LIQUID CRYSTALLINE POLYMERS. IV. THERMOTROPIC LIQUID CRYSTALLINE POLY(ARYLIDENE-ETHER)S AND COPOLYMERS CONTAINING N-METHYLPIPERIDONE LINKED TO THE MAIN CHAIN THROUGH SPACERS OF VARIOUS LENGTHS

Two novel series of poly(arylidene-ether)s and copoly(arylidene-ether)s were synthesized from N-methylpiperidone and/or cyclohexanone respectively. The first series (homopolymers) was derived from 4,4′-diformyl-α,ω-diphenoxyalkane or 4,4′-diformyl-2,2′ dimethoxy-α,ω-diphenoxyalkane with N-methylpiperidone. The second series (copolymers) was derived from the diphenoxyalkanes (I–VIII) with N-methylpiperidone and cyclohexanone. The inherent viscosities of the polymers thus prepared were in the range of 0.37–0.98 dI/g. The majority of the polymers and copolymers are soluble in chlorinated hydrocarbons. DSC measurements and microscope observation under polarized light demonstrate that this type of poly(arylidene-ether)s form nematic mesophase over a wide temperature range in contrast to the corresponding copoly(arylidene-ether)s. All of the polymers and copolymers exhibited thermotropic liquid crystalline properties. In most cases, the mesophase extends up to 315°C, where thermal decomposition prevents further observation. The morphology of polymer IXb and copolymer XIb as a selected example was examined by scanning electronic microscope.     

A New Solvent-free Synthesis of a, a''''-Dibenzylidenecycloalkanones from Acetals with Cycloalkanones under Microwave Irradiation

a, a'-Dibenzylidenecycloalkanones are very important intermediates for synthesis of bioactive pyrimidine derivatives1. Usually, their preparation is achieved by the cross-aldol condensation, which has low yield and too many by-products2. The methods with catalyst such as RuCl33a, TiCl3 (SO3CF3)3b, InCl34H2O3c or BMPTO d require expensive catalysts and long reaction times and give more by-products. Acetals have been successfully applied as a protective group in organic synthesis4, and…     

A New Solvent-free Synthesis of α,α'-Dibenzylidenecycloalkanones from Acetals with Cycloalkanones under Microwave Irradiation

A new rapid synthetic method is described for synthesis of α,α'-dibenzylidene- cycloalkanones by the reaction of acetals and cycloalkanones without solvent using BF3·Et2O as catalyst under microwave irradiation.     

LIQUID CRYSTALLINE POLYMERS. 3. SYNTHESIS AND LIQUID CRYSTAL PROPERTIES OF THERMOTROPIC POLY(ARYLIDENE-ETHER)S AND COPOLYMERS CONTAINING CYCLOALKANONE MOIETY IN THE POLYMER BACKBONE

Two novel series of poly(arylidene-ether)s and copoly(aryl-idene-ether)s were synthesized by polycondensation of 4,4^′-diformyl-α,ω-diphenoxyalkane and 4,4′-diformyl-2,2′-dimeth-oxy-α,ω-diphenoxyalkane with cyclohexanone and/or cyclo-pentanone. The inherent viscosity of the polymers and copolymers thus prepared were in the range of 0.42–1.27 dL/g. The phase behavior of these polymers was studied by differential scanning calorimetry (DSC), optical polarizing microscopy using a heated stage, and thermogravimetric analyses. Almost all the polymers and copolymers exhibited thermotropic liquid crystalline properties. In most cases, the mesophase extends up to 310°C, where thermal decomposition prevents further observation. Methoxy substituents, on the benzene ring of these polymers, lower the transition temperature significantly. The morphology of polymer IX_f was examined by scanning electronic microscope.     

Synthesis of cycloalkanone-fused cyclopropanes by Au(I)-catalyzed oxidative ene-yne cyclizations

Au(I)-catalyzed oxidative cyclizations that successfully convert 1,5-ene-ynes and a 1,6-ene-yne to the corresponding cycloalkanone-fused cyclopropanes are described. This Au(I)-catalyzed oxidative cyclization can be effectively applied to various substrates and is an alternative to the previously used intramolecular cyclopropanation that required potentially explosive diazo compound.     

New transformation of cycloalkanone acetals by peracids α,ω-dicarboxylic acids synthesis

A new process of oxidation of cycloalkanone acetals under the action of in situ generated performic acid has been found. The main products of the reaction are α, ω-dicarboxylic acids obtained with the yield up to 77% depending on the size of acetals ring. The process has been explored and optimized on the example of the dodecanedioic acid synthesis (a valuable industrial product).     

An efficient non-catalytic, regioselective approach to the synthesis of angularly fused polycyclic systems

A novel approach to the synthesis of partially reduced different ring sizes of PAH analogs with sec.amino and nitrile functionalities is delineated through base-induced ring transformation of 4-sec.amino-2-oxo-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles by a carbanion, generated in situ from cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone separately in good yields. An increase in the size of cycloalkanone ring beyond cyclooctanone restricts the ring transformation under analogous reaction conditions possibly due to bulky conformation of higher homologs. The synthetic method provides an efficient general route for the construction of angularly fused partially reduced polycyclic aromatic hydrocarbons: 5-sec.amino-2,3,6,7-tetrahydro-1H-cyclopenta[c]phenanthrene-4-carbonitriles, 6-sec.amino-2,3,4,7,8-pentahydro-1H-benzo[c]phenanthrene-5-carbonitriles, 7-sec.amino-2,3,4,5,8,9-hexahydro-1H-cyclohepta[c]phenanthrene-6-carbonitriles, and 8-sec.amino-2,3,4,5,6,9,10-heptahydro-1H-cycloocta[c]phenanthrene-7-carbonitriles.