Synthesis of 4,7′-Bibenzo[b]thiophenes Bearing Several Different Substituents at 2-, 2′-, 4′-, and 7-Positions; Structurally Featured Molecular Scaffolds for Selective Substitution

Four isomers of 4,7′-bibenzothiophene scaffolds bearing two different halogen (Br, Cl) and triisopropylsilyl substituents have been synthesized from the two multihalobenzo[b]thiophenes via iodoselective Miyaura borylation reaction using potassium benzoate as a base. Further investigation into the reactivity of 4,7′-bibenzothiophenes in substitution reaction, Suzuki–Miyaura cross-coupling reaction, and C–H direct arylation reaction revealed that tetrasubstituted 4,7′-bibenzothiophenes can be synthesized site- (chemo-) selectively, which are promising novel components for molecular architecture.

Levels of Benzoic and Sorbic Acid Preservatives in Commercially Produced Ready to Serve Products in Sri Lanka

Benzoic acid, sorbic acid are widely used for food preservation. The analyses of these preservatives in 100 different food products were performed. Therefore 100 samples including, 10 carbonated beverages, 20 jams, 10 jelly drinks, 10 jelly cups, 30 ready to serve drinks, 10 nectars, and 10 sauces were analysed by using high performance liquid chromatography. The HPLC determination of the preservatives was performed using a reversed – phase C18 column and UV detection at 235 nm. Flow rate approximately 1.2ml/min. Eluent for HPLC, mix 50 volume parts of Ammonium Acetate solution with 40 volume parts of methanol for HPLC and adjust to a pH of 4.5 to 4.6 with acetic acid. The preservative concentration in samples was used as external standards for sodium benzoate and potassium benzoate. Levels were compared with Food Act and Food Standards Regulation in Sri Lanka. Both benzoic acid and sorbic acid were detected in a range of 1120ppm to 30ppm and 582ppm to 16ppm respectively. Although 65% of the samples was not compliant with the Food Act and Food Regulations in Sri Lanka.