CA1201128A - Process for preparing ceric carboxylates - Google Patents

Abstract

PROCESS FOR PREPARING CERIC CARBOXYLATES
ABSTRACT OF THE DISCLOSURE

A process is provided for preparing ceric carboxylates which comprises oxidizing cerous carboxylate with aqueous hydrogen peroxide in a two-phase system comprising an aqueous phase of hydrogen peroxide having a pH of at least 6 and an organic phase comprising a solution of cerous carboxylate in a water-immiscible hydrocarbon solvent at a temperature at which the reaction proceeds but below the temperature of rapid decomposition of hydrogen peroxide, thereby converting cerous to ceric ion and forming a solution of ceric carboxylate in the hydrocarbon solvent; heating the reaction mixture at a temperature at which any ceric-hydrogen peroxide complexes present are decomposed; and separating the organic phase containing ceric carboxylate from the aqueous phase of the reaction mixture.

Description

- SPECIFICATION
Heavy metal soaps such as cobalt, lead, vanadium, zirconiurn, nickel and other nalphthena~es are widely used as accelerators or driers to speed up the dr~ing and curing of 5 oil~based varnishes and ~paints. They are also used as additives in plastics, in flame-retardant compositions, silicones, and fuels.
Cerium soaps are lL~own to have drying action but have not come into wide use because they are expensi~e to prelpare.
Recently ~ey also haYe been proposed as additives in fuels~
10 flame-retardant compositions and plastics and silicones and have other potential applications. The cerium soaps described in ~e . literabure are cerous soaps. To o~r knowledge there is only one description in ~e literature of ceric soa~s or ~eir prepara~ion9and ~at is by B. I,. K~sotra et al Transition Metal Chemistry, 1, 15 158-161 (19q6), who state that a good deal of work has be~n carried out on cerous carbo2~ylates 'rl3ut there is no reference in ~e literature to the preparation of ceric carb~xylat~s"~ The paper deals wi~
the prepa~a~ion a~d chara~terization of ceric carbo~{yla~es by ~e reaction of ~I2CeCl6 with HCO~7 a mixture o~ (MeCC))20,EtCO~, 20 n-PrCO~ and ~CO~I7 re~pecti~ely:
YI2CeCl~ RCOOH , C~e(OO~R)Cl~ ~{ H20 -~ 3HCl The carboxylates prepared by thîs me~ud contain ~ree chlorine atoms,as shown above. l~ttempts by Kalsotra et al to l~le~ ceric~carbo~ylates by ~e reaction of dipyridinium ceric ~q~
~' ~

~2~2~

he7~chk-ride (C5H6N)~CeCl6 with sodium salts of fatty acids, analogous to the preparation of ceric cyclopentadienyl and ceric indenyl compounds,failed.
There are however cerium soaps on ~e market ~at are 5 actually a mixture of cerous and ceric carbo2~ylates; ~ese are cerium naF~enates con~inin~ from 30~C to 50% ceric na~enate.
The method for ~eir preparation has not been divulged; ~ey are being manufactured in France.
The me~od used for preparing hea~ry metal soaps depends 10 on t~e reacti~rity of the particular metal or derivatives thereof.
The processes most commonly used are:
(a) anion e~ch~n~e7 displacing an inorganic anion by carboxylate anion, carried out by allding a base to a well agita~ed aqueous $olution of a metal inorganic salt in ~e presence of a 15 solution of the desired carboxylic acid in an ~o~l-iate wa~er-immiscible sol~ent;
(b) precipitation of ~e metal soap ~om a~Lueous ~oltl~?o~q of ~he metal salts with alkali soaps;
(c) fusion of metal oxides7 hyd~o~ides or salts wi~ organic 20 acids or esters; and (~ direct reaction of finely-divided metals in heated organic acids.
Process-wise, me~ods (a) and (b~ are the easiest to carry out, alld are usually also the most economical. T~ey are :~J

~%~

applicable to cerium as well as to many other metals. Any a~aila~l~
soluble common cerous salt such as cerou~ nitra~e or chloride ccm be used in method (a) to prepare ~erous soaps. Theoretically, by analog~ to cerous~ soaps, water-soluble ceric ammonium nitrate 5 or ceric sulfate can be used to prepare ceric soaps. There is no litera~ure reEerence showing that this has ever been done, however. The pro~lem is ~at ceric ammonium nitrate and ceric sulfate, the only commercially available wa~er-soluble ceric salts~
are prohibitively e}~?ensive. This is perhaps one reason why only 10 cerous alld no ceric soaps are described in ~e literature.
.... ..
When ~e solid metal soap is desired, process (b) îs most suitable, and is applicable to cerium. Any availabl~ soluble cerium salt such as cerous nitrate or chloride ca~ be used to prepa~e cerous soaps in solid form. While t~eoretically t~e water-15 solul~le ceric salts such as ceric ammonium nitra~e or ceric sulfatecould be used, an~ perhaps are used i~ preparing ~e available mixed cerous/ceric naph~enates, ceric ~oaps are ei~el~ liquids or waxy substanc~s, and would be hard to isolate.from ~e rea~ti~n mixture.
M~eover, i~ is also prohibiti~ely expensive to prepare ceric soaps aecording to metllo~l ~b)5, beca~e ~e only a~ailable ~olllhle inol~ganic ceric salts are ~e e~pensi~e ceric ammonium nitra~e and eeric sulfate.

