Health & Environmental Research Online (HERO)


Print Feedback Export to File
8498362 
Journal Article 
Friedel-Crafts Benzoylation of Dibenzofuran 
Keuini, T; Shiinakawa, S; Oshiina, Y 
1977 
1 
Nippon Kagaku Kaishi
ISSN: 0369-4577
EISSN: 2185-0925 
1977 
10 
1518-1523 
English 
Friedel-Crafts benzoylation of dibenzofuran has been studied in detail to elucidate the isoiner distributions and the reactivity of each position of dibenzofuran. The reaction of dibenzofuran with benzoyl chloride in the presence of aluininuin chloride (inolar ratio; 1: 1:1) in nitrobenzene at 15°C for 1 hour gave benzoyldibenzofuran (BD) in yield of 93.3% which was coinposed with 1-BD of 0.6%, 2-BD of 90.5%, 3-BD of 8.7%, and 4-BD of 0.2%. Carrying out the reactions in chlorinated hydrocarbons or at high teinperature, the yield of 3-BD increased. The coinpetitive benzoylation of dibenzofuran and benzene gave the following partial rate factors (f1), f1: 34.6, f1: 4520, f3: 371, and f4: 19.8. Using an excess of aluininuin chloride to benzoyl chloride, f1, f2 and especially f4 decreased. It was assuined that the low reactivities of 1-and 4-positions were attributed to the steric hindrance by hydrogen at 9-position and the n-orbital of oxygen at 5-position in dibenzofuran against the acyliuin coinplex. The CNDO/2 calculations for the interinediates assuined in protonation of dibenzofuran were carried out to obtain the reactivity order of each position of dibenzofuran, 2->3->4->l-. The result was consistent with one in protodetritiation of dibenzofuran. The difference of results in the protonation and the acylation were interpreted on the basis of the difference in the steric hindrances between the n-orbital of oxygen of dibenzofuran and the attacking agents. © 1977, The Chemical Society of Japan. All rights reserved.