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meso-Stilbene dibromide is an organic compound with a formula of (C 6 H 5 CH(Br)) 2. [3] It is one of three isomeric stilbene dibromides, the others being the pair of enantiomers. All are white solids. [4]
Stilbenoids are hydroxylated derivatives of stilbene and have a C 6 –C 2 –C 6 structure. They belong to the family of phenylpropanoids and share most of their biosynthesis pathway with chalcones. [1] [2] [3] Under UV irradiation, stilbene and its derivatives undergo intramolecular cyclization, called stilbene photocyclization to form ...
Stilbene exists as two possible stereoisomers. One is trans-1,2-diphenylethylene, called (E)-stilbene or trans-stilbene. The second is cis-1,2-diphenylethylene, called -stilbene or cis-stilbene, and is sterically hindered and less stable because the steric interactions force the aromatic rings out-of-plane and prevent conjugation. [4]
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The activation energy for thermal E-Z isomerization is 150–190 kJ mol −1 for stilbene, meaning that temperatures above 200°C are required to isomerize stilbene at a reasonable rate, but most derivatives have lower energy barriers (e.g. 65 kJ mol −1 for 4-aminostilbene). The activation energy of the electrocyclization is 73 kJ mol −1 ...
One of the two meso isomers of 1,2,3,4-tetrafluorospiropentane, with S 4 symmetry. Since a meso isomer has a superposable mirror image, a compound with a total of n chiral centers cannot attain the theoretical maximum of 2 n stereoisomers if one of the stereoisomers is meso. [4] A meso isomer need not have a mirror plane.
For stilbene and other chemicals containing a double-bond linker between the two aromatic rings, the excited structure can undergo reversible cis-trans isomerization. Although only cis structures can undergo the cyclization step themselves, trans structures can isomerize in situ and then cyclize. [ 2 ]
A completely uncharged structure cannot be written and mesoionic compounds cannot be represented satisfactorily by any one mesomeric structure. [1] Mesoionic compounds are a subclass of betaines. [1] Examples are sydnones and sydnone imines (e.g. the stimulant mesocarb), münchnones, [1] [2] and mesoionic carbenes.