US2000069A - Preparation of lead alkyls - Google Patents

Description

Patented May 7, 1935' Emi -em V .-=2,000,069' V ntertainers 0F LEAD ALKYLs rreaericwnrimwn' mg, cameyyrism, aim Louis si -Bakepfennsgtove,

' e 1 an 51 New & fl nivan fi' n f Del.,'a corporationnf Delaware (i -Drawing; Ai'iiilicatipn 'EMay 3 24,. 1932, Sei-ialZ-No. 813,260

i fllhislliiivention deletes to am i'fiiproifme'nt' in .zthej production-of lead' alkyls by he mman nt alk-yl halides upon a=lead sodiuni aHoyfand -iriore particularly to the alloys' en-iployed irisucl1' p'roc :ilrr theprocessiasord' 'arily 'practi'ced at t-he .spresent timeiiaiilead sodium alloy consistin 'of lead and I0 sodium is reacted vvith 'ethyl fichloridektoefor-m a' dry reaction -meiss containing lead alkyl absorbed by finely dividd lead, rsodiumihalide and an 'iappreciable amoiint of *un'd'ecomposedi alloy. Theilead alkylis' recovered from; the .mass: 'bys drowning in wat'er and 'liistillingrout thelead 'alliyl by meansof stam B'y the usezofsuch- .proc'ess,'=*ezriploying ethyl-chloride, yields of fromz'83a%' OF35'%- of itetra- 'e'thyl lald have beenf'obtaind the laboratory, with amounts of about -5%ltoi il0 of the alloy left undecomposed. Such undecomposed sodium tends to cause trouble in the recovery of the alkyl lead compounds by steam distillation, due to the fact that the undercomposed sodium. reacts with the water in which the reaction mass is drowned with the result that the metalic lead tends to form large balls, cakes or rings which lower the recovery of the alkyl lead and are removed from the still only with great difficulty.

In order to eliminate this balling of the lead, as

much as possible, it has been necessary to add a. protective agent such as, for example, thiocarbam'lide or a dispersing agent such as engine oil, or both, to the reaction mass during distillation. However, these expedients have not proved to be entirely satisfactory as a large percentage of the distillations give trouble even in the presence of these substances.

An object of the present invention is to provide a process wherein these difliculties are eliminated. A further object is to provide a new composition of matter in the nature of an alloy to be used in such process which composition of matter is substantially completely decomposed during the reaction and has no tendency to cause balling or caking of the metallic lead. Still further objects are to provide a new composition of matter and to advance the art. Other and further objects will appear hereinafter.

These objects may be accomplished according to our invention which comprises substituting for a small proportion of the lead, in the lead sodium alloy of the process as heretofore practiced, a small amount of magnesium. We have found that when'amounts of magnesium varying from 0.05% to 1.0% of the weight of the alloy is substituted for an equivalent weight of'"thelead'in'the preparation'ofthe'alloy and sucmnevw compositicm bf matter. is use'dfimi the inanufactureof l'ead'- -'alkyl compounds, higher yields am ne 1m :aikyi compounds.- 'resulti tlie comp'osi-tibmis mor completely:*deeom osdiduringdbhs actionraxid agglomeration of the Head particles during distillation is practica'l'ly' elimi n'ated without re'qui'ring the use of a =protectiwe or dispersing agent. f'li on eka-mple," when uch --compositiorfiofi rnatter is employed in -'the proj duction of t etra ethylrl eadgi'yields ofiwfnonii about 185%flto 88 701 215obtained and .thel amount'liof i undecompcsed composition the 'reaction;-mass at the eempiemcm of the rea'ctio'n amounts to fro'm 4 to 0%g both 'theyield ofrtetra ethyl file'ad ndfitlieiamount of undecompo'sed composiitiomdeperiding upon the ammmt bf magnesium present in the*izomposition employed. :flt :has been found that as little as 0.1% of magnesium in the composition is sufficient to practically eliminate all agglomeration of lead particles during the distillation, which appears to be due to the fact'that a much more complete reaction is obtained with less undecomposed composition present in the reaction mass. However, we preferably employ from about 0.15% to 0.4% of magnesium as such amount gives most satisfactory results. In order to more clearly point out our invention and illustrate the preferred mode in which we contemplate carrying the same into effect, the following examples are given:

