Trisubstituted benzenes

2-Amino-1-methoxy-4-methylbenzene
( p-cresidin ), a tri-substituted benzene

The trisubstituted benzenes form a large group of aromatic compounds . The structure consists of a benzene ring with three attached substituents , which can be either the same or different. Their different arrangement results in three substitution patterns with the same empirical formula . Depending on the arrangement, one speaks of vic. -, asym. or sym. isomer.

With the same substituents three constitutional isomers are formed , with two different six and with three different ten.

Naming

If one looks at the combinations of substituents on aromatics using the example of the methyl group  (–CH ₃ ) and the hydroxyl group  (–OH), one can see very different name combinations and forms of origin. In all cases the connections have common names.

• The three trimethylbenzenes have no common tribe name. The three isomers have three completely separate and different names - hemellitol , pseudocumene and mesitylene - which refer to their origin and discovery.
• The three trihydroxybenzenes also have no common tribe name. The three isomers also have three completely separate and different names - pyrogallol , hydroxyhydroquinone and phloroglucine - which also refer to their origin and discovery.
• In the third case of combining both substituents, there are two groups of compounds, each with six constitutional isomers:
  • with two methyl groups and one hydroxyl group: They can be called dimethylphenols or hydroxylenes . This is where the common trivial name Xylenole developed.
  • with two hydroxyl groups and one methyl group: They can be understood as methyl derivatives of catechol (2 isomers), resorcinol (3 isomers) and hydroquinone (1 isomer). A uniform naming in this way is difficult because the dihydroxybenzenes do not form a common common name. They are therefore referred to as dihydroxytoluenes , since only -toluene forms a common new common tribe name . There is no common trivial name like the xylenols. Individual fabrics have individual names, such as B. Orcin (3,5-dihydroxytoluene).

Benzene (-H)	2 × (-CH 3 )	2 × (-OH)
Toluene (-CH 3 )	Trimethylbenzenes vic. :  Hemellitol asym . :  pseudocumene sym . :  mesitylene	Dihydroxytoluenes Orcin
Phenol (-OH)	(Dimethylphenols / Hydroxyxylole) xylenols	Trihydroxybenzenes vic. :  Pyrogallol asym . :  hydroxyhydroquinone sym . :  phloroglucine

Same substituents

Trisubstituted benzenes
Surname	vic.	asym.	sym.
same substituents

• Trimethylbenzenes
• Trihydroxybenzenes
• Trimethoxybenzenes
• Triaminobenzenes
• Trinitrobenzenes
• Trifluorobenzenes
• Trichlorobenzenes
• Tribromobenzenes
• Triiodobenzenes
• Benzenetricarboxylic acids

Two different substituents

Trisubstituted benzenes
Surname	vic.	asym.	asym.	vic.	asym.	sym.
two different substituents

Benzene (-H)	2 × (-CH 3 )	2 × (-OH)	2 × (-OCH 3 )	2 × (-NH 2 )	2 × (-NO 2 )	2 × (–F / –Cl / –Br / –I)
Toluene (-CH 3 )	Trimethylbenzenes vic. :  Hemellitol , asym. :  Pseudocumene , bal. :  Mesitylene	Dihydroxytoluene 3,5-Dihydroxytoluene: Orcin	Dimethoxytoluenes	Diaminotoluenes (methylphenylenediamines)	Dinitrotoluenes	Difluorotoluenes Dichlorotoluenes Dibromotoluenes Diiodotoluenes
Phenol (-OH)	(Dimethylphenols) (Hydroxyxylole) xylenols	Trihydroxybenzenes vic. :  Pyrogallol , asym . :  hydroxyhydroquinone , sym . :  phloroglucine	Dimethoxyphenols	Diaminophenols (hydroxyphenylenediamines)	Dinitrophenols	Difluorophenols Dichlorophenols Dibromophenols Diiodophenols
Anisole (-OCH 3 )	Dimethyl anisoles (methoxyxylenes)	Dihydroxyanisoles	Trimethoxybenzenes	Diamino anisoles (methoxyphenylenediamines)	Dinitroanisole	Difluoro anisole Dichloro anisole Dibromanisole Diiodanisole
Aniline (-NH 2 )	(Dimethylaniline) (Aminoxylole) xylidines	Dihydroxyanilines	Dimethoxyaniline	Triaminobenzenes	Dinitroaniline	Difluoraniline Dichloraniline Dibromaniline Diiodaniline
Nitrobenzene (-NO 2 )	Nitroxylenes	Nitrodihydroxybenzenes	Dimethoxynitrobenzenes	Diaminonitrobenzenes (Nitrophenylenediamines)	Trinitrobenzenes	Difluornitrobenzole dichloronitrobenzenes Dibromnitrobenzole Diiodnitrobenzole
Halobenzene (–F / –Cl / –Br / –I)	Fluorxylole chloroxylenes Bromxylole Iodxylole	Fluorodihydroxybenzenes chlorodihydroxybenzenes bromodihydroxybenzenes iododihydroxybenzenes	Dimethoxyfluorobenzenes, Dimethoxychlorobenzenes, Dimethoxybromobenzenes, Dimethoxyiodobenzenes	Diaminofluorobenzenes (fluorophenylenediamines) diaminochlorobenzenes (chlorophenylenediamines) diaminobromobenzenes (bromophenylenediamines) diaminoiodobenzenes (iodophenylenediamines)	Dinitrofluorbenzole Dinitrochlorbenzole Dinitrobrombenzole Dinitroiodbenzole	Trifluorobenzenes Trichlorobenzenes Tribromobenzenes Triiodobenzenes
Benzoic acid (-COOH)	Dimethylbenzoic acids	Dihydroxybenzoic acids	Dimethoxybenzoic acids	Diaminobenzoic acids	Dinitrobenzoic acids	Difluorobenzoic acids Dichlorobenzoic acids Dibromobenzoic acids Diiodobenzoic acids

Three different substituents

Trisubstituted benzenes
Surname	vic.	asym.	asym.	vic.	vic.	asym.	sym.	asym.	asym.	asym.
three different substituents

• Hydroxymethoxybenzyl alcohols: vanillyl alcohol , isovanillyl alcohol , ortho-vanillyl alcohol , ...
• Hydroxymethoxybenzaldehyde: vanillin , isovanillin , ortho-vanillin , ...
• Hydroxymethoxybenzoic acids: vanillic acid , isovanillic acid , ortho-vanillic acid , ...
• Cresidines
• Nitrotoluidines
• Nitroanisidines
• Chlorocresols

See also

• Disubstituted benzenes