[1]2,880,067 PROCESS FOR PREPARING METAL CARBONYLS Rex D Closson, Northville, and George G. Ecke, Ferndale, Mich., ,d Lloyd R. Buzbee, Huntington, W. Va., assignors to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Application October 3, 1956 10 Serial No. 613,595 11 Claims. (Cl. 23-203) This invention relates@ to trangition metal carbonyls and 15 to a novel method for the preparation of these compounds, particularly chromium and meinganese carbonyls. The transition metal carbonyls are useful compounds both as chemical intermediates and in certain direct cOm20 mercial uses. In the past great difficulty has been experienced in preparing certain of these transition metal carbonyls in high enough yield to make their use commercially feasible. In particular no process has been known heretofore which produces manganese carbonyl 25 in sufficient yield to make its industrial application an achieved practicality, even though this compound is known to have valuable utility both as an antiknock agent in liquid -hydrocarbon fuels, and as an intermediate for preparing other manganese compounds. It is, therefore, an object of this' invention to provide a novel process for the synthesis and manufacture of transition metal carbonyls. Another object is to provide a process for the manufacture of chromium carbonyl. A for the production of manganese carbonyl in good yield. The above and other objects of this invention are accomplished by a process for preparing transition metal carbonyls which comprises reacting carbon monoxide with a compound having the formula. 40 Uni'ted States Patent Office 2@8809067 P ' a t , 6 n t e d M a r . 3 1 , 1 9 5 9 2 intermediates in this reaction have.formulae@@corresponding to: : R , R 3 R2 Ra R2@e-A-ml I I RI-C-A Ri Rs @2 R2 Rs R,-@ C R3 .1@l RI-C-A A@C-4, @@3 @6m,;,---@. it Rr-A \ A-Rs I RI--C C-R, R2 @2 wherein M', M" and @ M"' represent mono-, di-, alid trivalent metals respectively, A, RI, R2 and @R3 are as defined above. The non-transition metals preferred in the preparation of these intermediates include 'the alkali metals alkaline earth metals, aiid aluminum. The' radical R3 in . the above formulae is @ an @ organic radical inclusive of alkyl, aryl, alkenyl, alkaryl, aralkyl radicals and the like These radicals @ contain I from 1 to about 16 carbon atoms. Organic hydrocarbon radicals are preferred. A preferred class of comppupd .for use in the preparation of the metal-containing intermediates referred to above are those in - *,hich 'A : in the I above @ formulae . is nitrogen; that is, an imine compoun'd. Compounds:of this type are preferred' as they arel more reddily prepared particuiar object of this invention is to provide a process @l;j than the corresponding phosphorus compound, @and@t@eir use leads to ekcellent yields of metal @carbonyls. Nbenzohydrylidenephenylimine whicli has thelformula: Ri R3 = N - e 1-@-A- M, 45 R2 R3 -z serves as an exam le. where A is an element of group V of the periodic table @ p Therefo re, -a preferre d embodi ment df @this inventio n hav,ing an atomic number no greater than 15, i.e., nitro- 5( is a process which compris es reacting carbon monoxid e gen and phospho rus, R, and R2 are organic' groups charwith a transition metalcotitaining intermedi ate, whi6h ,acterized by.the absence of (1) olefinic unsaturati on and interme diate i,s formed as the reaction product df a (2) a h dro en atom on the carbon atom immediately ly 9 tra nsition metal salt and monosodio benzohydrylideneadjacent the carbon atom to which the group V element ph enylimine. This embodiment of the invention is paris bonded, R3 is an organic radical, M is a transition 55 ticularly applicable of the synthesis of manganeseicarmetal, x and y depend upon the valence of M, x ranging bonyl. from I to 3 inclusive, and y ranging from I to 2 incluTh e non-transition mettil intermediate is prepared. from sive. By transition metal is meant a metal of groups the metal and an imine meeting the above