CA1049033A - Chromium salt catalysts and their use - Google Patents

Abstract

ABSTRACT

This patent describes the catalytic promotion of the reaction of oxirane-containing compounds with carboxylic acid compounds at high, ambient, and low temperature. Specifically, this patent describes the method of reacting oxirane-containing compounds with carboxyl-containing compounds, preferably at temperatures at or around ambient in the presence of active chromium III tricarboxylate salts which have unoccupied coordination sites. More specifically this patent describes the preparation of catalytically active chromium III-tri-carboxylates from normally catalytically inactive chromium III-tri-carboxylate hydrates. These compounds are powerful catalysts for the reactions of oxirane compounds with both organic carboxylic acids and cyclic primary imides.

Description

BACKGROUND OP THE INVENTION
Chromium salts are known in which the oxidation state of chromium varies between one and six. Extensive investigation has shown, however, that chromium III is the most stable and important oxidation state of the element. An important characteristic of the chromium III ion is that it has six coordination sites arranged in an octahedral configuration about the central ion. The coordination sites of chromium III
account for the existence of stable complex ions such as the hexaaquochromium ion Cr(H20)6+++ and the hexaminochromium ion Cr(NH3)6 . In both of the above examples the water and ammonia, commonly called ligands (L), occupy the six coordinat-ion sites of chromium III and are arranged in an octahedral configuration about the central chromium III ion.

L L

~ ( :r L I L

Ligands may be electricallr neutral, as in the cases of water and ammonia, or negatively charged as in the case of the cyanide ion which gives rise to the negatively charged hexacyanochromium ion Cr(CN)6 2U Purther, chelating agents, such as the acet~lacetonate anion, form exceedinglr stable chromium chelates in which all of the chromium III coordination sites are occupied.

Cll ~ CU

The removal of the above-mentioned ligands from the chromium III
ion or the displacement of these ligands by other ligands is an extremely difficult and slow process. It is largely because of this kinetic inert-ness that so many complex chromium III species can be isolated and that they persist for relatively long periods of time in solution, even under condi-tions where they are thermodynamically quite unstable. Thus, the normally occurring form of chromium III compounds is the fully coordinated State. The kinetic stability of its widely found complex coordination compounds sets the chromium III ion apart from most other trivalent transition metal ions.
We have found that the commonly occurring fully coordinated chromium III
carboxylates are poor catalysts for carboxylic acid-oxirane reactions. Quite surprisingly, however, we have found that Chromium III compounds where~coor-dination sites are readily available for coordination (complexing) by either `~ charged or neutral ligands act as superior catalysts for such reactions and `~ also for the acit-imide reaction.
The present invention provides a novel catalyst suitable for the preferential reaction of oxirane compounds with compounds containing at least ~ one acitic proton, said catalyst comprising a CrIII tricarboxylate of the `, 20 formula j CrlOOCRa) where OOCRa is a carboxylate group containing at least 4 carbon atoms, said i catalyst being prepared by heating a hydrated CrIII tricarboxylate in an ex-cess of organic acid to a temperature above 140C to prepare a product of the following characteristics:
1. emerald green in color,

2. slightly soluble in hexane but freely soluble in acetone, .
.
~ - 3 -

3. melts slightly above room temperature,

4. does not exhibit water absorption peak at 2750 m~ in the near infrared, and

5. at least 90% of the carboxylate carbonyl absorption is at 1615 cm 1 and not at 1540 cm 1.
Additionally, the invention provides a process for preparing 2-hydroxyalkyl esters which comprises reacting an oxirane compound with a car-boxylic acid wherein either one or both of the said oxirane and the said -acid are mono functional, in the presence of an effective catalytic amount of a catalyst as defined above.
Furthermore~ the invention provides a process of forming ester linkages which comprises reacting a mono functional carboxylic acid with an organic compound having at least one oxirane group in the presence of an effective catalytic amount of a catalyst as defined above, and also a process of forming ester linkages which comprises reacting a mono functional oxirane compound with an organic compound having at least one carboxylic acid group in the presence of an effective catalytic amount of a catalyst as defined above.
, Finally, the invention provides a process for the preparation of polymeric esters which comprises reacting a polyfunctional oxirane compound ` with a polyfunctional organic carboxylic acid, in the presence of an effect-;~ ive catalytic amount of a catalyst as defined above, and the process of preparing poly b-hydroxyalkyl esters which comprises reacting a polymeric, ~`~ polyfunctional oxirane with a compound which contains at least two carboxylic acid groups in the presence of an effective catalytic amount of a catalyst as defined above.
Henceforth, the term "active chromium III tricarboxylate salts"
will be used to mean those chromium III salts having readily available coor-, dination sites that can interact with charge bearing or neutral ligands of the type described earlier.

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~ ~a~ - 4 -.~
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1 llhile not hound by any theory, it is helieved that the catalysis 2 1¦ o~ the acid-epoxy reaction by Cr(~C~R)3 is based on the transient occupation 3 ¦ of the available chromium III coordination sites by either an epoxide and/or 4 a carboxylic acid molecule. This unique activate~ comnlex places the epoxide and the carboxylic acid in the proper geometric and enernetic environment

6 for reaction to occur. The catalyst is regenerated and thus is able to

7 participate in further reactions. A typical reaction wherein both the epoxide

8 and acid are coordinated to the chromium is shown below.
g RCOOH~
10 r~COOI~ ~ R'CII - \ C~IR" 3 > ,CrtoOCRa~3 11 . , O", 13 R' CH CHR"

(Activatcd Compl~x) 7 . I~ ~
18 RCOOC~IR'CHR" ~ Cr(t)COR) 3 19 where ~a is aliphatic, aromatic, cyclo aliphatic~ aralkyl, alkaryl,of from 20 1 to about 1~ carbon atoms~ as well as their containinq imide, epoxy or 21 acid non-reactable substituents such as halogens, cyano, ether, ester and 22 amide. R, R' and R" are the same or different hydrocarhon group. .
23 These active chromium III tricarboxylate salts fulfill three prerequisites for 24 effective catalysis of the acid-epoxy reaction: (a) Solubility in the re-25 action media, (b) coordination sites available for catalysis, and (c) the 26 capahility of forming kinetically stable coordination complexes so that reagent 27 residence times on the chromium III ion are sufficient to oermit reaction to 28 occur. ~enerally the active chromium III salt will be in the carboxylate form, 29 wherein Ra is a hydrocarbon group. Ilowever, p~a may be partially substituted 30 as above to impart desirable specific physical properties to the catalyst for 31 certain applications. These properties include im~roved solubility, better 52 catalyst stability, lower melting point and the like.

.

