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  2. Arene substitution pattern - Wikipedia

    en.wikipedia.org/wiki/Arene_substitution_pattern

    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 ...

  3. Electrophilic aromatic substitution - Wikipedia

    en.wikipedia.org/wiki/Electrophilic_aromatic...

    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 ...

  4. Electrophilic aromatic directing groups - Wikipedia

    en.wikipedia.org/wiki/Electrophilic_aromatic...

    There are 2 ortho positions, 2 meta positions and 1 para position on benzene when a group is attached to it. When a group is an ortho / para director with ortho and para positions reacting with the same partial rate factor, we would expect twice as much ortho product as para product due to this statistical effect.

  5. Ortho effect - Wikipedia

    en.wikipedia.org/wiki/Ortho_effect

    There are three main ortho effects in substituted benzene compounds: Steric hindrance forces cause substitution of a chemical group in the ortho position of benzoic acids become stronger acids. Steric inhibition of protonation caused by substitution of anilines to become weaker bases, compared to substitution of isomers in the meta and para ...

  6. Hammett equation - Wikipedia

    en.wikipedia.org/wiki/Hammett_equation

    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.

  7. Discovery and development of beta-blockers - Wikipedia

    en.wikipedia.org/wiki/Discovery_and_development...

    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.

  8. Aromatic compound - Wikipedia

    en.wikipedia.org/wiki/Aromatic_compound

    Activators are known as ortho-para directors, and deactivators are known as meta directors. [9] Upon reacting, substituents will be added at the ortho, para or meta positions, depending on the directivity of the current substituents to make more complex benzene derivatives, often with several isomers.

  9. Terphenyl - Wikipedia

    en.wikipedia.org/wiki/Terphenyl

    Infobox references. Terphenyls are a group of closely related aromatic hydrocarbons. Also known as diphenylbenzenes or triphenyls, they consist of a central benzene ring substituted with two phenyl groups. There are three substitution patterns: ortho -terphenyl, meta -terphenyl, and para -terphenyl. Commercial grade terphenyl is generally a ...