United States Patent Office Patented Aug
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2,950,304 United States Patent Office Patented Aug. 23, 1960 1. 2 with mercuric acetate at 20 to 100° C. in the presence of water and in the further presence of a minor amount of sodium hydroxide. 2,950,304 The present invention is of particular advantage over PREPARATION OF ORGANOMERCURY the prior art methods for producing organomercury COMPOUNDS compounds in that high yields are obtained employing James M. Riddle, Baton Rouge, La., assignor to Ethyl less stringent conditions. For example, the process pro Corporation, New York, N.Y., a corporation of Dela vides high yields of the desired organomercury product Ware employing materials which are not sensitive to water and O are less hazardous to handle. Another advantage is that No Drawing. Filed May 1, 1959, Ser. No. 810,237 a completely liquid reaction system wherein all reactants 5 Claims. (CI. 260-431) are miscible is possible. A still further advantage is that the product is readily recoverable from the reaction sys tem since, in most cases, it is more dense and immiscible 15 The present invention is concerned with a process for dropping to the bottom of the reaction mixture. These the production of organomercury compounds, particul proceeds.and other advantages will be evident as the discussion larly dialkylmercury compounds. In general, any mercury salt of an organic acid is There are numerous methods reported in the literature applicable in the process. While organic acids are gen for the preparation of organomercury compounds. With 20 erally considered as having carboxylic groupings, it is out attempting to mention all such processes, the follow also recognized that certain organic compounds not hav ing are typical: mercury has been reacted with alkyl ing such acid groupings but having strongly acidic hy halides to form alkylmercury halides; sodium amalgam drogen are organic acids, for example, alcohols and has been reacted with alkyl halides to form dialkylmer phenols. Thus, the mercury salts of organic acids em cury compounds; and certain mercury halides have been 25 ployable in the process can be characterized as mercury reacted with certain organometallic compounds, e.g. the compounds wherein mercury is attached to at least one Grignard reagent, to form the dialkylmercury com carbon-containing organic radical through an intermedi pounds. All of the presently known procedures are pri ate atom of oxygen or sulfur. For practical reasons, the marily of academic interest and suffer particular disad hydrocarbon portions of such acids will generally con vantages. So far as now known, a simple and conven 30 tain not more than about 25 carbon atoms, even though ient method for the preparation of dialkylmercury com higher molecular weight materials can be employed. Il pounds, readily adaptable to commercial operation, has lustrative examples of the mercury salts of organic acids not been available. include mercuric and mercurous formate, mercuric ace The alkyl mercury compounds are of considerable tate, mercuric propanoate, mercuric butanoate, mercuric utility. For example, they are useful as intermediates 35 octanoate, mercurous myristate, mercuric octadecanoate, for forming other organometallic compounds, a typical mercuric linoleoate, mercuric octadecenoate, mercuric reaction being that of diethylmercury with sodium metal butyrate, mercuric ethylate, mercuric phenolate, mercul to form ethylsodium. Another use for the mercury com ric benzoate, mercuric thiophenolate, mercuric naph pounds, and derivatives thereof, is in agricultural chemi thenate, mercuric thioacetate, mercuric isobutyrate, mer cal applications. Still other uses are known and a more 40 curic propiolate, and the like. it is to be understood that practical method for their preparation is desirable to the hydrocarbon portions of Such acid salts can be fur further amplify the utility of these compounds. ther substituted to result in branched chain isomers or Accordingly, an object of this invention is to provide substituted with functional groups such as the halogens, a new and novel process for the production of organo keto, and the like groups, provided such are essentially mercury compounds. A further object is to provide a 45 inert in the reaction. The mercury salts, particularly the process whereby greater and more economical yields mercuric salts, of the lower alkanoic acids, especially of organomercury compounds are obtained. A particu those having up to about 8 carbon atoms in the hydro lar object is to provide a new and novel process for the carbon portions, are preferred because of their greater manufacture of dialkylmercury compounds. These and availability, economy, solubility in the reaction system, other objects will be apparent as the discussion proceeds. 