4- -6-chlororesorcinol

The synthesis of 2,4-dihydroxyacetophenone [89-84-9] (21) by acylation reactions of resorcinol has been extensively studied. The reaction is performed using acetic anhydride (104), acetyl chloride (105), or acetic acid (106). The esterification of resorcinol by acetic anhydride followed by the isomerization of the diacetate intermediate has also been described in the presence of zinc chloride (107). Alkylation of resorcinol can be carried out using ethers (108), olefins (109), or alcohols (110). The catalysts which are generally used include sulfuric acid, phosphoric and polyphosphoric acids, acidic resins, or aluminum and iron derivatives. 2-Chlororesorcinol [6201-65-1] (22) is obtained by a sulfonation—chloration—desulfonation technique (111). 1,2,4-Trihydroxybenzene [533-73-3] (23) is obtained by hydroxylation of resorcinol using hydrogen peroxide (112) or peracids (113). 

Preparation of phlorogluciaol or its monomethyl ether by reaction of a halogenated phenol with an alkaU metal hydroxide in an inert organic medium by means of a benzyne intermediate has been patented (142). For example, 4-chlororesorcinol reacts with excess potassium hydroxide under nitrogen in refluxing pseudocumene (1,2,4-trimethylbenzene) with the consequent formation of pure phlorogluciaol in 68% yield. In a version of this process, the solvent is omitted but a small amount of water is employed (143). 

Much work on the hydroperoxidation of triisopropylbenzene to make phloroglucinol, similar to the process of phenol from cumene, has been reported (149—155). The shortest route is based on readily available 4-chlororesorcinol. World production of phloroglucinol is estimated to be in excess of 200 metric tons aimuaHy (156). 

Other ketones may be reduced by this same procedure. The submitters report that the following have been reduced with yields of 70-90 per cent 0- and p-butyryl phenols, 0- and p-valeryl phenols, 0- and />-caproyl phenols, 0- and />-heptanoyl phenols, 0- and -octanoyl phenols, o- and />-pelargonyl phenols, o- and />-undecylyl phenols. The same procedure applies to acyl resorcinols and acyl chlororesorcinols. Caproyl and octanoyl resorcinols reduce to the corresponding alkyl derivatives in yields of 70-80 per cent. Butyryl, valeryl, caproyl, heptanoyl,... 

Primary alkyl phenols have been prepared by the reduction of acyl phenols 1 by the demethylation of the corresponding ethers 12 by the diazotization of the corresponding amines 3 and by the alkali fusion of sulfonates.4 Alkyl resorcinols have been prepared by the reduction of acyl resorcinols.1 5 6 Alkyl chlororesorcinols have been prepared from the corresponding acyl chlororesorcinols by reduction.7... 

The principal red couplers are 3-aminophenol [591-27-5], 5-amino-2-methyl-phenol [2835-95-2], and 1-naphthol [90-15-3]. Yellow-green couplers include resorcinol [108-46-3], 4-chlororesorcinol 195-88-5, benzodioxoles, and 2-methyl-resorcinol [608-25-3] and its derivatives. The importance of the yellow-green couplers lies in the broad-band absorption of the dyes produced, which makes natural-looking hair shades possible. Table 5.4 lists a range of colors obtained by reaction of primary intermediates with different couplers. 

Ready conversion of nitro compounds to amines further extends the applicability of the deamination process. For example, the nitro group may be introduced into an aromatic nucleus for the purpose of closing a position to other groups in subsequent steps of a synthetic sequence, and, finally, the nitro group is replaced by hydrogen. This blocking effect is utilized in the preparation of 2-chlororesorcinol, which cannot be obtained by direct chlorination of resorcinol.187... 

Extraction of urinary phenols [13]. An aliquot of a 24-h urine sample corresponding to 5—10 min excretion was adjusted to pH 5 with acetic acid, incubated at 37°C for 16 h with 100 jul of Helix pomatia juice, then 100 pi of aqueous 4-chlororesorcinol solution (1 mg/ml) and 2 ml of phosphate buffer (pH 7,0.5 M) were added. The mixture was saturated with sodium chloride and extracted with three 10-ml volumes of diethyl ether followed by three 10-ml volumes of ethyl acetate. In this instance, the addition of a salt did not significantly improve the recovery, but it considerably reduced the amount of water taken up by the solvents. 

Mills et al. performed extensive investigations into the photocatalytic degradation of 4-chlorophenol. These included studies on the effects of different titania samples [102], effects of annealing temperature on the photocatalytic efficiency of titania [ 103] and a mechanistic study of the decomposition process. The rate of chlorophenol destruction was found to drop when using titania photo catalysts that had been heated above 600 °C. This was believed to be due to a build up of the rutile phase and a reduction of surface area following heat treatment above these temperatures. A number of intermediates were reported including 4-chlorocatechol, hydroquinone, benzoquinone and 4-chlororesorcinol [104],... 

By exploiting the modularity of the template method, we have shown that linear templates can be used to organize unsymmetrical reactants to achieve regiospecific control of reactivity. Specifically, co-crystallization of 4-chlororesorcinol (4-Cl-res) with 2,4 -bpe produced an unsymmetrical assembly, 2(4-Cl-res) 2(2,4 -bpe), with two molecules of 2,4 -bpe oriented in a head-to-head geometry.71 UV-irradiation of the solid produced the head-to-head photoproduct 2,4 -tpcb in 100% yield. Similarly, co-crystallization of 1,8-nap with 3,4 -bpe produced the unsymmetrical assembly, 2(1,8-nap) 2(3,4 -bpe), with two molecules of 3,4 -bpe oriented in a head-to-head... 

Materials 4-Chlorophenol, 4-chlororesorcinol, hydroquinone, and hy-droxyhydroquinone were purchased from Aldrich Chemical Co., Milwaukee, WI 4-chlorocatechol was purchased from TCI American, Portland, OR. Acetonitrile, hexane, methylene chloride, methanol, and pyridine were obtained from the Fisher Scientific Co., Fulton, CA. The photocatalyst was Degussa P-25 titanium dioxide [mainly anatase form surface area 50 m2/g pHzpc (pH at zero point of charge) 6.3 contains some impurities such as Al203 (<0.3%), Si02 (<0.2%), Fe203 (<0.01%), and HCl (<0.3%)]. 

C-4 position will result in a dechlorination reaction to generate hydroquinone, an attack at the C-2 or the C-6 position will generate 4-chlorocatechol, and an attack at the C-3 or the C-5 position will produce 4-chlororesorcinol. These three dihydroxy-benzenes can be identified by using authentic standards. 

The GC-MS retention times and mass spectra of peaks C and D are closely matched with the retention times and mass spectra of 4-chlorocatechol and 4-chlororesorcinol standards, respectively. The mass spectra of 4-chlorocatechol and 4-chlororesorcinol show the same M+ peak at m/e 228 and [M-AC2] + at m/e 144 as peaks C and D. That is, peak C corresponds to an acetylated 4-chlorocatechol and peak D is equivalent to an acetylated 4-chlororesorcinol. 

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