requirements, IVB, VB, VIB, VIIB and VIII of the periodic table. by adding the metal to an equivalent,.amount.of the imine The compound elucidated in the above general formula rO compound. Alternatively, the reverse procedure may be is referred to herein as "the transition metal - intermediem ployed when convenient. When the metal is particiiate" and is formed, for example, as the reaction product larly reactive the process is preferably carried out in of a transition met@Ll salt and a "non-transition metal inan inert atmosphere under conditions -such that neither termediate' " This latter intermediate is conveniently the metal nor the product intermediate come in contact prepared by reacting@ a metal with an organic compound 65 with the air. Thus, for example, @a dispersion of sodium having the formula: in mineral off is added to benzqhydrylidenephenylimine Ri wwle the system is agitated aiid ke t uiider, a nitroeen p @,C=A@R3 atmosphere. It is advisable td heat the mixtur@ at reflux to prep4re the.nontransition metal intermedi ate. The tr@nsiiion @ metal intermedi ate ' is conveni6 nti@ prepartd from the nontransition interiiiedi ate' by wherein @ Ri, R2,'@gs @and. A are as ddfined above. ',T'Ile metal interchan ge. That is, a@salt df the@trans ition met@l
[2]2,880,067 3 is reacted with the non-transition metal intermediate. Elevated temperatures are ernployed when necessary to complete the reaction. The transition metal interm6diate is' also prepared by reacting an appropriate imine with a non-transition metal 5 in the presence of a transition metal salt. In this manner the transition metal intermediate is prepared from the non-transition metal intermediate as the latter is formed. The process of this invention is conveniently carried out in an inert solvent. A preferred class of solvents 10 comprise cyclic ethers such as dioxane and tetrahydrofuran. The transition metal intermediate is reacted with carbon monoxide in the process of this invention to form the transition metal carbonyl. This carbonylation is carried 15 out in a sealed vessel at elevated temperatures and pressures. A preferr@d method of carrying out the reaction with carbon monoxide coriiprises pressurizing the vessel with carbon monoxide while the contents of the vessel, that is, the reaction mixtiire from the preparation of the 20 transition metal inte'rmediate i8 at room temperature. After the vessel has been pressurized with carbon monoxide and sealed it is then heated slowly to the reaction temperature and allowed to remain at that temperature until the reaction is substantially complete.. Reaction 25 ternperatures of from about 50' C. to about 500' C. and pressures,from about 200 to about 10,000 p.s.i.g. are employed. Reaction time of from about V2 hour to about 10 hours is ordinarily sufficient. Embodiments of the instant invention will become ap- 30 parent by reference tck the following specific examples in which all parts and percentages are by weight. Example I ,To a glass reaction vessel equipped with gas and 35 liquid inlet means, heating means and reflux condenser was charged 800 parts of tetrahydrofuran and 129 parts of N-benzohydrylidenephenylimiiie. The contents of the vessel.were kept under an atmosphere of nitrogen and the ternperature was controlled at 20' C. while.23 parts 40 of a 50 percent sodium dispersion in mineral oil were added. After the sodium addition was completed, 31.5 parts of manganous chloride were added while the mixture was agitated. . The resultaiat intermediate was charged to a pressure resistant ve8sel having a plurality 45 of gas inlet and outlet means, pressure and temperature measuring devices, heating and cooling means, and an arrangement for charging and discharging liquids and solids. The vessel was flushed with nitrogen and pressurized with carbon monoxide at room temperature and 50 heated gradually over a 50-minute p@riod to a maximum temperature of 150' C. and a. maximum.pressure of 3000 p.s.i..g. 11 These conditions were maintained