Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01K—ELECTRIC INCANDESCENT LAMPS
  • H01K1/00—Details
  • H01K1/50—Selection of substances for gas fillings; Specified pressure thereof
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
  • C07F7/24—Lead compounds

Definitions

• This invention relates to a catalytic process for the manufact re of alkyllead compounds.
• the process employed in present commercial practice for the manufacture of tetraethyllead has been in use for a number of years and, in general, is satisfactory. However, it has certain disadvantages which are overcome by practicing our invention.
• the present commercial process proceeds by reacting a sodium-lead alloy, of composition controlled to correspond substantially to NaPb, with ethyl chloride according to the following equation:
• a further object is to produce tetraethyllead and related compounds by a process which can convert a surprisingly large amount of the lead charged to the reaction into the desired end product, thereby avoiding the expensive reprocessing of large quantities of lead.
• Another object is to increase substantially the yield of tetraethyllead while using the existing equipment of the present commercial process.
• a still further object is to produce tetraethyllead in large quantities, without the consumption of correspondingly 1arge quantities of metallic sodium.
• alkyllead compounds can be produced by the alkylation of sodium-lead alloys having a wide range of sodiumto-lead ratios, provided these alloys contain sufficient magnesium to activate them.
• the proportion of lead converted to alkyllead compounds can be controlled within an unexpectedly broad range.
• the amount of sodium required for any given yield of alkyllead compound can, if desired, be considerably less than that to which the present commercial process is limited.
• Such high efficiencies in the use of these metals may be at the expense of the alkyllead yield, but this, under some condigreater importance than high lead utilization.
• our ternary alloys have a composition such that the subscript b is at least 0.2 but less than 3, and the sum of the subscripts a and b varies between the limits of about 0.5 and 3.
• a and b can be varied independently within the limits prescribed for their sum.
• a ternary alloy of sodium, mag-v nesium and lead in which the sum of a and b is less than about 0.5 contains more than 94.5 parts by weight of lead per 100 parts of alloy.
• Such alloys resemble metallic lead in their physical properties, in that they possess high malleability and ductility and are difficult v to comminute. For these reasons, alloys in' which I of alkyllead compounds generally, such as tetra- I of the present commercial process.
• This invention is adaptable to the production ethyllead, tetramethyllead, dimethyldiethyllead, triethylphenyllead and tetrapropyllead. Nevertheless, for convenience, specific reference hereinafter will be made to tetraethyllead, the most widely known alkyllead compound. Whenever in the following description this material is referred to,- it is to be understood that other alkyllead compounds and mixtures thereof, are .also intended, in the same manner as though specifically referred to. Further, whenever in the following descriptionreference'is made. to ethyl chloride as the ethylating agent, it is to be understood that other ethylating and alkylating agents canbe-substituted therefor or used-in. admixture therewith. a
• our invention is practiced as follows: the comminuted ternary alloy consisting of the magnesium-activated sodium-lead alloy is placed in a reaction vessel such as the autoclave The vessel is then closed except for the liquid feed line through which the fluidv reactants are passed. The necessary quantity of an alkylating agent such as ethyl chloride is then introduced into the autoclave, followed by delivery 'of a catalyst such as diethyl ether, or: the latter can be added along with theethyl chloride. In the former method, the time interval between the addition oi? the alkylating agent and the catalyst can be short or long.
• Variations in the above processes can be made. such as introducing part of the catalyst along with the initial feed of the alkylating agent, followed by additional catalyst. Also, while it is possible in our two-stage process to add only a limited amount of alkylating agent for the first non-catalytic stage and then add an amount s-u-flicient to complete the. reaction in the second stage, it is possible to. add most or all of the alkylati-ng agent in the first stage. It should be noted that while the. presently used commercial process proceeds to completion without a catalyst and is essentially non-catalytic, our reaction is essentially catalytic and requires a catalyst for the full utilization of the alloy.
• Example I One stage reaction using sodium-magnesiumlead alloy, ethyl chloride and other: A charge of 100 parts. of sodium-magnesium-lead alloy consisting of 9.5 parts sodium, 5.7 parts magnesium and 84,8 parts of lead is added to the reaction vessel equipped with an agitator, a jacket for circulation of heating or cooling liquids, a reflux condenser, charging and discharging ports, liquid feed lines, and means for releasing the pressure. A mixture of alkylating agent and catalyst: consisting of 130 parts of liquid ethyl chloride and 5 parts of other is added under pressure to the stirred alloy in the vessel over a period of one-half hour.
• the temperature of the reaction mass is permitted to risefrom the initial temperature of 50 G; to a temperature of 85 C. during this feed.
