Methods of reducing color in alkanolamine compositions and compositions produced thereby

Abstract

A method of reducing color in an alkanolamine is described. The method includes contacting the alkanolamine with a color-reducing amount of a borane complex effective to provide a color-reduced alkanolamine composition having a Platinum-Cobalt Color Value, according to Test Method ASTM D1209, of less than 50.

Claims

1. A color-reduced alkanolamine composition, the composition comprising: an alkanolamine; and from 5 to 30 wt. % of a borane complex of the formula L.Math.BR.sub.aH.sub.3-a; wherein: L is ammonia; at least one R group is a C.sub.1-12 alkyl group; and wherein a is 1 or 2; wherein the alkanolamine is a mono(C.sub.1-10 alkanol)amine, a di(C.sub.1-10 alkanol)amine, a tri(C.sub.1-10 alkanol)amine, an N-(C.sub.1-10 alkyl) di(C.sub.2-4 alkanol)amine, an N,N-di(C.sub.1-10 alkyl) (C.sub.2-4 alkanol)amine, an N-(C.sub.1-10 alkanol)pyrrolidine, N-(C.sub.1-10 alkanol)imidazolidine, an N-(C.sub.1-10 alkanol)piperidine, an N-(C.sub.1-10 alkanol)piperazine or a combination comprising at least one of the foregoing.

2. The composition of claim 1, wherein the alkanolamine is a mono(C.sub.1-10 alkanol)amine.

3. The composition of claim 1, wherein the alkanolamine is a tri(C.sub.1-10 alkanol)amine.

4. The composition of claim 1, comprising less than 5 wt % of water based on the total weight of the alkanolamine.

5. A color-reduced alkanolamine composition, the composition comprising: an alkanolamine and from 5 to 30 wt. % of a borane complex based on the weight of the composition, wherein the composition has a Platinum-Cobalt Color Value, Test Method ASTM D1209, of less than 50, wherein: the borane complex is of the formula
L.Math.BR.sub.aH.sub.3-a wherein L is ammonia and each R is a C.sub.1-12 alkyl group, wherein a is 1 or 2.

6. A color-reduced alkanolamine composition, the composition comprising: an alkanolamine and from 5 to 30 wt. % of a borane complex of the formula L.Math.BR.sub.aH.sub.3-a; wherein L is ammonia; wherein at least one R group is present and is selected from the group consisting of a C.sub.1-12 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group and a C.sub.3-15 heteroaromatic group; and wherein a is 1 or 2.

7. The composition of claim 6, wherein the at least one R group is a C.sub.6-10 aromatic group.

8. The composition of claim 1, wherein the borane complex is present in an amount of from 10 to 30 wt. % by weight of the composition.

9. The composition of claim 1, wherein the borane complex is present in an amount of from 20 to 30 wt. % by weight of the composition.

10. The composition of claim 1, wherein borane complex comprises at least two R groups, wherein another of the at least two R groups is selected from the group consisting of a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group and a C.sub.3-15 heteroaromatic group.

Description

EXAMPLES

(1) Color determination was carried out on a Lico® 690 Colorimeter from Koehler Instrument Company in accordance with the Pt—Co test method as described in ASTM D1209 (2011). Results are reported as Pt—Co Color Values.

Example 1

Color Stability of a Color-Reduced Triethanolamine Composition

(2) Triethanolamine (1000 g, Sigma Aldrich, 99% purity) having a Pt—Co Color Value of 23 is mixed with a borane-ammonia complex (100 mg, obtained from Sigma Aldrich, 95% purity). The mixture is vigorously shaken to allow the borane-ammonia complex to distribute homogenously in the triethanolamine. Over a period of 6 hours the mixture clears. A sample is taken for color analysis, and found to have a Pt—Co Color Value that was calculated to be less than 15 after 2 years at room temperature (20-25° C.).

Example 2

(3) A sample of triethanolamine (TEA) with a borane-ammonia complex was stored in an oven at 45° C. for six months. The sample was removed, cooled, and found to have a Pt—Co Color Value of 20. According to Van't Hoff's law, chemical reaction rates double to quadruple for every 10 degrees Celsius increase in temperature. It is therefore calculated that if TEA with borane complex was stored at room temperature (25° C.), its color index would be less than 20 for as long as 6 years (if reaction rate quadrupled every 10° C. increase).