for an additional 4Q minutes, after which time the vessel was cooled, ven,ted and the contents discharged. The reaction mix- 5,5 ture was hydrolyzed with 200 parts of water and steam distilled. The portion distilling above 80' C. was extract@d with benzene; the benzene extract was concentrated by distillation and 5.8 parts of dimanganese decacarbonyl, [Mn(CO),512, melting at 149-152' C. were 60 reco.ve.red. This material is a yellow orange crystaIIine solid melting at 156' C. when pure. Flame photometric analysis of the benzene extract before concentration indicated that the reaction produced a total of over 12 parts of dimanganese dicarbonyl representing approxi- C,5 mately a'. 25 percent yield. Example 11 Thp general procedure of Example I wAs followed with -diate which. 70 tho fbllo@vi@g differences,: The reaction intermc. was charg6d t6 ifie @res@ur6 resiii'an't v'es'sel was prepared from 90 1 parts of benzoh@dryIidefie-ri-hexylimine, 630 parts bf tetrahydrofuran 6s a @olvent, 15.6 parts of sodium,dispersion, and 21.4-parts,.of mafiganous chloride. ies The p sure resistant vessel Was heated uiider car@pn 'T@ 4 monoxide pressure over a one hour period to 2001 C. and 3000 p.s.i.g. These conditions were maintained -for 30 minutes. The reaction gave an 11 percent yield of dimanganese decacarbonyl as measured by 'Lhe flame photometer. Example III The procedure of Example I is repeated except that 78. parts of N-methyl-2,2,4,4- tetramethyl-3-iminopentane dre used to prepare the intermediate, and the reaction with carbon monoxide is conducted at a total pressure of 250 p.s.i.g. at 50' C. for a total of three hours and 40 minutes which time includes 40 minutes necessary to bring the reaction vessel to reaction conditions. A good yield of dimanganese decacarbonyl results. Example IV To a glass reaction vessel of the type described in Example I is added 350 parts of ndecyl-pp'-dimethyl benzohydrylidenimine (p-CH3C6H5)2C=N-ClOH2,, 450 parts of dioxane and 107 parts of manganous bromide. To this mixture is added 40 parts of potassium in incremental portions. The temperature of the vessel is maintained between 20 and 30' C. during the potassium addition. When the addition is completed, the mixture is refluxed for about half an hour, cooled and charged to a pressure resistant vessel of the type described in Example 1. The vessel is sealed, charged with carbon monoxide, and heated over approximately a one and a half hour period to 300' C. and a maximum pressure of 10,000 p.s.i.g. These conditions are maintained, for an additional 30 minutes, after which time the vessel is cooled, vented and the contents are discharged, hydrolyzed and rectified as described above to produce a good yield of dimanganese decacarbonyl. The reaction mixture obtained on an addition of the metal to a mixture of imine compound and the transition, metal salt in an appropriate solvent is less viscous than the product obtained when the transition metal salt is added to the reaction product of the metal and the organic compound. Thus, the procedure used in Example IV greatly facilitates handling of the intermediates from the glass reaction vessel to the pressure vessel used in the carbonylation step of the reaction. - Substantially identical yields are obtained under identical conditions of temperature, pressure and time of reaction regardless of the manner of preparation of the transition metal intermediate. The procedure as outlined in Example IV is preferred as the final reaction mixture is more easily handled and is prepared . with one less reaction step than is necessary when the metal is reacted initially with the imine in the ab@&nce of the transition metal salt. As a variant in the above procedure, the metal may be added to the mixture of the organic compound, the transition metal salt and the solvent while the mixture is maintained at reflux temperature. This latter method is advantageous in that a portion of the heat liberated by the metal addition is utiiized