride in the , as 1,l'-oxybis-(2-chloroethanol) . Treatment of gaseous state into water at cool to moderate s... C concentrated aqueous solutions of chloroacetalde- temperatures,e. g. at from 0° C. to 40° C. Recov hyde with a solid alkali, e. g. sodium hydroxide, eryvof the chloroacetaldehyde from the dilute results in rapid polymerization of the chloro~ aqueous acid solution has heretofore been acetaldehyde and usually, separation of the solu accomplished by increasing the concentra~ . tion into an aqueous layer and a sticky polymeric. tion of hydrogen chloride in the reaction layer. Other of the usual solid drying agents mixture to approximately 20 per cent and there such as calcium chloride, calcium sulfate, mag after distilling the aqueous acid mixture to ob nesium sulfate, etc., when added to concentrated tain chloroacetaldehyde in a concentration of aqueous solutions of chloroacetaldehyde fail to from '70 to 80 per cent. By passing the distil dehydrate the solution to form anhydrous chloro late vapors over a layer of calcium chloride, 20 acetaldehyde. heated to 100° C., anhydrous chloroacetaldehyde I have found that aqueous chloroacetaldehyde has been obtained. However, this known mode of from 50 to 85 per cent concentration may be of ‘dehydrating the chloroacetaldehyde is costly distilled under vacuum directly from the dilute‘ and inconvenient. When the concentrated aqueous mixture, resulting from the reaction bee aqueous solution of 70 to 80 per cent chloro- ‘ tween , vinyl chloride, chlorine and water. By acetaldehyde is redistilled and the vapors con carrying such distillation out under vacuum, e. g. densed directly, there is obtained a product, dis~ at from 100 to 300 mm. of Hg absolute pressure, - tilling at 85°-85.5° C. at atmospheric pressure, the step, heretofore considered necessary, of first which has heretofore been referred to as a enriching the reaction mixture with hydrochloric, hydrate of chloroacetaldehyde. The product acid may be omitted. As mentioned above, the‘, crystallizes to a solid at room temperature, has chloroacetaldehyde in the concentrated solution a chemical composition corresponding to the obtained as distillate is largely combined with.‘ formula CH2C1'CHOH-O-CHOH'CH2C1, and may water as l,1'-oxybis-(2-chloroethanol). ‘ be named 1,1 '-oxybis- (2-chloroethanol). I have further found that l,l'-oxybis-(2 Attempts to convert this material to anhydrous - chloroethanol) can be dehydrated to form chloro chloroacetaldehyde by usual dehydration proce acetaldehyde in good yield, by heating the com» dures such as treatment of the material in liquid pound, or a concentrated aqueous solution of the form with solid drying agents, e. g. calcium compound, in admixture with an entraining chloride, sodium hydroxide, calcium sulfate, > agent, consisting of an inert water-immiscible anhydrous sodium sulfate, activated alumina‘, etc., 40 organic liquid having a boiling point below 70°. results in failure, or poor yields of chloroacetalde C. at atmospheric pressure, and removing by dis- ; hyde product. Extraction of the material with tillation, water, together with a portion of the organic‘ solvents such as ethylene dichloride, entraining ‘agent. Apparently, a reaction of benzene, toluene, ethylbenzene, hexane, tetra? ' splitting water from the l,1'-oXybis-(2-chloro-_, chloroethylene, beta,beta'-dichloro-diethyl ether, 45 ethanol) molecule to form chloroacetaldehyde etc., fails‘ to produce anhydrous chloroacetalde occurs quite rapidly at temperatures in the order _ hyde. The compound was found to be either of from 40° to 70° C. and the chloroacetaldehyde completely miscible with, or substantially insolu product is stable at these temperatures. How- _ blew in, the organic liquids which were tested. ever, the reaction is of an equilibrium type and Extraction of concentrated aqueous chloro 50 watermust be removed as it is formed for the acetaldehyde solutions, i. e. containing 50 per reaction to be observable or to permit recovery. cent by weight or more of chloroacetaldehyde, of the chloroacetaldehyde product. with water-immiscible organic solvents either The process as a whole may be carried out in . fails to produce anhydrous chloroacetaldehyde-or .a series of steps comprising, (1) distilling at; the'proportion of chloroacetaldehyde extracted 65 subatmospheric pressure the dilute aqueous reac 2,540,998 3 4 'tion mixture, prepared by causing vinyl chloride as the water-entraining agent the reaction may and chlorine to react in admixture with water, advantageously, be carried out under a pressure to obtain aqueous chloroacetaldehyde of from of from 10 to 45 inches of Hg, gauge, so as to 50 to 85 per cent concentration, as distillate; (2) produce a temperature of from 50° C. to ‘70° C. adding as an entraining agent a water-immis in the reaction vessel and the water removed as cible organic liquid,’ having a boiling point below distillate together with a portion of the methyl ‘70° C. at atmospheric pressure, .to the concen ene chloride. trated aqueous c‘hlo'roacetaldehyde solution;v .