Example 1.One hundred grams of a lead-sodium alloy containing 90% lead and 10% sodium by weight, equivalent to equalmolecular 1'.

proportions of the two metals, were reacted with 50 cc. of ethyl chloride in a small pressure autoclave in. a water bath of 75 C. for 5 hours. The resultant reaction mass was drowned in. 500 cc. of water and the lead ethyl distilled off, with. steam. The weight of lead ethyl recovered was 29.2 grams, equivalent to 84.3% yield, based on the sodium.

The unreacted sodium which was present as sodium hydroxide in the residue from the steam distillation was determined by titration with standard acid solution and the results calculated as sodium. This unreacted sodium was found to be 0.51 grams or 5.1%.

Example 2.-One hundred (100) grams of magnesium bearing lead sodium alloy consisting of 89.6% lead, 10% sodium and 0.4% magnesium were reacted with 50 cc. of ethyl chloride and the lead ethyl recovered in the same manner as recited in Example 1.. The yield of the lead ethyl I was found to be 30.98 grams or 88.1% based on the sodium.

No unreacted sodium was present in the reaction mass as shown by the fact that the residue from the steam distillation torremove the lead tetra, ethyl, was neutral to phenol phthalein.

The results obtainable by varying the amounts of lead and magnesium in" the composition are shown in the following table:

Alloy Yield based on sodium per- Undecom- V centage of posed alloy Lead Na Mg theory Percent Percent Percent Percent 90 l 0 84. 3 52 1 89. 9 10 0. 1 86. 2 4 2 89. 8 10 0. 2 87. 3 2. 5 89. 7 0.3 88.0 w 1. 0 89. 6 10 0. 4 88. 1 0.0 89. 5 10 0. 5 87. 0 0 0 89. 0 10 1. 0 86. 0 0 0 Although the use of about 0.4% of magnesium in the composition appears to be most desirable from a theoretical standpoint, we have found that, for practical purposes, the use of from about ,0.15% to 0.2% of magnesiumispreferable as larger amounts introduce certain problems into the manufacture ofpthe composition and the recovery of the alkyl lead'compounds.

invention is to be limited solely by the appended claims construed as broadly as is permissible in view of the prior art.

We claim:

1. The method of producing lead alkyls which comprises reacting an alkyl halide with a composition of matter comprising 10% sodium, 89.95% to 89.00% lead and 0.05% to 1.00% magnesium.

a 2. The method of producing lead alkyls which comprises reacting an alkyl halide with a composition of matter comprising 10% sodium, from about 89.85% to 89.80% lead and from about 0.15% to 0.20% magnesium.

3. The method of producing lead alkyls which comprises reacting an alkyl chloride with a composition of matter comprising 10% sodium, 489.95% to 89.00% lead and 0.05% to 1.00%

magnesium.

4. The method of producing lead alkyls which comprises reacting an alkyl chloride with a composition of matter comprising 10% sodium, from about.89.85% to 89.80% lead and from about 0.15% to 0.2 0% magnesium.

5. The method of producing tetra ethyl lead which comprises reacting ethyl chloride with a composition of matter comprising 10% sodium, 89.95%to 89.00% lead and 0.05% to 1.00% magnesium and distilling off the tetra ethyl lead with steam.

6. The method of producing tetra ethyl lead which comprises reacting ethyl chloride with a compositionofmatter comprising 10% sodium, from about 89.85% to 89.80% lead and from about 0.15%, to 0.20% magnesium and distilling on the tetra ethyl lead with steam.

FREDERICK B. DOWNING.

LOUIS S BAKE.