MXPA99006732A - Process for obtaining cholesteric liquid crystals by stereoselective recrystallization - Google Patents

Abstract

Process for synthesizing polymers +, PTOBEE (C26H20O8)n and PTOBDME (C34H36O8)n, with the addition of acid dichloride and DL-treo-1,2-butanediol in Cl-naphtalene and DL-1,2-dodecanediol with diphenyl oxide, respectively, by passing them through a nitrogen stream at room temperature, heating the mixture, settling in toluene the mixture and filtering. In the resulting settling toluene, the polymer precipitates the enantiomer (-) PTOBEE. The compounds obtained are of the cholesteric liquid crystal type, obtained by stereoselective recrystallization in toluene.

Description

METHOD OF OBTAINING LIQUID CRYSTALS COLESTBRICQS POE RECRISTALSZACIÓW ESTEREOSELICTIVA TECHNICAL SECTOR The present invention is framed within a first chemical sector with both optical implications (sensitive response to temperature: thermal indicators and radiation sensors) / as well as biological properties due to its liquid crystal character (VI Elser and RD Ennulat, "Advances in Liquid Crystals", "Vol.2, Brown, GH- (De.), Academic Press, New York, 1976, pp. 73.) Liquid chambers are self-organizing systems. crystalline to molten isotropic, when heating, but they form mesophases that combine the order of the perfect crystal with the mobility of the liquid.The molecular base is almost always simple: they form anieotropic or amphiphilic molecules with a rigid geometry (mesogenic unit) attached to another part flexible (spacer), which pack blocks with anisotropic properties (H. Ringsdorf, B. Schlarb and J. Venzmer, "" Molecular Architec- ture and Function af palymeric Orien ed Systems: Models for tt Study of Organ? za iap, Surfacé Becognition, and Dynamics of Bxomembranes ". Ang. Ctiem. Item. Ed. Engl. 1988, 27, pp. 116), the parallel orientation of its axis can be distinguished tferabicas (with its molecular centers isotropically distributed and eatactic (molecular centers organized in planes) .The spatial arrangement of nematic pianos stacked in a * helical superstructure, characterized by a preferred chirality It is known as a cholesteric mesophase, the colistis reflect the incident light and when its helix pitch is comparable to the wavelength of the visible lu2, exhibit typical bright colors, _ ^ The development of liquid polymer crystals followed the monomers and began with polymers whose main chain, as a whole, acted as a mesogen, both prepared from solution (lyotropic) as a from the melt (thermotropic) - The megogenic units were subsequently introduced well hung from the main chain through a flexible spacer (side chain) or joined along the main chain by a flexible aliphatic spacer (main chain) ). In 1982, Lenz et al. (C.Ober, J.-i.Jin, .Lenz, Polym, J. 1982, J., 9), synthesized liquid polymers terotropic crystals whose mesogenic unit, previously studied in works of garlic molecular weight, was based on a central residue of terephthalic acid flanked by two paxibenzoyl residues connected by flexible polymethylene spacers. They obtained high temperatures of transition to the mesofaee and to the isotropic melt. Also in 1982, Galli et al. (G. Galli, E.

Chiellini, C.K. Ober, R.W. Lenz, Makromol-Chem., 1982, Í83, pp. 2693), introduced the same mesogen Flexible spacers compatible with the aqueous system under physiological conditions ie spacers "Hydrophilic of b ^ or molecular weight with hydroxy termination, of the oligo-oxy-ethyl-propane type and oligo-oxypropylene, the latter containing chiral centers in each unit.These spacers had also been used in liquid crystals of low molecular weight, in order to decrease lae transition temperatures.

They observed the influence of the type, length and distribution of the spacers on the behavior of the formed esophases, limiting the liquid crystal character of the polymers to 10 units in the spacer.

