US3254008A - Process for the electrolytic production of tetramethyl lead - Google Patents

Process for the electrolytic production of tetramethyl lead Download PDF

Info

Publication number
US3254008A
US3254008A US196586A US19658662A US3254008A US 3254008 A US3254008 A US 3254008A US 196586 A US196586 A US 196586A US 19658662 A US19658662 A US 19658662A US 3254008 A US3254008 A US 3254008A
Authority
US
United States
Prior art keywords
aluminum
lead
tetramethyl
electrolyte
compound
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US196586A
Other languages
English (en)
Inventor
Ziegler Karl
Lehmkuhl Herbert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZIEGLER AG
Original Assignee
ZIEGLER AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ZIEGLER AG filed Critical ZIEGLER AG
Application granted granted Critical
Publication of US3254008A publication Critical patent/US3254008A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/01—Products
    • C25B3/13—Organo-metallic compounds

Definitions

  • a number of processes are known which permit the production of metal alkyl compounds, particularly tetraet-hyl lead and metal alkyls containing higher alkyl groups, by electrolysis with the use of, for example, lead anodes and preferably with the use of aluminum-organic complex compounds'serving as electrolytes.
  • these processes include those disclosed in U.S. Patent 2,985,568, U.S. Patent 3,069,334, application Serial No. 262,285, filed February 4, 1963, U.S. Patent 3,164,538, application Serial No. 258,102, filed February 4, 1963, application Serial No. 320,607, filed October 29, 1963.
  • the invention does not only take advantage of the fact that electrolyte complex compounds containing methyl groups can be produced by the process mentioned above but also provides a novel electrolytic process for the production of tetramethyl lead by combination with other essential features, this process constituting a technical progress.
  • the electrolytic process is operated with electrolyte baths which consist of solutions containing aluminum complex compounds of the general formula MeAl(CH (OR')
  • suitable solvents include inert polar solvents, particularly inert, polar organicsolvents such as tertiary amines or ethers, the latter being preferred.
  • Aromatic hydrocarbons may also be used to a limited extent.
  • Particularly preferred solvents are open-chain or cyclic ethers, particularly suitable being cyclic ethers, especially those of the te-trahydroifu'rane type.
  • Other cyclic and straight-chain ethers such as d-iox-ane, diethyl ether, dibutyl ether; polyethers such as ethylene glycol-dialkyl ether and the like, may also be used in the process of the invention. It may be desirable to use relatively high-boiling solvents, particularly those having boiling points higher than that of tetramethyl lead.
  • Particularly suitable solvents are tetrahydrofurane or its homologues. Electrolyte solutions prepared with their exhibit surprising characteristics. If, for example, a solution of NaAl(OH in tetrahydrofurane is subjected to electrolysis, it is found that this solution has an approximately constant conductivity with a miximum of conductivity at medium concentrations. The conductivity drops greatly only with very dilute solutions. This situation is illustrated by the data in the following Table I.
  • the most favorable range of concentrations for the electrolysis in the system described is between about 40 and about gms. of aluminum-organic complex compound per 100 ml. of tetrahydrofurane.
  • the solubility of the potassium compound is somewhat lower than that of the sodium compound in tetrahydrofurane.
  • the amount of NaAl(CH dissolved in 100 ml. tetrahydrofurane is 67.2 gms. at 100 C. and 54.7 gms. at 66 C.
  • only about 40 gms. of the corresponding potassium-aluminum tetramethyl compound are dissolved in the same amount of solvent at 66 C.
  • the conductivity of the dissolved potassium complex compound is higher than that of the dissolved sodium complex compound at the same concentration. Comparative-data are listed hereafter in Table II.
  • solutions of these aluminum complex compounds are decomposed at a mercury cathode with formation of potassium amalgam at the cathode, then it is found that such undesirable reaction between anodic decomposition products and the amalgam liberated at the cathode does not longer occur. This is due to the fact that the solvent present, e.g., tetrahydrofurane, immediately combines with the free aluminum trimethyl liberated at the anode to form the corresponding tetral1ydrofuranate.' This addition product is substantially less reactive with potassium amalgam than is free aluminum trimethyl.
  • free aluminum trimethyl is formed as a dissociation product of the electrolyte in addition to tetramethyl lead.
  • free aluminum trialkyls react with alkoxyaluminum complex compounds of the general formula MAIRgOR with reformation of the aluminum tetraalkyl complex compound and simultaneous formation of the free alkoxy aluminum dialkyl compound.
  • MAIRgOR alkoxyaluminum complex compounds of the general formula MAIRgOR with reformation of the aluminum tetraalkyl complex compound and simultaneous formation of the free alkoxy aluminum dialkyl compound.
  • dialkyl aluminum alkoxy compound is then isolated in free state in addition to tetramethyl lead.
  • This procedure is applied in one embodiment of the process of the invention.
  • This embodiment may entail several advantages.
  • it is possible by variation of the alkoxy group to adjust the boiling point of the free alkoxy aluminum compound formed in addition to tetramethyl lead in a manner such as to permit easy separation of the two compounds by distillation.
