Phenols simple, brominated

Tribromophenol and other simple brominated phenols (No. 66, 2005) Tributyltin oxide (No. 14, 1999)... 

The toxic Japanese gastropod Turbo marmorata contains the two toxins, turbotoxins A (1983) and B (1984), isolated as bis-trifluoroacetates (1824, 1825). The turbotoxins A and B show LD99 = 1.0 and 4.0 mg kg 1 in mice. The simple iodinated ammonium salt 1985 is also found in this animal (1826). The red alga Halopytis incurvus contains the simple brominated phenols 1986 and 1987, which were isolated as the methyl esters and methyl ethers (1827). These presumed degradation products of tyrosine are related to earlier reported brominated metabolites (1). 

Pedersen, M. and DaSilva, E.J., 1973. Simple brominated phenols in the bluegreen alga Calothrix brevissima West. Plants, 115 83—86. 

Effective use can sometimes be made of removable blocking groups on the ring. Suppose you are set the task of making pure < -bromophenol. Simple bromination of phenol will fail because of the dominant formation of the para isomer or of poly-brominated compounds (Fig. 14.90). A solution to this problem is first to sulfonate... 

Because of its mild reaction conditions, simple experimental operations, and generally excellent yields of o/t/zo-bromophenols, our method is practical for a wide variety of bromination of phenols (Scheme 6) and expected for industrial preparation of fine chemicals. 

The direct bromination of aniline and phenol derivatives in solution results in polybromination to give a complex mixture. But bromination by gas-solid and solid-solid reactions proceeds more efficiently and selectively. Bromination by gas-solid reaction can be accomplished through a very simple procedure. For example, the powdered crystalline aniline 13 and Br2 were placed in... 

The extension of the Srn 1 reaction to polycyclic aromatic substrates has been limited almost entirely to the simple halogenated derivatives (see tables and references in Section 2.2.3). The substrates used include 4-halobiphenyls, 1- and 2-halonaphthalenes, 9-bromoanthracene and 9-bromophenanthrene. There appears to be only one report on the effect of additional substituents on these ring systems the ionized phenolic group in l-bromo-2-naphthoxide causes substitution of the bromine by CH2CN to be completely supplanted by a reductive process.39... 

Poly(4-vinylpyridine)-supported bromate in nonaqueous solution has been used in the bromination of aromatic compounds with potassium bromide <2005SC1947>. This bromination method is simple, efficient, mild, and selective for methoxyarenes, anilines, and phenols. 

During the second year of UG, simple one step organic synthesis (e.g. preparation of bromo or nitro derivative) and quantitative estimations based on specific reactions (e.g. estunation of phenol/aniline by bromination) are introduced along with qualitative analysis. The qualitative analysis is at micro-scale level and is more complex in UG second year, as compounds with multifunctional groups arc given for analysis. In addition to characterisation, students have to identify the compound by performing the confirmatory tests. 

Acetals of a-bromo aldehydes are obtainable from <%,/ -dibromoalkyl acetates by an analogous procedure in which these esters are prepared from enol acetates and bromine and are then converted into acetals by means of alcohols.939 A simple synthesis of <%-keto aldehydes is to treat a-brominated phenacyl phenyl ethers with alkoxides or phenoxides.940 This method is particularly useful for the preparation of aryl acetals because it avoids the side reactions that can complicate reactions between phenols and aldehydes in an acidic medium. 

A brominated diterpene, concinndiol, an isomer of aplysin-20, has been recently described from the alga Laurencia concinna (171). Some simple bromophenols also occur in algae (160, p. 88) and a highly brominated phenolic pyrrole has been found in a marine bacterium (111, 132). 

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