Sentences with word «alkene»

The effect of a trans - locked Gly - Pro alkene isostere on collagen triple helix stability.

Chemists have long wanted to find better ways to achieve anti-Markovnikov selectivity in alkene oxidations — for example, to convert the aldehyde products to linear alcohols, which are commonly used in flavorings, perfumes, lubricants, and cosmetics.

The researchers showed that quantum mechanical tunneling greatly enhances the production rate of hydroxyl radicals in alkene ozonolysis reactions, which sever multiple bonds under atmospheric conditions.

Markovnikov oxidation of terminal alkenes (left) to form ketones (center) is energetically favored, whereas anti-Markovnikov reactions leading to aldehydes are more difficult.

Selective hydrogenation is the key to producing valuable chemicals, for example, turning triple - bonded hydrocarbons called alkynes selectively into double - bonded alkenes — starting materials for the synthesis of plastics, fuels and other commercial products.

Last month, the pair's paper, «Computationally designed zirconium organometallic catalyst for direct epoxidation of alkenes without allylic H atoms: aromatic linkage eliminates formation of inert octahedral complexes,» was published in Theoretical Chemistry Accounts.

Synthesis and biological evaluation of selective CXCR4 antagonists containing alkene dipeptide isosteres.

The rhodium azavinyl carbenes react with alkenes, yielding cyclopropanes or dihydropyrroles with good stereoselectivity.

The team now reports using directed evolution, an iterative process of protein mutation and screening for activity, to identify amino acid substitutions that convert an enzyme into a predominantly anti-Markovnikov alkene oxidation catalyst (Science 2017, DOI: 10.1126 / science.aao1482).

Related research (Pereira HJ, et al., 2012) used two different lines of evidence to explain the increase in the ratio of anteiso — to iso - branched alkenes that was observed during the transition from early to late stationary phase in M. luteus: structural studies of a key enzyme involved in fatty acid biosynthesis in M. luteus (FabH, or ß - ketoacyl - ACP synthase III) and transcriptional (whole - genome microarray) studies of M. luteus during different growth phases.

Ethylene (or IUPAC name ethene) is the simplest alkene hydrocarbon, consisting of four hydrogen atoms and two carbon atoms connected by a double bond.

JBEI researchers identified three genes in the bacterium Micrococcus luteus that are associated with long - chain alkene biosynthesis from fatty acids (Beller H, et al., 2010).

In order to evaluate the electrostatic effects of the amide carbonyl groups within the peptide bonds on the activity of FC131, a comparative study using unsubstituted and fluorinated alkene isosteres has been attempted.

Wiktelius D, Luthman K. Taking control of P1, P1» and double bond stereochemistry in the synthesis of Phe - Phe (E)- alkene amide isostere dipeptidomimetics.

The Caltech researchers started with an iron - based cytochrome P450 enzyme called P450LA1because it catalyzes a related reaction, metal - oxo alkene oxidation, in which a metal - linked oxygen attacks the double bond, typically forming an epoxide.

In conjunction with other reagents and catalysts, the enzyme could one day convert terminal - alkene substrates to a variety of aldehyde, alcohol, and amine products for commodity and fine chemical, pharmaceutical, and agrochemical use.

The main areas covered in this work booklet are: Alkanes Alkenes Fractional distillation Cracking Polymerisation Burning Alcohols Organic acids Oil Within the booklet are a range of different activities for students to work through to help them remember the content.

aMOx works well because it stabilizes high - energy radical and carbocation intermediates created when its iron - oxo group attacks styrene's terminal alkene, allowing anti-Markovnikov aldehyde formation to predominate.

Stereoselective synthesis of [L - Arg - L / D -3 -(2 - naphthyl) alanine]- type (E)- alkene dipeptide isosteres and its application to the synthesis and biological evaluation of pseudopeptide analogues of the CXCR4 antagonist FC131.

The replacement of the Arg3 - Nal4 peptide bond with an (E)- alkene isostere in compound 7 produced a negative effect on CXCR4 inhibitory activity, probably due to the lack of H - bonding of amide moiety and a different interaction of pseudo -1,3-allylic strain between the Arg3 carbonyl group and the Nal4 side chain.

«It's easy to add fluorine groups to alkenes, but not so easy to change them later,» first author Hironobu Sakaguchi says.

Alkenes are groups featuring a carbon double bond with four other groups or atoms attached.

All chemists are well - acquainted with alkanes, alkenes and alkynes, which have single, double and triple carbon - carbon bonds respectively.

Both (E)- alkene and (Z)- fluoroalkene analogues (5 and 6) with substitutions at the Arg2 - Arg3 dipeptide moderately inhibited SDF - 1 binding to CXCR4 with IC50 values of 1.46 and 1.78 μM, respectively.

Peptide bond mimicry by (E)- alkene and (Z)- fluoroalkene peptide isosteres: synthesis and bioevaluation of alpha - helical anti-HIV peptide analogues.

On the basis of these considerations, the effects of the Arg2 - Arg3 and Arg3 - Nal4 peptide bonds on the activity of FC131 have been investigated through the synthesis and evaluation of the alkene analogues such as compounds 5 - 8 (Figure 6)[69].

In particular, due to their electrostatic and steric properties, the fluorinated or substituted alkene isosteres represent more appropriate peptide bond mimetics than the unsubstituted alkene isosteres [71 - 76].

It is now well known that a systematic replacement of the planar peptide bond with an alkene bioisostere is useful for the estimation of the electrostatic effects and for the SAR evaluation of peptide derivatives.

Oxidizing the end carbon atom of a terminal alkene to form an aldehyde, a process called anti-Markovnikov alkene oxidation, is difficult because the reaction is energetically unfavorable.

The team figured out the steps that occur when a catalyst helps split an alcohol, generating water and a carbon - based molecule known as an alkene.

Topics include: States of matter Diffusion Atomic Structure Separation Techniques Covalent Bonding Ionic Bonding Metallic Bonding Oxygen and Oxides Acids, Alkalis and Salts Rates of Reaction Equilibrium Energetics Organic Chemistry - alkanes, alkenes, alcohols, isomers, fractional distillation, cracking, polymerisation Chemistry in industry - Haber Process, Contact process, Extraction of Metals

Keywords: organic chemistry, functional groups, alkanes, alkenes, alcohols, aldehydes, ketones, carboxylic acids, esters, halogenalkanes, game.

A team of researchers in France has discovered an algal photoenzyme that catalyzes the decarboxylation of free fatty acids to n - alkanes or - alkenes in response to blue light.