  • regeneration may under certain circumstances be effected easier and with less troubles when proceeding via these dialkyl-aluminum alkoxy compounds than via aluminum trialkyls.
  • This variation of the process of the invention may also be modified in a manner such that the electrolysis is effected with the altuninum tetramethyl complex compound alone while the reaction with the alkoxy-aluminum complex compounds in the sense described is carried out subsequently, e.g., outside the electrolytic cell.
  • boron tetraalkyl complex compounds of the general formula MBR can be used in the electrolytic production of metal alkyls.
  • the alkali metal-boron tetramethyl complex compound MB (CH is mixed with the.
  • the aluminum complex compound MAl(CH (OR') used in accordance with the invention is used together with the alkali metal-boron tetramethyl compound in one embodiment.
  • This also results in the formation of the product mixture of tetramethyl lead and free alkoxy-aluminum dimethyl already described for the case of aluminum complex mixtures.
  • the boron complex compound remains unchanged and stationarily in the cell, i.e. it quasi acts only as a conducting salt while the aluminum alkoxy complex compound is decomposed and continually supplied to the cell.
  • a special embodiment of the invention combines known and novel characteristics into a novel process which permits the electrolytic production of tetramethyl lead with best results in spite of the presence of a solvent in the electrolyte and the concomitant difficulties encountered in separating tetra-methyl lead from the mixture of substances produced during electrolysis.
  • electrolytes which contain aluminum complex compounds wherein m reaches a value of at least 3, i.e., compounds where m is 3 and/or 4.
  • the preferred electrolyte is a liquid mixture containing up to 950 parts by weight of the electrolyte complex compound in 100 parts of tetrahydrofurane, particularly preferred being the above-mentioned relative proportions Where maximum conductivity is obtained.
  • the electrolysis is then effected at a temperature in the range between about 50 and about 100 C.
  • the procedure used in recovering the tetramethyl lead and regenerating the electrolyte is determined by the nature of the electrolyte bath used.
  • Tetramethyl lead may be withdrawn from the electrolyte in a very simple manner by distillation, particularly by distillation in vacuo. This may be done either in the cell itself by using electrolysis in the vacuum cell as repeatedly described in earlier suggestions of applicant or after the electrolysis 'in a separate reaction step.
  • hydrocarbon is isooctane. While tetramethyl lead is then obtained only in mixture with, for example, the same amount of this hydrocarbon, this mixture is just as suitable for use as antiknock compound as is pure tetramethyl lead itself.
  • the addition compound aluminum trimethyl-tetrahydrofuranate is formed as was already mentioned. This compound is very stable and boils Without decomposition at 90 to 91 C./13 mm. Hg, i.e., about 80 to 90 C. above the boiling point of tetramethyl lead. Therefore, the separation of tetramethyl lead by distillation is accomplished without any difficulty.
  • the electrolyte is then regenerated by mixing it with sodium and introducing methyl chloride. In doing so, the tetrahydrofurane necessary to dissolve the electrolyte is liberated from its combination with aluminum trimethyl.
  • the reaction is preferably effected at a temperature between 50 and 160 C. in accordance with the following equation:
  • this oxygen-containing complex compound is added in an amount just suflicient that the free aluminum trimethyl which is formed is immediately reconverted into the tetramethyl complex compound and the compound Al (CH 0R is formed.
  • the regeneration i.e., the reaction with methyl chloride in a sodium suspension then proceeds via this oxygen-containing aluminum compound which does not entail any difi'lcultly.
  • oxygen-containing complex compounds in which the OR group contains a sufiiciently high number of carbon atoms, e.g., more than 3 and preferably from 6 to 10. This will shift the boiling point of the free alkoxy aluminum dimethyl compound in a manner such that easy separation from the tetramethyl lead by distillation becomes possible.
  • alkali metal dissolved in mercury
  • potassium amalgam in case of potassium-containing electrolytes
  • the potassium amalgam may also be converted into sodium amalgam by exchange with sodium containing electrolytes.
  • Example 1 The electrolytic apparatus used for the experiments described hereafter comprised a cylindrical glass vessel having a surface-ground upper edge and a capacity of 1 liter.
  • the vessel was sealed on top with a plane cover of an insulating plastic material (Bakelite).
  • the cover was provided with openings for inserting a thermometer and the lead-in wire for the cathode, a screwed-in socket with ground joint for mounting a reflux condenser, a nozzle for passing over a protective gas and the stirrer bearing for the rotary lead anode.
  • the bottom of the glass vessel contained a mercury pool of 300 ml. Provided above the mercury surface at a distance of about l mm. was the lead anode which was a circular lead disc of 15 mm. thickness and 6 cm.
  • This disc simultaneously served as the stirrer for the electrolyte and, therefore, was equipped at its border with a plurality of inclined blades.