in the process. Example V The procedure of Example IV is repeated using 9 parts of aluminum, 63 parts of manganous chloride, 600 parts of the dimethyl ether of ethylene glycol as a solvent and 322 parts of p,p'-dichlorobenzohydrylidene benzyl phosphine (p-CIC6H4)2C=PCH2C6H5. The carbonylation reaction is carried out at 200' C. and 50,000 p.s.i.g. for 15 minutes after a preliminary heating period of one hour. A good yield of dimanganese decacarbonyl results. Example VI The procedure of Example V is repeated except that the preliminary heating is conducted in the absence of carbon monoxide, and when the reaction mixture reaches 2009 C., the vessel is pressurized with carbon monoxide@... p.@ nd re' re e to 50,000 ig- @ ihe miitu @6t (I f6r'15- ihiniit6@:
[3]2,880 967 A greatly reduced y@eld of 'dimanganese decacarbonyl results.-", Exampl@,Yil.@ ne-- procedurel.of,, E -Xample, IV is repeated,lusingt@80O.;@., 5 par.ts.@@of;ftetrahy&.of.uran @@53@partsj,.oflchromic@.chLoridei@ 44@'parts of@@strontiilm@,@@,metal,@and,l@290 parts@@of@313,5i5,7' tetr,amethyl @ 4'r. heptylidene . m - ethylphenyl@ pho@phine. c 4 ; i, ICH'3CH2C(CH3@)212C)-=@P7@-(ln,- 2,H5C6@l ). The',@ car:@@. bonylalion,,reaction@is! carried@out.at 3000 psi.g. and 20,0,'@ - 10, C for @ 3 0 minutes - afti@r 7 a , one liour. period: @.to bring@ th-e reaction mixture to these conditions. A.:good@' yield @of@ chr,omitim@.he@xacarbonyl results. ExaMple Vlll' i5@ The procedure of Example VII is followed using 500 r parts of dioxane, 66 pa ts of,,-chromic sulfate, 6 parts of magnesium metal and 130 @ parts of benzohydrylidenephenylimine. An excellent yidld of chromium hexacarbonyl results. 20 E.tampl,@.@ IX A good yield of ditnanganese decacarbonyl is produced following the general procedpre of Example VII using 600 parts of dioxane, 87 parts@ of manganous acetate, 23 25 parts of sodium and 232I parts @ of (C6H5),C=P-CH3, benzohydrylidenemethylphosphine. Example. X Example VII is repeated using 900 pa,rts of toluenp, 30 11 3 @parts,of chromic@ iodide, 23 !parts of @'sodium,- and 355 parts - of p;pl-dinitrobenzoh ydrylidene-n-hexylimine'. Al@ lower yield of chromium @carbonyl@ results - than that achieved in Example VIII due to the non-polar nature of the solvent. 35 The organic portion of th@e transition metal intermediate which is reacted with carbon monoxide in the practice of this invention is derived from an imino compound or the corresponding phosphorus compound in which the imino carbon is substituted 'with two organic radicals and 40 whiph.@,contains no, hydrogen, on, a carbon atom. adjacqnt,, the - imino, carbon. These compounds have at least,, 1 01 @ carbon., atoms,, and. those having.. up to 25 carbon, atoms, ;@ in the molecule are suitable inthe practice of thisinveiRtion., Examples -of such.compounds are, p,p?@diamino,- 4.5 benzohydrylidene methylimine, p,p'-diphenyjb-enzohY7 drylidene @- n. - hexyl phosphine, mm' - dinitrobfnzohy,- drylidene benzyl phosphine, 4, 4,6,6-tetramethyl-5-non@yl- - idenel.ethytimine, and the @like. Ho,wever, a,r preferred class of compounds - comp@ise, 50 the imines@ , which have no. hydrogen alpha . to the , imino car.bon and @,which contain. -from 1 0 to@ about,20,ica oA@ rb ' atoms. These compounds are preferred -as.@it has,-.been-,", found that a good yield of metal carbonyl is produced when they are employed. Examples of these include 55 benzohydrylidenephenylimine,-, 2,2,,4,4,-tetramethyl - 3 pentylidene methylimine, P-me thylbenzohydrylidene benzylimine, benzohydrylidene-n-hexyliriiine, 2,4-diethyl-2,4- dime 1-3-peAtylidene-p-,ni heaylimi and,,, the@@@ lil@gi@ @@hy trop ne The Apn-transition@ metal @ which is, react.ed with-. the;, c)o imine @ in -preparing the intermediate is a reactive @;metal@ selected from-;the group consisting of alkpli-, metals;,,.al-,7 kaline earth-metals. aluminum and theclike.- Thus sod' @ -.Lum, lithium,@ . potassiumi . rubidium, cesium, beryllium, magnesium, calcium,, strontium, barium and @. alurninum are all useful@:in,prpparingthe non7transition,metal,@inter ,@. mediateinthe,,pTactiQeofthi s@invention. The-,all@ali@.