~2~2~

Ceric hydroxide is of low reactiYity and solubility, and not suitable for ei~er n~e~nd (a) or (b).
In a~cordance wi~ ~e present invention, ~e use of e~pensive ceric ammonium nitrate or ceric sulfa~e is avoided by 5 sta:r~ing wi~ ~e correspon~ing cerous soap, o~ritli ~i ng ~e cerous soap to ~e ceric soap with aqueolls hydrogell pero}cide.
The problems in h?/n~li n~ and recovery of ceric soap from ~e rea~tion mixture are eliminated by carrying out ~e o~ida~ion wi~h aqueous hydrogen peroxide ln a two-phase system com~ising 10 a~ aqueous phase of hydrngen peroxide ha~ing a p~I of at least 6 and an organic phase comprisîng a solnti~n of cerous ca~bo~late in a water-immiscible hydrocarbon solvent at a tempera~ure ~ which the reaction proceeds but below ~he temperature of rapid decompo-sitio~ of hydrogen peroxide~ lhereby converting cerous to ceric ion 15 and formirlg a ~olution o cerîc carb~?~ylate in ~e hydroca~on solvent. Then, when reaction is complete, ~e reaction ml~ture is heated at a tempel dl.Ul e at which any ceric ~hydrogen pe~o~ide complexes are decomposed, and ~e organic -phaLse ~en separated from the a~Lueous phase o~ ~e reaction mixture. The ceric carboxyl-20 ate is normally used in ~e ~olution as prepared and can 'be res~overedfrom the organic phase by any desired procedure, such a5 ~)y sol~ent distillation at low temperature ~d pressure.

~,i ' ~2~2~

The reaction is ~eoretically capable of qualltit~tively corlYerting cerous $o ceric carbox~Tla~e. It is not however neces5a~y for most commercial purposes to effect a complete conversion. The r~tio o Ce*~ produced over ~e total cerium present can be varied 5 as desired from l~c up to ~ ~c -The usefulness of only 1~c Ce~4 in Ce~3 carbo~ylate solutions can be appreciated by ~e une~pected reduced viscosity of ~e Ce~3/Ce~4 carboxyla~e solution which o~erwise could pose problems. Bo~
cerous arld ceric carbo~late are chemically equivalen:t as a sourcè
10 ~ cerium for rea~tions where cerium is desired, as în driers or accelel~lo~s. Howe~el~ organic solvent solutions of cerlc ca~boxyl-ates ha~re a much lower viscosity ~an organîc solvent solutîons oP
cerous carbo~ylates at like cerium concentrations, and Mle reductîon in vîscosity is already marked when ~e total cerium is 1~c ceric.
~L5 It îs ~u~ suitable fol many purposes to convert as lîttle as 1~c of cerous c0rîum to ceric. How~e~ ~ ît îs normally desira1~1e t~
collYert from 30~ZC to 60% and preferably fro~m 50~ to 95% of ~e cerou~ to cerîc cel ium, for applîcatîons where hîgher Ce~ content is s~ught.
The cerolls caxboxylate can be used directly as a star$ing ma$erial, insolutiollin~ewater-îmmîsciblehydroca~bonsolva~
a~d ~e aqueous hydrogen pero2~ide solutîon ha~ing a p~I o a~ lea~ 6 combined wi~ ~is solution în forming ~e two-phase reaetion system.
The cerous carbo~la~e ca~ also be formed in ~Itu from a cerous