1 llhile as stated, it appears that only one coordination site need 2 be utilized for reactant coordination to achieve catalytic activity for the 3 active chromium compound, it is seen that the more sites rade available 4 for such coordination the ~reater the catalytic activity of the compound as will be set forth in detail elsewhere, the sites are rendered available 6 for coordination by deaquation, namely the removal of coordinated water.
7 The preferred chromium III tricarbox~vlate salts are those in which 8 three of the six coordination sites on chromium III are unoccupied and are thus available to participate in catalysis. ~!ere, three chromium III
coordination sites are occupied by the carboxylate aninns to produce a 11 neutral molecule; the remainin~ three sites beinq unoccunied. The R side 12 chain ~roup of the carboxylate anions may be ad~justed in order to effect the13 necessary solubility necessary solubility in various reaction media necessary 14 for efficient catalysis. The structure of a typical chromium III tricarboxyl-ate salt possessing three unoccupied coordination sites may be envisioned as 16 follows:

19 O ¦tr ¦ ' R~
21 . 0 22 R~C~0 23 * ~ J~vailablc coordination sites.

2s Each Ra may be as defined above.
26 The advantages of the present invention have been found to be 27 obtained usin~ any soluble trivalent chromium III tricarboxylate salt con-28 tainin~ unoccupied coordination sites. In this form, the compounds are said 29 to be in the activated state. Typical compounds which when activated find use 30 in this invention, include but are not limited to, trivalent chromium 31 hexanoate, trivalent chromium pentanoate, trivalent chromium butyrate, trivalent 32 chromium 2 ethyl-hexanoate, trivalent chromium decanoate, trivalent chromium oleate, trivalent chromium stearate, trivalent chromium toluate, trivalent chromium cresylate, trivalent chromium benzoate, tri-valent chromium alkyl-benzoates, trivalent chromium alkoxybenzoates, trivalent chromium naphthanates and trivalent chromium alkoxides.
Generally, although not necessarily, the dehydrated trivalent chromium catalysts of our invention contain in toto from about 6 to about 60 carbon atomsO We have found that these catalysts are at least somewhat soluble in the reaction system. This solu-bility is essential to the effectiveness of the catalyst. How-ever, the exact degree of solubility is not critical.
The catalysts of the present invention may be utilized in any of several reactions between oxirane moieties and car-boxylic acid moieties.
The catalysts can be used for any of the below set forth reactions, to aid in the formation of any of the polymers~
monomers, and capped large chain molecules.

1. R-A + R10 ~A ti e)~R~Es (Hy)R
~Green~

2. 2 R-A ~ R'-0 -L-0 -R' (Active) R~EIs(Hy)-L-(Hy)~s-R
(Green) R~ R~

3- R-(A )-L-(A )-R + 2R~-0 - (A ti )tR'-(H ) E -L-ES (H )-R' (Green) R R

. .

4- R(Ac)~L~l (Ac)-L-]m(Ac)-R + (m+2)R~0x III

CActive) R'-(Hy) Es-L-~Es~Hy~~L~~mEs ~ )-R' ~Green) R
or ditto L-~tHy)Es-L-]m ditto 5. (m~2) R-A + R'-0 - L-0 -L-) 0 -R' c x x m x CrIII
(Active) Is(Hy)~L~~Es~Hy)~L~]mE (H )-R' (Green) R' or ditto L-[(Hy)E5~L~]m ditto 6- R-(AC)-L-[(Ac)-L-]m(Ac)-R + R'-0x-L-lOx-L-)mOx-R' Cr Polymer (Green) Ac is a carboxylic acid moiety x is sn oxirane moiety Es is an ester moiety Hy is a hydroxyl moiety L is a multivalent orgsnic linking group which may be any of alkyl, aryl, ara-lkyl, aryl, alkylene, or any of the above with non interfering substituents such ss fluoro, chloro, bromo, ioto, cysno, keto, ester, ether, etc.
R is a proton or an orgsnic rsdical of ]-20 carbon atoms which may be sny of alkyl, aryl, aralkyl, alkaryl, alkylene, or any of the above hydro-carbon m moieties substituted with non-interfering groups as described in the definit-ion for -L-. All R's may be the ssme or different. R' is defined the ssme as Wherein a~Ac moiety, and any Hy moiety may be relatively position-ed as a terminal or pendant group; and any x moiety may be relatively posit-ioned as either a terminal group or a divalent internal group positioned along the molecular backbone.
m = o or a positive integer.

~049033 1 DESCRIPTION OF PREFERRED EMBO~IMENTS

3 Chromium III salts in which the coordination sites are occupied by4 water, are referred to as "aquated" chromillm III compounds. The aquated compounds are those that are generally available in the market place as 6 chromium III salts. Aquated chromium III coordination complexes differ 7 from most simple metal salt hydrates in that dehydration of simple metal 8 salt hydrates may be accomplished by storaqe over dehydrating a~ents such asg sulfuric acid. Alternatively, mild heatina (ca. 100C) is routinely employed to dehydrate common metal salt hydrates such as calcium and magnesium sulfate 11 hydrates. On the other hand, aquated chromium III carboxylates can be 12 heated to hi~h temperatures with only moderate loss of water. However, it 13 should be understood that the mere drivina off of a portion of retained 14 water is not sufficient to prepare our novel catalysts.
The novel catalysts are prepared by the dehydration of the 1~ chromium III commercial carboxylate salts in the presence of an acidic 17 deaquation aid during this dehydration a chemical structure rearrangerent18 takes place.
19 When only heat is applied the normall~ violet carboxylate salts will either remain violet or change to a blue cast. This chan~e indicates 21 that approximately 2 of the 3 water molecules present have been removed.
22 Continued heating does not remove the third molecule of water, the third~
i 23 water molecule is only readily removed when~erform ed in the presence of 24 aboutO.7 mole percent acidic material such as or~anic carboxylic acids, as for 25 instance additional acid corresponding to the carboxylate anion of the j.~ 26 chromium compound or a different acid such as para toluene sulfonic acid.
`~ 27 l~hen the final water molecule is removed, a product results havin~ the follow-28 ing characteristics.
29 (1) It is emerald green in color, (?) slightly soluble in hexane,30 but freely soluble in acetone, (3) it melts sli~htly above room temperature, 31 (4) it does not have a water absorption peak at 275~ mm in the near infra-red, 32 t5) and it has a carboxylate carbonyl absorption at ~ cm 1 in the _g ,~

1 infra-red re~ion which is shifted from that for the hydr~ted form.
2 These properties are in marked contrast to the comnercial hydrated3 chromium III carboxylates. The hydrated form on the other is readi1y soluble in hexane, and comp1etely insoluble in acetone, does not show any tendency to melt up to 300C., it is violet in color, it has a stron~ absorption at 6 2 55 in the near infrared, and it has a broad characteristic carboxylate 7 carbonyl absorption at _ 15~0 cm 1 in the infra-red region.
8 Previously we have mentioned that the third water molecule can g be removed from a typical salt such as chromium III tri 2-ethyl hexanoate by the use of an acidic dea~uation aid subsequent to the removal of the 11 first two water molecules. If, however, the acidic aid is added at the 12 commencement of the heating cycle, then dehydration and rearranaerent to 13 the catalytic (active form) of the chromium compound can occur simultaneously.
14 In this manner a random statistical mixture of hydrated~ non-hydrated and partially dehydrated salt is formed.- The fully dehydrated portion will 16 rearrange to the catalytically active charge. The color is seen to vary 17 from the original blue-violet through blue to ~reen. The catalytic 18 capability is proportional to the amount of green material present. The 19 ratio of active to inactive catalyst in this mixture can be measured 20 spectrophotometrically by determing the ratio of the carbonyl absorption at 21 ¦ 1615 _ cm 1 to the carbonyl absorption at _ 40 cm 1 22 . . .

