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    Synthesis and properties of novel polyimides from dichloro (1,3-p-dimethylaminobenzylimidazolidine-2-ylidene) p-cymene ruthenium (II)
    (Taylor & Francis Ltd, 2003) Seckin, T; Köytepe, S; Çetinkaya, B; Özdemir, I; Yigit, B
    A novel diamine derivative, dichloro (1,3-p-dimethylaminobenzylimidazolidine-2-ylidene) p-cymene ruthenium (11), bearing a potential site for imide formation, was prepared starting from p-dimethylaminobenzaldehyde. It was used as a monomer to prepare polyimides with several dianhydrides via a one-stage procedure without going through tedious steps. The polyimides have inherent viscosities that range from 1.18 to 1.24 dl/g in N-methyl-2-pyrrolidinone at 30degreesC. These new polymers are soluble in polar aprotic solvents. The polymeric catalyst was added to (Z)-3-methylpent-2-en-4-yn-1-ol without a solvent and the pure furan was isolated by distillation under reduced pressure and GC determined the conversion of the starting enynol.
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    Synthesis and properties of polyimides from 1,3-di(p-dimethylaminobenzyl)-imidazolidine-2-thion
    (Springer, 2003) Seckin, T; Çetinkaya, E; Köytepe, S; Yigit, B
    A synthetic strategy is presented that allows the preparation of dimethylamino functionalized. heterocyclic system 1,3-di (p-dimethylaminobenzyl)-imidazolidine-2-thion that was then used to prepare polyimides by the two-stage polycondensation method. The key to this success was the development of an efficient procedure leading highly pure dimethylamino monomer. Polyimides derived from 1,3-di(p-dimethylaminobenzyl)-inmidazolidine-2-thion and commercial dianhydrides exhibited excellent solubility in various polar solvents. These polymers showed glass transition temperatures between 290-360degreesC, and initial decomposition temperature 490-485 degreesC and 10% mass loss ranging from 505-575degreesC in air.
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    Synthesis of a water-soluble carbene complex and its use as catalyst for the synthesis of 2,3-dimethylfuran
    (Elsevier Science Sa, 2001) Özdemir, I; Yigit, B; Cetinkaya, B; Ülkü, D; Tahir, MN; Arici, C
    1,1,3,3'-Tetrakis(p-dimethylaminobenzyl)-2,2'-biimidazolidinylidene, L-2(R) (R = CH2C6H4NMe2-p) which contains four peripheral NMe2 substituents, was obtained from 4-dimethylaminobenzaldehyde by a three-step reaction sequence, and was used for the preparation of imidazolidin-2-ylidene Ru(II) and Rh(I) complexes 1 and 2. Etherial HCl readily protonates the NMe2 functionality on the carbene ligand of 1 to give the corresponding salt, 1'; whereas the reaction of 2 with HCl gave a hygroscopic and ill-defined rhodium species. In aqueous solution the salt 1' is an efficient and active catalyst for intramolecular cyclisation of (Z)-3-methylpent-2-en-4-yn-1-ol into 2,3-dimethylfuran. The catalyst 1' could be recovered by simple phase separation and the catalytic reaction was maintained for five different runs. All of the new compounds were characterised by elemental analyses, IR and NMR spectroscopy and the molecular structure of I was determined by X-ray crystallography. (C) 2001 Elsevier Science B.V. All rights reserved.