Charge distribution, dipole moments and infrared spectra of some thiol and thio acids

The dipole moments of thioglycollic (2.28 D), β-mereaptopropionic (2.25 D), thiomalic (2.47 D), malic (3.12 D), and dithiodiacetic (3.17 D) acids have been measured in dioxan at 35° C. Using the scheme of Smith, Ree, Magee and Eyring, the formal charge distribution in and hence the electric moments of these acids have been evaluated, compared with the theoretical moments, and discussed in terms of their various possible structures. Infrared spectra of these acids (liquid and nujol mull) indicate association through hydrogen bonding. These bonds are broken in solution.

Electron temperature distribution across a shock wave in a partially ionized gas

The electron temperature structure in a weakly ionized plasma is studied allowing the degree of ionization to vary across the shock wave. The values of the electron temperature and the downstream equilibrium temperature obtained with variable ionization are less than those for frozen ionization. The electron temperature rises sharply behind the shock for variable ionization while a gradual increase is predicted by frozen ionization.

Charge distribution in and dipole moments of some aliphatic alcohols

Using the treatment of Smith, et al.,1 charge distributions in several aliphatic alcohols and consequently their dipole moments have been evaluated. The dipole moments of trichloroethanol (2.04 D) and 1,3-dichloropropan-2-ol (2.11 D) have been measured in benzene solution at 35°. The results of evaluation and measurements are interpreted in terms of the occurrence of intramolecular interaction between the hydroxyl hydrogen and an acceptor atom X (halogen or oxygen) at the β-carbon atom.

Charge distribution in and electric moments of some aliphatic acids

Using the treatment of Smith et al., charge distribution in and consequently the dipole moments of several aliphatic acids have been evaluated. The electric moments of chloro (2·86 D), bromo (2·90 D), iodo (2·06 D) and trichloro (3·00 D) acetic acids have been measured in dioxan solution at 35°. The experimental values are compared with those calculated theoretically and discussed in terms of the various possible structures.

Charge distribution, dipole moment and molecular structure of silyl compounds

The formal charge distribution and hence the electric moments of a number of halosilanes and their methyl derivatives have been calculated by the method of Image and Image . The difference between the observed and the calculated values in simple halosilanes is attributed to a change in the hybridization of the terminal halogen atom and in methyl halosilanes to the enhanced electron release of the methyl group towards silicon compared with carbon.

Synthesis of Unnatural Selenocystines and beta-Aminodiselenides via Regioselective Ring-Opening of Sulfamidates Using a Sequential, One-Pot, Multistep Strategy

A variety of N-alkyl-beta-aminodiselenides have been synthesized in high yield from sulfamidates under mild reaction conditions using potassium selenocyanate and benzyltriethylammonium tetrathiomolybdate ([BnNEt3](2)MoS4) in a sequential, one-pot, multistep reaction. The tolerance of multifarious protecting groups under the reaction conditions is discussed. The methodology was successfully extended to the synthesis of selenocystine,3,3'-dialkylselenocystine, and 3,3'-diphenylisoselenocystine and their direct incorporation into peptides.

Intracellular distribution of coenzyme Q in rat liver

Coenzyme Q was found to be distributed in rat liver cell fractions. Mitochondria accounted for only 40–60% of the total. The presence of coenzyme Q in nuclei, isolated by several methods, could always be correlated with the presence of oxidative enzymes. It has been established that coenzyme Q is a constituent of microsomes. Administered coenzyme Q10-C14 was preferentially taken up by mitochondrial and microsomal fractions. Exogenous coenzyme Q appears to be rapidly metabolized.

Distribution of coenzyme Q in rat liver cell fractions

COENZYME Q (CoQ), which is widely distributed in animal, plant and microbial sources, has been implicated in electron transport1 and generally assumed to be associated with mitochondria. However, it has also been found in non-mitochondrial fractions of green leaves, although it appears to be concentrated in mitochondria2. A similar distribution has now been demonstrated in rat liver cell fractions.

Distribution of products around a burning droplet: an analytical approach

A knowledge of the concentration distribution around a burning droplet is essential if accurate estimates are to be made of the transport coefficients in that region which influence the burning rate. There are two aspects of this paper; (1) determination of the concentration profiles, using the simple assumption of constant binary diffusion coefficients for all species, and comparison with experiments; and (2) postulation of a new relation for the therinal conductivity, which takes into account the variations of both temperature and concentrations of various species. First, the theoretical concentration profiles are evaluated and compared with experimental results reported elsewhere [5]. It is found that the agreement between the theory and experiment is fairly satisfactory. Then, by the use of these profiles and the relations proposed in the literature for the thermal conductivity of a mixture of nonpolar gases, a new relation for thermal conductivity: K = (A1 + B1 T) + (A2 + B2 T) xr (21). is suggested for analytical solutions of droplet combustion problems. Equations are presented to evaluate A1, A2, B1, and B2, and values of these terms for a few hydrocarbons are tabulated.

Synthesis, aggregation behavior and cholesterol solubilization studies of 16-epi-pythocholic acid (3 alpha,12 alpha,16 beta-trihydroxy-5 beta-cholan-24-oic acid)

Synthesis, aggregation behavior and in vitro cholesterol solubilization studies of 16-epi-pythocholic acid (3 alpha,12 alpha,16 beta-trihydroxy-5 beta-cholan-24-oic acid, EPCA) are reported. The synthesis of this unnatural epimer of pythocholic acid (3 alpha,12 alpha,16 alpha-trihydroxy-5 beta-cholan-24-oic acid, PCA) involves a series of simple and selective chemical transformations with an overall yield of 21% starting from readily available cholic acid (CA). The critical micellar concentration (CMC) of 16-epi-pythocholate in aqueous media was determined using pyrene as a fluorescent probe. In vitro cholesterol solubilization ability was evaluated using anhydrous cholesterol and results were compared with those of other natural di-and trihydroxy bile acids. These studies showed that 16-epi-pythocholic acid (16 beta-hydroxy-deoxycholic acid) behaves similar to cholic acid (CA) and avicholic acid (3 alpha,7 alpha,16 alpha-trihydroxy-5 beta-cholan-24-oic acid, ACA) in its aggregation behavior and cholesterol dissolution properties. (C) 2010 Elsevier Inc. All rights reserved.