PROCEDURE FOR PRODUCING SUBSTITUTED CHLOROTHIOFORMATE

Description

TITLE •PROCEO IMENT…ftt.fROOttRW ………………. ΤΗ·Ιβ »e«Hftcetoi *PR(KFCt«F«TO TO PRODUCE INFORMED CIOROT. .................................................................................................................................................................. I* OVERALL ·! àp»vo <io <Ι«·βο4· ···**3 …………………………………………………………………………………………………. - Description tn duplicate of n………………aoriture page. - Drawings, tables n.............* hWlbptM· pTOW. XX XXX Doc increase priority c Italian translation. Power of attorney, letter of assignment, withdrawal to proxy b*'· 3·*··''' j ... » 6, χ4ϊ ι«ϊϊ»«Λίϊϊ.ί)<ίνΜ'χχ 7. - Declaration of consent of the inventor to be mentioned in the patent. KKKfcXXfcXXAKXAXXXKXXXXXXXXXXXXHXXXKKKXKXXXXKXKAKX 8. - Proof of payment (eul c / c poet.nl / 11770, registered in the UHtdo Regìetro per Yasee Conceseion Government - Rome) of 1 ir< fe JQO»·.............. issued by the Poet. Office of ............... I date ... 6,3,1 m.....n.......................... 9. « Revenue stamp of L. 1500 10. rlohledenL..^|..- 0 do Beo The request, the descriptions and the drawings listed above have been signed by IC*, signed and stamped with the official seal. A copy of this report has been submitted by me to the interested party. The Depositor! 5 ROGANTE CiV·' I f Prejwrii-.K i^'r!· die J TO THE MINISTRY OF INDUSTRY, COMMERCE AND CRAFTS ί ; ύίι,'ϋ cjvj. CENTRAL PATENT OFFICE The undersigned SOCIETÀ ITALIANA BREVETTI, Cavattoni, de Benedetti, Omodeo-Salè sas, domiciled in Rome, Via Poli n. 42, by power of attorney and mandate of the American company STAUFFER CHEMICAL COMPANY of WESTPORT, Connecticut, USA request a PATENT OF INVENTION certificate for an invention entitled: PROCEDURE FOR PRODUCING AND USE OF CHLORIDE FORM I ATO TITUS, 3 AMENDED: PROCEDURE FOR PRODUCING CHLORINE SUBSTITUTED TIOFORMATE 1° COMPLETE to patent application η. 52358A / 76 of 26 November 1976 with priority: USA, 9 MARCH 1977, 775.821 for the purpose of having the exclusive right to manufacture, sell and use in industry and commerce the said invention, ITALIAN PATENT COMPANY Cavattoni, de Benedetti, Omoded-Salè sas pp STAUfFER CHEMICAL COMPANY / Rome, March 7, 1978 Attachments: {see back) : / 'Uffiddi .Process and intent to produce and substitute chlorophosphate. Modified title. Process for producing chlorine, substituted chlorophosphate. STAUEEER CHEMICAL COMPANY WESTPORT, Connecticut, U.6,A 1st Supplement to the patent, number 52358A / 78, filed on November 26, 1976 The present invention relates to the production of chlorothiophorates by the reaction of a mercaptan with phosgene in the presence of an activated carbon catalyst, RSH + COC1 2->RSCC1 + HCl In this invention R is alkyl, sub-cycloalkyl, methylmethyl, sub-cycloalkyl, sub-alkenyl, phenyl, chloro-substituted phenyl, benzyl, or chloro-substituted alkyl, wherein the chloro substituent is located at least as far from the sulfur atom as the carbon atom Y. By the term alkyl or chloro-substituted alkyl are meant those groups having from 1 to 15, preferably from 1 to 10, and more preferably from 1 to 6 carbon atoms, for example methyl; ethyl, n-propyl, isopropyl, n-butyl, sec.butyl, n-pentyl, neopentyl, n-hexyl, neohexyl, n-heptyl, n-octyl, n-decyls, n-dodecyls, and n-tetradecyl. By inf -si chen.yl and si, we mean those groups having from 2 to 5 carbon atoms and at least one olefinic bond. By inf.cycloalkyl we mean cycloaliphatic groups having from ≥ to ≥ 2 carbon atoms, for example cyclopropyl and cyclohexyl, the term inf.''cycloalkylmethyl'' includes groups having from 5 to 7 carbon atoms in the cycloalkyl moiety such as cyclopropylmethyl and cyclopentylmethyl.'' The term ''cycloalkylphenyl'' includes both mono- and polychlorinated phenyl rings in which the chlorine atom(s) may be * variously substituted.'' In a preferred embodiment of this process, R is alkyl, inf«cycloalkyl, inf»ci. chloralkylmethyl, benzyl, phenyl or phenyl chloro... substituted. The preferred embodiments for the various possibilities of R are: for alkyl, those groups having from 1 to 6 carbon atoms, in particular ethyl, n-propyl, isopropyl, n-butyl, sec.butyl, D-pentyl and neopentyl; for sub-cycloalkyl, cyclobutyl; for sub-cycloalkylmethyl, cyclopropylmethyl and cyclopentylmethyl; for sub-alkenes, 1 and 2: allyl; for chloro-substituted, p-chlorophenyl; for haloalkyl, 5-chloropropyl. Such chlorothioformates are useful intermediates for the production of thiocarbamates as effective as disulfides and similar compounds. This reaction between mercaptans and phosgene to produce chlorothioformates is described in UBA Patent 5,165,544 which describes the operation of this process in a laboratory-sized apparatus. It is emphasized that reaction temperatures should be kept as low as possible, consistent with reasonable reaction rates because at elevated temperatures the disulfide byproduct begins to form in significant quantities. Maximum temperatures for this reaction between about 20 and 120°C are suggested. One process that has been used for the commercial production of sub-alkylchlorothioformates by this reaction employs two catalytic beds of activated carbon arranged in series. The first bed is preferably contained in tubes of a multitube reactor; the second bed is in the form of a packed-bed reactor containing a single bed of catalyst. The first reactor is operated as a continuous liquid-phase reactor; more specifically, as an upward-flow tubular catalytic reactor, with starting materials