(4) The methods and compositions are further illustrated by the following embodiments.

(5) Embodiment 1: A method of reducing color in an alkanolamine, the method comprising: contacting the alkanolamine with a color-reducing amount of a borane complex effective to provide an alkanolamine composition having a Platinum-Cobalt Color Value, Test Method ASTM D1209, of less than 50, preferably less than 30, more preferably 0 to 20.

(6) Embodiment 2: The method of embodiment 1, wherein the alkanolamine is a mono(C.sub.1-10 alkanol)amine, a di(C.sub.1-10 alkanol)amine, a tri(C.sub.1-10 alkanol)amine, an N-(C.sub.1-10 alkyl) di(C.sub.2-4 alkanol)amine, an N,N-di(C.sub.1-10 alkyl) (C.sub.2-4 alkanol)amine, an N-(C.sub.1-10 alkanol)pyrrolidine, N-(C.sub.1-10 alkanol)imidazolidine, an N-(C.sub.1-10 alkanol)piperidine, an N-(C.sub.1-10 alkanol)piperazine or a combination comprising at least one of the foregoing; preferably monoethanolamine, diethanolamine, methyldiethanolamine, isopropanolamine, diisopropanolamine, (2-hydroxyethyl)piperazine, or a combination comprising at least one of the foregoing.

(7) Embodiment 3: The method of embodiment 1, wherein the alkanolamine is a tri(C.sub.1-10 alkanol)amine, preferably triethanolamine.

(8) Embodiment 4: The method of any one or more of embodiments 1 to 3, wherein: the borane complex is of the formula L.Math.BR.sub.aH.sub.3-a wherein L is ammonia, hydrazine, an organic amine, a thioether, an organic phosphine, or a heterocycle, each R is independently a C.sub.1-12 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group, or a C.sub.3-15 heteroaromatic group, optionally wherein any two R form a ring with the boron atom; and a is 0 to 2; the borane complex is of the formula (G.sup.+c).sub.x(B.sub.yH.sub.z).sup.−xc, wherein G is an ammonium ion, a quaternary ammonium ion, a tertiary sulfonium ion, or a quaternary organic phosphonium ion, c is 1 to 3, x is 1 to 2, y is 2 to 20, and z is 4 to 14; or the borane complex is of the formula

(9) ##STR00008##
wherein each R.sup.7 is independently a C.sub.1-8 alkyl or a C.sub.1-8 alkoxy.

(10) Embodiment 5: The method of any one or more of embodiments 1 to 4, wherein: the borane complex is of the formula L.BH.sub.3, wherein L is ammonia or a C.sub.1-24 organic amine, an organic phosphine substituted with three C.sub.1-12 hydrocarbyl groups, a C.sub.3-18 heterocycle, or a C.sub.2-20 thioether; or the borane complex is of the formula H.sub.3N.Math.BR.sub.aH.sub.3-a, wherein a is 1 or 2, and each R is independently the same or different, and is a C.sub.1-12 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group, or a C.sub.3-15 heteroaromatic group, optionally wherein two R form a ring with the boron atom, preferably wherein each R is independently a C.sub.1-6 alkyl group, a C.sub.3-6 cycloalkyl group, or a C.sub.6 aromatic group.

(11) Embodiment 6: The method of embodiment 5, wherein L is ammonia or a C.sub.1-24 amine of the formula (R.sup.1).sub.3N wherein each R.sup.1 is independently hydrogen or a C.sub.1-8 hydrocarbyl group, optionally wherein any two R.sup.1 form a ring with the nitrogen atom, and provided that not all R.sup.1 are hydrogen; or hydrogen, a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-18 aromatic group, or a C.sub.3-15 heteroaromatic group, or any two R.sup.1 together form a C.sub.2-6 ring with the nitrogen atom that can optionally have 1 or 2 heteroatoms as ring members, and provided that not all R.sup.1 are hydrogen, more preferably hydrogen or a C.sub.1-6 alkyl group, or two R.sup.1 are joined to form a 5- or 6-membered ring with the nitrogen, optionally further containing a nitrogen or oxygen atom as a ring member, and provided that not all R.sup.1 are hydrogen; most preferably hydrogen or a C.sub.1-2 alkyl group, or two R.sup.1 are joined to form a morpholine, and provided that not all R.sup.1 are hydrogen.

