Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/361—Preparation of halogenated hydrocarbons by reactions involving a decrease in the number of carbon atoms

Definitions

• ABSTRACT Process for the continuous manufacture of carbon tetrachloride from benzene or mixtures of benzene with chloro-substituted aromatic or aliphatic hydrocarbons and chlorine wherein the chlorination is first carried out in the liquid phase in a reaction zone containing hexachlorobenzene and then continued in a second reaction zone in the gaseous phase.
• the present invention relates to a process for the manufacture of carbon tetrachloride.
• the present invention provides a process for the continuous manufacture of carbon tetrachloride by reacting benzene or a mixture of benzene with chlorosubstituted aromatic or aliphatic hydrocarbons with chlorine which comprises passing the starting products at a temperature of from 100 to 350C and under a pressure above atmospheres gauge through a prereaction zone containing liquid hexachlorobenzene or a solution of hexachlorobenzene and then reacting the reaction components in a second main reaction zone under the same pressure and at a temperature of from 350 to 800C in the gaseous phase to carbon tetrachloride.
• the process of the invention offers the further advantage that by the rapid distribution of the hydrocarbons in the liquid sump of prereaction zone.
• the liquid sump in the prereactor should consist of hexachlorobenzene or a solution of hexachloroben-,
• the solution may additionally contain low chlorinated benzenes, such as mono-, di-, tri-, tetra-, or pentachlorobenzenes.
• the starting product contains diphenyls or terphenyls the sump may consist partially or substantially of highly chlorinated diphenyls.
• highly chlorinated compounds of this type may also be contained in the prereactor. In this connection, it should be mentioned that under the reaction conditions highly chlorinated naphthalene is readily transformed into perchloro-indene.
• the sump product of the prereactor may consist partially or substantially of the very stable.
• hexachlorocyclopentadiene Even if short-chain aliphatic compounds are used, a small amount of hexachlorobenzene is formed by cyclization during the course of reaction which remains at first in the prereaction zone.
• the liquid in the prereactor containing hexachlorobenzene should be at a temperature in the range of from to 350C.
• the starting temperature in the prereaction zone should be at least 227C, i.e. the melting temperature of hexachlorobenzene.
• the temperature may be reduced since the admixture of chlorine and partially chlorinated hydrocarbons reduces the melting temperature of hexachlorobenzene to an extent such that even at temperatures down to about lOOC.th'e presence of liquid in the prereaction zone is ensured.
• the lower temperature strongly depends on the amount and entraining effect of the introduced chlorine and also on the type of the carbon-containing materials used so that the melting points of the lowest eutectic mixtures may be reached.
• hexachlorobenzene may be introduced into the prereaction zone or it may be produced therein.
• the reactor is operated, for example, with a small load (up to about 0.5 mole of benzene per liter of reaction space and per hour) and a high excess of chlorine (more than 100 of the amount of chlorine stoichiometrically required for the formation of carbon tetrachloride).
• a lower temperature in the main reaction zone, whereby a lower amount of hexachlorobenzene is further chlorinated and a greater amount remains in the prereaction zone may be of advantage for as rapid as possible a build-up of the liquid level in the prereaction zone.
• Benzene or the mixture of the wholly or partially chlorinated aromatic or aliphatic hydrocarbons and chlorine are pumped into the reactor in the liquid state 3 and mixed at the beginning of the prereaction zone. In most cases cooled chlorine is pumped at low temperature into the prereaction zone. If the temperature in the reactor shall be increased, the chlorine may be warmed up. In general, the hydrocarbon mixture is pumped as liquid at room temperature into the prereaction zone. If, however, chlorinated hydrocarbons having a high melting point are used, for example hexachloroethane, the mixture must be preheated above its melting point.
• the prereaction zone may have various constructions. There may be used, for example, a tube mounted directly in front of the reactor and heated to the desired temperature from outside by means of a special heating device, for example with high pressure steam, an oil bath or a salt bath, or an electric heating. It is also possible to install the prereaction zone directly in the reactor in the form of a tube which ensures a better utilization and additional control of the reaction heat. A further variation consists in using a longer tube reactor the lower part of which serves as prereactor and maintaining therein the specified temperature of from 100 to 350C. Other designs of the prereaction zone, different from those described above, may also be chosen to maintain the desired temperature range and to mix the starting products.
• the reaction mixture passes from the prereaction zone into the main reaction zone where it is transformed into carbon tetrachloride under the same pressure and at temperatures in the range of from 350 to 800C, preferably 550 to 700C.
• the pressure in the prereaction zone and in the main reaction zone should be above 20 atmospheres gauge, a pressure in the range of from 80 to 300 atmospheres gauge being preferred.
• the pressure is produced by means of fluid pumps and maintained constant by a relief valve.