2~1 compound and a carbo~la$e compound~ :~or example, an inorganlc cero~s salt sllch as cerous nitrate or cerous sulfate, and ~e carbo~;ylic acid wi~ alkali, or ~e carboxylic acid salt, in which case alkali is not necessary. The cerous carbo~rla~e forms in situ 5 as a~ i.ntermediate, but in any event ~e product is ceric sarbo~ylate, in solution in ~e solvent.
Whell cerous carboxylate is used as a starting material7 ~e procedure is referred to herein as Me~hod 1, and when a cerous coml~ound a~d a carboxylate compound are used as a sta~ting 10 material, ~e procedure is leferled to herein as Me~od 11. These two procedures, while similar in principle7 are ra~er different in e~ecution, process~wise7 and t~ere~le will be considered separ~ely.
Met~od 1, sinc~ it invol~es cerous carbo~ylate as ~he sta~ing material, can also inclllde ~e prepara~ion of cerous car~
15 bo2~ylate from an ~norganic cerous salt and a ca:rboxylic acid, and in ~is ~ve~ ~e reactîoxl mi~ure can be used directly in the hydrogen pe3~oxide o~ tion~ wi~out separation of cerous ca~boxylate sol~ion from t~ aqueous layer. This is ~e most economical way to apply lhe proce~s, a~d i~ therefore L~e~e- ~e~.
YVhile ~e most practical ~d economical way to produce ~e ceric soaps is by integra~ing all o~idation step in ~e process of m~kin~ cerous soaps, ~e o~idation can also be applied t~` a solution of any cerous soap in a hydrocarbon sol~ent by adding an aqueous solution of hydrogen peroxide. For in~t~n~e~ any commercial cerous carbox~rlate solution can be mixed wi~ an aqueous solution ~ hydrogen peroxide9 whereupon ~e oxidation will take place.
Excess carboxylic acid, pre~erably as ~e ammonium or.alkali metal salt, can also be added.
5 Method ~ -For syn~lesis of cerous carboxylate, method (a) above canbe used. A base such as all~li metal, Io~ e~ample sodium or po~assium, llydrOxide or ammonium hydroxide is added to a two-p~ase system co~t~inin~ water-immiscible solvent alld a well-10 agi~ed aqueous-solution of a solu~le cerous salt such as cerous nitra~e, cerou~ chloride, or cerous ~~ te a~d the correspo~ n~
carbo2ylic acid, all in a~ least stoichiom~ ric amount but preferably USiIlD a~ excess of ~e acid. Cerous carbo~ylate obtained in ~his nner is ~hen e~ra~:te~ from the aqueous reaction mi~re wi~ a 15 water-immiscible hydrocarbon sol~rent in which it is solwble~ ~d which ad~ tageously can be present a~ tihe time ~ addition oiE ~e base, ~us forming a two-phase system alrea~y in ~is stage, or ~t ffle en~ of ~e preeipitation o cerous carbo~late from ~e a~Lueous ~ase~ The orga~ic pllase of cerous carbox~late di~solved in hydro-20~carbon so.lvent can ~en be separa~ed flom *lLe aq~leous phase, but ~is i; not necessary.
Three moles of ca~bo~rlic acid is stoichiDmetrically required per n~ole of Ce~3 salt to make ~e Ce~3 ~bo~lalte. Theo-retically~ one e:x~ra mole of acid is needed if all Ce+3 is to be ;~

converted to Ce~4 in the form of ceric carboxylate. The fact is t~at ~e oxid~tion proceeds well at less than the theoretical amoun~ of acid. This is an indication that the Ce~4 carboxylate produced by ~e process contains o~er functions such as--~H or o~er bondings.
~he base t~at is used in carrying the me~od (a) ~r prepal-lng cerollS so~ps can be sodium or potassium hydroxide, carbonate or bicarbonate7 or am:monium hydro~ide. The amount of base is important7 at least ~e stoichiometric amount for ~e cerium î~
reqlired in order to comrert all cerium into sol~ent-soluble cerium cal~boxylate, ~nd to adjust ~iH to at least 6, a~l preferably higher ~an 7, prior to ~e oxidation wi~ hydrogen peroxide.
~Iydrogen peroxide is added as all aqueous solution ~hortly after the addition of ~e base has been completed7 and prior to the separatioll of ~e two layers. P;referably, t~e pH of ~e reaction ~5 mi~ture`prior to ~e H202 a~ldition is abave 6. While ~e order oP
combining ~e reactallts can be va;rietl7 the addition of H20z should be last, for better results.
The reaction mi~ture is kept under vigorouS agitation while ~e aqueous solution o h~rogen pero~ide iS being added. The ~ -2û reaction begins a~ l~oom ~mp~alw-e and ~e reaction mixture r~pidly .
de~elops a reddish d-drk bl~own color. ~ydrogen peroxide is lmown to form colored water-soluble comrlP~s wi~ inorganic ions an~
probably ~e same is occurring in ~is case wit~ ceric ioll. In ~e process of the inventio:n, ~e ce:rium carboxyla~e/hydrogen perog~de 25 system forms a dark colored organic solven:t so~ution dlle ~ the complex, which upon heating decomposes by releasing H2O2. There-fore, a~ter a short period of time during which some of the hydrogen pero~ide oxidizes Ce+3 to Ce~4 and ~e rest becomes immobilized in forming the said complex, ~e temperature of ~e reaction mixture is brought to from 60 to 75C, to destro~ ceric-~1202 comple~es, where-up~n the color li~tens to a p~rmanellt yellow orange, indicating ~heir decomposition.
The ~moun~ of hydrog~n peroxide added can ~rary considerably, according to l~e extent desired of ~e conversion OI cerous to ceric9 10 from 5~O to abo~e 90%. A 100% conversion is difficult to obtain as ~her~ appea;rs to be som~ degree of reduction o Ce~ to Ce~3, which in some cases, depending on ~e carbo~yla~e ion, is responsible or a drop in. and l~us a limitation upon the rn~ m Ce~ content. S:mall O~ .S ~f H2O2 can also be used, ~vhich will result in a lesser 15 conversion of cerous to ceric. A small con~rersion, ra~glng from 1% to 5%~ could be desira~le for some applic~ions. The degree of co~lvel~;ion depends also on lhe na~ure of ~e carbo~rlic acid alld ~e` impurities l?reseng. The degree of consrersion of cerous to ceric îs g~rea~er in ~e case of neodecanoic a~id ~an for naph~enic acid, 20 fo~
To achie~e a high conversion of ce~us to ceric9 two more ~ tio~s of hydrogen pero~cide followed each time by a heating~
~ooling sequence to decompose ceric-H202 complexes may be required, dependîng upon ~e car~oxyla~e anion. In ~e case of some carbo~ tes, 9 ' ~f!
,,~

one addition of H20~ is enou~h to raise ceric to over 90~c. Wi~
o~er carboxylates, in order to reach 90~c, two or ~ree addi~ions of :H202 are needed, as for in~t~nce wi~ ceric naph~enate. One reason for ~is is that ~e mi~ture sold as naphthenic acid is itself 5 oxidi~able by ceric, and ~is secondary reaction consumes ceric~
collverting it to cerous and holding down the ceric content.
lhe amount of carbo~ylic acid as already in~ te~ should be more than stoichiometrically required for ~e cerous soap, i. e. 9