(12) Embodiment 7: The method of embodiment 5, wherein L is an organic phosphine of the formula (R.sup.3).sub.3P, wherein each R.sup.3 is independently a C.sub.1-12 hydrocarbyl group, preferably a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, or a C.sub.6-10 aromatic group, more preferably a C.sub.1-6 alkyl group or C.sub.6 aromatic group, most preferably a C.sub.1-4 alkyl group or C.sub.6 aromatic group.

(13) Embodiment 8: The method of embodiment 5, wherein L is a C.sub.2-20 thioether of the formula (R.sup.2).sub.2S wherein each R.sup.2 is independently a C.sub.1-10 hydrocarbyl group, preferably a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group, or a C.sub.3-15 heteroaromatic group, more preferably a C.sub.1-6 alkyl group, most preferably a C.sub.1-2 alkyl group.

(14) Embodiment 9: The method of embodiment 5, wherein L is a C.sub.3-18 aliphatic heterocycle with 3 to 12 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, phosphorus, silicon, or sulfur; preferably a C.sub.3-12 aliphatic heterocycle with 3 to 8 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, or sulfur, more preferably a C.sub.3-12 aliphatic heterocycle with 5 to 7 ring members wherein 1 or 2 ring members are each independently nitrogen, oxygen, or sulfur, still more preferably an aliphatic heterocycle of the formulas

(15) ##STR00009##
wherein each R.sup.4 is independently a C.sub.1-6 alkyl group, a C.sub.1-6 alkoxy group, a halogen, nitrile, or nitro group, R.sup.5 is hydrogen or a C.sub.1-6 alkyl group, e is 0 to 4, preferably 0, f is 0 to 3, preferably 0, n is 1 to 2, and m is 1 to 2, preferably 2; most preferably an aliphatic heterocycle of the formulas

(16) ##STR00010##

(17) Embodiment 10: The method of embodiment 5, wherein L is a C.sub.3-18 aromatic heterocycle with 1 to 3 rings and 5 to 14 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, or sulfur; preferably a C.sub.3-18 aromatic heterocycle with 1 or 2 rings and 5 to 10 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, or sulfur, more preferably a C.sub.3-18 aromatic heterocycle with 1 ring and 5 or 6 ring members wherein 1, 2, 3 ring members are each independently nitrogen, oxygen, or sulfur, most preferably an aromatic heterocycle of the formula

(18) ##STR00011##
wherein each R.sup.6 is independently a C.sub.1-12 hydrocarbyl group, preferably a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, or a C.sub.6-10 aromatic group, more preferably a C.sub.1-6 alkyl group, and f is 0 to 5;

(19) most preferably wherein L is pyridine.

(20) Embodiment 11: The method of embodiment 5, wherein L is ammonia, dimethylamine, trimethylamine, triethylamine, tetrahydrofuran, morpholine, or pyridine.

(21) Embodiment 12: The method of any one or more of embodiments 1 to 11, wherein contacting is with 1 to 5,000 ppm by weight of the borane complex, or 5 to 2,000 ppm, or 5 to 1,000 ppm, based on the weight of the alkanolamine.

(22) Embodiment 13: The method of any one or more of embodiments 1 to 12, wherein the borane complex is dissolved in a solvent before contacting, preferably an aqueous or alcoholic solvent, preferably an aqueous or a C.sub.1-2 alcoholic solvent.

(23) Embodiment 14: The method of embodiment 13, wherein the concentration of the borane complex in the solvent is 1 to 30 wt %, based on total weight of the components, preferably 1 to 20 wt %, more preferably 1 to 20 wt %, even more preferably 1 to 10 wt %.

(24) Embodiment 15: The method of any one or more of embodiments 1 to 14, further comprising mixing the alkanolamine and the borane complex during or after the contacting.

(25) Embodiment 16: The method of any one or more of embodiments 1 to 15, wherein the contacting is at 20° C. to 250° C., preferably 20° C. to 40° C., more preferably 20° C. to 30° C.; and for 10 minutes to 50 hours.

