Synthesis and some Physical Properties of Phenylpyrimidines

Boller, A.; Cereghetti, M.; Schadt, M.; Scherrer, H.

doi:10.1080/15421407708084509

Cited by 107 publications

(16 citation statements)

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“…All four pyrimidines have molecules of the same length and geometry, the dipole moments of the polar groups 1 and 2 add and result the high dipole moment of the molecules. Its value estimated from the principle of additivity is n = 6.5 ± 1 D, while that calculated according to [13] from the experimentally measured dielectric constants of the binuclear analogs [7] is /u = 6 to 7D. Dielectric constants of compound 1 are available in [8]; the dipole moment estimated then by us is somewhat smaller, viz.…”

Section: Discussionmentioning

confidence: 67%

“…The lengths of the isolated molecules were calculated under the assumptions that the lengths of the bonds and the valency angles are the same as in smaller molecules, the alkyl chain assuming the trans configuration, the Van der Waals radii of the terminal atoms having been accounted for. The dipole moments of the pyrimidines 1-4 have been estimated by adding the contributions of the particular parts of the molecule as well as from the dielectric permittivity of the binuclear analogs given in [7], and for compound 1 after [8], The phase transition temperatures were determined by the thermomicroscope method with use of the VEB Analytic Dresden device. The samples of the mixtures were placed between two thin microscope glasses.…”

Section: Methodsmentioning

confidence: 99%

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Binary Smectic Systems Including Trinuclear Pyrimidines with and without Nematic Gap

Dąbrowski

Baran

Sosnowska

et al. 1987

Zeitschrift Für Naturforschung A

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Phase diagrams of binary mixtures are presented in which one component has been selected from among four trinuclear isomeric pyrimidines forming a nematic or smectic A, phase, and the second one from cyanocompounds forming an A d smectic phase. Depending on the molecular structure of pyrimidine, mixtures were obtained that show or show not a nematic gap between the A, and A d smectic regions. In the latter case it was found that the relation = f(x) has two independent branches in different ranges of the concentration JC. The measured spacing of the smectic layers in such mixtures points to the possibility of the pyrimidine monolayer being transformed into a bilayer.

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Section: Discussionmentioning

confidence: 67%

Section: Methodsmentioning

confidence: 99%

Binary Smectic Systems Including Trinuclear Pyrimidines with and without Nematic Gap

Dąbrowski

Baran

Sosnowska

et al. 1987

Zeitschrift Für Naturforschung A

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“…A 5.4M solution of sodium methoxide in methanol (31 cm3) was added dropwise to a mixture of (2-methoxymethy1idene)heptanal [35,36) 250 mmol) and t-butyl methyl ether (100 cm3) was added dropwise to a mixture of methoxymethyltriphenylphosphonium chloride (1 40 g, 407 mmol), potassium t-butylate (45 g, 400 mmol) and t-butyl methyl ether (400 cm') at 0°C. The reaction mixture was stirred at room temperature for a further 48 h and then added to water (1000 cm3) and shaken with ether (3 X 100cm').…”

Section: -(4-pentyloxybiphenyl-4'-ye)-5-pentylpyrimidinementioning

confidence: 99%

Alkyl/alkenyloxy phenyl/biphenylpyrimidines: Dependence of the liquid crystal transition temperatures on the position of the nitrogen atoms and the position and configuration of carbon-carbon double bonds

Kelly

Fünfschilling

1995

Liquid Crystals

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The influence on the transition temperatures of a carbon-carbon double bond in the terminal alkenyloxy (ether) chain of four series of three-ring phenylhiphenyl-pyrimidines has been systematically investigated. The position and configuration of the double bond has been varied systematically in order to determine the optimal configuration and conformation of the terminal chains for smectic C formation. Four positions of the two nitrogen atoms were chosen. This produced four isomeric series of pyrimidines and differences in the mesomorphic behaviour were observed. The dependence of the transition temperatures on chain length was studied for the same four isomeric pyrimidine series. Comparisons between the new three-ring phenyV biphenyl-pyrimidines and the corresponding two-ring phenylpyrimidines revealed almost identical tendencies. These results are consistent with a linearly-extended conformation of the chain. Several of the new ethers exhibit remarkably low viscosity values (i.e. short response times) and wide switching angles in an optically active base mixture used for evaluation and comparison purposes. Hence they can be used to widen the temperature range of mixtures designed for electro-optic display devices based on ferroelectric effects (FLCDs) without leading to longer response times.

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“…Liquid crystal system between 5-n-heptyl~2~ (4-cyanophenyl)pyrimidine and 5-n-pentyl-2-(4-cyanophenyl)pyrimidine [4]. Both these compounds are commercially available liquid crystals with one nematic phase.…”

Section: Diphenylamine-benzophenone Phase Diagrammentioning

confidence: 99%

Application of simultaneous thermomicroscopy/DSC to the study of phase diagrams

Wiedemann

Bayer

1985

Journal of Thermal Analysis

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The correlation between morphological changes and DSC recordings gives valuable information on the mechanism of phase transformations. The present paper describes a new instrument for simultaneous DSC and thermomicroscopy in transmitted light, where a DSC device is placed in a commercially available hot-stage. The application of this DSC/thermomicroscopy is exemplified by study of the phase diagrams for KNO3--NaNO v diphenylamine---benzophenone and a liquid crystal system.Results obtained from thermoanalytical measurements such as DSC are usually reproducible and quantitative, but they cannot always readily be correlated with the respective phase transformation or chemical reaction occurring in the substance. Attempts have therefore been made to improve such thermoanalytical methods by a correlation between their results and the physical or chemical changes of the substances investigated.These combinations of methods have proved very successful. When performed simultaneously with DTA or DSC, for example, TG is a very powerful tool for studying the chemical stability and decomposition of a variety of materials. This paper demonstrates the usefulness of simultaneous DSC and hot-stage microscopy. Effects which do not show any significant enthalpy change in DSC can often be detected with microscopy. On the other hand, thermomicroscopic investigations often require estimates of heats of transformation, fusion or crystallization.Further, thermomicroscopy with DSC is a very good teaching method to introduce beginners to thermoanalytical investigations, for one can see changes in the investigated substance together with the course of the measured curve. However, the method can also be used for theoretical and practical considerations. For example, differences in the measurement of the same substance in various crucible materials, e.g. glass, aluminium and sapphire, become visible and can be studied.For the recognition of phase boundaries, it is mostly more simple if simultaneous thermomicroscopy/DSC can be used for the determination of phase diagrams, especially for very small concentrations of one of the components.

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Synthesis and some Physical Properties of Phenylpyrimidines

Cited by 107 publications

References 10 publications

Binary Smectic Systems Including Trinuclear Pyrimidines with and without Nematic Gap

Binary Smectic Systems Including Trinuclear Pyrimidines with and without Nematic Gap

Alkyl/alkenyloxy phenyl/biphenylpyrimidines: Dependence of the liquid crystal transition temperatures on the position of the nitrogen atoms and the position and configuration of carbon-carbon double bonds

Application of simultaneous thermomicroscopy/DSC to the study of phase diagrams

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