-.mptals are preferred as it is found that high yields of carbon-. yl are obtained@.by their .@usi@@,, Of-,. the alk4...,me ,talsi,,,son dium is particularly preferred-. as,@, it, is @, reidily, avaflab'le@@ -0 and-@,react@,,,rapidly,@,@wit@h-@the,@keto e@-a,,,.,higli,,;yield@,@ Ae,@ @.iv - of the intermediate. WhPA:!the7,met used-is:one@,wh ich:@.is@sensitive,,Lto."-air,@ . @Al @ I I or water it is preferably used in the form@ of @a:.dispersion in a;,, suitable,.,., inert, carrier.. such@ as, anhydrous I minerd.@@ 75 6 oil. it is often advisable to add the metal in amalgamatg@d, fomr-to@iiisure@reacti6a., 'Me@transitibn@metal compounds@which are@used@'in@Llhe@@ process of this invention to produce the transition metal intermedidte iiiclude,generaliy the ionic compoundg of the metal, T suc h@ as the halides, including, the - bromides, iodides@and@thl6rides, the @nitrates,@ sulfates, oxalates, acetates@@and@ other,,ionic or-ganic and inorganic,@salts ExMnSO4, ampdles of,, thdse are 1 MnCl@ @ MnBr2, Mnli,, mang anous.@@oxalate,. manganous acetate, CrCl,, CtBrs@, Crl3, chromid, acetate, chromic sulfate, and the like@ The@ p@ocess @ of this invention is most @ advantageously carried"out ine@alisuitable solvent. In general,@,organicsolvents4,whieh,@are inertito the reactants@under,the conditionsof @the,;,reaction are suitable.- Examples ofsuitable@, solvents include benzene, toliiene, hexaine and@like-hydrocarbons, Particularly good 7 results areobtaiiied@ when the@.solvent embloyed@is!an inert, polar,,non-reactiVe cy-i clid@ ether, such as, dioxane.@ Tetrahydtoftiran; @is a -par@@ tirularly,.preferred,solvent@of:this latter type. W@henthe transition@,metal intermediate is reacted@with, carboa@,,@lmono,xide,;at elevated temperature@ and@'pressure,. higher yidlds@ ,of . carbonyl, are obtained when the, intermediateis contacted,,with;carbon@monoxide at temperatures and pressures substantially below final reaction conditionsi@ If;. after. this initial@ contact the reactioni mass is then,,-Jleat ed-:.to@the:proper conditions of temperattire and pressure-,,a@.good yield iof carbonyl -results. The -ptocess of thisiinvention is also operative when the transition metal iinterinediate@is heated in the absence of carbon monoxide iand-,then@.. contacted with carbon monoxide at elevated.'.temperatures. However,theyieldof@carbonyl@produced.- ,,Vy@@thi@ procedure@ is@ substantially lower as il lustratodby@Example @VI. Th@,,,, carbonylation step @ is conveniently carried out: at carbgn-.Monoxide;-pressures of from about Z50'@p.s@i.g. to pres5,qms@-i abovei @ 50 000@ p.s..i.g. Pressures of "from 500@ P.@@i@g;@-to:10;000 p.s.i.g.@ are preferred as,a@good yidld@of metal @ carbonyl can @ be, separated from @the reaction mikturel@whexi pressures.@in@this range are employed@ Pressures of@from@5,00@Tto.3,000 p.&i.g. are@particularly preferred7 as,,theycan.be@ safely obtained in readily avaflable, processing iequipment. Within, the pressure range i outlined above @ the 7. car, bonylation- step is,conveniently carried out@at te mperatures between 50 and 3000 C. Temperatures of from 150@'to 230'@C. are preferred as an excehent yield of carbonyl is produced, at these@ temperatures. After the@. reaction mixture in contact with carbon@ monoxi de reaches reaction conditions the temperature and carbon monoxide pressure are conveniently;maintaiiied@ until the, @ reaction; has, produced a high yield of @ metal carbonyl. If desired,@ reaction conditions can l@e maintained@ ,@untit th7e @system no longer absorbs carbon mon-, oxide. How'ever, reaction times of as little as 15@minutes can@@beempjgyfd to give a@satisfactory yield of carbonyl@ Genprally, reaction @ times of between 0.5 hour and. 2.5@, hours are Preferred as excellent @ yield8 of carbonyl @ ar-obtained- in.,this manner. The,am unt solvent:eniployed in the process of this 0 @o@f invention,,isi.dependent@upon the fluidity required of:the reaction mass prior to the carbonylation step and the method of preparation of thetransition metal intermediate.