Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Naphthalene Compound, index

The rate constant kTD for fluorescence of the pyrene intermolecular solution excimer has been found to follow the relation kFD = n2(kFD)n=I, where n is the the refractive index of the solvent69 . The values of kTO for the 1-methylnaphthalene excimer in ethanol at various temperatures are also consistent with the above relation 76). The fact that (kFD)n=I is independent of solvent and temperature indicates that the excimer has a specific structure, according to Birks 69,71). Experimentally, it was observed much earlier that kFM = n2(kFM)n=i for the polycyclic aromatic hydrocarbons, and that k /kp is independent of solvent and temperature. Table 5 shows that agreement between independent investigators of the excimers of naphthalene compounds is not always good, as in the case of 1-methylnaphthalene. [Pg.46]

Similarly, the increase in the number of isomers in other homologous series (e.g., in the series starting with naphthalene and anthazene) is asymptotically proportional to the number of isomers of the alcohol series. The proportionality factor can easily be derived from the cycle index of the permutation group of the replaceable bonds of the basic compound. [Pg.8]

The same template as for compound 71 was used by Peukert et al. for a 2D similarity search in the Aventis in-house compound collection [144]. 75 Compounds with a similarity index >0.80 were biologically tested. The moderately active l-carboxy,8-sulfonamido-naphthalene (IC50 = 9.5pM), with insufficient chemical stability, was the starting point for the design of substi-... [Pg.406]

In addition to CN and ON, the smoke point (SP), which is the maximum smoke-free laminar diffusion flame height, has been employed widely to evaluate the tendency of different fuels to form soot. This tool was first applied to kerosenes, later diesel, and then jet engine fuels.19,20 Researchers have tried to relate smoke points of pure compounds to their molecular structure. It was found that the inverse of smoke point, which measures the potential of a fuel to form soot, increases from n-paraffins to iso-paraffins to alkylbenzenes to naphthalenes.21,22 Since smoke points vary with experimental conditions, the concept of a threshold soot index (TSI), which is calculated from the smoke point, molecular weight, and experimental constants, has been used to compare the soot-formation tendencies of different fuel molecules.23... [Pg.32]

A set of n = 209 polycyclic aromatic compounds (PAC) was used in this example. The chemical structures have been drawn manually by a structure editor software approximate 3D-structures including all H-atoms have been made by software Corina (Corina 2004), and software Dragon, version 5.3 (Dragon 2004), has been applied to compute 1630 molecular descriptors. These descriptors cover a great diversity of chemical structures and therefore many descriptors are irrelevant for a selected class of compounds as the PACs in this example. By a simple variable selection, descriptors which are constant or almost constant (all but a maximum of five values constant), and descriptors with a correlation coefficient >0.95 to another descriptor have been eliminated. The resulting m = 467 descriptors have been used as x-variables. The y-variable to be modeled is the Lee retention index (Lee et al. 1979) which is based on the reference values 200, 300, 400, and 500 for the compounds naphthalene, phenanthrene, chrysene, and picene, respectively. [Pg.187]

Before 1925, there were a few compounded oils made for special purposes, such as lubrication of marine engines and steam cylinders, but additives were not used in automotive crankcase oils. In the 1930 s, chemical compounds made by condensation of chlorinated paraffin wax with naphthalene were found to lower the pour points of oils. Pour depressants (9) apparently are adsorbed on small wax crystals which separate from oils when they are chilled. The protective adsorbed layer of additive prevents the normal interlacing of larger wax crystals which forms a gel. In 1934 polymerized unsaturated hydrocarbons first came into large scale commercial use to lower the temperature coefficient of viscosity of oils. Other compounds for increasing the viscosity index of oils have since become common. [Pg.241]

The index 7 is assigned as 100 for benzene. The values are scaled for ring size and ring fusions, and increase with ring size so that naphthalene (142) and anthracene (206) have higher indices than benzene. This method is particularly useful for comparing heterocyclic compounds with hydrocarbons (see Section 8.6). [Pg.719]

Scheme 8.6. Stabilization Energy and Index of Aromaticity for Heteroaromatic Compounds Isoelectronic with Benzene and Naphthalene... [Pg.759]

Among the multitude of organic compounds, there is a small number of objects with p 0 (all types of acyclic compounds most topologically relevant to n-alkanes). The increase in number of cycles in the molecules leads to the increase of p up to 0.3-0.5 (cycloalkanes, arenes, etc.), 0.5-0.8 (naphthalenes, biphenyl, etc.), and 1.0 and more retention index units per degree (i.u./deg) for tri- and polycyclic structures. Hence, it is not surprising that RI data for isoalkanes, ethers, esters, etc. being measured at different conditions, are in good accordance with each other (standard deviations of randomized interlaboratory values are not more than 1-3 i.u.). The same statistical characteristics for substituted benzenes is about 8 i.u., and for naphthalenes and other condensed arenes, it may exceed 10-15 i.u. [Pg.1308]

A useful 2ilternative to the Kovats system is the Lee retention index (isotherm2il and temperature dependent), based on the polynuclear aromatic hydrocarbon (PAH) standard compounds naphthalene (/ = 200), phenanthrene (/ = 300), chrysene (/ = 400), and picene or benzo(g,h,i)perylene (/ = 500). Isothermal (and temperature-dependent) Kovats and Lee retention indices for many compounds are tabulated in the NIST Chemistry Web Book (Ref. 8). [Pg.1439]

Vol. 19. General subject index and group index Vol. 20. General formula index Series 1 and II (volumes 1-11) were never published. Volume 12 was issued in two parts, 12A Bicyclic compounds, and 12B Naphthalene, in nine volumes (1948-1955). Volume 13 was published in 1946 and volume 14 in 1940 to which six supplements were added 1951-1962. Supplements 5 and 6 were issued under the auspices of the Beilstein Institute who took over the encyclopaedia in 1954 and combined it with the current supplement to Beilstein. The system of arrangement of Elsevier depends on the structure of the compound and brings together those that are most closely related. Occurrence in nature and in technical products is discussed followed by syntheses from systems with fewer carbon atoms and formation by the degradation of more complicated systems. [Pg.149]


See other pages where Naphthalene Compound, index is mentioned: [Pg.228]    [Pg.1630]    [Pg.614]    [Pg.1260]    [Pg.171]    [Pg.545]    [Pg.766]    [Pg.193]    [Pg.106]    [Pg.886]    [Pg.138]    [Pg.719]    [Pg.1058]    [Pg.134]    [Pg.167]    [Pg.480]    [Pg.31]    [Pg.691]    [Pg.814]    [Pg.295]    [Pg.11]    [Pg.12]    [Pg.43]    [Pg.83]    [Pg.96]   


SEARCH



INDEX compounds

Naphthalene compounds

© 2024 chempedia.info