United States Patent Office Patented July 8, 1969 2 3,454,661 Dichloro-2-Methylene-Propane, Respectively, As By-Prod PROCESS for PREPARING ALLYL CHLORIDE Ucts
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3,454,661 United States Patent Office Patented July 8, 1969 2 3,454,661 dichloro-2-methylene-propane, respectively, as by-prod PROCESS FOR PREPARING ALLYL CHLORIDE ucts. The reaction is especially smooth with propylene and AND ITS MONOMETHYLSUBSTITUTION isobutylene. Therefore, these olefins are prefered as start PRODUCTS ing products. Löthar Hörnig, Frankfurt am Main, Lothar Hirsch, When a monochloroparaffin is reacted with oxygen, Kelkheim, Taunus, and Ginther Mau, Frankfurt am Main, Germany, assignors to Farbwerke allyl chloride (3-chloro-propylene-(1)) is obtained from Hoechst Aktiengesellschaft vormals Meister Lucius 2-chloropropane (isopropyl chloride) and 1-chloropro & Bruning, Frankfurt am Main, Germany, a cor pane (n-propyl chloride). Using 2-chloro-2-methyl-pro poration of Germany pane (tert, butyl chloride) and 1-chloro-2-methylpropane No Drawing. Filed June 7, 1965, Ser. No. 462,084 0 (isobutyl chloride) the reaction furnishes methallyl chlor Claims priority, application Germany, June 16, 1964, ide (3-chloro-2-methyl-propylene-(1)). With the use of F 43,185; Dec. 7, 1964, F 44,626 2-chlorobutane (sec. butyl chloride) and 1-chlorobutane Int, C. C07c 17/34, 21/04 (n-butyl chloride), a small amount of crotyl chloride (1- U.S. C. 260-654 9 Claims chlorobutene-(2)) and 3-chlorobutene-(1) is obtained. In all cases the stoichiometric amounts of water are formed. ABSTRACT OF THE DISCLOSURE The secondary and tertiary monochloroparaffins (iso Process for preparing allyl chloride or its monoethyl propyl chloride, tert. butyl chloride, Sec. butyl chloride) substituted derivatives from C or C4 olefins, hydrogen are more readily oxidized, i.e. under milder conditions, chloride, and oxygen, or from oxygen and C3 or C4 mono 20 to give the corresponding allyl chlorides (allyl chloride, chloroparaffins, in the presence of a catalyst of tellurium methallyl chloride, crotyl chloride) than the primary and/or tellurium compounds. monochloroparaffins (n-propyl chloride, isobutyl chlor ide, n-butyl chloride). It is remarkable that isopropyl chloride reacts more readily than sec. butyl chloride, al The present invention relates to a process for preparing 25 though both compounds contain the chlorine atom in allyl chloride and its monomethyl-substitution products. secondary position, and that isopropyl chloride and tert. It is known to react olefins directly with chlorine to butyl chloride have about the same reactivity, although in yield compounds in which one or more carbon atoms the former compound the chlorine atom is a secondary one directly adjacent to the carbon atoms of a double bond while in the latter compound it is a tertiary one. Hence, each carry a chlorine atom. Propylene, for example, re 30 it follows that isopropyl chloride and tert, butyl chloride acts with chlorine at high temperature and with a short especially react smoothly to yield allyl chloride and residence time to form 3-chloropropene-(1) (allyl chlor methallyl chloride, respectively. Therefore, the two former ide). When butene-(2) is used the chlorination reaction compounds are preferred as starting products and the takes place at lower temperature and leads to the forma two latter compounds as reaction products. tion of 1-chloro-butene-(2) (crotyl chloride). Isobutene 35 As catalyst elementary tellurium or one or several tel can be transformed at low temperatures and under the lurium compounds are used. The tellurium compounds action of chorine into 3-chloro-2-methyl-propene-(1) can contain the tellurium in any valence stage. It is ad (methallyl chloride). vantageous to use compounds that are readily obtainable In the aforesaid chlorination processes, some of which in industry, above all compounds of tetravalent tel are carried out on an industrial scale, such as the high 40 lurium, such as tellurium dioxide, tellurium tetrachloride temperature chlorination of propylene, one mol of chlor and tellurium oxychloride. It is likewise possible to use ine (C2) is used for one mol of olefin. Only one half compounds of bivalent tellurium such as tellurous oxide of the chlorine is used up for the formation of the allyl and tellurous chloride, as well as tellurites and tellurates. chloride, while the other half forms hydrogen chloride as Mixtures of the aforesaid compounds with one another or by-product. As in many chlorination processes in this 45 with elementary tellurium may also be used. case, too, the economy of the process is impaired by the The catalyst containing elementary and/or bound tel formation of hydrogen chloride. lurium is suitably supported on an inert carrier material, A process for transforming an olefin into the cor for example aluminum oxide, aluminum silicate, silica responding allyl chloride, avoiding the formation of hy gel, pumice, asbestos, feldspar, sandstone, clay, Zeolithe drogen chloride and utilizing