A new interesting class of thermotropic liquid crystalline copoly(arylidene-ether)s based on cyclohexanone derivative moieties was synthesised by solution polycondensation of 4,4′- diformyl-α,ω-diphenoxyalkanes (Ia−f) or 4,4′- diformyl-2,2′- dimethoxy-α,ω-diphenoxyalkanes (IIa−f) with methyl-cyclohexanone and 4-tertiary-butyl-cyclohexanone monomers. A model compound III was synthesised from X with benzaldehyde and characterised by elemental and spectral analyses. The inherent viscosities of the resulting polymers were in the range 0.23−0.91 dL/g. All the copoly(arylidene-ether)s were insoluble in common organic solvents but partially soluble in halogenated solvents. The mesomorphic properties of these polymers were studied as a function of the diphenoxyalkane space length. Their thermotropic liquid crystalline properties were examined by differential scanning calorimetry (DSC) and optical polarising microscopy and it was demonstrated that the resulting polymers form nematic mesophases over wide temperature ranges. The thermal properties of those polymers were evaluated by thermogravimetric analysis and DSC measurements and correlated to their structural units. X-ray analysis showed that polymers have some degree of crystallinity in the region 2θ = 5−60°. In addition, the morphological properties of the selected examples were tested by scanning electron microscopy (SEM).

Using hybrid density functional theory calculations with the B3LYP functional, the reaction mechanisms for cleavage of R2N−CN (R = H, Me) bonds in the presence of unsaturated molybdenum(II) silyl catalyst, Cp(CO)2MoSiMe3 (Cp = !5-C5H5), were studied. The catalytic cycle takes place in two stages; the first involves cleavage of the R2N−CN bond. The favorable sequence of reactions for this stage is as follows: (i) coordination of a nitrile through the lone pair of electrons on the nitrile nitrogen atom (NCN) to give an end-on complex; (ii) isomerization of the end-on complex to a side-on complex; (iii) migration of the silyl group to NCN to form a stable Mo−C−NCN three-membered-ring intermediate with an Mo−NCN dative bond; (iv) dissociation of NCN from Mo and coordination of an amino N atom (NNR2) to Mo, leading to an Mo− C−NNR2 three-membered-ring intermediate; and (v) cleavage of the R2N−C bond to form a silylisocyanide complex. The second stage involves the regeneration of the active catalyst through two "-metathesis steps. In the first, Cp(CO)2MoNR2 reacts with HSiMe3 to give Cp(CO)2MoH and R2NSiMe3, and in the second, "-metathesis of Cp(CO)2MoH with HSiMe3 regenerates Cp(CO)2MoSiMe3. Step (iv) in the first stage possesses the largest activation energy and is the rate-determining step. The activation energies for this step for the reactions of H2NCN and Me2NCN were calculated to be 36.4 and 38.3 kcal/mol, respectively, based on potential energies with zero-point energy correction. After dissociation of the silylisocyanide ligand from the silylisocyanide complex, it will be isomerized to silylcyanide, as in previous studies. The catalytic cycle for the cleavage of R2N−CN bond is compared with that of MeO−CN bond. The effects of the metal atoms are also discussed.

A new synthetic approach for the synthesis of novel 5H-dibenz[b,f]azepine, 5H-dibenz[b,f]- azocine, 11H-benzo[f]pyrido[2,3-b]azepine and 6H-benzo[g]pyrido[2,3-c]azocine derivatives is reported. The key step of this methodology is based on Friedel-Crafts ring closure of nitrogen containing carboxylic acids and alkanols in the presence of AlCl3, P2O5 or PPA catalysts in overall high yields. The starting carboxylic acids were prepared via an unequivocal synthetic pathway by the basic hydrolysis of trimethyloxindole followed by N-arylation reactions.

A new synthetic approach for the synthesis of novel 5H-dibenz[b,f]azepine, 5H-dibenz[b,f]- azocine, 11H-benzo[f]pyrido[2,3-b]azepine and 6H-benzo[g]pyrido[2,3-c]azocine derivatives is reported. The key step of this methodology is based on Friedel-Crafts ring closure of nitrogen containing carboxylic acids and alkanols in the presence of AlCl3, P2O5 or PPA catalysts in overall high yields. The starting carboxylic acids were prepared via an unequivocal synthetic pathway by the basic hydrolysis of trimethyloxindole followed by N-arylation reactions.

A simple and convenient procedure for the synthesis of some novel alkyl-substituted and aryl-substituted julolidines is reported. Julolidines were smoothly synthesized in excellent isolated yields via Friedel–Crafts intramolecular alkylations of heteroarylalkanols in the presence of both Brønsted (PPA) and Lewis (AlCl3/CH3NO2) acid catalysts. The precursors alkanols, 1a–i, were readily prepared both by reaction of selectively synthesized carboxylic acid esters and ketones with different Grignard reagents and also by reduction of the synthesized ketones with LAH. A plausible carbocation mechanism is proposed to account for the results. The structures of the compounds are established using both spectral and analytical data.

A simple and convenient procedure for the synthesis of some novel alkyl-substituted and aryl-substituted julolidines is reported. Julolidines were smoothly synthesized in excellent isolated yields via Friedel–Crafts intramolecular alkylations of heteroarylalkanols in the presence of both Brønsted (PPA) and Lewis (AlCl3/CH3NO2) acid catalysts. The precursors alkanols, 1a–i, were readily prepared both by reaction of selectively synthesized carboxylic acid esters and ketones with different Grignard reagents and also by reduction of the synthesized ketones with LAH. A plausible carbocation mechanism is proposed to account for the results. The structures of the compounds are established using both spectral and analytical data.

A simple and convenient procedure for the synthesis of some novel alkyl-substituted and aryl-substituted julolidines is reported. Julolidines were smoothly synthesized in excellent isolated yields via Friedel–Crafts intramolecular alkylations of heteroarylalkanols in the presence of both Brønsted (PPA) and Lewis (AlCl3/CH3NO2) acid catalysts. The precursors alkanols, 1a–i, were readily prepared both by reaction of selectively synthesized carboxylic acid esters and ketones with different Grignard reagents and also by reduction of the synthesized ketones with LAH. A plausible carbocation mechanism is proposed to account for the results. The structures of the compounds are established using both spectral and analytical data.