  • the lead disc was screwed into a vertical hollow shaft. Inserted into the bore of this shaft was a glass stirrer which stirred the mercury at a speed of rpm. while the lead anode rotated at a high speed.
  • a solution of 200 gms. N-aAl(CH in 400 gms. of tetrahydrofur-ane was introduced into this cell under a protective gas atmosphere and the electrolysis was effected for 7 hours at 90 C. and a terminal voltage of 5.5 v. with 3.8 amperes, i.e.,14 a./dm.
  • reaction solution was removed from the electrolytic cell by siphoning and tetrahydrofur-ane and tetramethyl lead formed were distilled off into a cooled receiver while gradually raising the temperature of the oil bath from 70 to 90 C. and finally applying a vacuum of 20 to 30 mm. Hg.
  • aluminum trimethyltetrahydrofuranate was distilled off at 90 to 91 C. and 13 mm. Hg.
  • the distillation residue consisted of NaA1(CH3)4 and could be reused for another electrolysis after dissolution in tetrahydrofurane which had been separated from the tetramethyl lead by distillation with a 50 cm. Vigreux column.
  • the residue obtained after having distilled off the tetrahydrofurane is substantially pure tetramethyl lead which may be subjected to another purification by steam distillation.
  • Example 2 A solution of 200 gms. NaAl(CI-I in 400 ml. of tetrahydrofurane is subjected to electrolysis underthe conditions and in the apparatus described in Example 1. A solution of 224 gms.
  • the alkoxyaluminum dimethyl may be reconverted with sodium in finely divided form and methyl chloride into by the process of Serial No. 193,330, filed May 8, 1962 (process for the production of sodium-organic complex compounds of aluminum and boron) and re-used for another electrolysis.
  • the residue from distillation is pure NaAl(CH which is dissolved in 400 gms. of recovered tetrahydrofurane and used as electrolyte for another electrolysis.
  • Example 3 A solution of 220 gms. NaAl(CH in 400 guns. of tetrahydrofurane was electrolyzed for about 14 hours at 100 C. and 3.8 a. (i.e. about 15 a./dm. in the apparatus described in Example 1. A terminal voltage of about 5 v. was necessary to maintain the current density mentioned above. A solution of 190 gms. NaB(CH in 145 gms. of tetrahydrofurane was allowed to drop into the electrolytic cell at a rate consistent with the amount of current passing through, i.e., 25 gms./hr. A receiver cooled to 80 C. was provided downstream of the reflux condenser. In this receiver, the boron trimethyl which formed was condensed. Upon termination of the electrolysis, tetrahydrofurane and tetramethyl lead were distilled off commonly from the electrolytic cell and separated by fractionation as described in Example 1.
  • the distillation residue is NaAl(CH which is dissolved in part of the tetrahydrofurane recovered and may thus be re-used for another electrolysis.
  • Example 4 The procedure is the same as in Example 1 except that a solution of 200 gms. NaAl(CH in 500 gms. diglyme is used as the electrolyte. Electrolysis is effected at 100 C. and 7.6 a., i.e. 30 a./dm. the terminal voltage necessary to maintain the current density being about 8 v. The electrolysis is discontinued after about 2.5 to 3 hours, the appropriate moment being perceptible by an increase in terminal voltage. The reaction solution is removed from the electrolytic vessel by siphoning and the tetramethyl lead formed by electrolysis is distilled off under a vacuum of about 50 mm. Hg while gradually raising the bath temperature to 85 C. and while cooling the receiver to -80% C.
  • Example 5 The procedure is the same as that decribed in Example 4 except that triglyme mixed with by volume of toluene is used as the solvent under otherwise identical conditions.
  • Example 6 A solution of 250 gms. NaA1(CH (-On butyl) in 400 gms. of tetrahydrofurane is electrolyzed' for 7 hours at 3.8 a. and about 9 v. in the apparatus decribed in Example 1. Upon termination of the electrolysis, the reaction solution was removed from the electrolytic vessel by siphoning and tetrahydrofurane and tetramethyl lead produced are distilled off while gradually increasing the temperature of the oil bath from 70 C. to 90 C. and finally applying a vacuum of 20-30 mm. Hg. The mixture of tetrahydrofurane and tetramethyl lead was subsequently separated by distillation with a 50 cm. Vigreux column.
  • Example 7 The electrolysis may be effected with the use of the corresponding potassium complex compounds using the same procedure as described in Examples 1 to 6.
  • a process for the production of tetramethyl lead by electrolysis on lead anodes of complex compounds of elements of main group III of the Periodic Table, which complex compounds contain alkyl groups which comprises using electrolytes which contain an aluminum complex compound of the general formula wherein M is selected from the group consisting of sodium, potassium and mixtures of sodium and potassium, R is selected from the group consisting of alkyl, cycloalkyl, and aryl, and m is 1-4.
  • electrolytes are mixtures consisting of diflerent organometallic complex compounds and contain oxygen-containing complex compounds of the formula MA1(CH OR' as one component and said oxygen-containing aluminum complex compounds are added to the electrolyte at a rate at which they are consumed in the electrolysis with formation of the compound Al(CH OR.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
US196586A 1961-05-23 1962-05-22 Process for the electrolytic production of tetramethyl lead Expired - Lifetime US3254008A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEZ8764A DE1220855B (de) 1961-05-23 1961-05-23 Verfahren zur Herstellung von Tetramethylblei durch Elektrolyse