readily available hydrogen 50 or silicium carbide. The system consisting of catalyst and chloride and oxygen as chlorinating agents would con carrier material is advantageously prepared by mixing a siderably advance the art. tellurium-containing solution, for example a solution of It has now been found that allyl chloride and mono tellurium tetrachloride in hydrochloric acid, with one of methyl-substituted allyl chloride can advantageously be the specified carrier materials and evaporating the mixture prepared by passing oxygen and (a) mixtures of ole 55 to dryness. A catalyst thus obtained which contains the fins with 3 or 4 carbon atoms and hydrogen chloride or tellurium substantially in bound form, can be directly (b) monochloro-paraffins with 3 or 4 carbon atoms or used in the reaction. It is likewise possible, however, to (c) mixtures of (a) and (b) over a catalyst containing reduce the tellurium compound to the metal by treating elementary tellurium and/or tellurium compounds. 60 the catalyst with a reducing agent such as hydrogen or Using olefins having one methyl group in o-position, sulfur dioxide. the reaction of the olefin with oxygen and hydrogen It is not decisive for the activity of the catalyst whether chloride leads practically exclusively to the formation of elementary tellurium or a tellurium compound is used. the corresponding allyl chloride. Propylene and butene Whether elementary tellurium or a tellurium compound (1) yield practically exclusively allyl chloride and 3 is used, in most cases, after some time of reaction the chloro-butene-(1), respectively. When olefins are used 65 catalyst contains a mixture of elementary tellurium and having two c-methyl groups, dichloro-olefins are obtained bound tellurium. The presence of selenium does not show in addition to the corresponding methyl-substituted allyl a detrimental effect. It is advantageous to use a catalyst chlorides. From butene-(2) and isobutene, 1-chloro system containing 0.5 to 20% by weight of tellurium. It butene-(2) (crotyl chloride) and 3-chloro-2-methyl-pro is also possible, however, to carry out the process ac pene-(1) (methallyl chloride), respectively, are obtained ! cording to the invention with a catalyst containing a as principal products and 1.4-dichlorobutene-(2) and 1.3- smaller or higher proportion of tellurium. Alternatively, 3,454,661 3 4 the catalyst can be used without carrier material, for ex limits for the oxygen-containing gas mixtures in the re ample in the form of tellurium metal powder or tellurium action zone, prior to entering it, and after leaving it. In dioxide. Catalyst solutions may be used, too, for example general, oxygen is used in an amount below the stoichio a solution of tellurium chloride in aqueous hydrochloric metric amount. The molar proportion of monochloro acid through which the gaseous starting components are paraffin to oxygen is advantageously between 5 and 1, conducted. more advantageously between 4 and 2. However, a ratio In general, the reaction according to the invention is above 5 and below 1 may also be used. When an olefin, carried out in a manner such that the starting compo hydrogen chloride and oxygen are used as starting com nents, hydrogen chloride, oxygen and olefin, or oxygen and ponents, the molar amounts of the olefin and hydrogen monochloroparaffin, advantageously in admixture with chloride suitably do not differ, and are for example in the one another, are passed over the solid or dissolved 0 range of from 1:5 and 5:1, while the oxygen can be used catalyst. When the olefin or the monochloroparaffin is not in deficiency or in excess. In general, the reaction is not gaseous but liquid under the reaction conditions or is dis quantitative. After separation of the reaction products, solved in a solvent, the mixture of oxygen and hydrogen the starting components are reconducted into the reactor. chloride, on the one hand, and the liquid olefin, on the 15 The temperatures and pressures to be maintained are other, or the oxygen, on the one hand, and the liquid not critical. In order to obtain high conversions it is ad monochloroparaffin, on the other, are passed in counter vantageous to work at high temperatures and high pres current flow or in parallel flow over a fixed catalyst bed, sure. However, too high a temperature favors the for this being a mixed phase reaction. Alternatively, the re mation of undesired oxidation products, while too high action can be carried out in a suspension of the catalyst 20 a pressure favors the formation of addition products of in a liquid. In this case, too, the catalyst may contain a hydrogen chloride on the olefin, for example 2-chloro carrier material. The liquid used to suspend the catalyst propane and 1-chloropropane with the use of propylene. can be the olefin or the monochloroparaffin itself or a It is, therefore, suitable to operate at a temperature in solution thereof in a solvent inert to the reaction. the range of from 20 to 350° C. and preferably 100 to The starting components can likewise be used in ad 25 300° C.