(26) Embodiment 17: The method of any one or more of embodiments 1 to 16, wherein the Platinum-Cobalt Color Value, Test Method ASTM D1209, does not increase by more than 40%, preferably more than 30%, or more preferably more than 20% for a period of six months to eight years, or one to eight years, or two to eight years, or three to seven years, or four to six years, after storage at room temperature.

(27) Embodiment 18: The method of any one or more of embodiments 1 to 17, wherein the Platinum-Cobalt Color Value, Test Method ASTM D1209, does not increase by more than 40%, preferably more than 30%, more preferably more than 20% for a period of one month to three years, or one month to two years, or three months to one year, or 4 to 8 months after storage at 45° C.

(28) Embodiment 19: A color-reduced alkanolamine composition, the composition comprising: triethanolamine and an effective color-reducing amount of a borane complex, wherein the composition has a Platinum-Cobalt Color Value, Test Method ASTM D1209, of less than 50, preferably less than 30, more preferably 0 to less than or equal to 20.

(29) Embodiment 20: The composition of embodiment 19, wherein the alkanolamine is a mono(C.sub.1-10 alkanol)amine, a di(C.sub.1-10 alkanol)amine, a tri(C.sub.1-10 alkanol)amine, an N-(C.sub.1-10 alkyl) di(C.sub.2-4 alkanol)amine, an N,N-di(C.sub.1-10 alkyl) (C.sub.2-4 alkanol)amine, or a combination comprising at least one of the foregoing; preferably monoethanolamine, diethanolamine, methyldiethanolamine, isopropanolamine, diisopropanolamine, (2-hydroxyethyl)piperazine, or a combination comprising at least one of the foregoing.

(30) Embodiment 21: The composition of any one or more of embodiments 19 to 20, wherein the alkanolamine is a tri(C.sub.1-10 alkanol)amine, preferably triethanolamine.

(31) Embodiment 22: The composition of any one or more of embodiments 19 to 21, wherein: the borane complex is of the formula L.Math.BR.sub.aH.sub.3-a, wherein L is ammonia, hydrazine, an organic amine, a thioether, an organic phosphine, or a heterocycle; each R is independently is a C.sub.1-12 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group, or a C.sub.3-15 heteroaromatic group, optionally wherein any two R form a ring with the boron atom; and a is 0 to 2; the borane complex is of the formula (G.sup.+c).sub.x(B.sub.yH.sub.z).sup.−xc, wherein G is an ammonium ion, a quaternary ammonium ion, a tertiary sulfonium ion, or a quaternary organic phosphonium ion, c is 1 to 3, x is 1 to 2, y is 2 to 20, and z is 4 to 14; or the borane complex is of the formula

(32) ##STR00012##
wherein each R.sup.7 is independently a C.sub.1-8 alkyl or a C.sub.1-8 alkoxy.

(33) Embodiment 23: The composition of any one or more of embodiments 19 to 22, wherein: the borane complex is of the formula LBH.sub.3 wherein each L is independently ammonia or a C.sub.1-24 organic amine, an organic phosphine substituted with three C.sub.1-12 hydrocarbyl groups, a C.sub.3-18 heterocycle, or a C.sub.2-20 thioether; or ; or the borane complex is of the formula H.sub.3N.Math.BR.sub.aH.sub.3-a, wherein a is 1 or 2, and each R is independently the same or different, and is a C.sub.1-12 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group, or a C.sub.3-15 heteroaromatic group, optionally wherein two R form a ring with the boron atom, preferably wherein each R is independently a C.sub.1-6 alkyl group, a C.sub.3-6 cycloalkyl group, or a C.sub.6 aromatic group.