24 Once the necessary coordination sites on chromium III have been 25 freed for catalyst participation, care must be taken to insure catalyst 26 activity during the reaction. Inert solvents such as benzene, toluene, 27 methylisobutyl ketone, etc., are acceptable. Electron donatinn solvents 28 ¦ such as methanol, ethanol, dimethylformamide, dioxane and tetrahydrofuran,29 however, were found to retard catalysis at certain temperatu~es in ~
such instances. . These electron donating solvent molecules tend to con-31 gregate around the chromium III coordination sites and block the transient 3~ ¦¦ residence ~f e actd-epoly reagents on these sites and tbus prevent reaction ,.

~ . . . , . . . ., . . . _ 1 catal sis. 1 O ~
2 In general, the inactive (hydrated) chromium III tricarboxylate 3 salts are prepared bv the reaction of an aquated inoraanic chromium III salt4 such as aquated chromium nitrate with three moles of sodium carboxylate.
6 n Cr(N~3)3(H2n)9 + 3 n RC~Na --Crn(~2~)3n + (CR)3n 3 3 2 7 The chromium III Sdlt obtained by this method is catalytically inactive since 8 the six chromium III coordination sites are occupied by the water. In orderg to produce the active catalyst, the aquated form must be subjected to a high temperature, acid catalyzed process in which the coordination sites are 11 freed of water as recited above.

13 Crn(~l2n)3n ~CR)3n -l~C~Z~r-- n Cr(o~cR)3 + 3 n 1~2n 14 Active Catalyst 15 In the above two equations, R is a monovalent or~anic radical such as alkyl, 16 aryl, alkaryl or aralkyl, and preferably contains from l to about 20 carbon17 atoms.
i 18 While we have previously defined the term active chromium III, ~9 by the term "inactive" as a modifier for salt, chromium III, etc., we mean that the level of catalytic activity is up to and no ~reater than that of other 20 commonly used metal~organo salt catalysts such as stannous octoate, and iron 22 oleate , and in many instances non-catalytic at all.
23 The anion (negatively charged) portion of the catalyst is also critical to its activity in the sense that it may not cause complete coordination. For example, if the carboxylate anion is replaced by the `....... 25 26 acetylacetonate anion the resulting chromium III acetylacetonate is catalyti-27 cally inactive under our test conditions. The reason for this is that the 28 acetylacetonate groups effectively occunV all of the chromium III coordination :i sites.

,~ . . . . .

~ 1049033 1 The same inactivity occurs if the active chromium III t~icarboxylate is 2 contacted with a non-charged specie such as ethylene diamine to form the 3 ethylene diamine comp1ex of the salt.

6 ~ !l I

9 ~I Cr(lOCn)3 'll12CH2Cll2NH2 ~ OCR)3

10 active ~ 3 inactive

11 (~reen) (P~rple)

12 It is seen that while this application is directed to the reaction

13 of oxiranes with carboxylic acids, both monomeric and polymeric that the

14 catalysts will aid in the reaction of axiranes with other compounds which contain labile hydrogens, such as organic cyclic Primary imides 16 both monomeric and polymeric, monofunctional and pol~functional.
. . .

::
. ... . , : ; . . . .. .

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.. : ~ . .

.. ' ~ .,' . ' ' "' 1 The following example~ are presented solely to illustrate the invention 2 and accordingly should not be regarded as limiting in any way. In the 3 example~, the parts and percentages are by weight unless otherwise 4 indicated .

6PREPARATION OF NON-CATALYTIC, 8A solution of lZO g (3. 0 moles) of sodium hydroxide was 9dis~olved in SOO ml of distilled water. 2-Ethylhexanoic acid (475g, 3. 3 10 moles) was added with stirring to form sodium 2-ethylhexanoate. In a 11 separate contained, 200 g (O. 5 mole) of chromium nitrate nonahytrate 12 was dissolved in 500 ml of distilled water. The chromium nitrate 13 solution was slowly added to the sodium 2-ethylhexanoate solution with 14 good stirring. When the addition was complete, 500 ml of hexane were

15 added and stirring was continued for 10 minutes. The layers were

16 separated and the hexane layer containing the aquated chromium III tri-2-

17 ethylhexanoate was washed with dilute sodium hydroxide solution, water,

18 tilute sodium carbonate solution and finally with distilled water. The

19 hexane solution was then dried over anhytrouo magnesium sulfate. Most

20 of the hexane was removet under reduced pressure and the resulting

21 concentrate was slowly added to 500 ml of acetone. The resulting blue

22 granular solid was filtered and air driet to yielt 130g (54%) of aquate~

23 chromium tri-Z-ethylhexanoate. Molecular weight tetermination

24 ir~dicated that the compound i8 polymeric in nature, probably due to the

25 oxygen britging of chromium atoms.

26 Anal. Calct for C24H510~Cr: C, 53.8; H, 9.6; Cr, 9.7.

27 Found: C, 53. Z; H, 8. 7; Cr, 9. 4.

28 Azeotropic tata indicatet three molecules of water per

29 chromium atom.
The discrepancy in the hydrogen analy~is i8 believed to be caused 32 by chr~mium inter~erence.

:-` , .

.. .. . . . . .. _ . . . . . . . ..

1EXAMPLE Ila 4A stock solution of 5. 0g of aquated chromium tri-2-ethylhexanoate 5 and 2. 5g of 2-ethylhexanoic acid in chloroform was prepared. Ten-ml 6 aliquots of thi~ 60lution were transferred to each of ten 50-ml volumetric 7flasks and placed in a 140 oven for 0 (control), 0. 5, l. 5, 3 and 6 hours.
8 After each time interval two of the flasks were removed from the oven.
9 One was diluted to the mark with carbon tetrachloride and the conver~ion 10 from aquated to active chromium tri-2-ethylhexanoate was determined 11 by measuring ~:he absorption intensity of the solution at 275~' milimicrons.
12 It was determined ~hat fully aquated chromium tri-2-ethylhexanoate 13 absorb~ strongly at 275, milimicrons while the active deaquated 14 chromium compound does not absorb at this wavelength. The conversion 15 from catalytically inactive fully coordinated aquo chromium tri-2-16 ethylhexanoate to the active form is illustrated in Table 1.

