Absorption for Di-Substituted Benzene Derivatives Page

In disubstituted benzenes, two situations are important:

When electronically complementary groups, such as amines and nitro, are situated para to each other, there is a pronounced shift to longer wavelength in the main absorption band.

Alternatively, when two groups are situated ortho or meta to each other or when the para disposed groups are not electronically complementary, then the observed spectrum is usually closer to that of the separate, noninteracting chromophores.


Absorption for Di-Substituted Benzene Derivatives

R	R'	Orientation	K		B
			l_max	e_max	l_max	e_max
-OH	-OH	ortho	214	6000	278	2630
-OR	-CHO	ortho	253	11000	319	4000
-NH₂	-NO₂	ortho	229	16000	275	5000
-OH	-OH	meta	277	2200
-OR	-CHO	meta	252	8300	314	2800
-NH₂	-NO₂	meta	235	16000	373	1500
-OH	-OH	para	225	5100	293	2700
-OR	-CHO	para	277	14800
-NH₂	-NO₂	para	229	5000	375	16000
-Ph	-Ph	meta	251	44000
-Ph	-Ph	para	280	25000