In 1983, Malanga et al. (C. Malanga, N. Spassky, R. Menieagly, E. Chiellini, Polymer Bulletin 1983, 9,? P.336), extended the synthesis, using optically active diolee flexibers of different length and length as spacers. degree of substitution, capable not only of imparting to the polymers a hydrifile character but also the cholesteric stereochemical disposition to their mesophase. Starting from _ chiral glycols (an enantiomer of determined sign) as a spacer, they obtained in all cases polymer with the same optical sign. Using starting the recmemica mixture of glycos as a spacer, they always obtained non-chiral polymer, "anemic" with mesof neatty, never cblesteric (E. Chiellini, R. Po, S. Carrozzino, G. Gal i and B. Gallot , "Chiral Liquid-Crystalline Polymers, IX, The Effect of High Spacer Structure in Thermotropic Polyesters", Mol.Cryst.LiqdCryst., 1990, Vol. 179, 405-418); E. Chiellini, R. ~ Solar, G. Leonardi, R. Lieciani, G. Mazzanti, Eur. Pat. Appl., 19p ?, EP 509968 AT 9210215; C. Chiellini, R. Solaro, L. Bemporad, S. D'Antoine, Eur. Pat. Appl., Llpp, EP 486445 a2 920520; E. Chiellini, R. Solaro, L. Bemporad, Eur. Pat. Appl., 13 pp, EP 486437 A2 920520. The concept of selective recrystallization is a current concept in organic chemistry (P. Renaud, T. Bourquard, M. Gerster, N. Moufíd, "Stereoselectave Reactions of Sulfinylated Benzyl Radicáis: Effect of Solvents and Lewis Acids, "Angew, Chem. Int. Ed. Engl., 1994, 33, No. 15/16, 1601-1603, R. Taura, S. Susuki, N. Azuma, A. Matsu , F, Toda, A. Kamimura, K. Hori, "Prepared for Chiral Nitroxide Radicals and Spontaneous optxcal Resalution by ZRecrystallizatian", Angew, Chem. Int. Ed. Engl., 1994, 33, No. 8, 878-879; HJ Federsel, "Cftirotechnology Industrial Synthesis of Optical Active Compunds", Angew, Chem. Int. Ed. Engl. 1994, 33, No. 9, 1013). The separation of racemic mixtures into their two enantiomers is so complex, expensive and laborious that the esteroselective crystallization of a component in a given solvent solves many practical problems, in addition to its undeniable industrial and economic interest.

D • 'E * SCRIPTION OF THE IH •' • V-E - H-CIÓ '-M The technological and biological interest of thermostropic polyesters with chiral character, led us to propose the synthesis of these materials using spacers with Asymmetric carbon in its molecular formula and different lengths in the lateral aliphatic chain of the flexible spacer, which did not exceed by its length the critical to possess character of liquid crystal. In the present invention, the same mesogenic unit has been used as Chiellini et al .: [HTH = 4, 4'-terephthaloi-dioxy dibenzoic acid] in the main chain and two different glycols as a spacer that have given rise to two different ter otic polyesters. "The present invention relates to a process for obtaining cholesteric liquid crystals, (-) PTOBEE or coleetheric PTQBDME, which comprises the d & steps: preparing a mixture by adding dichloride of 4,4, terephthaloi-dioxy dibenzoic acid and, to obtain PTOBEE Dl-threo-l, 2-butadiene in Cl-naphthalene Q to obtain PTOBDME, Dl-trea-1, 2-dodecaniol in diphenyl oxide, passing a stream of nitrogen through the mixture, at room temperature, for more than 35 minutes (to obtain PTOBEE); or for more than 30 minutes (to obtain PTOBDME); heating the mixture above 100 ° C in a stream of nitrogen for more than 3 hours; decant the mixture in toluene, filter, dry with vacuum pump and wash with ethanol in order to drag Cl-naphthalene (to obtain PTOBEE) so that the polymer is obtained PTOBEE (C26H2? Oß) or PTOBDME is obtained, respectively; keeping the toluene solution resulting from decanting the J? TOBEE polymer or the PTOBDME polymer in a sealed enclosure; and obtaining (-) PTOBEE or P-CHLORME from the solution by precipitation, filtration and drying.