18CnNVE RS I ON FROM I NACt I V T~
19ACTIVE CHROMIUM III TRI-2-E~HYLHEXANOATE
Time at ,~ % Free 21 140 C, Hour %~Deaquated Chromium r Coordination Sites O O O

2S 0.5 6.9 6.9 24 1.5 14.0 14.0 3.0 33.0 33.0 6.0 44.0 44.0 * 90.0 90.0 28 * In order to free the desired large percentage of the coordination sites 29 on chr~mium III, additional 2-ethylhexanoic acid was added and

30 the solution was heated at 200C.

31

32 .14-..

l 1049033 1 1¦ To the other 50-ml volumetric flasks removed frcm the 140 2 1 oven at the above time intervals waq added 30 ml of a sol~ltion containing 3 ¦ 144 g (2. 0 moles) of 1. 2-butylene oxide and 14. 4g (0.1 molej of 4 2-ethylhexanoic acid diluted with toluene to a volume of 500 ml. The flasks were then diluted to lhe mark with toluene. This operation provided 6 iolutions for the kinetic study having the following reagent concentrations:
2-ethylhexanoic acid 0.12 molar 8 1, 2-butylene oxide 2. 40 molar 9 ch romium compound 0. 01~ molar A control sample containing no chromium compound was also 11 prepared. Five-ml aliquots of ~hese solutions were quenched into 50-ml12 portions of methanol and the unreacted acid determined by titration with 13 base. The catalytic activity of the chromium tri-2-ethylhexanoate in 14 various stages of aquation is summarized in Table II.
EXAMPLE I I~
16 When the 2-ethylhexan~ic acid was replaced by cleic acid in 17 the amount of 928 grams, utilizing a substantially similar procedure, 18 as in Example I, aquated chromium oleate was prepared, the conversion 19 to the actjve form was carried ouL by heating at elevated temperatureslhe aquated form of the compound in a distilling flask with a l~éan Stark 21 tube connecLed thereto for removal of the moisture. During the course of Z2 ll the heating esd nf ~leic acid is added as d deaqUdt10n d;d.

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~049033 1 As shown in Table 2, the active chromium IIl salL having 90~o 2 open coordination sites caused the acid-epoxy reaction to be 100%
3 complete in one hour at 22C. The fully aquated chromium salt, on the 4 other hand, caused only 10. 6% reaction to occur in 72 hours, only slightly faster than the uncatalyzed reaction. More sophisticated 6 kinetic calculations indicate tha~ the acid-epoxy reaction proceeds appro-7 ximately 10, 000 timeq faster at 23C when catalyzed with 1% active 8 chromium tri-2-ethylhexanoate than in the uncatalyzed reaction. The 9 data also show that the active chromium tri-2-ethylhexanoate having unoccupied coordination sites is approximately 1000 times more effecti~re 11 than the fully aquated chromium III salt. Superior catalytic activity 12 is not achieved until nearly all of the occupied coordination sites on 13 chromium III have been freed for catalyst participation.
~*****~******
14 The invention is applicable to any monofunctional oxirane oxygen 15 compound including ethylene oxide; 1, 2-propylene oxide, 1, 2-butylene 16 oxide, 2, 3-butylene oxide, 1, 2-epoxyhexane, cyclohexene oxide, styrene oxid 17 and others of the Formula R3-C~I-tH-R4 wherein ~3.h ~4 are hydroqen 18 or alkyl~ total carbon content bein~ from 1 to 20 carbon ato~s.
19 ¦ The polyfunctional epoxide materials for use in the invention 20 ¦ include organic materials having a plurality of reactive 1, 2-epoxy groups.
21 1 The mono and polyfunctional epoxide materials can be saturated or 22 ¦ unsaturated. aliphatic, cycloaliphatic, aromatic or heterocyclic, and 23 ¦ they may be sub~tituted if desired with other substituents be6ites the 24 ¦ epoxy groups, e.g. hydroxyl groups, ether radicals, halogen atoms, and 25 the like. Such oxiranes having a plurality of epoxy groups utilizeable 26 ¦ include 1, 2, 3, 4-diepoxy butane, 1, 2, 5, 6, -diepoxy hexane, diepoxide of 27 ¦ divinyl benzene, and the like. The invention is particularly adapted to 28 ¦ the reaction of any epoxyalkanes or epoxycycloalkanes, typically con-29 ¦ taining from 2 to about 20 carbon atoms, with organic carboxyl~c acids.
30 ¦ It i~ within the scope of this invention to utilize as oxirane 31 constituenUnot only the di dlddition products of such phenols as 32 ¦ Bisphenol A with epichlorohydrin and the like, but also the higher 1 I molecular weight diepoxides of polybisphenol compourids, as well as the2 polyepoxy novolac compounds wherein the molecular weights vary 3 stati stically, 4 As indicated previously the catalyst of this invention can be S utilized in the reaction of epoxy materials which are themselves polymeric 6 ¦ with carboxylic acids. If the acid component has monoacid functionality,7 ¦ then hydroxyalkyl esters are formed on the epoxy resin backbone. If 8 ¦ however multi acid functionality compounds are used the compounds 9 ¦ formed are larger block polymers linked by monomeric units. If 10 ¦ however the multifunctional acids are themselves polymeric, a block 11 ¦ copolymer would be formed.
12 ¦ The epoxy resins which may be used in the practice of this 13 ¦ invention include any of those materials familiar to tho~e skilled in the 14 ¦ art. Typical epoxy resins suitable in the practice of the present invention are those disclosed in U. S. Pats. No. 2, 500, 600 and 2, 324, 483, the 16 disclosures of whicb are expressly incorporated herein by reference.
17 While not limited thereto, the epoxy resins of the present invention 18 normally have epoxy equivalent weight values of from about 100 up to 19 4000 or higher. The more common types of epoxy resins are the reaction products of epichlorhydrin and 2, 2-di(p-hydroxyphenyl) propane, the 21 glycidyl ether of mononuclear di- and trihydroxy phenols (resorcinol, 22 hydroquinone, pyrocatechol, saligenin and phloroglucinol),the glycidyl ether 23 of other polyhydroxyl phenols (Bisphenol F, trihydroxyldiphenyl dimethyl 24 methane, 4, 4'-dihydroxy biphenyl, tetrakis (hydroxyphenyl) ethane, long-chain bisphenols, dihydroxy diphenyl sulfone, and Novolacs), the 26 glycidyl ethers of polyalcohols (ethylene glycol, 1, 4-butanediol, glycerol, 27 erythritol, and polyglycols), and the epoxylated cyclic and straight 28 chain olefins (vinyl cyclohexene, dicyclohexene carboxylate, and poly-29 butadienes). These and many other epoxy resins are availableplasticizercommercially for example, under ehe trade name "Epon Resins" from the 31 Shell Chemicals Company, "Araldrite Resins" from the Ciba Company, 32 "DER Resins" from the Dow Chemical Company and "Unox Epoxides" from -1~^