3 moles per g atom of cerium. The corresponding cexic soap madè
10 in accordance wi~ ~is inve~ltion may contain some OH or other bonding, which is acceptable foI- many of ~e applic~lons. ~ite often, cerous soap solutions contain an e~ccess of ~e corresponding carboxylic acid. It is preferable to use about 4 moles of carbo~ylis acid, so as to have ~e a~noun~ stoichiometrically r~uired hr the 15 ceric soàp ~hat is to be made. More ~an 4 moles o~ acid can be used7 if desired.

Me~od II
In accordance with ~is me~odS cerous ion in the reaction medium is oxidized by addin~ an a~ueous solution of hydrogen pero2~ide:
(1) into an aqueous solution of alkali carbo~ylate and prior to the addition of the aqueous solution of cerous salt, or (2) into an aqueous solution of the inorganic cerous salt solution ei~er (a) prior $o ~e mixing wlth ~e alkali carbo~ylate ~olution9 or ~b) at a con~rolled rate during ~e rni7~in~ with the alkali lû carbo~rlate solution. The presence OI a~ organic solvent during th~
reaction is preferable7 to e:~ract the ceric soap as it is formed.
The amou~ of hydroge.n peroxide is-not critical, and can vary rom less ~an ~e stoichiometric amount required to a large e~cess. Norrnally7 an excess is preerred; because of the te~ çnc.y 15 of the cerlc iOIl to form comple~es wi~ ~e H2O2. After $he miging of t~e alkali carbo~Tlate and the cerous salt has been completed9 more hydrogen peroxide can be added to increaæe ~e ceric content, lf desired. It masr be necessary in some cases to he~t ~e solutiorl to ~rom. 65 to ~0C to destroy the colored ceri~H202 comple~c9 prior 20 to adding more Et202.
The addition of H22 iS preferably done a~ room tempera~ure, but ~e temperat~re can ~:~tend up to 7ûC, wil~ l~e penaltsr ~f a correspo~in~ly less ef~icient reaction, because of loss of H202.
A~ ~e son~lusion of the reaction7 ~e reaction mi2~ure îs heatesl at 60 to 75 C7 to decompose the ceric-~2O2 complex, and destroy all H O

eXcess 2 2-In both methods, the yield can be improYed by z2~tracting the aqueous phase with organic solverlt, and combining ~is with the 5 organic phase, when ~e ceric carbo~ylate is sparsely soluble in water.
The process of the inYention can be used for conversion of any cerous soap whish can be dissolYed in a wa~er-immiscible hydro~arbon sol~reIlt, in a sufficient amoun~ to permit ~e reaction 10 to proceed. The proces~ is of particular appllcatioll and commercial interest to the preparation of cel ic naphthenate, ceric 2-e~ylhe~oate9 and ceric n~decanoa~e, which are therefore preferred, but it can OI
course be applied for the preparation of any desired ceric carboxylate salt of any ali`phatic or cycloaliphatic satura:~ed or lln~:~hlrated 15 carboxylic acid or mixture ~ereoI ha~ing from about seven to ~bout eighteell carbon atoms, starting from ~e corresponding cerous carboxylate. ~ .
E~emplary carboxylic acids- p:ro~riding carbo~ylate anion include cap~ic, 2-et~yl hexoic" capryrlc~ ric, myristic9 stearic~
20 palmi~ic, oleic, linoleic, linolenic, ricinoleic? na~llL~enic, rnethyl cyclohe:~anoic, mel~yl cyclohexenoic, cyclohep~anoic, and t~e fatty aci~ mi~tures derived from na~ral fats arld oils, such as COCOllU~ oil fatty acids, tallow fatty acids~ lard fat~v acids~ corn oil fatty acids, lin~eed oil fatty acids, tUIlg oil fatty acids, rapeseed oil fatt~ acids~
25 cottonseed oll fatty acids, ~Eish oil fatty asids, soya~ean oîl fatty acids aIld sa~flowerseed oil fatty a~ids.

