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Multiple Bonds (multiple + bond)

Distribution by Scientific Domains

Chemistry	100%

Terms modified by Multiple Bonds

multiple bond correlation

Selected Abstracts

Metal-Organic Frameworks (MOFs) as Heterogeneous Catalysts for the Chemoselective Reduction of Carbon-Carbon Multiple Bonds with Hydrazine

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009
Amarajothi Dhakshinamoorthy
Abstract The as-synthesized metal-organic frameworks (MOFs), particularly that based on aluminium coordinated with benzenedicarboxylic acid, constitute selective catalysts for the reduction of carbon-carbon multiple bonds in alkenes, alkynes and ,,,-unsaturated esters with hydrazine hydrate in acetonitrile under mild conditions. The present protocol enjoys advantages such as convenient reaction conditions and benign, reusable and cost effective catalyst. [source]

ChemInform Abstract: Indium(III) Chloride Catalyzed Oxidative Cleavage of Carbon,Carbon Multiple Bonds by tert-Butyl Hydroperoxide in Water , A Safe Alternative to Ozonolysis.

CHEMINFORM, Issue 31 2008
Brindaban C. Ranu
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

A New Method for the Synthesis of Acyltitanium Complexes and Their Application to Copper-Mediated Acylmetalation of Carbon,Carbon Multiple Bonds in Aqueous Media.

CHEMINFORM, Issue 39 2005
Zhenfu Han
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Metal-Organic Frameworks (MOFs) as Heterogeneous Catalysts for the Chemoselective Reduction of Carbon-Carbon Multiple Bonds with Hydrazine

Understanding topological symmetry: A heuristic approach to its determination

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2008
M. L. Contreras
Abstract An algorithm based on heuristic rules for topological symmetry perception of organic structures having heteroatoms, multiple bonds, and any kind of cycle, and configuration, is presented. This algorithm identifies topological symmetry planes and sets of equivalent atoms in the structure, named symmetry atom groups (SAGs). This approach avoids both the need to explore the entire graph automorphism groups, and to encompass cycle determination, resulting in a very effective computer processing. Applications to several structures, some of them highly symmetrical such as dendrimers, are presented. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source]

A novel semi-empirical topological descriptor Nt and the application to study on QSPR/QSAR

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2007
Congyi Zhou
Abstract A novel semi-empirical topological descriptor Nt was proposed by revising the traditional distance matrix based on the equilibrium electronegativity and the relative bond length. Nt can not only efficiently distinguish structures of organic compounds containing multiple bonds and/or heteroatoms, but also possess good applications of QSPR/QSAR (quantitative structure-property/activity relationships) to a large diverse set of compounds, which are alkanes, alkenes, alkynes, aldehydes, ketones, thiols, and alkoxy silicon chlorides with all the correlation coefficients of the models over 0.99. The LOO CV (leave-one-out cross-validation) method was used to testify the stability and predictive ability of the models. The validation results verify the good stability and predictive ability of the models employing the cross-validation parameters: RCV, SEPCV and SCV, which demonstrate the wide potential of the Nt descriptor for applications to QSPR/ QSAR. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source]

Methylene as a possible universal footprinting reagent that will include hydrophobic surface areas: Overview and feasibility: Properties of diazirine as a precursor

PROTEIN SCIENCE, Issue 12 2000
Frederic M. Richards
Abstract Methylene is one of, if not the, most reactive organic chemical known. It has a very low specificity, which makes it essentially useless for synthesis, but suggests a possible role in protein footprinting with special importance in labeling solvent accessible nonpolar areas, identifying ligand binding sites, and outlining interaction areas on protomers that form homo or hetero oligomers in cellular assemblies. The singlet species is easily and conveniently formed by photolysis of diazirine. The reactions of interest are insertion into C-H bonds and addition to multiple bonds, both forming strong covalent bonds and stable compounds. Reaction with proteins and peptides is reported even in aqueous solutions where the vast majority of the reagent is used up in forming methanol. Species containing up to 5 to 10 extra : CH2 groups are easily detected by electrospray mass spectroscopy. In a mixture of a 14 Kd protein and a noninteracting 1.7 Kd peptide, the distribution of mass peaks in the electrospray spectra was close to that expected from random modification of the estimated solvent accessible area for the two molecules. For analysis at the single residue level, quantitation at labeling levels of one 13CH2 group per 10 to 20 kDa of protein appears to be possible with isotope ratio mass spectroscopy. In the absence of reactive solvents, photolysis of diazirine produces oily polymeric species that contain one or two nitrogen atoms, but not more, and are water soluble. [source]

Direct Estimate of the Strength of Conjugation and Hyperconjugation by the Energy Decomposition Analysis Method

CHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2006
Israel Fernández Dr.
Abstract The intrinsic strength of , interactions in conjugated and hyperconjugated molecules has been calculated using density functional theory by energy decomposition analysis (EDA) of the interaction energy between the conjugating fragments. The results of the EDA of the trans -polyenes H2CCH(HCCH)nCHCH2 (n=1,3) show that the strength of , conjugation for each CC moiety is higher than in trans -1,3-butadiene. The absolute values for the conjugation between SiSi , bonds are around two-thirds of the conjugation between CC bonds but the relative contributions of ,E, to ,Eorb in the all-silicon systems are higher than in the carbon compounds. The , conjugation between CC and CO or CNH bonds in H2CCHC(H)O and H2CCHC(H)NH is comparable to the strength of the conjugation between CC bonds. The , conjugation in H2CCHC(R)O decreases when R=Me, OH, and NH2 while it increases when R=halogen. The hyperconjugation in ethane is around a quarter as strong as the , conjugation in ethyne. Very strong hyperconjugation is found in the central CC bonds in cubylcubane and tetrahedranyltetrahedrane. The hyperconjugation in substituted ethanes X3CCY3 (X,Y=Me, SiH3, F, Cl) is stronger than in the parent compound particularly when X,Y=SiH3 and Cl. The hyperconjugation in donor,acceptor-substituted ethanes may be very strong; the largest ,E, value was calculated for (SiH3)3CCCl3 in which the hyperconjugation is stronger than the conjugation in ethene. The breakdown of the hyperconjugation in X3CCY3 shows that donation of the donor-substituted moiety to the acceptor group is as expected the most important contribution but the reverse interaction is not negligible. The relative strengths of the , interactions between two CC double bonds, one CC double bond and CH3 or CMe3 substituents, and between two CH3 or CMe3 groups, which are separated by one CC single bond, are in a ratio of 4:2:1. Very strong hyperconjugation is found in HCCC(SiH3)3 and HCCCCl3. The extra stabilization of alkenes and alkynes with central multiple bonds over their terminal isomers coming from hyperconjugation is bigger than the total energy difference between the isomeric species. The hyperconjugation in MeC(R)O is half as strong as the conjugation in H2CCHC(R)O and shows the same trend for different substituents R. Bond energies and lengths should not be used as indicators of the strength of hyperconjugation because the effect of , interactions and electrostatic forces may compensate for the hyperconjugative effect. [source]