Synthesis of oxygenated derivatives of 2,3,7,8-tetrachlorodibenzo-p-dioxin

Abstract

Four monomethoxy, five dimethoxy and four dihydroxy derivatives of polychlorodibenzo-p-dioxin have been synthesized, and their physical and spectral properties (NMR and MS) have been reported. The general method for the synthesis of specific mono-and dimethoxy derivatives in reasonable yields has been found to be the condensation of 4,5-dichlorocatechol with appropriately substituted o-chloronitrobenzenes. The monomethoxy derivatives thus prepared were demethylated by boron tribromide dimethyl sulfide. Several mono-and dihydroxypolychlorodibenzo-p-dioxins have been identified as metabolites of the highly toxic environmental contaminant 2,3,7,8tetrachlorodibenzo-p-dioxin (TCDD). However, most of these metabolites have not been fully characterized due to the lack of appropriate standards. The availability of these synthetic oxygenated derivatives of TCDD can be used to establish the structure and the potential toxicity associated with these metabolites.

Hapten Synthesis and Antibody Development for Polychlorinated Dibenzo-p-dioxin Immunoassays

“…Ethyl 6-(3,7,8-Trichlorodibenzo-p-dioxin-2-yloxy)hexanoate (XIV). 2,3,7-Trichloro-8-hydroxydibenzo-p-dioxin (3.1 mg, 10 µmol) (Mason and Safe, 1986;Singh and Kumar, 1993) was alkylated with ethyl 6-bromohexanoate (99%, 3.4 mg,15 µmol), with finely grounded potassium carbonate (0.02 g, 0.15 mmol) as base and Aliquat 336 (0.2 mg, 0.5 µmol) as a phase transfer catalyst (Dehmlow, 1983), in 1 mL of dry DMF. The mixture was vigorously stirred under nitrogen at 90-100 °C for a day.…”

Application of Soluble Membrane Filter in Simultaneous Determination of Trace Levels of Cadmium, Copper, Lead and Zinc in Food Additives by Inductively Coupled Plasma Atomic Emission Spectrometry

“…So, they must be edible and nontoxic at least. Heavy metals and the essential metals that become toxic when brought in excess, which result in poisoning and disease if accumulated in human tissues [1,2]. Accordingly, it is necessary to set up sensitive and reliable method for determination of the heavy metal ions in food materials and additives.…”

Conformational investigation of α,β‐dehydropeptides Part VI. Molecular and crystal structure of benzyloxycarbonylglycyl‐(Z)‐dehydrophenylalanine

“…u, P-Dehydroamino acids provide conformational constraint to the peptide backbone and to the side-chain orientation at the same time (1). Depending on the specific sequence, folded structures such as various P-bends, 310-and u-helices have been found in studies on model (Z)-u,p-dehydropeptides (2)(3)(4)(5)(6)(7)(8)(9), and attempts have been made to exploit this knowledge for designing bioactive compounds (e.g. refs.…”