introduced at the bottom and products removed from the top. The partially reacted mixture is then then introduced into the top of the second reactor, which operates as a trickle-pack (downward flow) batch. That is, the second reactor is operated in the continuous gypsum phase since the product hydrogen chloride gas is continuously passing through the bed. The reaction products are removed from the lower portion of the second reactor and passed to a downstream apparatus to separate the chlorothioformate. It has been found, however, that operation of this process for the production of ethyl chlorothioformate yields this product in a purity of only about 91 to about 95%. The highest purity is diethyl disulfide, present in a concentration of about 3.5%, with most of the remaining impurities being diethyl disulfide.When used to produce n-propylchlorothium formate, the amount of disulfide by-product is in the range of 1.5 to 15.7% and averages just under 5%, and the purity of the chlorathiophosphate averages about 95%. It is an object of the present invention to provide an improved process for the production of chlorothioformates by the reaction of a mereaptanol and phosgene in the presence of an activated carbon catalyst. A further object of the present invention is to provide such a process which minimizes the development of disulfide byproduct. A third object of the present invention is to provide such a process with enhanced production capability. Yet another object of the present invention is to provide such a process having good temperature control in the reactors. A still further object of the present invention is to provide such a process having good conversion of mercaptan to mixed chlorothioform. The present invention comprises a process for producing chlorothiophores having the formula ϕS₂Cl₄, wherein R is alkyl, subcycloalkyl, subcycloalkylkylethyl, subalkenyl, phenyl, chlorosubstituted phenyl, benzyl, or a chloro-substituted alkyl wherein the chlorine substituent is at least as far from the sulfur atom as the carbon atom Y, by reacting the corresponding mercaptan with phosgene in the presence of an activated carbon catalyst comprising: (a) contacting the mercaptan with phosgene in a first continuous liquid phase reaction zone in the presence of acatalyst comprising activated carbon; (b) removing a first reaction product from the first reaction zone; (c) contacting the first reaction product with a catalyst comprising activated carbon in a second continuous liquid phase reaction zone; and (d) removing a second reaction product comprising chlorothioform from the second reaction zone. The invention is more particularly described with reference to the single figure of the accompanying drawing which shows a generalized flow chart for carrying out the process. Referring to the figure, a mercaptan in a conduit 1 is combined with phosgene in a conduit 2 and the mixture introduced through a conduit A into the lower portion of a first reactor Kt reactor 10 is operated with reactants and products in a continuous liquid phase. Preferably, reactor 10 is a tubular packed bed reactor containing numerous tubes packed with activated carbon of an appropriate particle size such that each tube operates in the conventional manner as a miniature packed bed reactor. The reactants in conduit 4 are introduced into the lower portion of the reactor, then into the lower portions of the individual tubes and pass upward through the tubes. The average outlet temperature is generally between about 0° and about ?0°C, preferably between about 0° and about 50°C. The reactants 2 are between about 0 and about 10.5 kg / cm' effective and preferably between about 0 and about 3.5 kg / cm' effective.Partially reacted products from the first reactor 10 are removed from the upper part of this reactor as overhead products in conduit 6 and passed through conduit 8 into a second reactor 11. If desired, gaseous products from reactor 10 may be separated from the mixture in conduit 6 prior to its introduction into reactor 11. Reactor 11 contains a packed bed 12 of activated carbon. The reaction is completed in the reactor there in a continuous liquid phase.As shown in the figure, this is accomplished by introducing the reactants into the lower portion of the reactor 11 so that this reactor operates under the so-called flood-upflow condition. The reactor is generally operated at average outlet temperatures between about 0° and about 20°C, preferably between about 10° and about 50°C, more preferably at a temperature within this range below 50°C. The pressures are between about 0 and about 10.5 kg / cm* effective, preferably between about 0 and about 20°C. 5.5 kg / cm* effective. The residence time of the reactants in reactor 11 is generally between about 1 and about 180 minutes, preferably between about ? and about 90 minutes. The reaction products are removed from reactor 11 through an overhead conduit 9, passed into separation drum 15, and the chlorothium formate produced is removed in conduit 15 for further purification. Gaseous byproducts (primarily hydrochloric acid with some unreacted phosgene) are removed at conduit 14 and passed to downstream purification units (not shown) for recovery of unreacted starting materials for recycling and removal and further treatment of the hydrochloric acid. When, as in the previous procedure, the second reactor 11 is operated as a continuous gas-phase reactor (e.g., as a trickle-packed bed reactor), the mean outlet temperature can also be maintained