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Bromophenols (as well as PBDEs) were detected in 88% of samples, with 2,4,6-Tribromophenol present in 84% of breast milk samples alone. This was widely reported [ 2 ] [ 3 ] and has raised questions about restricting the use of brominated flame retardants in the future.
There are six structural isomers, each with the molecular formula C 6 H 4 Br 2 O, which differ by arrangement of the substituents. Dibromophenols: Name 2,3-Dibromophenol,
At room temperature, 2,4-dibromophenol is a solid with needle-like crystals. It melts at 38 °C (100.4 °F) and boils at 238.5 °C (461.3 °F). it has a molecular weight of 251.905 g/mol. It is soluble in water, ethanol, ether and benzene and slightly soluble in carbon tetrachloride. [1]
2,6-DMP is produced by the methylation of phenol. With production >100,000 tons/y, it is the most important xylenol. The methylation is carried out by contacting gaseous phenol and methanol at elevated temperatures in the presence of a solid acid catalyst: [2] [3] C 6 H 5 OH + 2 CH 3 OH → (CH 3) 2 C 6 H 3 OH + 2 H 2 O
This alkylation provides a means to separate 2,4-xylenol from 2,5-xylenol since 2,4-dimethyl-6-tert-butylphenol is insoluble in 10% NaOH but 2,5-dimethyl-6-tert-butylphenol is soluble. Subsequent to separation, the tert-butyl group can be removed in strong acid. [1]
Monobromotoluene isomers [1] [2] [3] Common name Structure Systematic name: 1-bromo-2-methylbenzene 1-bromo-3-methylbenzene 1-bromo-4-methylbenzene Molecular formula: C 7 H 7 Br (C 6 H 4 BrCH 3) Molar mass: 171.03 g/mol Appearance colorless liquid colorless liquid white crystalline solid CAS number [95-46-5] [591-17-3]
The main xylenols in such tar are the 3,5-, 2,4, and 2,3- isomers. 2,6-Xylenol is produced by methylation of phenol using methanol in the presence of metal oxide catalysts: [1] C 6 H 5 OH + 2 CH 3 OH → (CH 3) 2 C 6 H 3 OH + 2 H 2 O. Typically, xylenols also ethylphenols, which have very similar physical properties. [2]
Microbial metabolism in products treated with TBP is known to produce 2,4,6-tribromoanisole (TBA), [9] which has a musty odor. In 2010 and 2011, Pfizer and Johnson & Johnson voluntarily recalled some products due to TBA odors from wooden pallets which were treated with TBP. [10] [11] [12] [13]