'~

~2~

If ~e cerous carbo~ylate is not a~ailable, the process of the invention is combined with its preparation as a first ~tep, using a wa~er~soluble cerous salt such as cerous ammonium nitrate, cerous nitrate, cerous sulate or cerous aceta:te with ~e ree carboxylic acid in ~e stoichiometrically equi~alent a~ount as staxting materials.
Arly water-immiscible liquid hydrocarbon solvent in which ~e cerous soap can be dissolved to form ~e organic ~hase of ~e reaction mi~ture can be employed, includm~ alipha$ic, cycloaiiphatic and arom~tic hydrocarbon solvents having from about six to about 10 fou~teen carbon atoms such as, for e2~ample, petroleum e~ers7 which are composed of para~finic hydrocarbons? cycloaliphatic hydrocarbons, and mixtures ~ereof 7 he~ane, hepta~e9 octane, no~ne~ decane, dodecane7 tetradecane, cyclohexan~, cyclohep~ane, cyclope~t~ne~ cyclooctane, cyclohexene, cyclohep~ene, cyclooctene, 15 benæene, toluene, p-cymene, psuedo-cumene? ~he ~rlene~, m:lesit~lene, ethylbenzene, 172,3-trimethylbenæene9 tetrame~yl-. benzene7 propylbenzene, isopropylbenzene, ~e dipropylbe~ enesand the diisopropylbenzenes.

"`:

2~3 The following Exarnples in t~e opinion of the inventors :represe~ preferred embodiments of ~e invent;on.
~MPLE 1 In a four-necked three-liter rourld-bottom ~lask equipped 5 with a rapid-stirring mech~nic~l stirrer~ thermometer, condenser aIld additioll funnel were placed 146. 8 g of aqueolls cerous nitrate solution (23. 86~C cerous), 0. ~50 mole~ 190 g neodeca~oic acid"
1. 011 moles, a~d 358. 9 g Amsco 140 (a petroleum ether sol~en~ -composed o~ 92~ZC nap}l~enic ~y~rocarbons a~d ~8~c paraffinic 10 hydloca~bons). ~ueous ~mmnnhlm hydroxide, 1035 g, 1.006 moles, was added dropwise to the well agi~ated mixture of neo~ec~noic acid, cerous nitrate solution and petroleum ether. Followin~
compl~hoIl of the a~ldition of ~e arnmonil~m hydroxide over a two hour period, 26. 0 g o 30% a~ueous hydro~en pero~ide, 0. 23 mole~
15 was added i~ an equ~l weigllt, 2~ g~ o water. The re~ction mi~re turned a deep brown, ~s3 a~ter forty minu~eæ of rea~tion lleating was beguh to 7~0C, to decompose ~e Ce~4~ comi le~es~ and contirlued f~r an af1ditional twenty nlinutes. In 1~e ~ou~se oE ~le decomposition, ~e Teacti~ migture turlled orange, ~en bright yellow. After cooling?
- ~o ~e rea~tion mix~ure separated into two layersj a clear orange upper orgallic layer and a~ almost clear yellow lower ~ueous layer.
The layers wlere separated; and washed wi~ 200 g of water. The organic layer was diluted with 300 g hexane, arld the ~ ater azeotroped out, aIter which ~e hexane was distilled. T~e 25 Ce~4 in ~he residue ~581. 9 g) was 9D~ OI the total cerium.

* Trademark ... ~,~

~20~

- EX~MPLE 2 To ~e reactiorl vessel described in Example 1 was added 29. 4 g aqueous cerous nitra~e solution ass~yir~ 23. 79% Ce (0. 05 mole), 38. 0 g neodecarloic acid tO. 20 mole~ d 72. 6 g 'Amsco 140.' TM
The ~ueous arnmonium h~dlo~ide 167. 2 g (0.16 mole) was added dropwise to ~e well-a~itated mixture OI neo~canoic acld, aqueous cerous nitrate and petroleum e~er solvent o~rer ten minutes. There was ~hen added ~e a~ueous hydrogen peroxide,, 5. 2 g, 30% H2O2, toge~er WLEh all egual weight~ 5. 2 g,~f water. The ~ix~are turned 10 daxl~ brown, and the tempel ~lul e began to rise. ~ter Porl;y mimlteS of reaction, heating was begun to 78C.ovex~ l~en mim to decompose the (; e~4/H202 comple~; whereupon ~e reactio mixture became orange-yellow, and ~en yellow.
The reaction mixtur~ was cooled to 40C ~d ~e mixture 15 separated into two layers, ~s~ upuer pe~rl~;c~nt y~llow organic laye and a lower sli~htly yellow ~queous l~yer.
Tlhe wet hexane s~ ic)n w~s ~x~ ot~ope~l ~ry. The cool solutlon was ~ilte~ rou~hlSupeir~ellfilf:er aid .~nd t~e ca~e w~hed wi~ he~ne. The collected orange shiny solid ceric nPo~c~n~e 20 was 0. 26 g. ~fter di.still~ion of the hex~ne flom the organic layer, 119~ 6 g of product was reco~ered7 assaying 5. 09% Ce~4.