• the gas mixture the pressure of which has been wholly or partially released is separated by known methods such as distillation, fractionating condensation, or extraction. Chlorine and hexachlorobenzene still contained in the reaction gas after pressure release may be recycled. After separation of hydrogen chloride, chlorine and hexachlorobenzene, the carbon tetrachloride formed is practically free from by-products. Assuming the hexachlorobenzene is conducted in a cycle and transformed into carbon tetrachloride, the yields are almost quantitative.
• EXAMPLE 1 The reaction was carried out in a vertical steel tube having good high temperature characteristics and lined with nickel. The tube had a length of 3,300 mm and an internal diameter of 52 mm. The reaction components chlorine and the organic compounds were pumped at room temperature into the lower end of the reactor. The reaction mixture was withdrawn at the head of the reactor. At the head of the reactor a relief valve was mounted to maintain in the reactor a pressure of 80 atmospheres gauge. The released reaction gases were cooled first at atmospheric pressure in separators and then in cooling traps, and condensed. The reactor was heated by means of two electric jack heatings. The lower jacket heating reaching to a height of 1,000 mm was heated to at most 250C, the temperature being measured by an internal thermo-element.
• This lower section including a reactor volume of 2 liters was the prereaction zone.
• the upper jacket heating was adjusted so that the internal temperature of the reactor was in the range of from 590 to 600C.
• This upper section including a reactor volume of 4.6 liters represented the main reaction zone.
• the reactor Prior to heating, the reactor was charged with 2 kilograms of hexachlorobenzene. After having heated the prereaction zone to the specified temperature by the electric jacket heating, the reaction components were pumped in in an amount of 475 grams of benzene per hour, corresponding to 6.1 moles and 9,959 grams of chlorine per hour, corresponding to moles, i.e. an excess of 53 After a time of reaction of 5 hours the temperature, pressure and flowing conditions in the reactor were constant. In a separator in the form of an empty vessel having a capacity of 10 liters, which was operated at atmospheric pressure and had no special cooling means, the hexachlorobenzene was separated.
• EXAMPLE 3 The reaction was carried out in the reactor described in Example 1, the temperature in the main reaction zone being 600C. The pressure in the reactor was maintained at 240 atmospheres gauge.
• EXAMPLE 4 The reaction was carried out as described in Example 2. During the first hour of operation 78 grams of benzene and about 1,700 grams of chlorine were pumped in. At a temperature of from 650 to-660C in the main reaction zone the reactor was then fed per hour with 1,100 grams of a mixture consisting of 5.5 of benzene,
• EXAMPLE 5 The reaction was carried out as described in Example 2. During the first hour of operation at a reactor temperature of 650 to 660C, 110 grams of a mixture of 5.5 of benzene,
• EXAMPLE 7 The reaction was carried out in the apparatus described in Example 1 under the pressure specified in that example. The temperature in the reactor was 600C. The chlorination was started by pumping in 79 grams of benzene and about 2.5 kilograms of chlorine over a period of 1 hour. Then 1,410 grams of a mixture of 20 of benzene,
• EXAMPLE 8 The apparatus used was the same as that in Example 1. The reaction was carried out under a pressure of 80 atmospheres gauge at a temperature of 600 to 610C in the hottest section of the reactor. During the course of 1 hour there were introduced 90 grams of a mixture consisting of 5.0 of benzene 9.5 of carbon tetrachloride 60.8 of hexachloroethane 1.9 of pentachloroethane 18.0 of tetrachloroethylene 1.8 of trichloroethylene and 6.0 kilograms of chlorine.
• Chlorine was cooled at 12C prior to entering the pressure pump and, after increase in pressure to 80 atmospheres gauge, it streamed into the prereaction zone at a temperature of about 0C.
• the amount of premixed starting mixture was increased to 2,860 grams per hour, while the amount of chlorine remained unchanged.
• the reaction conditions were constant after an operation period of 6 hours.
• the temperature in the prereaction zone measured 10 cm above the mixing point of the reaction components, was 190 to 200C and the wall temperature in this section was to C.
• EXAMPLE -9 The reaction of Example 8 was repeated under a pressure of 260 to 280 atmospheres gauge under the same temperature conditions. The amounts of hydrocarbon mixture and of chlorine were tripled. There were obtained per hour 15.3 kilograms of carbon tetrachloride and 450 grams of hexachlorobenzene. Calculating the conversion of the chlorinated hydrocarbons to be 100 the conversion of benzene was 70 7 The space-time-yield was 3,320 grams of carbon tetrachloride per liter per hour.

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• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (5)

• 1969
  • 1969-12-29 NL NL6919490.A patent/NL167407C/xx not_active IP Right Cessation
• 1970
  • 1970-01-12 CS CS22270*#A patent/CS153059B2/cs unknown
  • 1970-01-21 US US004747A patent/US3928479A/en not_active Expired - Lifetime
  • 1970-01-21 GB GB2912/70A patent/GB1294761A/en not_active Expired
  • 1970-01-27 CH CH114670A patent/CH518889A/de not_active IP Right Cessation
  • 1970-01-28 AT AT78770A patent/AT294789B/de not_active IP Right Cessation
  • 1970-01-28 ES ES375973A patent/ES375973A1/es not_active Expired
  • 1970-01-28 BR BR216343/70A patent/BR7016343D0/pt unknown
  • 1970-01-28 JP JP45007120A patent/JPS5022011B1/ja active Pending
  • 1970-01-29 PL PL1970138464A patent/PL80454B1/pl unknown
  • 1970-01-29 CA CA073,416A patent/CA953738A/en not_active Expired
  • 1970-01-30 BE BE745272D patent/BE745272A/xx unknown
  • 1970-01-30 FR FR707003309A patent/FR2029719B1/fr not_active Expired

Patent Citations (5)

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