between approximately 0°C and approximately 20°C, as in the present design. However, operation according to the previous procedure results in an uneven temperature profile across the reactor due to poor heat transfer, resulting in local zones of high temperatures or hot spots. It is known from U.S. Patent 3,165,5^ that undesirably high temperatures contribute to the formation of disulfide byproducts. The presence of very hot spots in reactor 11 therefore increases the possibility of formation of this byproduct. When the process is practiced using the present invention, however, operation of the second reactor 11 as a continuous liquid phase packed bed reactor results in a marked decrease in disulfide formation since such operation provides improved heat transfer and a more uniform temperature distribution throughout the catalyst bed. Operation according to the present invention, with reactor 11 being the continuous liquid phase reactor, results in an increase in residence time in the second reactor at the same flow regime as the preceding process by a factor of at least about 10. In the preceding process, for example, the residence time in this reactor is often on the order of 1 to 5 minutes. In the present process, the residence time may be between about 5 and about 180 minutes, or even longer, depending on the flow regime. Preferably, the residence time is between about 45 and about 180 minutes, more preferably between about 45 and about 90 or 120 minutes. One might reasonably expect that operation at longer residence times would result in increased by-product formation: however, it was surprisingly found that the.Operation at such long residence times does not result in increased byproduct formation as long as the temperature is maintained under good control. Alternatively, the material flow rate can be increased to allow operation at lower residence times in this reactor and increased capacity, as well as increased conversion of mercaptan to chlorothioformate. Preferably, the flow rate can be increased to 2-2.5 times that previously used. At increased flow rates, the residence time in the first reactor 10. -~η~ is also decreased. The desired temperature control in reactor 13 and the entire process may be increased by introducing excess liquid phosgene into the system, either as part of the feed into conduit 2 or separately into reactor 10. Some or all of this excess will vaporize under normal operating conditions of reactor 11, the evaporation absorbing heat generated during the reaction. As an alternative method of temperature control and also to aid in increasing the total chlorothioformate production, a relatively cool recycle stream in line 5, obtained from downstream processing units (not shown) and comprising primarily unreacted starting materials, may be introduced into the system. The recycle stream in line 5 may be introduced into reactor 11 via lines 7 and 8; its presence helps maintain a desirably low temperature in reactor 11, preferably below approximately 50°C. Alternatively, the recycle stream in line 5 may be introduced via lines 5 and 4 into the first reactor 10. More preferably, temperature control is maintained by a combination of the utilization of excess liquid phosgene and the introduction of the recycle stream into reactor 11. Operation in accordance with the present invention, as will be further seen from the following example, results in a conversion of about 98% of the starting ethylmex-capsules and the production of a product of about 98% purity, generally containing less than 1% diethyl disulfide. Furthermore, the use of a continuous liquid phase reactor, through the increased residence time, provides greater capacity than a similar unit operated using a trickle-pack or down-flow reactor, in which the residence time is substantially shorter. Similar results are found in the case of n-propyl chlorothioformate, as can be seen from example. Based on these results, and on the general knowledge of this compound, e.g., the information contained in U.S. Pat. No. 0165.9^4· it is reasonable to expect similarly good performance for other types of compounds included herein. As an alternative to the flooded upflow reactor type shown in the figure, reactor 11 may be operated as a continuous liquid phase reactor in any other more convenient manner, for example, as a downflow flooded packed bed reactor. The following example illustrates the implementation of the present invention. Example A two-reactor system is used as shown in the figure, which has a capacity to produce approximately 10 ... In the first reactor, corresponding to reactor 10 in Figure 1, 11 kg mol / hr of phosgene and 10 kg mol / hr of n-propyl mercaptan are fed. A recycle stream containing approximately 5 kg mol / hr of phosgene and approximately 2.2 kg mol / hr of n-propyl chlorothioformate is also fed into reactor 10. The reactor is operated at an inlet temperature of approximately 15–40°C, an outlet temperature of approximately 40–55°C, and an outlet pressure of approximately 1.8–2.1 kg / cm* effective. Partially reacted products from the first reactor are sent to the lower portion of the reactor. Second reactor. The second reactor is operated at an inlet temperature of approximately 40-55°C and an outlet temperature of approximately 40-55°C, an outlet pressure of approximately 1.5-3.8 kg / cm³, and a residence time of approximately 75 minutes. The conversion of n-propylmercaptan to chloroform is 94%. The product is produced with a purity of 98-99%.

