Phloroglucinols

It reacts chemically as if it were either 1,3,5-trihydroxybenzene or the triketone of hexa-hydrobenzene. The trialkyl derivative of the hydroxy-form or the trioxime of the keto-form can be obtained from phloroglucinol by reacting in a suitable manner. In certain cases derivatives of the two forms are interchangeable. Used in printing, photography, adhesives, pharmaceuticals. 

Phloroglucinol contains two molecules of water of crystallisation these are removed by heating for 12 hours at 120°. 

Gunzherg s reagent (detection of HCl in gastric juice) dissolve 4 g of phloroglucinol and 2 g of vanillin in 100 mL of absolute alcohol use only a freshly prepared solution. 

The Wiesner Reaction. The reaction of lignified tissue and phloroglucinol—hydrochloric acid gives a visible absorption spectmm with a maximum at 550 nm. This has been attributed to coniferaldehyde units in lignin as the groups responsible for the color formation. 

The formation of (9) is evidence for the abiUty of pyrogaHol to react in keto forms. However, in contrast to phloroglucinol, pyrogaHol does not react as a ketone with hydroxjlamine. 

The synthesis and phase stmcture of a three-arms—nine-chain Hquid crystal (17) based on pyrogaUol and phloroglucinol has been reported (61), as has a complexing agent for amino acids in water (18) (62) (Fig. 1). 

Phloroglucinol (42) is a colorless and odorless solid which is only spariagly soluble ia cold water (82). It was discovered ia 1855 ia the hydrolysis products of the glucoside phloretia, which was obtained from the bark of fmit trees. Phlorogluciaol occurs ia many other natural products ia the form of derivatives such as flavones, catechins, coumaria derivatives, anthocyanidins, xanthins, and glucosides. 

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). 

Grades and Specifications. Two grades of phloroglucinol, ie, grades 2 and pure, are offered in the United States by Haake, Inc., who resell material made by Fisons (Table 1). The product discolors slowly on exposure to light. 

Health and Safety Factors. Phloroglucinol has low toxicity by ingestion. Prolonged severe overexposure may dismpt the thyroid function. High dust concentration may cause respiratory irritation the product is irritating to eyes and skin. Toxicity data include LD q oral (rat) = 5800 mg/kg ... 

Phloroglucinol is Hsted in the Colourindex as Cl Developer 19. It is particularly valuable in the dyeing of acetate fiber but also has been used as a coupler for azoic colors in viscose, Odon, cotton (qv), rayon, or nylon fibers, or in union fabrics containing these fibers (157). For example, cellulose acetate fabric is treated with an aromatic amine such as (9-dianisidine or a disperse dye such as A-hydroxyphenylazo-2-naphthylamine and the amine diazotizes on the fiber the fabric is then rinsed, freed of excess nitrite, and the azo color is developed in a phloroglucinol bath at pH 5—7. Depending on the diazo precursor used, intense blue to jet-black shades can be obtained with excellent light-, bleach-, and mbfastness. 

The condensation on the fabric of 1-amino-3-iminoisoindo1enines or 2-amino-5-iminopyrro1enines with phloroglucinol, preferably in the presence of metal salts and solvents, yields fast dyeings in brown shades (158). Metallized azo dyes derived from phloroglucinol yield fast dyeings on leather (qv) or silk (qv) (159). 

The use of phloroglucinol and its derivatives as developer for light-sensitive planographic plates and for other photographic purposes has been described (163—167). 

Phiorog1iicino1-3,5-dimethyl-1-(2-amino-3-hydroxyhutyryl)ether is characterized by antiarrhythmic activity (176). 2,4-Diacylphloroglucinols were patented as compounds with pronounced anthelmintic activity (177). Phloroglucinol mono- and di-(2-chloroethyl) ethers have antispasmodic or tranquilizing activities (178). 2-(3,5-DiaLkoxyphenoxy)ethylamines have antispasmodic, choloretic, sedative, and vasodilating effects (179). 

Dimethylaminoethyl-2,4,6-trimethoxybenzoates and similar esters are useful as spasmolytics and in relieving indigestion (180). Bis-chromonyl compounds derived from phloroglucinol are valuable in the treatment of asthma (see Antiasthmatic agents) (181). 

Diacetylphloroglucinol and its homologues have been prepared and found to be inhibitors of the herpes vims (188). Syzygiol (50), a skin tumor promotion inhibitor, has been prepared from phloroglucinol (189). The first natural morphogen (cell-differentiation agent) (51) has also been identified as a phloroglucinol derivative (190). 

Alkanoyl esters of phloroglucinol, eg, phloroglucinol trisheptanoate, are high temperature-resistant lubricants and high performance fluids (194). An aqueous solution of phloroglucinol (or of several of its simple derivatives) is used as a corrosion-resistant coating on galvanized sheet (195). The alkaU or... 

Alkaline degradation was used to determine the stmcture of pelargonidin [134-04-3] cyanidin [528-58-5] and delphenidin [528-53-0] by treating each of them with concentrated potassium hydroxide at 140—150°C (89). Each of them produced phloroglucinol (27) and the corresponding phenoHc ben2oic acid ... 

---