* Trademark :E~AMPL:E 3 Tn a reaction flask was added 176. 4 g a~ueous cerous nitrate solution assaying 23. 79% cerium (0. 3 mole), 169. 2 g neodecanoic acid (0.9 mole), and 208.8 g Amsco 140, and stirringbegun. Aqlueous ammonium hydro}cide, 1044~4 g (1. 009 moles) was a~ded dropwise to ~e well-agitated mixture over a period of one hour at 22 to 23C.
A~ ~e conclusion of ~is period ~e ~I was 7. Hydro~en pe~oxide was ~en a~ded (0.2 mole, as 30% solul;ion) toge~er with an e~ual am~unt of w~ter o~rer a few minutes. The mi~*are was allowed to 10 react for twenty minutes7 and then t~e tempel~lu~e was brought to 70C and held ~ere for twe~ty minutes to decompose the C~t'lH202 complex. The reaction mixture was then cooled to 90C~ whereupon it separated into two l~yers; an upper organic layer, which was viscous and ta~, in ~e form of an em~ io~7 and a lower~ ueous 15 layex~ whLch was colorless and clear.
To ~e mix~ure was added 100 g OI he2~ane. The layers were ~en separated. The ~queous layer was e~ctra~ted wi~ tw~o portions o~ 130 g each of hexane ~d ~e organic wa~hings were then combined wlth ~e orgallic layer~ ~e water azeotroped out from ~e orgallic 20 layer, a~ter which ~e hexane was ~i.qtillefl off. The residual 443.1 g ~msco solution was assayed at 1. 3'3~ Ce~.

~6 , Into a 500 ml round-bottom flask equi~ped wi~ a rapid stirrer and a droppillg furmel was charged 29. 4 g aqueous cerous nitrate solution assaying 23. 86G/c Ce (0. 05 mole~, 29. 3 g 2-e~ylhexoic acid (0. 20 mole) and 81 g of Arnsco 140. Aque~us ammonium h~d, .,~Lde solution, 205. 7 g, ~ 6~c NH3~ was then added dropYvise over forty nnulutes. At ~e end of ~e addition the p~I of the rea~tion mi~ure was 7. 5. The orga~ic layer was s~i~htly viscous, and ~e aqueous laye~ was clear. There was then added 5. 22 g hydrogen ~o peroxide, 30~C H2Oz~ wi~ vigorous stirringO A dar~ brown color formed almost at once, and ~e organic layer became lessviscous.
Stirring was contimled for fortg-five min~tes. Upon completion ~ t;his reaction time, heating to 70Ct was then begun, to destroy t~e unreacted Ce~4/H2O2 comple~es. Af~er 75C was re~ch~, tihis .

15 temperature was m~int~;ned ~o~ thirty ~imltesO The darkbro~1vn col~ disappeared? resulting in an orange? sl tly yellow oil and an a~ueous layer.

... ... .. . . .... .. _ . . . ..................................... . . . .. .. ..
The reaction mi~ure was cooled with ice to 20C~ There was ~en added 5 g ~nmo~i~m lly~ ide ~ollltiQn~ followed by 20 1. 53 g 30% hydrogen peroxide solutioql, -and ~e reaction mii~ture was ~n stirr~d for thirty ~nimlt~sO The mixture was l~en heated to 70C and held at fflis temperature for thirty minutes.
The re~ction mL~re was ~en cooled to 20C, ~ which point ~e pH was 7. 0. There was ~en a~ded l. 53 g hydrogen peroxLde 25 as a 30~c H2O2 .sollltio~- The reaction mixture was ~tirred for one 17 ~

2~

hour, and then heating to 70C begun. The reaction mixture was held at 72C for ~irty miJQutes, and ~en cooled to 20C in an ice water bath.
I'he organic layer was separated from the aqueous layer, 5 and washed with two portions of 25 g each of w~er. The weight of ~e organic laye~ was 110. Q g~ There was ~en added 100 g hexane, and ref~ n~ begun to remo~e the water. Xexane was then removed under 40 to 80 m m at a pottenn~elalule of 42 to 62C. The product was a ye~ow-green oil, 114.6 g, 5.17% Ce~
1~

EX~MPLE 5 In the reaction system of Example ~ ~ere was placed 29. 9; g aqueous cerous nitrate solution assaying 23 . 86~C cerium (G. 05 mole), 50. 5 g (0. 20 mole) naph~enic acid and 59. 3 g Amsco 140.
5 Stirring was begun9 alld aqueous ammonium hyd-l o~ide solution 170. O g (O. 17~ mole) was then added dropwise over a period of ~r~ mi~utes.
Ne~ was a~lded 3.1 g lH202, 30~c H202 solution (0. 0327 mole) to ~e Yigorollsly stirr~d reactiorl mi~re. A dark ~rown color formed.
Stirring was co~ti mle/1 for fo:rl;y-fi~re mimltes and ~e mixture then 10 heated to 75CC to destroy ~e Ce~4/hydrogen peroxide com~31e~e.~7 and held a~ ~is temperature for ~irty minu~es. The mix~re was thell cooled in a wa~er/ice bath to 20C,w~ereupon it separated into two layers. The organic layer wa~s rem~ed, lO0 g he~ne added7 and ~e mixhlre ~he~ heated to reflux. :~efln~ E was contimle~
5 azeotroping out ~e wa~er. The rem?/ining hexane was ~hen distilled under low pressure, yielding an oily material which was dried o~er S~ill~ .S llf~e. Total cerium b~ alysis was 3 . 07~/c, of which ~~c or 2.15% was Ce~4. Weight 21~ g.