~049033 Union Carbide Chemicals Company.
Carboxylic acids utilizeable herein may be monofunctional as well as di and polyfunctional. They may also be saturated or unsaturated aliphatic, aromatic, heterocyclic, monomeric and polymeric in nature. They may also contain non-interfering groups other than carboxylic acid as sub-stituents on the organic backbone. Typical of the monofunctional acids are acetic, formic, 2-ethyl hexanoic, octanoic, salicyclic, dodecanoic, oleic, 2-methoxy propionic, toluic, ascorbic, linoleic, linolenic, acrylic, methacrylic, benzoic, naphthoic, chloroacetic, lactic, ricinoleic, stearic, benzylic, butyric, cyclohexane carboxylic, picolinic and furane carboxylic, acids~
Polyfunctional monomeric acids utilizeable include citric, citro-conic, maleic, itoaconic oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, brassylic acid, trimellitic acid, trimesic acid, phthalic acid, isophthalic acid, o, m and p, dicarboxy benzophenones.
Mention should also be made of polyfunctional polymeric acids, these include carboxy functional polyesters, carboxyterminated polyolefins, ~` e.g. polybutadiene, carboxy terminated polyethers such as the succinic acid half ester of polyether glycols; dimerized and trimerized fatty acids~
In the practice of the invention, the activated trivalent chromium compound is used in an effective catalytic amount, of from about 0.1% to about 10% based on the total weight of the three key components, namely the oxirane, acid, and catalystO Thus if a 1 (one) per cent level is desired, 99 grams of a mixture of the oxirane and acid components would be utilized with 1 gram of catalyst.
If other miscible or soluble ingredients are added to the system the catalyst level must be based upon the total weight in grams of the solution phase. Thus if a plasticizer is added to the 99 grams of reactants, and is present in the weight of 49O5 grams, the catalyst level -` need be set at 1.5 grams to maintain a catalyst c~ncentration of 1% if it is desired to maintain comparable reaction rates to the above reaction 1` . . , . , _ _ 1 ~/ithout plasticizer.
2 If inert insoluble materials such as carbon black, silica gel, 3 CaC03 and the like are added to the system, their weinht is not to be taken 4 into consideration in calculatin~ the catalyst level.
The foll~qin~ examples relate to the preparation of monomeric a compositions in the presence of the catlyst of this invention.

g PREPARATI~I OF HYDROXYPROPYL ACRYLATE
The reaction of 5 0 moles acrylic acid with 5.5 moles propylene 11 oxide under pressure in the presence of the catalYst of Ex. II (0.28% by 12 weiaht of total system) at 70-75C gave both B~hy~roxy alkyl ester isomers. The 13 material wasJisolated by wiped-film distillation (b.p. 55 to 60C at 0.02 to 14 ¦ O.OS mm)~ in 86.7% yield and 99.3% purity based on titration with alcoholiclS ¦ potassium hydroxide, and on ~as chromato~raphy analysis for unreacted acid.

17 ¦ EY~PLE IV
18 ¦ PREP~RATION OF 2-~YDROXYETHYL ACETATE
19 ¦ The 2-hydroxylethyl ester of acetic acid was Drepared in methyl 20 ¦ isobutyl ketone by allowing 5.0 moles acetic acid and 5 5 moles of 21 ethylene oxide to react in the presence ofo.28Xof the catalyst of Example II
22 (based on weight of total system) under pressure at 150-1600C for 2 hours. The 23 acid was quantitively converted as determined by titration with aqueous N/10 24 sodium hydroxide. Vacuum distillation of the crude ester ~ave a colorless product boiling at 64-67C at 2 mm pressure, havin~ a refractive index of 8 1 . 4202 dt 25 . , . . , . .. _ . . . , _ 1 ¦ E AMPLE V

3 ¦ PREPARATION OF
4 ¦ BIS(2-HYDROXYETHYL)ADIPATE

5 ¦ Adipic acid (36.5g, 0.25 mole) and thc catalyst of 6 Examplc II (0.4g) in methyl isobutyl ketono (250 ml) were hcated 7 at 160C and subsequcntly ethylenc oxide (24.23~, 0.55 mole) 8 was added; th~ temperature was kept at 160C. Aftor 60 minutes, g the pressure dropped from 103 psi to 57 psi. After solvent ovaporation, the crude product (60.4g) was distilled under ~acuum; a light yellow material (3S.0g) was obtsincd boiling at 2 202-203C at 1 mm pr~ssure in 60.0~ yiold, ha~ng a r~fractive 3 ind~x o~ 1.4619 at 25-C. The infrared spectrum was consist~nt 4 with that expected for the estor (34S0 cm'l (Ol~), 2~70 cm' . 15 tC~l2), 1730 cm~l (C~O), and li80 cm'l (C-O)). Anal. Calcd.
16 for Cl0~ll806 C, 51.28; H, 7,6g; O, 41,03 , Found: C, 50.80;
7 ~l, 7.76; ~olecular weight by hy~roxy number: Theory:
2S4. Found: 234.
19 . .

22 pREpARATlnN nF
2 BIS(2-HYDROXYETHYL) AZELATE
24 The reaction of p.25 moles azelaic acid with 0,s5 moles ethylene 2s oxide under pressure usin~ methyl isobutyl ketone in the presence of the 26 catalyst of Example II(0.15g by wt. of total system) at 1530C gave bis(2-hydroxy 27 ethyl)azelate in quantitative crude yield. The material was isolated as a 28 grey-white solid meltin~ at 46-47C from a n-butyl chloride-acetone mixture 29 in 88.5X yield.

, . . .

,1 1049033 1 F.XA~1PLE VII
2 ¦ PREPARATInN OF
3 ¦ ~IS(2-HYDRlXYETHYL)OXALATE -4 ¦The 2-hydroxyethyl ester of oxalic aci(l was prepared in the l-liter ¦autoclave using ethylene oxide and 0.1~ of the catalyst of Example II (based ~ ¦ on total weight of system) in methyl isobutyl ketone at 150-1700C for 2 hours.
7 ¦ The conversion of acid was 76% of theory and vacuum distillation of the crude 8 1 ester gave a product boiling at 194-1~60C at 8~m. The product was of high g purity as established by hydroxyl number and elemental analysis.
Examples III to VII when repeated usinn activated forms of tri-11 valent chromium butyrate, trivalent chromium oleate, and trivalent chromium12 toluate in lieu of the cat~lyst of Example II, give rise to similar results.
13 Each of these catalysts is prepared and activated in the manner described in 14 Example II, using the corresponding carboxylate as recited here.
.
1~ EX ~PLE VIII
lr PREPARATION OF
18 TRIS(2-HYDROXYETHYL)CYCLOHEXANETRICARB()XYLATE
Cyclohexanetricarboxylic acid was allowed to react under pressure 20 with ethylene oxide and 0.15% of the catalyst of Example II. (based on total wt.
21 of system) in the presence of methyl isobutyl ketone at 150-160C for 2 22 hours. A viscous oil of good purity was obtained after charcoal treatm~nt and 23 evaporation of a methyl isobutyl ketone solution. The infrared spectra and 24 elemental analysis were consistent with the desired product.
26 _XAt~P E IX
27 . PREPARATION OF
28 TRIS(2-HYDROXYETHYL)TRIMESATE
29 Trimesic acid (1,3,5-benzene tricarboxylic acid) was converted to its t is-hydroxyethyl derivative usina the catalyst of Example II at IoX by 31 weight of reactants level. The trimesate ester ~ave an infrared scan con-32 sistent withthe structure of the product and melted sharply at 145C after ` . ~

1 purification. The reaction was carried out in methyl isobutyl ketone at 2 room temperature for 44 hours, and ~ave an 89% conversion of the acid and 3 an 87% recovery of the ester.

EX~ PLE X
6 PREPARATIO~I OF 2-~lYDROXYETHYL ~CRYLATE
7 Acrylic acid (3609, 5.0 mole: inhibited with p-methjoxy-phenol) in the presence of ethylene oxide (242~, 5.5 mole) and the catalyst of Example II
9 (3.69,0.6~ by weight of syste~) was heated in a l-liter pressure autoclave at 52~65C for 50 minutes; during the reaction. the Dressure dropped from 12 39 to O psia. The crude yield was 92% based on the converted acid as deterrnin-ed by titration of an aliquot with cold aqueous N/10 sodium hydroxide for 13 unreacted acid. Distillation of the crude material ~ave a colorless product 14 with a refractive index of 1.4495 at 23C.
When the foregoing example is repeated usin~ 1,2-propylene oxide 16 and ;,2-butylene oxide~ 2-hydroxypropyl acrylate and 2-hydroxybutyl acrylate, 7 respectively, are obtained respectively.

' 19 . .
. 80 ~ .

PREPARATION OP BISt2-HY~ROXYETHYL)SEBACAT~ ' 24 Sobacic acid (50.5g, 0.25 mole), tho catalyst of Bxample II tO.5g), and methyl ~sobutyl kotone (2SO ml) wore 2~ char~ed to the autoclave and heated to 150C. Ethylone oxido 27 (24.23g, 0.55 mo-le) was introduced from a nitrogen-pressurized 28 cylinder to tho autoclavo. Tho temperaturo roso to 160-C and . tho pressure ~ncreased from 25 psi to 100 psl. Aftor 60 ~inutos -~ 32 :. 23-. ~' .. . . .

1 at 160C, the prcssure dropped to 88 psi and the system was 2 vented. Thc ligll~ yellow green reaction mixture was mixcd 3 with cdrbon black, ~ hcated to boiling, and filto~od through a 4 sintcrcd-glass ~unnel containing some A1203. Upon cooling to 30~, thc prccipitated matcrlal was filtered, washed with cold 6 hexane, dried in a vacuum desicc~tor for 48 hours and weighod 7 (31.0g). Thc product was isolated in 44.0~ yi~ld and melted 8 at 47C. Tl~e infrared bands at 3350 cm~l (OH), 2970 cm~l g (Cll2) and 1730 cm~l (CoO) wero characteristic of the exp~cted cstor. Anal. C~lcd. for C14ll2fiOfi: C, 57.93; l~, 8.97; O, 33.10.
11 Found: C, 58.00; H, 9.02. ~lolocular weight by hydroxyl 12 numbcr. Theory: 290. ~ound: 289.

14 ¦ EXAMPLE XII

16PR~PARATIO~ OF
17BISt2-HYDROXYETt~L)TEREPHTIIALATE
18T~rephti~alic acid (0.2~ mole), the cstalyst of Example II (U.5g), ~nd methyl isol-utyl ketono t250 ml) is char~od to 21 an autoclavo and heated to about 150-C. A slight stoichiometric a oxcoss of othylene oxide is added to the autocla~e. A s~ight 2 exotllerm is observed. Aftcr about ono hour, the reaction ~ixture 2S is remo~ed from the autoclavc, cleaned, and filtored. Upon 24 cooling, a good yield of bis(2-hydroxyothyl)terophthalate is obtained in the form of a precipitate.

29An epoxy rcsin systcm comprising about 12 parts 30Unox Epoxide 201, equivalent weight 156 (3,4-epoxy-6-methyl--~4-. . . .

~049033 cyclohexylmethyl 3,4-epoxy-6-methyl-cyclohexane carboxylate) and about 8 parts Empol 1040 is treated at about 50C with about 2% by weight of the catalyst of Example II. The system cures in about 45 minutes. At 25C, the system cures in about 10-12 hours.
The following example illustrates a capping reaction.
EXAMPLE XIV
. . .
One mole of ethylene oxide is reacted with about 0.5 moles of carboxy-terminated polybutadiene (available commercially under the tradename Butarez CTL) for about 4 hours in the presence of 1% of the catalyst of Example II. The reaction temperature is about 40C. A hydroxyethyl diester ; of the carboxy-terminated polybutadiene is obtained.
In order to illustrate the difference between the active and non-active forms of the chromium carboxylate the following experiments were carried out.
EXAMPLE XV
` Into two 100 ml round bottom flasks, each equipped with a reflux .
condenser, was placed a solution of 1.0 g of anhydrous chromium 2-ethylhexan- ~
oate in 35 ml of MIBK in one flask and 1.2 g of non-active chromium compound -in the other.
To these portions were added 28g (17 moles) of terephthalic acid followed by 17g (170 moles) of cyclohexene oxide. The resulting mixtures were refluxed for 5 min. At this time all of the acid with anhydrous catalyst had reacted and was in the solution. Filtration of the reaction mixture employhydrated chromium catalyst allowed recovery of 2.5g(90%) of unreacted terephthalic acid.

. . . .
' ~ l ~049033 1~ E,~A~PLE XVI

4 1 Into two l25 ml Florence flasks ~las Dlaced l.O ~ of non-active l chromium octoate in the first and l gram of active chromium octoate S I i~ the other, both dissolved in 35 ml of toluene. To this solution was added 2.5~ of 2-ethylhexanoic(l7mmol)acid followed by l7~ of cyclohexene oxide 7 (l70mmol) The progress of the reactions was foll~/ed by removin~ 2.0 ml samples and ~uenching in 50 ml of methanol and ~itratin~with O.lN methanolic 10 KOH (phenopkthalein end point).
R act n Time _ours ~ on~;q~LY~ ~ ~
11 ml base m base 12 0 7.0 7.0 13 2.5 6.8 3.~
14 7.0 6.4 0.55 5.4 0.30 16 50 4.7 0.30 For the purposes of this application. thD ~.erm octoate an~ 2-ethyl 21 hexanoate are considered interchanaeable.
T erm COT is utllized to designate active chromium octoate.

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1 The ~llowing example~ serve t~ illustrate the fact that the 2 c~talyst o~ this inveDtion i9 utilizable for the catalysis -,f the 3 oxirane-imide reaction. It is to be seen that while 4 the examples relate to monofunctional monomeric reactants, the reaction ~ Polyfunctional materials is seen to be similarly catalyzed.

9WITH 1,2-PROPYIENE OXIDE AT 0C IN ACh~l~ONE
10SOLUTION, 11 ~ 0~ Acetone ~ ~ OH
32 ~ ~`N C 2 CH CH3 (a~cItI.Ie) ~ 'N-CH2-CH-CH3 14 ¦ Mol. Wt. 137 Mol. Wt. 58 0C.
. .
16 MATERIALS:
17 Chromium-III Tri-2-Ethylhexanoate as needed 18 3.43g(0.025m) Tetrahydrophthalimide 1 . 45g(0 .025m) 1 ,2-Propylene Oxi de Acetone to make 100 mlSolution 22 PROCEDURE: .
2S Two solutions o~ the above composition were prepared 24 having respectively 0 and 2~ Chromium III Tri-2-Ethylhexanoate.
These 601utions were prepared in 100 ml volumetric ~lasks which 26 were kept at 0C in an ice-water bath. Five ml aliquots were 27 taken at various tlme intervals and titrated ~or unreacted imide 28 wlth 0.25N alcoholic KDH using a pH titrimeter.

.

. ~RESULTS:

0% Chromium III 2% Chromium III
Tri-2-Ethylhexanoate Tri-2-Ethylhexanote Elapsed ~ Imide Eldpsed X Imide 6 Time, Min ~eac~ed Time, Min Reacted 6 O O O' O

8 ' 110 O 100 50 12 1 lllS O 1105 85 16 ¦ The table above illustrates the catalytic activity of the active : I chromium III tri-2-ethylhexanoate, for a t~pical oxirane-primary cyclic imide 18 ¦ reaction of 0 G.

20 1 . .

21 ¦ TtlE FOLLOWING EXAMPLES ILLUSTRATE THE PREPARATION' OF POLY~ERS
22 ¦ USING THE 'JOVEL CATALYST OF THIS INVENTION. ' 23 I EXAMPLE XVII~ ~
I .__ _ 24 ¦ tDIACID WITH TRIEPnXIDE) .
25 I A sto khiometric mixture of Emery 1025-94 acid (E.~l. 1600), a ' 2G ¦polyester dicarboxylic acid, and EPnN-X-901 (E.W. 10~), 1,3-diepoxypropyl, 27 I 2-phenylglycidyl ether, was prepared with 3% active chromium III-tri-2-ethyl-28 ¦hexanoate.
29 ¦ The sample was split into two parts. One part was placed in a 75C
30 ¦ overn where it cured to a tough, rubbery, greenish solid within fifteen 31 ¦ minutes. The other part was left at room temperature where it also cured to 32 I a tough, rubbery, greenish solid within twenty hours.

l -28-l . . .~, EXAMPLE XIX
.
~TRIACID WITH DIEPOXIDE) This example illustrates the high catalytic activity of the activated chromium III tricarboxylate catalysts for the oxirane/carboxylic acid reaction at room temperature and well below, as well as the tremendous accelerating effect of added heat.
A stoichiometric mixture of trimer acid (E.W. 290) a triacid derived from the trimerization of fatty acids, and ERL-4221 (E.W. 136), 3,4-epoxy cyclohexyl=methyl-~3,4-epoxy) cyclohexane carboxylate, was catalyzed with active chromium III tri-2-ethyl-hexanoate at three levels and cured at three temperatures. The catalyst levels, cure temperatures and mechanical properties are tabulated below:
Effect of catalyst level and cure temperature - on the Mechanical Properties of Emery Trimer ` Acid ~ ERL-4221 Catalyzed with active chromium III-tri-2-ethyl hexanoate.
Catalyst Level 1%, 3% 5%
Gel Time at 25C - 129 min57 min Cure Temp, & 60C 25C 2C

Mechsnical Properties 23 hr cure Tensile, PSI 734 238 " Elongation, % 147 155 47 hr cure Tensile, PSI 758 380 19 Elongation, % 133 139 441 115 hr cure `~ Tensile, PSI - - 112 Elongation, % - - 151 '~' .~ . . . .
- -~ MPLE _~v 2 The high specificity of the acti~/e c~romium III-tricarboxylate 3 catalysts for promotin~ the oxirane/carboxylic acid reaction is illustrated in this exa~ple, as we11 as their general applicabilit,y in this reaction.
The followin~ compositions were prepared from di- and polyepoxides 6 reacted with monofunctional carboxylic acids with active chromium III-tri-2- I' 7 ethylhexanoate (C~T) and inactive chromium III-tri-2-ethylhexanoate tri-8 hydrate (COT 3~2~)*' as well as wit~ no catalyst at all. The epoxides used 9 were the diglycidyl ether of bisphenol-A (~), the polynlycidyl ether of a pilenol-formaldehyde polymer (6) and vinyl cyclohexane dioxide, (C), the acids 11 used were acetic acid, (D) acrylic acid, (E) and 2-eth,ylhexanoic acid.

13 * Used in only one case for purposes of comparison.

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The products prepared in accordance with this invention are useful in films for wire and cable wrap, motor insulation, surface coatings, lacquers, textile fibers, adhesives, molding resins, fiber glass laminates for use in aircraft parts, honeycombs, electrical conductive films when properly coated, and foams, as well as for intermediates in the production of other chemical compounds.
Low molecular weight monomeric compounds are useful as diluents, plasticizers, polymeric intermediates and lubricants.
It should also be noted that one or more than one compound of each class of epoxides may be reacted with one or more than one acid.
Thus a monomeric monofunctional oxirane could be used in conjunction with a polyfunctional polymeric epoxide, for example if such is desired.
Similarly mono and poly acids can be utilized together.
Furthermore, the curable mixtures of the invention may be mixed at any stage prior to the completion of the degree of reaction possible as limited by the amount of one of the reactants, with fillers, plasticizers, pigments, dyestuffs,flame-inhibitors, mould lubricants or the like. Suit-able extenders ant fillers are, for example, asphalt, bitumen, glass fibers, mica, quartz meal, cellulose, kaolin, ground dolomite, colloidal silica having a large specific surface (Aerosil) or metal powders, such asaluminum powder.
Curable mixtures may be used in the unfilled or filled state, if desired in the form of solutions or emulsions, as laminating - resins, paints, lacquers, dipping resins, moulding compositions, coating compositions, pore fillers, floor coverings, potting and insulating com-pounds for the electrical industr~, adhesives and the like, and also in the manufacture of such p~oducts.
It is to be further understood that while the oxirane compounds can be reacted with the acids throughout the range of from about o& to 250&, there are certain situations wherein a particular temperature range should be utilized. For instance, if one of the reactants contains - I neaJv ~ensitive group~ such as carbon to carbon double bonds, temperatures 2 1l over about 50GC should be avoiaed. The desired rate of cata'ysis can also 3 1l be Pchieved by tne adjustment of catalyst level as well as by an increase - 4 ~ in temperature.
5 ¦ Operating temperatures are determined by the temperature necessary 6 ¦ to maintain mobllity of the reactive constituents Solvents help to main-7 l tain mobllity and thereby allow low temperature reactions to be carried out.

