Isotopic standards for carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide

Carbon isotope fractionation in plants

Forty-four odor-active compounds were quantified in Scheurebe and Gewurztraminer wines, respectively. Calculation of odor activity values (OAVs) of odorants showed that differences in odor profiles...

Quantitation and Sensory Studies of Character Impact Odorants of Different White Wine Varieties

Azobenzenes are ubiquitous motifs very important in many areas of science. Azo compounds display crucial properties for important applications, mainly for the chemical industry. Because of their discovery, the main application of aromatic azo compounds has been their use as dyes. These compounds are excellent candidates to function as molecular switches because of their efficient cis–transisomerization in the presence of appropriate radiation. The classical methods for the synthesis of azo compounds are the azo coupling reaction (coupling of diazonium salts with activated aromatic compounds), the Mills reaction (reaction between aromatic nitroso derivatives and anilines) and the Wallach reaction (transformation of azoxybenzenes into 4-hydroxy substituted azoderivatives in acid media). More recently, other preparative methods have been reported. This critical review covers the various synthetic methods reported on azo compounds with special emphasis on the more recent ones and their mechanistic aspects (170 references).

http://www.chtf.stuba.sk/~szolcsanyi/education/files/Organicka%20chemia%20II/Prednaska%202_Aminy_Reakcie/Doplnkove%20studijne%20materialy/Azobenzenes/Synthesis%20of%20azobenzenes%20-%20the%20coloured%20pieces%20of%20molecular%20materials.pdf

Synthesis of azobenzenes: the coloured pieces of molecular materials

The rational design, the synthesis via a new convergent approach, and the characterization of four generations of monodendrons based on the AB3 building block methyl 3,4,5-trishydroxybenzoate are described. The first generation monodendrons are crystalline. The second generation methyl 3,4,5-tris-3‘,4‘,5‘-[tris(n-dodecyloxy)benzyloxy]benzoate (12Gn-AG-CH3, n = 2), the corresponding benzyl alcohol (12G2-AG-CH2OH) and benzoic acid (12G2-AG), and all higher generation monodendrons with n = 3 and 4 exhibit in addition to the crystal phase an isomorphous cubic liquid-crystalline (LC) phase of Pm3n space group. The cubic unit cell parameters of 12G2-AG, 12G3-AG, and 12G4-AG are 68.3, 79.2, and 84.0 A, respectively. Computed electron density profiles demonstrated that in the cubic phase 12, 6, and 2 monodendrons of generation 2, 3 and 4 are self-assembled in supramolecular dendrimers resembling spherical micelles when they are centered at the corners and the body-center and respectively highly rounded tetrahedr...

Rational Design of the First Spherical Supramolecular Dendrimers Self-Organized in a Novel Thermotropic Cubic Liquid-Crystalline Phase and the Determination of Their Shape by X-Ray-Analysis

weight-average molecular weight of M = 40 X 106 with a probable error of 5%. In this determination of the molecular weights from light scattering no assumptions need be made about the percentage of hydration of the particles. If the length and molecular weight of the particles as determined by the light scattering measurements are used with a value of 0.73 for the partial specific volume of the virus, the diameter of the cylindrically shaped virus particles can be calculated to be 15.2 mp. This value is in agreement with that obtained in X-ray'22 and electron microscope16 studies. Summary Light scattering measurements were made on a freshly prepared sample of purified tobacco mosaic virus. The length of the particles determined from dissymmetry of light scattered by the solutions were found to be 270 mp. Application of the dissymmetry to turbidity measurements gave a weight average molecular weight of 40 millions for the particles. These values are in complete agreement with sizes determined from electron microscope and viscosity studies made on the same sample. This agreement indicates the validity of the light scattering method. For dilute solutions of tobacco mosaic in water the dissymmetry decreases with increasing virus concentration thus indicating that strong interaction with a consequent increase in order of the scattering particles is occurring. However, the dissymmetry is independent of concentration for dilute solutions of the virus in 0.1 M sodium phosphate buffer a t pH 7.

Reduction of Organic Compounds by Lithium Aluminum Hydride. I. Aldehydes, Ketones, Esters, Acid Chlorides and Acid Anhydrides

Reduction of Organic Compounds by Lithium Aluminum Hydride. II. Carboxylic Acids

EquaperaexAvertion ture Equations cluded Max. age 23 760 mm. Log 7s = 4.5 (10-6)T' 0.794 1 0.07 0.04 24 50 mm. Log qr 6.0 (10-6)P 0.700 1 .06 .035 25 760 mm. Log qu = 3.87(10-S)T' 0.804 0 .053 .02 26 50 mm. Log V M = 5.10(10-0)T* 0.72 0 .036 .023 27 150' Logqi 0.877-0.3logp 0 .OS .05 28 150' Log qu = 0.62&0.257 log p 0 ,046 ,029 a q = Viscosity, cps. ; T = boiling point, OK., and p = vapor pressure, mm.

Robert F. Nystrom

Papers

Reduction of Organic Compounds by Lithium Aluminum Hydride. I. Aldehydes, Ketones, Esters, Acid Chlorides and Acid Anhydrides

Reduction of Organic Compounds by Lithium Aluminum Hydride. II. Carboxylic Acids

Reduction of organic compounds by lithium aluminum hydride; halides, quinones, miscellaneous nitrogen compounds.

Reduction of Organic Compounds by Mixed Hydrides. II. Hydrogenolysis of Ketones and Alcohols1

Reduction of Organic Compounds by Mixed Hydrides. I. Nitriles