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lh~XAMPL~: 6 Molar (~harges Amount Mwt. ~c Moles ~atio Ce(NO3)3 solution 29. 4 g 140.12 23. 86 O. 050(Ce) 1. 00 Ce~3 .A~lSCO ld~O 61. ~i g 1232 g/
fflole Ce Naph~enic acid 48.2 g 240.8 0.200 4.0 NaOH solution 156 ml 40 O. 980N 0.153 3.06 H22 solution 4.8 g 34 32.7 00046 1,84 ~ 500 ml three-necl~l round bottomed flask was equipped with mer.h~niGal stirrer, ~ermometer~ ~I electrode and dropping unnel.
The cerium solution, r~ihthenir. acid a~d Amseo 140 were 15 combined a;nd stirred vigorously while ~e NaOX sol~ion was added o~er 2. 5 hours. The pero2dde was a~lded in ~ equal volume of wa~er o~ter ive minutes causing a d~ep re~ eolor. The mixture was - let ~irri~g for t~venty hours. The mi~ture was heated to qOC
for one~alf hour9 cooled a~d ~en ~e organic l~yer was assayed to 20 give 73% ce:ric.

~0 :, ~L~

~AMPLE '7 Charges Amoullt Mwt. ~c - Mola~ Ratio Ce(NO3)3 solutiorl 29.4 g 140. :12 23.86 Ce Amsco 140 81.0 g ---Octoic acid 29.3 g :l44.2 98.3 NaOH solution 16~ ml ~0 0.980 N 3.24 H2O2 solution 4.8 g 34 32. 9 1.84 A 500 ml ~ree~necked round bottomed flask was equi;pped with m~h~ al stirrer, ~ermometer, EiEI electrode and dropping 10 ~nnel.
The cerlum s~ tion, octoic acid alld Amsco were combined alld stirred vigol~ously while ~e N~C~H solution was ~dded o~rer two hour~
The hy~ o~,el~ peroxide sollltion (4. 8 ~) was added and 1 he 15 mi~re was sltirred seventeen hours. The mi~blre was hea~ed to 70C ~Ol~ one-ha~ hour, cooled, ~en assayed to give 70% ceric.
A seso~d portio~ f 3, 4 g pero~ide was a~lded followed by avernight stirring aIld ~hort heating to give 91~C ceric- The two layers spllit very q.uickly a~d cleanly.

EX,AMPLE 8 There were mi~ed 2. 0 g cerous e~yl hexoate solid with 50. 0 g of Amsco 1~0 and stirred until appro~imately 80~C dissolYed.
H ~O2 solutioll (0. 38 g o a 10~C ~ueous solution) was added and the 5 mi~ re stirred to obtain a red-orange solution which was allowed to stand for two hours and ~en placed in a 70~C ba~ for ~irty minllte,S to decompose Ce~2O2 comple}~es. The color became lighter, whereupon ~e mi~bare was allowed to cool an~ settle.
Titration wi~ ferrous ~mmo~ m sulfate solution indicated 10 24% Ce~4 total cerium.

~2~2~

E~AMPLE 9 There was added 2. 9~6 g cerous naph~enate solid moles to 50. 0 g Amsco 140 axld ~en stirred and heated to 60C to ol~tain a solution which was cooled to 25C. H2O2 solution (0. 58 g of a 10~c 5 a~Lueous solution) was added and the mixture stlrred for fi~e minutes, placed in a 70C ba~ for ~irt~ mltes and allowed to cobl to 25C. The upper layer was sampled and titrated wi~ ferrous ammonium sulfate, indicating 46. 2~c Ce~ ~otal cerlum.

., ~, 2-ethyl he~oic acid (l. 0 g~ was added to 2 g of solid cerous 2~thyl he;~:oate. Upon heating and addition of 50 g of Amsco all went in~o solu$ion. HydIogen p~roxide (10% solution) 0. 60 g was added 5 at room temperature, and ater five minutes ~e re~ctLon was heated to 70C and ~en cooled, A seconcl portion o 0. 6 g f H2O2 was added, a~ room temperat;lre and heated again to 70C. ~alysis ~n~ic~ 24~C o~ tl~tal ~ was c~ric.

E~AMPLE 11 TherQ was placed 4. 4 g 2-ethyl hexoic acid in a flask.
There were added 4. 0 g of 30~C NaO~I solution, followed by 0. 57 g of 30~ H2O2 solution, stirred and 5. 9 g Ce(NO3)3 solution added to 5 obtain an orange solution which solidified ater three rninutes. 10. 5 g Amsco 1~0 was added to make an a~ueous solution, whic~ was stirl~ed for five mixlutes and ~en placed in a 70C bath for t~irty mirlutes. The solutioll w~s allowed to cool and org~nis l~yers sar~pled for titration.
w~w~kTcOe~ralcce- 12~C
:Repea~ed additions of H202 increased ~e amount o ceric.

~o~ ~æ~

:EXA~PLE 12 Charges Wt. Assa~ 100 37C Moles Cerous 2-e~ylhe~oate 2.0 24.0 0.48 g Ce 0.0034 2-:E~ylhe~oic acid 1.0 98.3 0.9030 0.0070 Amsco 140 50.0 50.0 H2O2 1. 16 1b 0. 1~66 0. 0034 Cerous 2~e~ylhe2~oate alld 2-ethyJhexoic acid were combine~. 50. 0 g Amsco 140 and 0. 58 g E22 ~10~C W/W) were added, stirred f ive minutes and hea~ed to 70C over thirty 10 minutes a~d ~en cooled.
W/W~C~e- 46. 4%.
O. 58 g H22 '~D~C w/w) wa~ added a ~econd tirne, stirred five minutes, and ~eated at 70C over ~irf:y mimlte,s and t~en cooled. -w/w'3~ ~teallCe = 67. 8%.