- When the intermediate is @prepared as described in@ Example @IV-'a lovier proportion of solvent can @be employed due to the increased fluidity of the reaction mass@ However, when the procedure used in Example I is followed a more viscous intermediate results and thus t higher concentration of solvent is necessary particularly when the intermediate is p@epared in, a vessel other than that in which the carbon@l4@ion is.,,conducted. in gendral, an amount of solvent eq!iivalent to a weight ratio of from 4: 1 to 3 0: 1 of solvent to orgaiiic imine employed is used. The _preferred rang@ comptises a,solve4t to im' tne@ ivei-94t,@rdti6@-of--from 5,1 to, 10-1 as.low. viscosity, inter@
[4]2,880,067 m@diates which yield a @igh propordon of metal - carbonyl are prepared from reaction mixtures employing these proportions of solvents. The metal carbonyl is recovered from the final reaction mixture by hydrolysis and steam distillation fol7 5 lowed by extraction of the distillate with a suitable solvent and crystallization of the carbonyl from the solvent.- For example, dimanganese decacarbonyl is extracted from the steam distillate by the use of such inert organic solvents as cyclohexane, benzene, toluene and the like. @ 10 As pointed out above the transition metal carbonyls prepared by the process of this invention find utility as fuel additives, and in particular manganese carbonyl is an antiknock agent of outstanding effect in gasoline and other liquid hydrocarbon fuels. 15 The term "gasoline" pertains to liquid hydrocarbons and is inclusive of mixtures of aliphatic, olefinic, aroniatic and naphthenic hydrocarbons derived from mineral sources such as petroleum, coal, shale and tar sands, and which includes straight run, reformed, cracked and alkyl20 ated stocks, and mixtures of these. The initial boiling point can be from about 70 to about 90' F. and the final boiling points vary from less than 300 to more than 440' F. To a gasoline meeting the above requirements was 25 added various quantities of dimanganese decacarbonyl and the mixtures were agitated to give a homogeneous fuel blend. Tests were conducted of these fuel blends using a single cylinder CFR standard test engine according D908-51 to determine the octane number of the fuel containing the dimanganese decacarbonyl and the identical fuel with no antiknock additive. This procedure is referted to as the Research Method for Antiknock Testing. The addition of dimanganese decacarbonyl in quan35 tities sufficient to give 0.5, 1.0, and 1.5 grams of manganese per gallon of fuel, resuited in fuels having octane ratings of 84.9, 88.1, and 90.8 respectively. The fuel which contained no dimanganese decacarbonyl gave an octane number rating of 77.1. 3.75 grams of lead as 40 tetraethyllead are required to produce an octane number increase in this fuel equal to that produced by the addition of 1.5 grams of manganese as dimanganese decacarbonyl. The dimanganese decacarbonyl is, therefore, , 2.5 times as effective as tetraethyllead. 45 When employed as an antiknock agent, the diinanganese decacarbonyl prepared by the process of this invention is convepiently used in conjunction with i)ther fuel additives. Thus, other antiknock agents scavengers, dyes and antioxidants are advantageously added to the 50 fuel along with metal carbonyl. Similarly, antiknock fluid compositions containing any or all of the above ingredients in addition to the metal carbonyl find utility as fuel additives. The various other metal carbonyls such as chromium, 55 iron carbonyl, nickel c@irbonyl, cobalt, and the like, find various uses which are well known in the ait. For example, chromium carbonyl and iron carbonyl find utility in the gas phase plating of other metals. Further, these compounds are a convenient source of the pure metal 60 by the decomposition of the carbonyl. We