(34) Embodiment 24: The composition of embodiment 23, wherein L is ammonia or a C.sub.1-24 amine of the formula (R.sup.1).sub.3N, wherein each R.sup.1 is the independently hydrogen or a C.sub.1-8 hydrocarbyl group, optionally wherein any two R.sup.1 form a ring with the nitrogen atom, and provided that not all R.sup.1 are hydrogen, or hydrogen, a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-18 aromatic group, or a C.sub.3-15 heteroaromatic group, or any two R.sup.1 together form a C.sub.2-6 ring with the nitrogen atom that can optionally have 1 or 2 heteroatoms as ring members, and provided that not all R.sup.1 are hydrogen, more preferably hydrogen or a C.sub.1-6 alkyl group, two R.sup.1 are joined to form a 5- or 6-membered ring with the nitrogen, optionally further containing a nitrogen or oxygen atom as a ring member, and provided that not all R.sup.1 are hydrogen most preferably hydrogen or a C.sub.1-2 alkyl group, or two R.sup.1 are joined to form a morpholine, and provided that not all R.sup.1 are hydrogen.

(35) Embodiment 25: The composition of embodiment 23, wherein L is an organic phosphine of the formula (R.sup.3).sub.3P,

(36) wherein each R.sup.3 is independently a C.sub.1-12 hydrocarbyl group, preferably a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, or a C.sub.6-10 aromatic group, more preferably a C.sub.1-6 alkyl group or C.sub.6 aromatic group, most preferably a C.sub.1-4 alkyl group or C.sub.6 aromatic group.

(37) Embodiment 26: The composition of embodiment 23, wherein L is a C.sub.2-20 thioether of the formula (R.sup.2).sub.3S, wherein each R.sup.2 is independently a C.sub.1-10 hydrocarbyl group, preferably a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, a C.sub.3-7 heterocycloalkyl group, a C.sub.6-10 aromatic group, or a C.sub.3-15 heteroaromatic group, more preferably a C.sub.1-6 alkyl group, most preferably a C.sub.1-2 alkyl group.

(38) Embodiment 27: The composition of embodiment 23, wherein L is a C.sub.3-18 aliphatic heterocycle with 3 to 12 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, phosphorus, silicon, or sulfur; preferably a C.sub.3-12 aliphatic heterocycle with 3 to 8 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, or sulfur, more preferably a C.sub.3-12 aliphatic heterocycle with 5 to 7 ring members wherein 1 or 2 ring members are each independently nitrogen, oxygen, or sulfur, still more preferably an aliphatic heterocycle of the formulas

(39) ##STR00013##
wherein each R.sup.5 is independently a C.sub.1-6 alkyl group, a C.sub.1-6 alkoxy group, a halogen, nitrile, or nitro group, R.sup.6 is hydrogen or a C.sub.1-6 alkyl group, e is 0 to 4, preferably 0, f is 0 to 3, preferably n0 is 1 to 2, and m is 1 to 2, preferably 2; most preferably an aliphatic heterocycle of the formulas

(40) ##STR00014##

(41) Embodiment 28: The composition of embodiment 23, wherein L is a C.sub.3-18 aromatic heterocycle with 1 to 3 rings and 5 to 14 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, or sulfur; preferably a C.sub.3-18 aromatic heterocycle with 1 or 2 rings and 5 to 10 ring members wherein 1, 2, or 3 ring members are each independently nitrogen, oxygen, or sulfur, more preferably a C.sub.3-18 aromatic heterocycle with 1 ring and 5 or 6 ring members wherein 1, 2, 3 ring members are each independently nitrogen, oxygen, or sulfur, most preferably an aromatic heterocycle of the formula

(42) ##STR00015##
wherein each R.sup.6 is independently a C.sub.1-12 hydrocarbyl group, preferably a C.sub.1-8 alkyl group, a C.sub.3-8 cycloalkyl group, or a C.sub.6-10 aromatic group, more preferably a C.sub.1-6 alkyl group, and f is 0 to 5; most preferably wherein L is pyridine.

(43) Embodiment 29: The composition of embodiment 23, wherein L is ammonia, dimethylamine, trimethylamine, triethylamine, tetrahydrofuran, morpholine, or pyridine.

(44) Embodiment 30: The composition of any one or more of embodiments 19 to 29, comprising 1 to 5,000 ppm by weight of the boron complex, preferably 5 to 2,000 ppm, or more preferably 5 to 1,000 ppm, based on the parts by weight of the triethanolamine.

(45) Embodiment 31: The composition of any one or more of embodiments 19 to 30, comprising less than 5 wt % of water, preferably less than 1 wt % of water, based on the total weight of the triethanolamine.