EXAMPLE 1 4.5 g are added. of TOBC acid dichloride (C22H? 2? 6C 2) and 0.92 g. of Dl-threo-1, 2-butandol in 25.5 ml. of Cl-naphthalene to a 50 c.c. provided with a magnetic stirrer, a heating plate and a ball cooler. This was passed through a stream of nitrogen at room temperature for 35 minutes. Then, it was heated above IGOSC in a stream of 2 for 3 hours. Subsequently, the contents of the flask were decanted into toluene, dried in a vacuum pump and washed with ethanol in order to remove the Cl-naphthalene. The polymer thus obtained is PTOBEE (C26ÍÍ2o? A), characterized by NMR as: This compound has been reported by Chiellini (6) as neat liquid crystal. We report it as a cholesteric liquid crystal. EXAMPLE 2 The toluene solution resulting from decanting the jumper after its synthesis is clear and transparent, and stored in a sealed enclosure. Some time later a white precipitate is obtained that once analyzed by NMR confirms the structure of (-) PTOBEE. The value of your ORO (Optical Rotary Dispersion) is [cx] 25589 = 2.33 [0.0056 mol / 1, toluene]. The crietality evidenced by DSC (differential scanning calorimetry) is higher than that shown by the original PTOBEE synthesis product, previously precipitated in toluene and filtered. This product, (-) PTOBEE, is considered, therefore, obtained by recrystallization esteroselective in toluene, starting from the synthesis product. Its nature of cholesteric liquid crystal.

EXAMPLE 3 They are added to a 50 c matrix. c. : 4.5 g of TOBC and 2.05 g of DL-1,2-Dadecandial with 25.37 ml of 25.4 ml of Diphenyl oxide. Nitrogen stream is passed for 30 in at room temperature, then heating above 100aC in N2 stream for 3 hours. The clear solution is decanted in 250 ml of Toluene, filtering the precipitate and drying it in a vacuum pump. It is then washed with ethanol, filtered and dried under vacuum. The NMR structure of this new polymer PROBÓME (C2sH2o? A turns out to be: nature of liquid crystal coleetérico,

Claims (2)

1. CLAIMS 1. A process for obtaining cholesteric liquid crystals, comprising the steps, of: preparing a mixture by adding 4,4'-dichloride terephthaloi-díc-xi dibenzoic acid 7 and DÍ-threo-1,2 butadiol in Cl-naphthalene and passing a stream of nitrogen through the mixture, at room temperature for more than 35 minutes; heating the mixture above 100 ° C in a stream of nitrogen for more than 3 hours; To decant the mixture in toluene, filter, dry with a vacuum pump and wash with ethanol in order to remove the Cl-naphthalene so that the polymer is obtained to store the toluene solution resulting from decanting the PTOBEE polymer in a sealed enclosure; and obtain (-) PTOBEE from the solution by precipitation, filtration and drying.
2. 2. A process for obtaining liquid crystalline crystals comprising the steps of: preparing a mixture by adding 4,4'-dichloride teref-aloi-dioxy dibenzoic acid and Dl-threo-1,2-dodecanol in diphenyl oxide and passing a stream of nitrogen by the mixture, at room temperature for more than 35 minutes, heating the zcl above 100SC in a stream of nitrogen for more than 3 hours; decanting the methanol in toluene, obtaining a precipitate that is subjected to filtering, drying with a vacuum pump and washing with ethanol, filtering and drying thus obtaining polymer PTOBDME; keep the toluene solution resulting from decanting the PTOBDME polymer in a watertight enclosure; and and obtaining cholesteric PTOBDME from the solution by precipitation, filtration and drying.