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Main arene substitution patterns. In ortho-substitution, two substituents occupy positions next to each other, which may be numbered 1 and 2. In the diagram, these positions are marked R and ortho. In meta-substitution the substituents occupy positions 1 and 3 (corresponding to R and meta in the diagram). In para-substitution, the substituents ...
Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitutions are aromatic nitration, aromatic halogenation, aromatic sulfonation, alkylation Friedel–Crafts reaction and ...
Ortho effect is an organic chemistry phenomenon where the presence of a chemical group at the at ortho position or the 1 and 2 position of a phenyl ring, relative to the carboxylic compound changes the chemical properties of the compound. This is caused by steric effects and bonding interactions along with polar effects caused by the various ...
Electrophilic aromatic directing groups. In electrophilic aromatic substitution reactions, existing substituent groups on the aromatic ring influence the overall reaction rate or have a directing effect on positional isomer of the products that are formed. An electron donating group (EDG) or electron releasing group (ERG, Z in structural ...
Meta -selective C–H functionalization refers to the regioselective reaction of a substituted aromatic ring on the C–H bond meta to the substituent. Substituted aromatic ring is an important type of substructure in pharmaceuticals and industrial compounds. Thus, synthetic methods towards substituted aromatic rings are always of great ...
For meta-directing groups (electron withdrawing group or EWG), σ meta and σ para are more positive than σ’. (The superscript, c, in table denotes data from Hammett, 1940. [11] [page needed]) For ortho-para directing groups (electron donating group or EDG), σ’ more positive than σ meta and σ para.
Aromatic compound. 2D model of a benzene molecule. The carbon "ring" is what makes benzene "aromatic". Aromatic compounds or arenes usually refers to organic compounds "with a chemistry typified by benzene " and "cyclically conjugated." [1] The word "aromatic" originates from the past grouping of molecules based on odor, before their general ...
The R 1 group can only be a secondary substitution and branched is the optimal choice; Alkyl (—CH 3) substituents on the α, β or γ carbon (if X = —OCH 2 —) lower beta blockade, especially at the α carbon; The general rule for aromatic substitution is: ortho > meta > para. This gives non-selective β-blockers.