J hydroquinone

Figure 19 The cationic ( j -hydroquinone)Mn(CO)3+, the neutral ( -p-semiquinone)Mn(CO)3, and the anionic rf-benzoquinone)Mn(CO)3 used in the construction of metai-organic metal-organometallic coordination networks (MOMNs). Reprinted with permission from Oh, M. Carpenter, G. B. Sweigart, D. A. Acc. Chem. Res. 2004, 37(7), 1. 2004 American Chemical Society.

Texter, J., Hydroquinone development acceleration by tri-azolium thiolates, J. Photogr. Sci, 40, 83-88 (1992). 

Moini, M. Cao, P. Bard, A.J. Hydroquinone as a buffer additive for suppression of bubbles formed by electrochemical oxidation of the CE buffer at the outlet electrode in capillary electrophoresis/electrospray ionization-mass spectrometry. Anal. Chem. 1999, 71, 1658-1661. 

Thermotropic polycarbonates have been prepared from mixtures of 4,4 -dihydroxybiphenyl and various diphenols (10). Nematic melts were found for copolycarbonates prepared from methyfliydroquiaone, chlorohydroquiaone, 4,4 -dihydroxydiphenyl ether, and 4,4 -dihydroxybenzophenone. Slightly crystalline polycarbonates have been prepared from mixtures of hydroquinone and BPA (T = 154°C, =313°C, AH = 11.0 J/g (2.63 cal/g)), and... 

Sulfuric acid is also a very satisfactory catalyst aluminum alkoxides also are useful, especially when the alcohols would be adversely affected by strong acids. Sodium alkoxides produce undesirable side reactions and give lower yields. When alkaline catalysts are employed, an alkaline polymerization inhibitor, such as j j-phenylenediamine or phenyl-d-naphthylamine, should be used instead of hydroquinone. 

Distil rapidly through an efficient 25cm column after adding 0.5g of hydroquinone/200g of chloride, and then redistil carefully at atmospheric pressure preferably in a stream of dry N2. [J Am Chem Soc 72 72, 2299 1950.] The liquid is an irritant and is TOXIC. 

Bis(2-benzothiazolyl)hydroquinone [33450-09-8] M 440.3, m dec >200 . Purified by repeated crystn from dimethylformamide followed by sublimation in vacuum [Erusting et al. J Phys Chem 91 1404 1987]. 

Butyl acrylate [I4I-32-2J M 128.2, b 59 /25mm, d 0.894, n 1.4254. Washed repeatedly with aqueous NaOH to remove inhibitors such as hydroquinone, then with distilled water. Dried with CaCl2. Fractionally distd under reduced pressure in an all-glass apparatus. The middle fraction was sealed under nitrogen and stored at 0° in the dark until used [Mallik and Das J Am Chem Soc 82 4269 I960]. 

Propionaldehyde [123-38-6] M 58.1, b 48.5-48.7 , d 0.804, n 1.3733, n S 1.37115. Dried with CaS04 or CaCl2, and fractionally distd under nitrogen or in the presence of a trace of hydroquinone (to retard oxidation). Blacet and Pitts [J Am Chem Soc 74 3382 1952] repeatedly vacuum distd the middle fraction until no longer gave a solid polymer when cooled to -80°. It was stored with CaS04. 

Styrene is difficult to purify and keep pure. Usually contains added inhibitors (such as a trace of hydroquinone). Washed with aqueous NaOH to remove inhibitors (e.g. rert-butanol), then with water, dried for several hours with MgS04 and distd at 25° under reduced pressure in the presence of an inhibitor (such as 0.005% p-tert-butylcatechol). It can be stored at -78°. It can also be stored and kept anhydrous with Linde type 5A molecular sieves, CaH2, CaS04, BaO or sodium, being fractionally distd, and distd in a vacuum line just before use. Alternatively styrene (and its deuterated derivative) were passed through a neutral alumina column before use [Woon et al. J Am Chem Soc 108 7990 1986 Collman J Am Chem Soc 108 2588 1986]. 

An antipolymerization agent such as hydroquinone may be added to the reaction mixture to inhibit the polymerization of the maleate or fumarate compound under the reaction conditions. This reaction is preferably carried out at a temperature within the range of 20°C to 150°C. This reaction is preferably carried out at atmospheric pressure. Reaction time of 16 to 24 hours have bean specified for this reaction by J.T. Cassaday. The reaction is preferably carried out in a solvent such as the low molecular weight aliphatic monohydric alcohols, ketones, aliphatic esters, aromatic hydrocarbons or trialkyl phosphates. 

By the oxidation of hydroquinone in 60 per cent acetic acid with chromic acid. Craven and Duncan, J. Chem. Soc. 127, 1489 (1925). 

Balina LM, Graupe K (1991) The treatment of melasma 20% azelaic acid versus 4% hydroquinone cream. Int J Dermatol 30 893-895... 

Amer M, Metwalli M (1998) Topical hydroquinone in the treatment of some hyperpigmentary disorders. Int J Dermatol 37 449-450... 

Findlay GH, Morrison JG, Simson IW (1975) Exogenous ochronosis and pigmented colloid milium from hydroquinone bleaching creams. Br J Dermatol 93 613-622... 

Darby JM, DG Taylor, DJ Hopper (1987) Hydroquinone as the ring-fission substrate in the catabolism of 4-ethylphenol and 4-hydroxyacetophenone by Pseudomonas putida Dl. J Gen Microbiol 133 2137-2146. 

Xun L, E Topp, CS Orser (1992c) Purification and characterization of a tetrachloro-p-hydroquinone reductive dehalogenase from a Flavobacterium sp. J Bacterial 174 8003-8007. 

Lee J-Y, L Xun (1997) Purification and characterization of 2,6-dichloro-p-hydroquinone chlorohydrolase from Flavobacterium sp. strain ATCC 39723. J Bacterial 179 1521-1524. 

Xun L, J Bohuslavek, M Vai (1999) Characterization of 2,6-dichloro-p-hydroquinone 1,2-dioxygenase (PcpA) of Sphingomonas chlorophenolica ATCC 39723. Biochem Biophys Res Commun 266 322-325. 

Palm H, J Knuutinen, J Haimi, J Salminen, V Huhta (1991) Methylation products of chorophenols, catechols and hydroquinones in soil and earthworm of sawmill environments. Chemosphere 23 263-267. 

Whoi a solution of, say, 1 g. of hydroquinone in 4 ml. of rectified spirit is poured into a solution of 1 g. of quinone in 30 ml. of water, quinhydrone C,H40j,C,H (0H)j, a complex of equimolecular amounts of the two com-pcaients, is formed as dark green crystals having a gUstening metallic lustre, m.p. 172°. In solution, it is largely dissociated into quinone and hydroquinone. Quinhydrone is more conveniently prepared by the partial oxidation of hydroquinone with a solution of iron alum. 

Deisinger, P. J., Hill, T. S, English, C. J., Human exposure to naturally occurring hydroquinone, J. Toxicol. Environ. Health, 47(1), 31, 1996. (CA124 281730d)... 

Marvel, C. S. et al., J. Amer. Chem. Soc., 1950, 72, 5408-5409 Hydroquinone must be added to the oxime before distillation, to prevent formation and subsequent violent decomposition of a peroxide (there being 2 susceptible hydrogen atoms in the molecule). 

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