IL41101A - Process for preparing 1,2,3-trichloropropene - Google Patents

Description

PROCESS FOR PREPARING PROCESS FOR PREPARING 1 This invention relates to the preparation of unsaturated chlorinated More i relates to a process for producing compounds used as intermediates in the manufacture of various pesticides and other chemical More the invention is concerned with a novel method the preparation of from and the de ri of to obtain can also be recovered oroprppene from the and are important intermediates in the preparation of more particularly selective herbicides for the control of noxious weeds in various diisopropylthiol is an example of a selective herbicide be prepared from is a example of a selective herbicide which can be prepared from has been obtained through a ciehydrohalogenation of in a liquid phase reaction requiring the use of or mixtures of anhydrous procedure found to both costly and complicated in In British Patent there is described and claimed a process for the dehydrohalogenation of a polyhalohydrocarbon containing a saturated halohydrocarbon in the presence of an catalyst having a pore opening of at least 6 ft and formed by a membered ring in the presence of an inert diluent having a larger molecular dimension than the pore The starting compounds are dihaloalkanes and kanes whereas according to the present invention a preferred reactant is 1 propane which is reacted in vapor phase with a specific as described in detai l The process for preparing from by the method of this invention comprises passing vaporous through a catalyst bed of oxides or nixed oxides of condensing the vaporous and separating from the resulting liquid both the cis and trans isomers of are obtained in approximate ratios of abou In the present invention the pane is prepared by a process which comprises feeding a stream comprising to hase chlorinating the feed so that from about 20 to about percent by weight of the chlorinator remains as unreacted passing the chlorinator effluent which comprises and to actionating ractionating chlorinator effluent into a a a and and a and heavy ends fraction the fraction to and relieving the the process of this invention provides a integrated process for preparing from the preparation of trichloropropene from the temperature of reaction during of the vaporous charge with the catalyst bed is maintained within the range of from about to about and temperatures of from about 290 to are particularly At temperatures below about conversion rates are greatly and above about yield losses of are probably as a result of trichloropropene The initial maximum catalyst bed temperature should not exceed about At higher starting temperatures a large is observed which over increases the bed temperature to ith resulting yield losses of and rapid deactivation of the It is preferred to keep the maximum bed temperature in the range of about about In carrying out the process for dehydrochlorinating either a fixed or catalys bed may be employed a d bed being generally For any given pass of tetrachloropropane vapor through catalyst the residence time should be within the range of about 1 to 20 with from about 3 to 8 seconds being normally Residence time is defined as the average time a molecule spends in contact the catalyst Another important tor is vapor velocity through the reaction rates are significantly affected by the rate at which the vapor passes through the good results are obtained with vapor velocities in A tubular dehydrochlorination reactor is generally employed since this type of design involves large transfer The reactor if be preceded by a separate feed vaporizer and preneater of conventional or the region of the reactor near the input end may be utilized for vaporizing and preheating the Since hydrogen chloride is produced during the course of the employed in reactor construction must be resistant to this compound as well as to the halogenated charge and reaction Illustrative examples of suitable materials include glass and various inert The particle size of the dehydrochlorination catalyst is not critical and can vary over a wide range with a mesh size Sieve being particularly It is important that the tetrachloropropa e charge be free of any oxygen containing impurities since their presence causes the activity of the catalyst to drop off very Following the dehydrochlorination reaction the vaporous effluent from the reactor is It is convenient to condense the entire excepting the hydrogen chloride formed which is emitted from the and passed to a scrubber for collection or The liquid product from the condenser is then fractionally distilled to recover the From the reaction product there is also obtained unconverted tetrachloropropane and minor amounts of The unconverted can be recycled to the reactor for another pass in the dehydrochlorination It is desirable that the distillation equipment be that it is found that used construc on such as Stainless Monel 200 and As in the case of most catalytic the dehydrochlorination catalyst eventually becomes fouled materials which interfere with normal It has been found that the catalyst employed in this invention can be regenerated by burning off the fouling This can be conveniently carried out by passing a stream of air or other gas through the catalyst bed at a temperature of from about to Both the heat input and air flow must be carefully controlled to avoid exceeding in the catalyst At higher temperatures the catalyst tends to sinter and lose Examples of oxides of aluminum or magnesium useful as dehydrochlorination in the process of this invention are amorphous silica fumed ground and the Alumina is a preferred oxide catalyst in the process of this Examples of mixed oxides of at least two of the elements selected from the group consisting of aluminum and magnesium include but are not limited to the a variety of calcined and uncalcined clays such as hecto beidellite and other mineral salts of silica such as spodurnene and siliceous substances such as fibrous aluminum and earths such as diatomaceous earth as well as synthetic silicon aluminum magnesium Preferred mixed oxides are natural or synthetic siliceous based material of the silicate and magnesium silicate types used as contact material in hydrocarbon material is an attapulgite type clay composed of