• the pressure in the autoclave during this period is allowed to rise to about 85 pounds per square inch gauge.
• the stirred reaction mass is maintained at a temperature of 85 C. and a pressure of 85 pounds for an additional two and one-half hours. This period is referred to as the cooking period.
• the pressure in the autoclave is reduced to atmospheric by venting for 15 minutes, while the temperature is maintained at 85 C.
• nitrogen is passed over the reaction mass while the autoclave is open to the atmosphere. With a stream of nitrogen passing through the reaction vessel the mass is cooled to C. over an additional 30-minute period. Thus a total reaction time of fourhours is employed.
• the reaction mass is then discharged from the reac-- tion vessel and steam distilled or otherwise treated to recover the alkyllead product.
• yield of product is 66.2 parts, or a yield of Expressed in another way, the yield is 94% based on the combined sodium and magnesium present in the sodium-magnesium-lead alloy.
• Two-stage reaction using sodium-magnesium! lead alloy, ethyl chloride, and ether Using sub.-v stantially the same operating procedure as d e-H scribed in the above example, a two-stage modification is carried out by adding 100 parts of a sodium-magnesium-lead alloy consisting of 9.6 parts of sodium, 5.6. parts of magnesium and 84.8 parts of lead, with the variation that. all the ethyl chloride is added to the. system while the temperature is permitted to rise to 70 C. After a total contact time of one hour with ethyl chloride alone, 5 parts of. other is added and heating is continued to maintain the temperature at 70 C. for an additional hour.
• Example I The cooking, venting, cooling, discharging and recovery of the product are continued as in Example I.
• the total yield of product is, 5.1.6 parts, or 39%.. It is 73%, based on the total amount of sodium and magnesium present in the sodium-magnesium-lead alloy.
• Example HI Using substantially the same operating procedure as described in Example I, a one-stage modification of our process was carried out, with the. variation that the amount of, catalyst employed is 15 parts per parts of alloy.
• the alloy composition consists of 610* parts of sodium, 15.0 parts. of magnesium, and 79.0 parts of lead.
• Example I V- Example I is repeated for a period of four hours at a temperature of 70 C. using 100 parts of an alloy consisting of 0.5 partof sodium, 102 parts of magnesium and 89.3 parts of lead, in the presence of 5 parts of ether. With this alloy the yield of product is 48.4 parts, or 34.7 per cent.
• Example V 75 This may be accomplished by first mixing toing them continuously through a reactor under suitable reaction conditions.
• the yields obtained with each alloy are listed in columns 4 through 7.
• the yields tabulated in columns 4 and 5 represent the percentage of the lead present in the alloy which is converted to alkyllead compound, while columns 8 and 7 give the yield on the basis of the combined amount of sodium and magnesium present in the alloy.
• a series of examples was carried out for the alloys in the table, simi lar to working Example I.
• a similar series of examples was conducted for the alloys, but the catalyst was omitted.
• columns 4 and 6 list the yields obtained without the'catalyst
• columns 5 and 7 list the yields obtained with the catalyst.
• the conditions employed for the catalytic reaction were as follows: 100 parts of the ternary sodium-magnesium-lead alloy was reacted for four hours at a temperature of 70 C. with approximately 210 parts of ethyl chloride and 5 parts of diethyl ether. The non-catalytic results were obtained under identical conditions and with identical quantities of alloy and ethyl chloride, but in the absence of the diethyl ether.
• While our invention is not restricted to any particular class or classes of catalyst, we have found that organic compounds containing an atom capable of chemical coordination with magnesium are particularly eflective. Among these compounds are ethers, organo-ammonium derivatives, and amines.
• the amount of catalyst is not critical, and may be varied within wide limits, for instance, from 1 to 100 parts of catalyst to 100 parts of lead present in the alloy.
• ethers examples include diethyl ether, methylethyl ether, dipropyl ether, dibutyl ether, dihexyl ether, dimethyl ether of ethylene glycol, 1,4-dioxane and anisole.
• ethers as the catalyst and particularly the lower alkyl ethers, from methylethyl through dihexyl ether.
• organo-ammonium derivatives are tetraethylammonium iodide, trimethylethylammonium iodide and the like.
• amines which may be used are triethylamine, trimethylamine, and dimethylaniline. It is to be understood that combinations of the above and related catalysts can be employed with good results.
• alkyllead compound of 18.9, 43.1, 41.6, 47.7, 41.4, and'32.6 per cent were obtained under the same conditions with an alloy consisting of 9.6 parts of sodium, 5.6 parts of magnesium and 84.8 parts oflead, and in the presence of 0, 2, 5, 15, 50 and 100 parts of diethyl ether respectively.
