Substituent

About: Substituent is a research topic. Over the lifetime, 42877 publications have been published within this topic receiving 516716 citations. The topic is also known as: side chain & side group.

Low Molecular-Mass Gelators with Diyne Functional Groups and Their Unpolymerized and Polymerized Gel Assemblies

Abstract: A series of low molecular-mass organogelators (LMOGs) with conjugated diyne units, R−C⋮CC⋮C−R‘, has been synthesized from 10,12-pentacosadiynoic acid. R is a long alkyl chain and R‘ is a short or long alkyl chain containing an amide or ester group. The gelation efficiencies of these LMOGs and the parent acid (as assessed by the variety of liquids gelled, the amount of gelator needed for gelation, and the temporal and thermal stabilities of the gels) differ widely according to the nature of the substituents. An LMOG with an amide substituent is much more efficient than the corresponding molecule with an ester group, and LMOGs with longer R‘ chains are more efficient than those with shorter ones. When irradiated, some gel networks polymerize. In most cases, the polymerized aggregates phase-separate microscopically, but maintain the gel structure macroscopically. These gels are irreversibly photo- and thermo-chromic, and the thermal stabilities of some of the colored polymerized organogel networks are simila...

Arylation Reactions: The Photo-SN1 Path via Phenyl Cation as an Alternative to Metal Catalysis

Abstract: Photo(sensitized) cleavage of benzenediazonium salts as well as, when an electron-donating substituent is present, of aryl chlorides, fluorides, mesylates, triflates, and phosphates leads to the corresponding phenyl cations in the triplet state. These otherwise unavailable intermediates add selectively to alkenes, alkynes, and (hetero)arenes, giving arylation products in a good yield. The reactions are photochemical alternatives of metal-catalyzed Heck and cross-coupling reactions and bear some mechanistic analogy with them.

Aryloxyarylsulfonylamino hydroxamic acid derivatives

Abstract: A compound of formula (I) or the pharmaceutically acceptable salts thereof, wherein R1 is (C?1?-C6)alkyl; R?2? is (C?1?-C6)alkyl; or R?1 and R2? taken together with the carbon atom to which they are attached form a ring selected from (C?5?-C7)cycloalkyl, 4-tetrahydropyranyl and 4-piperidinyl; R?3? is hydrogen or (C?1?-C6)alkyl; and Y is a substituent of any of the carbon atoms of the phenyl ring capable of supporting an additional bond, preferably from 1 to 2 substituents (more preferably one substituent, most preferably one substituent in the 4-position) on the phenyl ring, independently selected from hydrogen, fluoro, chloro, trifluoromethyl, (C1-C6)alkoxy, trifluoromethoxy, difluoromethoxy and (C1-C6)alkyl.