, ~ .

Claims (22)

Having regard to the foregoing disclosure, the following is claimed as the patentable and inventive embodiments thereof:

1. A process for preparing ceric carboxylates which comprises oxidizing a cerous carboxylate with aqueous hydrogen peroxide in a two-phase system comprising an aqueous phase of hydrogen peroxide having a PH of at least 6 and an organic phase comprising a solution of cerous carboxylate in a water-immiscible hydrocarbon solvent a temperature at which the reaction proceeds but below the temperature of rapid decomposition of hydrogen peroxide, thereby converting cerous carboxylate to ceric carboxylate and forming a solution of ceric carboxylate in the hydrocarbon solvent; heating the reaction mixture at a temperature at which any ceric-hydrogen peroxide complexes present are decomposed; and separating the organic phase containing ceric carboxylate from the aqueous phase of the reaction mixture.

2. A process according to claim 1 in which the cerous carboxylate is used directly as a starting material, in solution in the water-immiscible hydrocarbon solvent, and the aqueous hydrogen peroxide solution combined with this solution in forming the two-phase reaction system.

3. A. process according to claim 1 in which the cerous car-boxylate is prepared from an inorganic cerous salt and a carboxylic acid by the addition of a base, and the reaction mixture used directly in the hydrogen peroxide oxidation, without separation of cerous carboxylate.

4. A process according to claim 3 in which an alkali metal hydroxide, carbonate or bicarbonate is added to a well-agitated aqueous solution of a water-soluble inorganic cerous salt, and the corresponding carboxylic acid in an at least stoichiometric amount, and extracting cerous carboxylate from the aqueous reaction mixture with a water-immiscible hydrocarbon solvent in which it is soluble.

5. A process according to claim 4, in which the solvent is present at the time of addition of the base, thus forming a two-phase system.

6. A process according to claim 4, in which the solvent is added at the end of the precipitation of cerous carboxylate from the aqueous phase.

7. A process according to claim 4, in which hydrogen peroxide is added as an aqueous solution shortly after the addition of the base has been completed, and prior to the separation of the two layers, and the pH of the reaction mixture prior to the H2O2 addition is above 6.

8. A process according to claim 7 in which the addition of H2O2 is made after base is added in a stoichiometric amount accord-ing to the amount of total acid present.

9. A process according to claim 7 in which the addition of H2O2 is made only after at least nearly the entire stoichiometric amount of base corresponding to the amount of cerium has been added, and the pH of the reaction mixture has been adjusted to above 6.

10. A process according to claim 1 in which the amount of hydrogen peroxide is selected according to the extent desired of the conversion of cerous carboxylate to ceric carboxylate within the range from at least 5% to about 95%.

11. A process according to claim 10 in which there are at least two incremental additions of hydrogen peroxide, each incre-mental addition being followed by a heat-cooling sequence to decompose ceric-H2O2 complexes.

12. A process according to claim 1 in which the cerous carboxylate is prepared by adding an aqueous solution of hydrogen peroxide into an aqueous solution of alkali or ammonium carboxylate, followed by addition of an aqueous solution of a water-soluble cerous salt, thereby forming the cerous carboxylate.

13. A process according to claim 12 which comprises adding an aqueous solution of hydrogen peroxide to the aqueous solution of cerous salt prior to the mixing with the alkali or ammonium carboxylate solution.

14. A process according to claim 12 which comprises adding an aqueous solution of hydrogen peroxide at a controlled rate during the mixing with the alkali or ammonium carboxylate solution.

15. A process according to claims 12, 13 or 14, carried out in the presence of an organic solvent to extract the ceric car-boxylate as it is formed.

16. A process according to claim 1 carried out at a tempera-ture within the range from room temperature up to 70°C.

17. A process according to claim 1 in which the cerous carboxylate is selected from the group consisting of cerous naphthen-ate, cerous 2-ethylhexoate, and cerous neodecanoate.

18. A process according to claim 1 in which the cerous carboxylate is derived from a carboxylic acid selected from the group consisting of aliphatic and cycloaliphatic saturated and unsaturated carboxylic acids and mixtures thereof having from about seven to about eighteen carbon atoms.

19. A process according to claim 1 in which the water-immiscible liquid hydrocarbon solvent is selected from the group consisting of aliphatic cycloaliphatic and aromatic hydrocarbon solvents having from about six to about fourteen carbon atoms.

20. A process according to claim 1, carried forward to an at least 5% conversion of cerous carboxylate to ceric carboxylate.

21. A process according to claim 1, carried forward to a conversion within the range from 30% to 60% of cerous caxboxylate to ceric carboxylate.

22. A process according to claim 1, carried forward to a conversion within the range from 50% to 95% of cerous carboxylate to ceric carboxylate.