Claims

CLAIMS 1. Process for producing chlorothioformate having the formula RS^Cl in which R is alkyl, inf. there. cloalkylmethyl, lower cycloalkyl, lower alkenyl, chloro-substituted phenyl / enyl, benzyl or alkyl chlorosubstituted, wherein the substituent chlorine is located at least as far apart from the sulfur atom as the gamma carbon atom, the which process comprises: a) contacting a mercaptan having the formula RSH with phosgene in a first continuous liquid phase reaction zone in the presence of a catalyst comprising activated charcoal; b) removing a first reaction product from 3. the first of reaction zone; c) contacting the first reaction product with a catalyst comprising activated carbon in a second continuous liquid phase reaction zone; and d) removing a second reaction product comprising cyprothioformate from the second reaction zone.

2. Process according to claim 1, wherein R is alkyl.

3. Process according to claim 2, wherein R is alkyl having from 1 to 10 atoms. carbons 4. Process according to claim 2, wherein R is alkyl having from 1 and atoms of. carbon r. wherein 5. Process according to R is n-propyl. claim 4, wherein 6. The process according to R is cycloalkyl. claim 1, wherein the process according to R is cyclohexyl. claim 6, wherein 8. Process according to R is benzy. claim 1, wherein 9. The process according to R is phenyl. claim 1, in the 10th process according to claim 3, wherein R is chloro-substituted phenyl." 11. Process according to claim 10, wherein R is p-chlorophenyl. 1.2., Process according to claim 1, wherein the operation (c) is carried out at an average outlet temperature between about 0 and. about ?0°C.

13. A yield according to claim 1, wherein operation (c) is performed at. an average outlet temperature of between about 10° and about >0°C. below about 50°C.

15. A process according to claim 1, wherein step (c) is carried out at a residence time of between about 3 and about 180 minutes.

16. Process according to claim 15, wherein step (c) is carried out at a residence time of between about 45 and about 180 minutes. 1?. Process according to claim 1, wherein an excess of liquid phosgene is introduced in step (a). The process according to claim 1, wherein an excess of liquid phosgene is introduced in step (c). The method of claim 1 further comprising recovering unreacted starting materials from the. product of operation (d) ©d the recycling of said starting water oils which have not reacted to operation (c)c 20. Process according to claim 1, further comprising the recovery of the starting materials which have not reacted from the product of 'ope. ration (d) and the recycling of said starting materials which did not react to operation (a). The process according to claim 1 further comprising recovering chlorothioformate from the products of step (d).

22. Process according to claim 1, wherein operation (c) is carried out by introducing the first reaction product into the lower portion of a. packed bed reactor containing an activated carbon catalyst bed.

23. A process for the production of alkylchlorothioformate by the reaction of an alkyl mercaptan with phosgene in the presence of a catalyst including activated carbon in a system comprising two reactors operating in series, in the. which process the second reactor is operated as a continuous liquid phase reactor.

24. The process according to claim 2 wherein the second reactor is operated as an upflow and flood packed bed reactor.

25. The process according to claim 25 wherein the alkyl merceptane and the alkyl Xoro~fcioforala, to have from 1 to 6 carbon atoms in the alkyl group 26. Process according to claim 25, wherein the alkyl group is n-propyl and p.p. STAUEEER CHEMICAL COMPANY 78903 SIB / U831ÌΑ / 78 p.p. STAUFFER CHEMICAL COMPANY