• alkylating agents can be employed in our process.
• the alkylating agents of our invention may be any of those described in the prior art such as alkyl chlorides, alkyl bromides and alkyl iodides.
• other alkylating agents such as the alkyl phosphates, for example, triethyl phosphate, may be used.
• our alkylating agents are those esters of inorganic acids capable of reacting with the sodium and magnesium in the ternary alloy and having the desired alkyl groups.
• the inorganic acid ester alkylating agents are the mono-chloro, -bromo and -iodo derivatives of the paraffin hydrocarbons such as methane, ethane, propane, butane and pentane, the corresponding trialkyl phosphates, .etc.
• the paraffin hydrocarbons such as methane, ethane, propane, butane and pentane
• the corresponding trialkyl phosphates .etc.
• n-amyl iodide and triethyl phosphate can-be successfully employed. Instead of or in admix- "9 ture with the normal alkyl halides, their isomers may be used. Various combinations of two or more alkylating agents may be used in the oneand two-stage processes.
• the alkylating agents of our proce s s ould be employed in excess of the amount required by the above-described eduation descripti e of our process. If less than the amount of alkylating agent required to completely alkylate the lead according to the above equation is used. the yield will be lower, .but will still be good when determined on the basis of the amount of alkylatin'g agent.
• a series of example was conducted in which 100 parts of a ternary alloy; consisting -of 0.6 parts of sodium, 5.6 parts of magnesium and 84.8 parts of lead. w a's heated for four hours a temperature of 70 C. with 3-0.
• the alkylating agent as a liouid. and to conduct our alkylation reaction in the liquid phase.
• the pressure within the autoclave is maintained within the range of about 70 to 125 pounds per square inch.
• the catalyst preferably is fed into the autoclave in the liquid phase under pressure. If desired the alkylating agent and catalyst can be mixed, and the mixture introduced under pressure into the autoclave.
• temperatures in the neighborhood of 70 C. may be employed in both the one-stage and two-stage operations with excellent results.
• the preferred embodiment of our invention is the manufacture of tetraethyllead.
• the amount of sodium is less than 14 weight per cent
• the amount of magnesium is within the limits of 2.5 and 20 weight percent
• the amount of lead is within the limits of 75 and 90 weight per cent.
• our preferred catalyst for the manufacture of tetraethyllead is a lower alkyl ether, and in particular we prefer to employ diethyl ether in amounts ranging from 2 to 30 parts by Weight per 100 parts of ternary alloy.
• Our preferred reaction temperature for tetraethyllead production is between 60 C. and 85 C. at
• reaction time of about 1 to 5 hours.
• a process for making lead alkyl compounds which comprises alkylating a sodium-magnesiumlead alloy containing more than 0.2 atom of magnesium for each atom of lead in the presence of an alkylating catalyst having an atom which chemically coordinates with magnesium.
• a process for making lead alkyl compounds which comprises alkylating a sodium-magnesiumlead alloy having a composition corresponding to NaaMgbPb in which the sum of a and b is within 12 the limits of approximately 0.5 and 3, and b is a least 0.2 in the presence of an alkylating catalyst having an atom which chemically coordinates with magnesium.
• a process for making lead alkyl compounds which comprises alkylating a sodium-magnesiumlead alloy having a composition corresponding to NaaMgbPb in which the sum of a and b is within the limits of approximately 0.5 and 3, and b is at least 0.2, said reaction being conducted at a temperature between approximately C. and 100 C., for a time between approximately one-half hour and 8 hours in the presence of an alkylating catalyst having an atom which chemically coordinates with magnesium.
• a process for making tetraethyllead whic comprises ethylating in the presence of a lower alkyl ether a sodium-magnesium-lead alloy having a composition corresponding to NasMgbPb in least 0.2, said reaction being conducted at a tem-'.
• a process for making tetraethyllead which comprises reacting an excess of ethyl chloride' in' the presence of diethyl ether with a sodiummagnesiumdead alloy in which the percentages by weight are less than 14 for sodium, between about 2.5 and 20 for magnesium, and between about and 90 for lead, said reaction being conducted at a temperature between about 60 C.-

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• 0
  • NL NL71969D patent/NL71969C/xx active
• 1949
  • 1949-07-28 US US107385A patent/US2535191A/en not_active Expired - Lifetime
  • 1949-10-11 GB GB26064/49A patent/GB673997A/en not_active Expired
  • 1949-10-14 FR FR997608D patent/FR997608A/fr not_active Expired
  • 1949-11-03 DE DEE213A patent/DE875355C/de not_active Expired

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