75630-75-0

Upstream product

• 39729-11-8 2'-hydroxychalcone dibromides 
• 39729-11-8 erythro-2'-hydroxychalcone dibromide 
• 888-12-0 (E)-2'-hydroxy-chalcone 
• 22029-75-0 (E)-2'-hydroxy-chalcone 

Downstream Products

• 525-82-6 FLAVONE 
• 37816-09-4 3-cyclohexylaminoflavone 
• 32374-87-1 3-cyclohexylaminoflavanone 
• 582-04-7 aurone 
• 67139-38-2 3-Phenyl-5-(2-hydroxyphenyl)isoxazole 
• 70188-21-5 (Z)-α-azido-2'-hydroxychalcone 
• 37542-14-6 aurone 
• 1025-85-0 2,3-cis-3-Bromoflavanone 
• 1025-85-0 trans-3-bromo-2-phenyl-chroman-4-one 

Relevant academic research and scientific papers

Routes to 3-Bromoflavanone from erythro-2'-Hydroxychalcone Dibromide: Spectral and Kinetic Evidence for the Dominating Role of Elimination-Addition Sequences via (E)- and (Z)-α-Bromo-2'-hydroxychalcones

Rate coefficients for the formation from erythro-2'-hydroxychalcone dibromide of (E)- and (Z)-α-bromo-2'-hydroxychalcone and for their cyclisation to 3-bromoflavanone in 4 : 1 water-ethanol at pH 7.88 are established by a combination of kinetic and spectrophotometric measurements.The E-isomer is formed in a yield (percent) of 35 +/- 2 as opposed to 63 +/- 8 for the Z-isomer.The Z-isomer cyclises over 20 times faster.Direct cyclisation of the dibromide, if any, is only a very minor route to 3-bromoflavanone.The implications for the elimination mechanism of the preference for syn- over anti-elimination, of the independence of rate of buffer (N-ethylmorpholine) concentration, and of the effect of pH change are briefly considered.Mechanisms discounted are E2 with N-ethylmorpholine or solvent molecules as base, and E1.No firm assignment is possible amongst a number of other mechanisms.

Pyrolitic Elimination of Hydrogen Halide and Halogen from 2,3-Dihalogenoketones

The thermal elimination of hydrogen chloride from 2'-hydroxychalcone dichlorides occured in two stages, initially forming 3-chloroflavones and then flavones; α-chloro-2'-hydroxychalcones, the likely intermediates in the formation of 3-chloroflavones, also yielded the same products.The pyrolysis of 2'-hydroxychalcone dibromides resulted in debromination as well as dehydrobromination with the consequent appearence of brominated flavones among the products.The formation of 3-bromoflavones was not observed but the isomeric (E)-α-bromo-2'-hydroxychalcones thermally isomerized to their (Z)-isomers and then underwent cyclization and dehydrobromination.The bromide were considerably more reactive than the dichlorides but, as a synthetic procedure, the pyrolysis of the dichlorides is cleaner and more productive.