(3) " The ‘distillation is preferably carried out at heating the mixture to distill therefrom water, atmospheric pressure until the dehydration is together with a portion of the entraining agent; L10 lsubstantially complete. The remaining entrain and (4) recovering anhydrous ,chloroacetalde; ing agent is usually distilled from the residue inghyde agent. from the residual wateriimmi'scible‘ _} Int' ‘,_ ' under reduced pressure, so as to avoid heating of the chloroacetaldehyde at temperatures above The, inert water-immiscible organic liquids ' i85° C. .Prolongedheating at 85° 0., or at .higher ' that may be employed in the'above s'tep"(3-) as . ‘temperatures 'lcauses polymerization of a sub entraining agents to remove water by distillation "stantial" portion of" the chloroacetaldehyde, to should be solvents for chloroacetaldehyde and gether with .formation of decomposition products preferably have boiling points’ at atmospheric which meniscus to separate from each other pressure between 50° C. and ‘70° C., although and results in lower yields of chloroacetaldehyde. solvents having boiling points of from‘ 40°“C. 20 After removal of the entraining agent the anhy~ to 70° C. may be used. They should be inert drous chloroacetaldehyde may be recovered, pref . to the chloroacetaldehydepat the temperatures érably'by continuing the distillation at'suba't employed Preferably, the solvents‘ are satu mospheric pressure. ‘ " ' " “ ‘ rated’ aliphatic chlorohydrocarbons containing The following examples illustrate practice of from one to three chlorine atoms in the mole 25 the invention, .but ‘are not to vbe construed as cule. Examples of such inertlwater-immiscible limiting the scope thereof. ' ’ ' “ ' organic liquids suitable for use in said step as entraining agents are chloroform,‘ sec-butyl Example ‘f chloride, methylene chloride, non-propyl' chloride A mixture ‘consisting of 1214 grams of solid and'ethylidene chloride. The entraining agent 30 l,l’-oxybi's-(2-chloroethanol) and ‘900 grams'of should, of course, be easily separated from the chloroform was placed in a round \bott'om‘?a'sk' chloroacetaldehyde. Water-immiscible organic equipped with" a" distilling column and'a con“; liquids that form constant boiling ‘mixtures with denser. The mixture was heated 'to a tempera chloroacetaldehyde are ‘not operable in the ture ‘of 65°“ to 57(1)?’ 0. to cause ‘distillation 6f the PIQCESS- . chloroform, together with water split'from ‘the The proportion of entraining agent employed 1,1"éoxybis-‘(2LchloroethanoD. The chloroform to remove‘ the water byidistillation may vary layer oft-he distillate was separated and returned Within wide limits, ‘A sui?cient amount of the to thev column as‘re?ux. Distillation ‘was con‘; entr'aining' agent is usually employed so that tinued until the material ‘distilling was clear and‘ the temperature-in the distillation vessel does not 40 apparently free of water. Approximately v‘11,35 become greater than the boiling point Zof ‘1,1’ gramsof water was collected in thedi'stillate; oxylois-(2-chloroethanol). In batch distillation, The liquid remaining in the reaction ve's’sel'lw’a's'r the process may advantageously be carried out fractionally distilled,‘ ?rst at atmospheric ‘presy' by using from 0.5 to 1.0 parts by. weight of en sure to remove‘most’of the chloroform, and’ithslen training' agent per part of concentrated aqueous 45 under a, reduced pressure Tof’ZQO mm.‘ of Hg abso’; chloroacetaldehyde solution or ‘ :per part of lute. There was ‘obtained 855 grams or recovered L-l'rDXybis-(Z-chloroethanol) used,‘ and separat chloroform and: 1055.5 areas of 'a'nh" ing :the entraining agent from the distillate and chloroacetaldehyde having the’vproperties': returning it to the distillation vessel. In a con-l 'tinuous process wherein the entraining agent 50 Boiling point 492512;)‘ at 209 mm. Hg is separated from the distillate and returned‘v to .S‘eci?c‘gravit; _, 236 “M " the distillation column, after operation of the ' a? rare? 2min» process for ‘a short while; an‘ inventory ‘of 'en training agent is accumulated'in the‘v system, which ‘is continuously recycled. Inthis instance, it is merely necessaryithat the entraining‘ agent ' be present in amount su?icient to distill together with the water and ‘it may be‘ used iii a'prope‘r'; tion' as small ‘as desired, relative'tothe amount of >1,1.’-oXybis-'(2-chloroethanol) " to ” "be" deny: drat'ed, i. 'e. the '1,1’-Oxybis—‘(r2-chlol‘oethaildl) heatedtb ._ may-be fed in continuousv manner to the distilr cjito ,glis‘tirll eh‘ , , latibn system containing such inventory of en' memes , ‘ training agent and anhydrous "'chloroacetalde