(46) Embodiment 32: The composition of any one or more of embodiments 19 to 31, wherein the Platinum-Cobalt Color Value, Test Method ASTM D1209, does not increase by more than 40%, preferably more than 30%, more preferably more than 20% for a period of six months to eight years, or one to eight years, or two to eight years, or three to seven years, or four to six years, after storage at room temperature.

(47) Embodiment 33: The composition of any one or more of embodiments 19 to 32, wherein the Platinum-Cobalt Color Value, Test Method ASTM D1209, does not increase by more than 40%, preferably more than 30%, more preferably more than 20% for a period of one month to three years, or one month to two years, or three months to one year, or 4 to 8 months, after storage at 45° C.

(48) In general, the methods and compositions can alternatively comprise, consist of, or consist essentially of, any appropriate steps or components herein disclosed. The methods or compositions can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any steps, components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives described herein.

(49) The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. “Or” means “and/or.” The endpoints of all ranges directed to the same component or property are inclusive and independently combinable. Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A “combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.

(50) All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

(51) As used herein, the term “hydrocarbyl” includes groups containing carbon, hydrogen, and optionally one or more heteroatoms (e.g., 1, 2, 3, or 4 atoms such as halogen, O, N, S, P, or Si). “Alkyl” means a branched or straight chain, saturated, monovalent hydrocarbon group, e.g., methyl, ethyl, i-propyl, and n-butyl. “Alkylene” means a straight or branched chain, saturated, divalent hydrocarbon group (e.g., methylene (—CH.sub.2—) or propylene (—(CH.sub.2).sub.3—)). “Alkenyl” and “alkenylene” mean a monovalent or divalent, respectively, straight or branched chain hydrocarbon group having at least one carbon-carbon double bond (e.g., ethenyl (—HC═CH2) or propenylene (—HC(CH.sub.3)═CH.sub.2—). “Alkynyl” means a straight or branched chain, monovalent hydrocarbon group having at least one carbon-carbon triple bond (e.g., ethynyl). “Alkoxy” means an alkyl group linked via an oxygen (i.e., alkyl-O—), for example methoxy, ethoxy, and sec-butyloxy. “Cycloalkyl” and “cycloalkylene” mean a monovalent and divalent cyclic hydrocarbon group, respectively, of the formula —C.sub.nH.sub.2n-x and —C.sub.nH.sub.2n-2x— wherein x is the number of cyclization(s). “Aryl” means a monovalent, monocyclic or polycyclic, aromatic group (e.g., phenyl or naphthyl). “Arylene” means a divalent, monocyclic or polycyclic, aromatic group (e.g., phenylene or naphthylene). The prefix “halo” means a group or compound including one more halogen (F, Cl, Br, or I) substituents, which can be the same or different. The prefix “hetero” means a group or compound that includes at least one ring member that is a heteroatom (e.g., 1, 2, or 3) heteroatoms, wherein each heteroatom is independently the same or different and is N, O, S, or P.

(52) “Substituted” means that the compound or group is substituted with at least one (e.g., 1, 2, 3, or 4) substituents instead of hydrogen, where each substituent is independently the same or different and is nitro (—NO.sub.2), cyano (—CN), hydroxy (—OH), halogen, thiol (—SH), thiocyano (—SCN), C.sub.1-6 alkyl, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl, C.sub.1-6 haloalkyl, C.sub.1-9 alkoxy, C.sub.1-6 haloalkoxy, C.sub.3-12 cycloalkyl, C.sub.5-18 cycloalkenyl, C.sub.6-12 aryl, C.sub.7-13 arylalkylene (e.g, benzyl), C.sub.7-12 alkylarylene (e.g, toluyl), C.sub.4-12 heterocycloalkyl, C.sub.3-12 heteroaryl, C.sub.1-6 alkyl sulfonyl (—S(═O).sub.2—alkyl), C.sub.6-12 arylsulfonyl (—S(═O).sub.2—aryl), or tosyl (CH.sub.3C.sub.6H.sub.4SO.sub.2—), provided that the substituted atom's normal valence is not exceeded, and that the substitution does not significantly adversely affect the manufacture, stability, or desired property of the compound. When a compound is substituted, the indicated number of carbon atoms is the total number of carbon atoms in the group, including those of the substituent(s).

(53) While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof.