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3,384,661 United States Patent Office Patented May 21, 1968 2 and fractional crystallization in the absence of a solvent. 3,384,661 Direct crystallization, with or without a solvent, is dis ALCOHOLATES OF BIS(p-AMNOCYCLOHEXYL) advantageous in that the solubility of the three isomers METHANE AND THEIR USE IN SEPARATHNG is similar and crystallization is difficult to achieve. A high STEREOISOMERS OF BIS(p-AMNOCYCLOHEX 5 degree of concentration of one isomer may require many YL)METHANE Wilfred J. Arthur, Charleston, W. Va., assignor to E. E. du recrystallizations. The formation of chemical derivatives Pont de Nemours and Company, Wilmington, Del., a gives a more positive crystallization scheme but has the corporation of Delaware disadvantage of usually requiring at least one reaction step No Drawing. Filed Dec. 28, 1964, Ser. No. 421642 and one or more subsequent chemical steps to regenerate 14 Claims. (C. 260-563) the diamine after separation. 0 I have discovered that PACM coordinates with cyclo aliphatic compounds of the following formula to form ABSTRACT OF THE DISCLOSURE what I call an alcoholate: Alcoholates of bis(p-aminocyclohexyl)methane and (4) HX-R cycloaliphatic alcohols such as cyclohexanol are prepared 15 by admixing the two components in the presence or ab wherein: sence of an inert organic diluent such as cyclohexane. The X is oxygen or sulfur; and alcoholates are useful in separating the stereoisomers of R is a compound of the following formulae bis(p-aminocyclohexyl)methane as the alcoholates of the stereoisomers have different solubilities one from the other 20 (2) CH and different solubilities than the stereoisomers themselves. c?, ich,CH). C Description of the invention and This invention relates to bis(p-aminocyclohexyl)meth 25 ane. More particularly it is directed to the bis(p-amino (3) m - cé5. a cyclohexyl)methane alcoholates of the following formula l, Yo?, (1) wherein: 30 n is a positive integer of from 1 to 9; NH HX - R Ra is hydrogen or alkyl of 1 to 5 carbons; and n- a n-(L)--. R3 is hydrogen or alkyl of 1 to 5 carbons; wherein: with the limitation that there be no more than a total of 25 carbon atoms in R. X is oxygen or sulfur; and It is to be understood that the R in the above formula, R is a compound of the following fromulae while illustrated as being saturated and unsubstituted is meant to include as well the unsaturated groups and both (2) CR the saturated and unsaturated groups containing any sub (CEI), 40 situtents which will not interfere with coordination of the HX-R molecule with the PACM molecule. and Stated differently the R of the above formula is meant (3) R2 CE to include unsaturated groups and all substituents which are less reactive with PACM than the OH or SH group. 45 The term alcoholate as used to describe the products --céR3 CH 3OH). of this invention means a compound of Formula 4 in as wherein: sociation with PACM by means of coordinate covalent bonds such as is commonly known in the chemistry of hy n is a positive integer of from 1 to 9; drates. The molecule of PACM and the molecule of the Ra is hydrogen or alkyl of 1 to 5 carbons; and 50 compound of Formula 4 are coordinated in a manner R3 is hydrogen or alkyl of 1 to 5 carbons; similar to water of hydration, with the compound of For with the limitation that there be no more than a total of mula 4 corresponding to the water. 25 carbons in R. While the exact formation and chemical structure of Bis(p-aminocyclohexyl)methane, hereinafter referred 55 these compounds is not completely understood their exist to as PACM, is known to exist in three stereoisomeric ence is readily ascertainable as will be more fully exempli forms. These stereoisomers exist because of the relative fied hereinafter. configuration of the two pendant amine groups and the These alcoholates are extremely useful in separating methylene group bridging the two cyclohexyl moieties. the stereoisomers of PACM. The alcoholates have dif The three stereoisomers are designated by common termi 60 ferent solubilities one from the other and markedly dif nology the cis,cis, the cis, trans, and the trans,trans iso ferent solubilities than the stereoisomers of PACM them CS. selves. By converting a stereoisomer fraction such as the As is often true of stereoisomers, these isomers some trans,trans isomer fraction to the corresponding alcoholate times differ in physical properties such as melting points. in a mixture of PACM stereoisomers a crystallization is In order to obtain a particularly desired property it is 65 easily obtained which permits the separation of the trans, often necessary to separate the stereoisomers or at least to trans stereoisomer from the other two isomers. Using this concentrate one or more isomers at the expense of the con method a mixture of the stereoisomers of PACM can be centration of the other isomers or isomer. reduced in trans,trans isomer content to 10% or lower. Various techniques are known for isolating or enriching Additionally, the alcoholate can, if desired, be decom the stereoisomers of PACM. Kirk et al., U.S. Patent No. 70 posed back into its component parts such as cyclohexanol 2,494,563 describes several techniques such as crystalliza and trans,trans PACM by simply subjecting the alcoholate tion from solvents, preparation and isolation of derivatives to fractional distillation under either atmospheric or re 3,384,661 3 4. duced pressure. Under these conditions the cyclohexanol cis,trans isomer. If a mixture of the PACM isomer al will boil off at its pure component point and the diamine coholates is formed their separation is ordinarily on the at its pure component point. This technique, utilizing the same order with the trans,trans isomer alcoholate crystal alcoholates of this invention, provides an easy, effective lizing first. and inexpensive method for separating or concentrating The crystallization of the alcoholates is accomplished the isomers of PACM. by methods well known in the art, with simple cooling, Starting materials agitation or sending being used as desirable. The PACM starting material can be prepared by any Separation of the crystallized alcoholate can also be ac suitable means. Satisfactory methods are described, for complished by methods well known in the art, such as example, in Kirk et al. U.S. Patent No. 2,944,563 issued 0. filtration, centrifugation, or concentration by decantation. Jan. 17, 1950; Whitman, U.S. Patent No. 2,606,925 issued If desired, the reaction can be conducted in the pres Aug 12, 1952; and Barkdoll et al., U.S. Patent No. ence of an inert organic diluent. It appears that most of 2,606,928 issued Aug. 12, 1952. the trans,trans isomer alcoholate which is formed during Suitable alcohols and thiols of Formula 4 can be ob the reaction is dissolved therein in the other PACM tained commercially or can be prepared by methods well 15 isomers or their alcoholates. Addition of an inert organic known to the art. For example, the alicyclic alcohols can diluent can therefore be used to advantage by decreasing be prepared by catalytic hydrogenation of the correspond the solubility of an alcoholate, such as the trans,trans ing ketones, the alicyclic carbinols can be prepared by the isomer alcoholate, in the other PACM isomers or their Bouveault-Blanc reduction of the corresponding esters, alcoholates. and the thiols can be prepared by treating the correspond 20 A diluent if used can be admixed with the other reac ing halides with potassium hydrogen sulfide. tants in any order. The amount of diluent used can range Alcohols of Formula 4 which have been found particu from trace amounts up to many times the volume of the larly satisfactory in forming readily separable alcoholates other reactants. For reasons of convenience and economy with the trans,trans isomer of PACM are as follows: the diluent will normally be used in amounts ranging from cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, 25 about 1 to 5 times the volume of the PACM used, with the cyclooctanol, cyclononanol, cyclodecanol, cycloundecanol, optimum recoveries obtainable at announts of about 3 cyclododecanol, 2 - methyl-cyclohexanol, cyclobutylmeth times the volume of PACM used. anol, cyclopentylmethanol, 1-(cyclohexyl)ethanol, cyclo In view of its purpose the diluent should be selected on hexylmethanol, cycloheptylmethanol, cyclooctylmethanol, the basis that the reactants dissolve in it while the al cyclononylmethanol, cyclodecylmethanol, cycloundecyl 30 coholate reaction product is readily separable from it such methanol, cyclododecylmethanol, 2-(cyclohexyl)butanol as by crystallization of the alcoholate followed by filtra 2, 3-(cyclooctyl) hexanol-3, 2-methyl-cyclopentanol, 4 tion, centrifugation or decantation. It is also desirable isopropylcyclohexanol and 2-methoxycyclohexanol. that the diluent be one which can be removed by distilla Thiols which have been found satisfactory in forming tion or evaporation. separable alcoholates with the trans,trans isomer of 35 As will be obvious to one skilled in the art the choice PACM include cyclopentanethiol, cyclohexanethiol cyclo of such a diluent would also be made on the basis that it heptanethiol and cyclohexylmethanethiol. is non-reactive with the starting materials or the alco holates being formed. For example, such classes of com Reaction conditions pounds as organic acids, aldehydes or ketones and or The preparation of the alcoholates and subsequent Sep 40 ganics containing active halogens are not considered aration of alcoholates from remaining stereoisomers can “inert' organic diluents for the purposes of this invention. conveniently be accomplished as will now be described. Classes of compounds which have been found valuable as The preparation of the alcoholate is accomplished by inert diluents include ethers, aromatic hydrocarbons, bringing together in a suitable vessed a quantity of PACM straight and branch-chained aliphatic hydrocarbons, ni with a stoichiometric amount of one of the previously de tries, ketals, aliphatic amines and stable chlorine contain scribed compounds of Formula 4.

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