magnesium silicate or magnesium aluminum silicate with varying minor Many synthetic type catalysts which are on the market for use in hydrocarbon conversion processes may be These may also contain minor amounts of magnesium zirconium beryllium and the Such contact materials may be in the form of particles or compressed Mere preferred lattice structure which allows rapid adsorption and desorption of Of particular value as catalysts in the present process are attapulgite and sepiolite As is attapulgite clay is sometimes characterized as a hydrous magnesium aluminum silicate of the formula and sepiolite as a magnesium silicate of the formula 2MgO In the embodiment of the process based upon the chlorinator substitutes chlorine for hydrogen by the free radical method to form the more highly chlorinated Formation of may be initiated by exposing the contents of the chlorinator to actinic light or by conducting the chlorination in contact with catalytic amount of a forming catalyst such as one of the benzoyl lauryl cumene urea tertiary butyl or other formers such as These chlorination methods are well known to the skilled artisan and the particular method employed is not a part of the it is critical that the extent of richloropropane in order to limit the number chlorinated products It is preferred to chlorinate so that from about 30 to about 50 percent by weight of the stream remains and more preferred to chlorinate so that from about 35 to percent by weight of the feed stream remains Control of the ehlorination within the stated limits gives an effluent comprised of the following compounds with Boiling Point Centigrate opropane 157 etrachloropropane 179 The compounds are readily separated into 5 fractions in a conventional fractionating The fractionating column may be of any suitable design and may utilize trays or packing to make the necessary Since corrosion is a a packed column is While the type of actionating column is not it is necessary that the five of the following be separated in order to obtain the high yields of the present process Fraction 1 Fraction 2 etrachloropropane Fraction etrachloropropane Fraction 4 and Fraction 5 in the This entire stream is recycled to the c Fraction 2 provides the which is the raw material for the preparation of op opene Fraction 3 is as to a caustic chlorinator which converts the tetrachloropropane to a mixture of The design of this dehydrochlorinator in the presence caustic are conventional and not critical to the After dehydrochlorination the effluent which normally consists essentially of and is passed to a second This second chlorinator by conventional means adds chlorine at the double bond to form and The effluent of this second chlorinator is then passed to second caustic The handling of Fraction 3 is another key feature of the Although the methods employed are admittedly the result is Fraction 3 it passes from the fractionator is a useless by removing HC1 and then adding this useless is converted to a valuable precursor for This conversion is important in obtaining the high yield of product from the present Fraction is also passed to the second caustic Fraction and the second chlorinator effluent may enter the second caustic dehydrochlorinator as separate streams or as a single The method of operation of this second dehydrochlorinator is not critical to the invention may be the same or erent om the Fraction 5 is a waste It may be sent directly to waste disposal or utilized for other The or utilization of Fraction is not critical to the present The effluent from the second caustic dehydrochlorinatcr normally consists essentially of product propene and This stream is passed to an which converts almost totally the to 1 This isomerization is a particularly unique feature of the present The isomerizer is a vessel of any suitable design packed with siliceous granules having a polar The size and shape of the granules will vary depending on the particular operating conditions desired for the Factors to be considered in determining granule size and shape are basically process design considerations known to the skilled process ouch as pressure drop across the vessel process flow tolerable packing silica compounds which may be used in this process include a variety of calcined and uncalcined clays such as beidellite and other mineral salts of silica such as spodumene and siliceous substances such as silica fumed fibrous aluminum silicate It is preferred that the granules be clay and more preferred that the granules be The isomerizer operates at a temperature of from about about preferably from about to about The isomerization is usually carried out at atmospheric The isomeriza may be carried out in a closed vessel or It is particularly preferred to carry out the under reflux at atmospheric Under the stated conditions the second caustic dehydrochlorinator effluent is to a consisting essentiall of chloropropene in from about to about 2 preferabl from about to about hours and more preferably from about to about 1 The effluent from the isomerizer may be as in the preparation or diisopropylthiolcarbamate or further purified for use in preparation or other By this integrated process about 39 percent by weight of is converted to propane from which is prepared and about percent by weight of is converted giving total conversion to useful products of about 85 percent by weight of As used the term refers to the product stream flowing from the specified The following examples are presented as illustrative of the process of this invention and are not to be construed as limitative EXAMPLE 1 This example illustrates the preparation of trichloropropene from To an hollow tube approximately βθ in length and in void there was charged attapulgite clay mesh This produced a packed catalyst bed 33 in length and in Extending down through the center of the catalyst bed was a hollow tube containing a thermocouple positioned in a layer above the catalyst The glass bead section acts as a preheater to vaporize the feed before it enters the catalyst Before the reactor was heated to approximately and held at this temperature for 12 hours with dry air passing through the catalyst bed to remove excess water from the The temperature of the catalyst bed was then lowered to at the hottest point and the tetrachloropropane