2.5- Dichloro-4-methoxyphenol

Pesticides containing methyl or other alkyl substituents maybe linked to N or 0 (i.e., N- or O-alkyl substitution). An N- or O-dealkylation catalyzed by microorganisms frequently results in loss of the pesticide activity. Phenylurea (see Chap. 1) becomes less active when microorganisms AT-demethylate the molecules (e. g., the conversion of Diuron to the normethyl derivative, Fig. 7). The subsequent removal of the second AT-methyl group renders the molecule fully nontoxic [169]. On the other hand, the microbial O-demethylation of Chloroneb creates the non-toxic product 2,5-dichloro-4-methoxyphenol (Fig. 7). 

Activated o-methoxyphenol reacts with sulfur dichloride to give, depending on the addition speed of the reactant, 2,8-dihydroxy-3,7-dimethoxythianthrene 150 or l,6-dichloro-2,7-dihydroxy-3,8-dimethoxythianthrene 151 <1997JCM272>. 

A general route to phenoxathiins 85 (Z = O, Z = S) utilizes the reaction of diphenyl ethers with sulfur. One route to thianthrene 85 (Z, Z = S) involves reaction of sulfur monochloride with benzene over aluminum chloride. Likewise, tf-methoxyphenol reacts with sulfur dichloride to give, depending on the rate of addition of the reactant, 2,8-dihydroxy-3,7-dimethoxythianthrene 89 or l,6-dichloro-2,7-dihydroxy-3,8-dimethoxythianthrene 90 <1997JCM272>. 

Common Name 4,5-Dichloroguaiacol Synonym 4,5-dichloro-2-methoxyphenol Chemical Name 4,5-dichloroguaiacol CAS Registry No 2460-49-3 Molecular Formula C7H6CI2O2 Molecular Weight 193.028 Melting Point (°C) 69-70 Boiling Point (°C) ... 

Preparation by reaction of 2,3-dichloro-benzoyl chloride with m-methoxyphenol in the presence of aluminium chloride for 8 h at 190° [77]. 

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