50 and higher yields obtained. Mercuric acetate comprises The above and other objects are accomplished by re an especially preferred mercury salt of an organic acid. acting a trialkyl- or trialkenylborane with a mercury Salt The organoborane compounds employed in the proc of an organic acid in an aqueous medium. The mercury ess are the trialkyl- or trialkenylboranes. In geeral, such salts of lower alkanoic acids, especially mercuric acetate, compounds will contain up to and including about 18 and the lower trialkylboranes, especially triethylborane, 55 carbon atoms in each hydrocarbon portion. Illustrative are preferred reactants. Particular advantage is achieved examples of the alkyl- and alkenylboranes are trimethyl when the reaction is conducted at a temperature between borane, triethylborane, tripropylborane, trihexylborane, about 20 to 100° C. and sufficient water is present to trioctylborane, tridecylborane, tridodecylborane, triocta provide a fluid reaction medium, especially one in which decylborane, trivinylborane, tri-1-propenylborane, tri-2- all of the reactants are dissolved. Still further advan 60 butenylborane, tri-1-hexenylborane, tri-1-octenylborane, tage toward an improved reaction is obtained when an tri-1-octadecenylborane, tri-2,4-octadecadienylborane and alkali metal hydoxide, particularly sodium hydroxide, is the like. The hydrocarbon portions of such compounds incorporated in the reaction mixture in at least a minor can be branched chain and further substituted with func amount. Thus, a particularly preferred embodiment tional groups which are essentially inert in the reaction, comprises the reaction of a lower trialkylborane with a 85 such as the halogens, carbonyl and the like. The tri mercury salt of an organic acid at a temperature be alkyl- and trialkenylboranes of the lower alkyl and al tween about 20 to 100° C. in the presence of a Sufi kenyl radicals, that is, having up to and including about cient amount of water to provide a fluid reaction System 8 carbon atoms in each of such groups, are preferred and in the further presence of at least a minor amount because of their greater availability and reactivity in the of an alkali metal hydroxide. A specific embodiment O process. The trialkylboranes having up to and includ of this invention comprises the reaction of triethylborane ing about 8 carbon atoms in each alkyl group are more 2,950,304 3 4. especially preferred, particularly triethylborane, because 500 parts of water and containing 1.0 part of potassium of their easier handling and greater availability. hydroxide at room temperature, divinylmercury forms The proportions of the reactants can be varied over a and drops to the bottom of the reactor in high yield. considerable range to still result in the desired organo Example V mercury compound. It is preferable, however, to em ploy at least the stoichiometric amount of the alkyl- or Di-1-hexenylmercury is obtained in essentially quan alkenylborane compound. Advantage is achieved in titative yield when 29.0 parts of mercuric formate are higher yields and faster reaction rates when a molar ex added to 30.0 parts of tri-1-hexenylborane in 750 parts cess between about 5 to 15 percent of the alkyl- or al of water over a period of 30 minutes at room tempera kenylborane is employed. In determining the stoichiom O ture and with continuous agitation. etry, one can base it upon the consumption of one or Example VI all of the alkyl or alkenyl groups in the trialkyl- and trialkenylboranes. Since faster reaction is obtained of When Example I is repeated substituting mercuric the first alkyl or alkenyl group of the organoborane com naphthenate for mercuric acetate and also incorporating pound, a particular embodiment of the invention.com 5 0.7 part of calcium hydroxide into the mixture, diethyl prises employing the above stoichiometric portions based mercury is obtained in high yield. upon reaction of only one alkyl group per molecule of Example VII the alkyl- or alkenylborane. The water employed in the In this run, 8.4 parts of trioctadecylborane are reacted system is usually provided in amount to result in a fluid with 2.4 parts of mercury octanoate in the presence of reaction mixture. It is also desirable to employ at least 20 1000 parts of water and 0.5 part of magnesium hydroxide 3 moles of water per mole of the trialkyl- or trialkenyl at reflux temperature (100° C.) for 15 minutes after borane. In a preferred embodiment, between about 5 completion of addition of the mercuric salt to the tri to 200 moles of water per mole of the alkyl- or alkenyl octadecylborane. At the completion of the reaction, di borane is employed. 25 octadecylmercury is withdrawn from the reactor in high The process is subject to relatively simple manipulative yield. - operations. In general, the requisite amounts of organo Example VIII borane compound and water are added to a reactor and then the mercury organic acid salt is added thereto. The When Example VII is repeated substituting mercuric reverse mode of addition is equally applicable although benzoate and tri-1-octadecenylborane for the mercuric higher yields are obtained when adding the mercury or 30 salt and organoborane respectively, di-1-octadecenylmer gano acid salt to the organoborane. The mixture is then cury is obtained in high yield.