feed was was fed from a bomb under nitrogen pressure through a rotometer and into preheater section of the reactor where it was The preheater and reactor furnace were set to maintain an average temperature in the catalyst bed of about and the charge flow rate was adjusted by means of the rotometer so as to a vapor velocity through the catalyst bed of about to with a residence time of between about 9 to The resulting vaporous reaction product was condensed and collected while the hydrogen given off during the was passed through a scrubber and Based on a run of seven there was charged grans of tetrachloropropane and collected grams of The reaction mixture obtained was separated by distillation and contained by oropropene and The overall yield and conversion on the tetrachloropropane were and EXAMPLE 2 This example illustrates a procedure for reactivation of using the reactivated Following the run described in Example 1 air was introduced into the hot reactor tube a rate of and the reactor was heated to about At this an exothermic reaction occurred between oxygen from the air stream and the carbonaceous material on the catalyst resulting in a rapid increase in temperature to from The emperature in the catalyst bed was exceed at this temperature catalyst tends to This was controlled the reactor furnace and the flow of air through the catalyst The progress of the reactivation step was b determining the location of the maximum temperature in the This point moved down the catalyst bed as reactivation and when it reached the the reaction was held an additional hour at with the air at The total time for reactivation was three after which the catalyst bed was allowed to cool down for the next Employing the catalyst regenerated in accordance with the procedure described a of to produce trichloropropene was carried out under the conditions as set cut in Example 1 Based on a run seven there was charged grams of and collected grams of reaction Upon separation via fractional the reaction mixture was found to contain the following on a weight 2 ichloropropene on tetrachloropropane were and EXAMPLE 3 This example illustrates the dehydrochlorination of when employing a fluidized bed of attapulgite clay to produce A hollow reactor was employed with fluidized catalyst positioned in one leg of the The opposing leg was as a preheater section with a sintered glass disc separating the preheater from the reaction In liquid tetrachloropropane is forced by nitrogen pressure from a bomb through a flowmeter and an appropriate valving system to the top of the The liquid then passes through the preheater where it is vaporized then through the sintered glass disc and up through the bed which it thus A hollow extending down the of the catalyst contains a movable couple used to measure the temperature along the length of the From the top of the reactor the exit stream passes to a condenser where it is condensed and the resulting liquids The gases generated during the reaction are scrubbed and The liquid reaction mixture is then separated in distillation column to recover the run of six hours was carried out at a temperature of from to with a residence time of to 1 seconds and a vapor velocity of from 2 to The overall conversion on the tetrachloropropane charged and the yield of trichloropropene was EXAMPLES 4 8 In each instance a satisfactory yield of trichloropropene is EXAMPLE CATALYST 4 5 6 Diatomaceous 7 Alumina 8 Meerschaum EXAMPLE The procedure of Example 1 is repeated wherein is used as the catalyst in place of attapulgite No yield of is detected in the reaction mixture at the completion of the EXAMPLE 10 This example illustrates the chlorination step in the integrated process of and from Chlorination of grams of propane is carried out in an open vessel exposed to ultraviolet light from a 5 inch quartz short wave lamp Angstrom suspended immediately above the surface of the The vessel is heated to from about 0 to about and about 555 grams of chlorine is bubbled through the at a rate of from about to about 1 per Upon completion of the chlorine the composition of the mass is determined by chromatographic analysis and to be about as follows 85 259 574 entachioropropanes 58 EXAMPLE 11 The procedure of Example except as noted is followed to give a chlorinator effluent composition about as of 358 of chlorine 125 Temperature 2 Chlorinator effluent Composition percent by weight and 6 and heavy ends 12 These examples illustrate chlorinations outside the process of this In these examples less than 20 percent of the feed remains as unreacted 2 which results in excessive number of chlorinated products in heavy The procedure cf Example except as noted is followed to give chlorinator effluent compositions as Example Example 12 13 of 2 1 of chlorine 99 Temperature 2 2 Chlorinator effluent Example 13 in percent by ne etyaehloropro ropanes and heavy ends V v insufficientOCRQuality

Claims (1)

1. THAT WHICH IS CLAIMED A process for dehydrohalogenating tetrachloropropane to obtain i oropropene which comprises contacting said in vapor phase with catalyst comprising finely divided oxides or mixed oxides of magnesium and aluminum at temperature in the range of om about to about for a time interval of from about 1 to 20 seconds and at a vapor velocity of from about 2 to centimeters per condensing the resulting vaporous reaction and thereafter separating from said condensed reaction The process of Claim 1 wherein said temperature is in the range of from about to The process of Claim 1 wherein said temperature is in the range to of Claim 1 wherein said inte a is from 8 seconds and said vapor velocity is about 6 to 15 centimeters per The process of Claim 1 wherein said catalyst is in the form of a fixed The process of Claim 1 wherein said catalyst is in the of a The process of Claim 1 wherein the catalyst is The process of Claim 1 wherein the catalyst is The process of Claim 1 the catalyst is The process of wherein the catalyst an attapulgite A prooess for dehydrohalogenating propane to obtain by contacting tetrachloropropane vapor phase with a finely divided catalyst comprising oxides or mixed oxides of magnesium and substantially as hereinbefore described and with referenoe to the whenever obtained by a prooess claimed in any of claims 1 to For insufficientOCRQuality