hydeThe‘ be mixture withdrawn.~ is heated ' 'under I 'condtions ' ‘ ' ofV tem perature and pressure ‘such ‘as to distill at tem peratures between 409 and 70°‘ _C.',' watchto gether with at least a portion of the inert water immiscible entrain‘ing" agent. "such distillation ~' may be' accomplished by ‘heating "the‘n'i'ixturé at ‘atmospheric’ pressure; subatm'ospherifpres; sure, or under a" slight sup ‘ratmo‘s‘pheric pres sure; depending'ontlie ‘eritrainiii'gagent used. Fbr iest'ahbéi whenseeqymeeeaee 1 5 6 termediate fraction, consisting of a ‘mixture of invention may be employed instead of those ex chloroform and chloroacetaldehyde, distilling at plained, change being made as regards the 25°70, to ‘50° C. at 200mm. absolute pressure, method or products herein disclosed, provided and 328 milliliters of chloroacetaldehyde distilling the steps or products stated in any of the follow‘ at 50.0 C. at 200 mm. absolute pressure. 5 ing claims or the equivalent of. such stated steps Example. 3 or products be employed. ‘ A mixture consisting of 600 grams of crystal I therefore particularly point out and distinctly line 1,1’-oxybis-(2-chloroethanol) and 464 grams claim as my invention: . of methylene chloride were placed in a 1 liter 1. In a method of making chloroacetaldehyde round bottom ?ask. The mixture was distilled by causing vinyl chloride and chlorine in gaseous to separate water together with a portion of the form to react in admixture with water, the steps methylene chloride, the distillate condensed, and of distilling the aqueous reaction mixture at from the methylene chloride separated from the aque 100 to 300 mm. of Hg, absolute pressure, separat ing as distillate chloroacetaldehyde in concentra ous layer and returned to the column as re?ux. 15 There was separated 72 milliliters of an aqueous tion of at least 50 per cent by weight, mixing the layer having a speci?c gravity of 1.013 at 25° C. distillate with a water-immiscible entraining Methylene chloride was recovered from the re agent selected from the group consisting of maining mixture by fractional distillation at chloroform, sec.-butyl chloride, ethylidene chlo ride, n-propyl chloride and methylene chloride, atmospheric pressure and the chloroacetaldehyde 20 distilled at an absolute pressure of 200 mm. of heating the mixture at temperatures between 40° Hg. There was obtained 359.7 grams of chloro and 85° C. to distill therefrom, water together ‘acetaldehyde having-a speci?c gravity of 1.253 with a portion of the entraining agent at tern“v at 20° C. and 43.5 grams of solid residue. In peratures between 40° and 70° C., and carrying addition 37.7 grams of chloroacetaldehyde were 25 the distillation to a point until substantially an collected in a cold trap inserted between the ' hydrous chloroacetaldehyde remains in the re receiver and vacuum pump and 40 grams of solid sidue. polymerized chloroacetaldehyde were removed 2. In a method of making chloroacetaldehyde from the condenser. by causing vinyl chloride and chlorine in. gaseous Example 4 30 form to react in admixture with water, the steps of distilling the aqueous reaction mixture at from A mixture consisting of 1267 grams of an aque 100 to 300 mm. of Hg, absolute pressure, separat ous solution containing 50 per cent by weight ing as distillate chloroacetaldehyde in concentra chloroacetaldehyde and 344 grams of sec.-butyl tion of at least 50 per cent by weight, mixing the chloride was placed in a round bottom ?ask distillate with chloroform, heating the mixture equipped with a fractionating column and con at temperatures between 40° and 85° C., separat denser. The mixture was heated to a tempera ing therefrom by distillation, water together with ture between 65° C. and 75° C. to distill there a portion of the chloroform and thereafter re from, water together with sec.-butyl chloride. covering anhydrous chloroacetaldehyde from. the The organic layer of the distillate was separated remaining chloroform. 