9 ¦ Rubbery end products are preferably prepared at temperatures below 75~C, 0 ¦ though elevated temperatures give rise to equally satisfactory products 2 1 with respect to certain physical properties.
l Since certain changes may be made in the above campositlons and 13 1 processes without departing from the scope of the inventian nerein involved, 14 1 it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

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' .

Claims (41)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A novel catalyst suitable for the preferential reaction of oxirane compounds with compounds containing at least one acidic proton, said catalyst comprising a CrIII tricarboxylate of the formula:
Cr(OOCRa)3 where OOCRa is a carboxylate group containing at least 4 carbon atoms, said catalyst being prepared by heating a hydrated CrIII tricarboxylate in an ex-cess of organic acid to a temperature above 140°C to prepare a product of the following characteristics:

1. emerald green in color, 2. slightly soluble in hexane but freely soluble in acetone, 3. melts slightly above room temperature, 4. does not exhibit water absorption peak at 2750 mµ in the near infrared, and 5. at least 90% of the carboxylate carbonyl absorption is at 1615 cm-1 and not at 1540 cm-1.

2. A catalyst according to claim 1 in which Ra is selected from the group consisting of butyrate, pentanoate, hexanoate, 2-ethyl hexanoate, de-canoate, oleate, stearate, toluate, cresylate, benzoate, alkyl benzoate, alkoxybenzoate and naphthenate.

3. A catalyst according to claim 2 in which OOCRa is 2-ethyl hexanoate.

4. A catalyst according to claim 2 in which OOCRa is oleate.

5. A catalyst according to claim 2 in which OOCRa is butyrate.

6. A catalyst according to claim 2 in which OOCRa is benzoate.

7. A process of preparing an active chromium III carboxylate catalyst of the formula:
Cr(OOCRa)3 where OOCRa is a carboxylate group containing at least 4 carbon atoms, com-prising the steps of heating a hydrated carboxylate in an excess of organic acid to a temperature above 140°C to prepare a catalyst of the given formula having the following characteristics:
1. emerald green in color, 2. slightly soluble in hexane but freely soluble in acetone, 3. melts slightly above room temperature, 4. does not exhibit water absorption peak at 2750 mµ in the near infrared, and 5. at least 90% of the carboxylate carbonyl absorption is at least 1615 cm-1 and not at 1540 cm-1.

8. A process according to claim 7 in which at least 0.7 moles of or-ganic acid is present during said heating step.

9. A process according to claim 8 in which the acid is the parent car-boxylic acid of the CrIII carboxylate.

10. A process according to claim 8 in which the temperature is no less than 200°C.

11. A process according to claim 7 in which the heating is commenced before addition of the acid to the hydrated carboxylate.

12. A process according to claim 7 in which the heating step is carried out in organic solvent.

13. A process according to claim 7 in which OOCRa is selected from the group consisting of butyrate, pentanoate, hexanoate, 2-ethyl hexanoate, de-canoate, oleate, stearate, toluate, cresylate, benzoate, alkyl benzoate, al-koxybenzoate and naphthenate.

14. A process according to claim 13 in which OOCRa is 2-ethyl hexanoate.

15. A process for preparing 2-hydroxyalkyl esters which comprises re-acting an oxirane compound with a carboxylic acid wherein either one or both of the said oxirane and the said acid are mono functional, in the presence of an effective catalytic amount of a catalyst according to claim 1.

16. The process of claim 15 wherein the reaction is carried out at about ambient temperature.

17. The process of claim 15 wherein the catalyst is as defined in claim 3.

18. The process of claim 15 wherein the oxirane is of the formula:

wherein each of R' and R" is selected from the group consisting of hydrogen and alkyl, and when either or both is alkyl, the total carbon content of the sum of R' plus R" being in the range of from 1 to 20 carbon atoms.

19. The process of claim 15 wherein the catalyst is present in an amount of from 0.1% to about 10% by weight of reactants.

20. The process of claim 15 wherein the oxirane compound is selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide and 2,3-butylene oxide.

21. The process of claim 15 wherein the carboxylic acid contains one (-COOH) group and the oxirane is mono functional.

22. The process of claim 21 wherein the carboxylic acid is selected from the group consisting of 2-ethylhexanoic, adipic, acrylic, acetic, azelaic, oxalic, cyclohexanetricarboxylic, trimesic, sebacic, and tere-phthalic acids and polyacrylic acids.

23. A process of forming ester linkages which comprises reacting a mono functional carboxylic acid with an organic compound having at least one oxirane group in the presence of an effective catalytic amount of a catalyst according to claim 1.

24. The process of claim 15 wherein a stoichiometric amount of acid is reacted in a stoichiometric amount of oxirane.

25. The process of claim 16 wherein the process is carried out at ambient temperature.

26. The process of claim 15 wherein the oxirane is selected from the group consisting of a glycidyl ether of mono functional alcohol and a gly-cidyl ether of a mono functional phenol, and a glycidyl ester of a mono functional organic acid.

27. A process of forming ester linkages which comprises reacting a mono functional oxirane compound with an organic compound having at least one carboxylic acid group in the presence of an effective catalytic amount of a catalyst according to claim 1.

28. The method of claim 15 wherein the oxirane is difunctional or polyfunctional.

29. The method of claim 27 wherein the oxirane is difunctional or poly-functional.

30. The process of claim 15 wherein the oxirane is a polyepoxide resin.

31. The process of claim 15 wherein the acid is a difunctional or poly-functional.

32. The process of claim 15 wherein the acid is a polycarboxylic acid resin.

33. A process for the preparation of polymeric esters which comprises reacting a polyfunctional oxirane compound with a polyfunctional organic carboxylic acid, in the presence of an effective catalytic amount of a ca-talyst according to claim 1.

34. The process of claim 33 wherein the reaction is carried out substan-tially stoichiometrically.

35. The process of claim 33 wherein the oxirane and the acid are poly-meric whereby block copolymers are formed.

36. The process of preparing poly B-hydroxyalkyl esters which comprises reacting a polymeric, polyfunctional oxirane with a compound which contains at least two carboxylic acid groups in the presence of an effective catalytic amount of a catalyst according to claim 1.

37. The process of claim 33 wherein the poly carboxylic acid is used in substantially stoichiometric amount with the oxirane.

38. The process of claim 33 wherein the catalyst is as defined in claim 3 or 4.

39. The process of claim 33 wherein the catalyst is as defined in claim 6.

40. The process of claim 33 or 36 wherein the reaction is carried out at about ambient temperature.

41. The process of claim 33 or 36 wherein the catalyst is employed in an amount of from 0.1% to about 10% by weight of reactant.