Publications (1)

Publication Number Publication Date
US3254008A true US3254008A (en) 1966-05-31

Family

ID=7620617

Family Applications (1)

Application Number Title Priority Date Filing Date
US196586A Expired - Lifetime US3254008A (en) 1961-05-23 1962-05-22 Process for the electrolytic production of tetramethyl lead

Country Status (4)

Country Link
US (1) US3254008A (en, 2012)
DE (1) DE1220855B (en, 2012)
GB (1) GB1009220A (en, 2012)
NL (1) NL278293A (en, 2012)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2849349A (en) * 1955-06-13 1958-08-26 Ziegler Process for the electrolytic deposition of aluminium
US2944948A (en) * 1956-02-06 1960-07-12 Ethyl Corp Method of purifying organometallic complexes and their use in the preparation of organolead compounds
US3028323A (en) * 1959-12-24 1962-04-03 Ethyl Corp Manufacture of organolead products
US3028320A (en) * 1960-02-01 1962-04-03 Ethyl Corp Manufacture of tin alkyl compounds
US3088885A (en) * 1959-12-24 1963-05-07 Ethyl Corp Manufacture of lead organometallic compounds
US3164538A (en) * 1960-06-07 1965-01-05 Ziegler Karl Electrolytic production of metal alkyls

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2849349A (en) * 1955-06-13 1958-08-26 Ziegler Process for the electrolytic deposition of aluminium
US2944948A (en) * 1956-02-06 1960-07-12 Ethyl Corp Method of purifying organometallic complexes and their use in the preparation of organolead compounds
US3028323A (en) * 1959-12-24 1962-04-03 Ethyl Corp Manufacture of organolead products
US3088885A (en) * 1959-12-24 1963-05-07 Ethyl Corp Manufacture of lead organometallic compounds
US3028320A (en) * 1960-02-01 1962-04-03 Ethyl Corp Manufacture of tin alkyl compounds
US3164538A (en) * 1960-06-07 1965-01-05 Ziegler Karl Electrolytic production of metal alkyls

Also Published As

Publication number Publication date
DE1220855B (de) 1966-07-14
GB1009220A (en) 1965-11-10
NL278293A (en, 2012)

Similar Documents

Publication Publication Date Title
US2985568A (en) Electrolytic process for the production of metal alkyls
US3779875A (en) Preparation of glyoxylic acid
JPH07188080A (ja) 高純度ヒドロキシドおよびアルコキシドの製造法
NO135843B (en, 2012)
US2944948A (en) Method of purifying organometallic complexes and their use in the preparation of organolead compounds
US3164538A (en) Electrolytic production of metal alkyls
LEHMKUHL Preparative scope of organometallic electrochemistry
US3007858A (en) Preparation of organo metallic compounds
Boujlel et al. Cathodic cleavage of carbon-oxygen bonds (V). direct and indirect electrochemical reduction of epoxides
US3254008A (en) Process for the electrolytic production of tetramethyl lead
US3361781A (en) Process for the manufacture of organic alkali complex compounds of aluminum and/or boron
US3779876A (en) Process for the preparation of glyoxylic acid
US3254009A (en) Production of metal alkyls
EP0083981A1 (en) Production of organotin halides
US3028319A (en) Manufacture of magnesium organo compounds
US3405179A (en) Method of preparing arylborane compounds
EP0084932B1 (en) Electrolysis of tin complexes
US2422468A (en) Electrolytic production of pinacols
US1538390A (en) Treatment of alkali-metal amalgams, especially for the production of alkali metals
US3088885A (en) Manufacture of lead organometallic compounds
US2918417A (en) Production of boron by fused salt bath electrolysis
US3234113A (en) Electrolytic separation of sodium
US3791945A (en) Method of production of alkali metals and their alloys
US3492207A (en) Electrochemical reduction of benzene
US3755101A (en) Process for the preparation of saligenol