40 and returned to the distillation column as re?ux. 3. A method of dehydrating 1,l’~oxybis- (2 There was separated 661.5 grams of an aqueous chloroethanol) which comprises, mixing the I layer having a speci?c gravity of 1.093 at 25° C. compound with an inert water-immiscible en After removal of substantially all of the water, training agent having a boiling point between the sec.-butyl chloride was separated from the 40° and 70° 0., selected from the group consisting remaining mixture by fractional distillation at of chloroform, sec.-buty1 chloride, ethylidene - atmospheric pressure and the chloroacetaldehyde chloride, nepropyl chloride, and methylene chlo separated by distillation under a reduced pres ride, heating the mixture at temperatures be sure of 300 mm. of mercury absolute pressure. tween 40° and 85° C. to distill therefrom water There was obtained 344.1 grams of sec.-butyl 50 together with a portion of the entraining agent chloride, 6.8 grams of an intermediate cut con at temperatures between 40° and 70° (3., and sisting chie?y of a mixture of sec.-butyl chloride carrying the distillation to a point until substan and chloroacetaldehyde, 276.6 grams of chloro tially anhydrous chloroacetaldehyde remains in acetaldehyde having a speci?c gravity of 1.253 the residue. at 20° C. and 191.6 grams of tar-like residue. In 55 4. A method of dehydrating 1,1'-oxybis-(2 addition, 104 grams of solid polymerized chloro chloroethanol) which comprises heating the acetaldehyde were removed from the condenser compound in admixture with chloroform at tem and 18.9 grams of liquid product collected in a peratures between 40° and 85° (3., and separating cold trap, cooled with a mixture of solid carbon from the reaction mixture by distillation, water dioxide and acetone. This latter product was 60 together with a portion of the chloroform. chie?y chloroacetaldehyde. 5. A method of dehydrating 1,1’-oxybis-(2 Anhydrous chloroacetaldehyde is an extremely chloroethanol) which comprises heating the corrosive chemical to animal tissue. Vapors of compound in admixture with ethylidene chloride the compound in admixture with air, in concen at temperatures between 40° and 85° 0., and trations of one per cent by volume, are extreme 65 separating from the reaction mixture by distilla irritants to mucous membrane. Thus, in prepar tion, water together with a portion of the ethyl ing and using the compound due precaution idene chloride. should be observed to avoid contact with the 6. In a method of making anhydrous chloro material or exposure to the vapors. Processes acetaldehyde the steps of mixing an aqueous employing the compound should be carried out 70 solution containing at least 50 per cent by weight with adequate ventilation and suitable protective chloroacetaldehyde with an inert water-immis facilities. For laboratory preparations, employ cible entraining agent having a boiling point be ing the chemical compound, the reactions may tween 40° and 70° (3., selected from the group conveniently be carried out under a hood. consisting of chloroform, sec.-butyl_ chloride, Other modes of applying the principle of my 75 ethylidene chloride, n-propyl chloride, and vi33>?r>§h75dé'rie ehiori'd‘e, heating the mixture at tem :mixtiirewith methylene ehloride at'teixiiiexeiutes" _‘ atsuresgbetween 40° and'85" C. to distillv there "between-40° and'=85"' (2., separatingtfrom them; em. svatentogether .with a» ‘portion vof the en "tu-liélby' distiiliatiqn. water together withapei ng ‘agent .at temperatures --between 40° and tion of the methylene chloride and ‘thereafter Y’ "carrying the- distillation to a point until separating chloroacetaldehyde from‘ the remain substantially anhydrous a-eh-loroacetaldehyde re ing methylene chloride. ' the residue and thereafter recovering 1C- .SIQWE- ' chloroacetaldehyde from the residue. 7 ' ' ~17, in .a, method of making anhydrous chloro REFERENCES JQITED aeetaldehyde the improvement which comprises 212' ‘ ril‘heiollowmg reierenees areof record mine I ting 'lilkoxybisd2echloroethanoi) in admix ?le of this patent: ' ' With .shioroform at temperatures between '“ separating from the reaction ‘URI’I‘ED "STATES , PATEN'IIS .2 ‘y distillation, water split from the 1,1’ n , ggi-kchlproethanol) together with a. por 4.5 9n ,f the chloroform and thereafter separating egetaldehyde :_from the remaining chloro enmethod ‘of making anhydrous chloro »9§Q@tai1__.,hyde :the "improvement which comprises tea g?‘lk?jQU-QQUS ‘solution containing at least pent 1,11‘.rgggyhisqr(2-ch10roethano1) in -ad—_ 5224623194 ___, Feb, @1949