Hydroquinone production

Resorcinol or hydroquinone production from m- or -diisopropylben2ene [100-18-5] is realized in two steps, air oxidation and cleavage, as shown above. Air oxidation to obtain the dihydroperoxide (DHP) coproduces the corresponding hydroxyhydroperoxide (HHP) and dicarbinol (DC). This formation of alcohols is inherent to the autooxidation process itself and the amounts increase as DIPB conversion increases. Generally, this oxidation is carried out at 90—100°C in aqueous sodium hydroxide with eventually, in addition, organic bases (pyridine, imidazole, citrate, or oxalate) (8) as well as cobalt or copper salts (9). 

It appears that only l-phenyltetra2ole-5-thiol (HSPT) (56) produces all three isomeric products when the initial hydroquinone product is further oxidi2ed and a second thiol is added (47). 

Validation of the model. Validation of this model using empirical data was not done, and this may cast doubt on some of its predictions. Of particular interest is the prediction that hydroquinone production is greater following phenol administration as compared to benzene administration. This is in opposition to the prediction of the Medinsky et al. (1995) model, described below. 

Benzoquinone was first produced commercially in 1919, and has since been manufactured in several European countries, Japan and the United States. Its major use is in hydroquinone production, but it is also used as a polymerization inhibitor and as an intermediate in the production of a variety of substances, including rubber accelerators and oxidizing agents (lARC, 1977). 

Kuhn and colleagues (797) investigated the kinetics of the heterogeneously catalyzed benzene oxidation at Pb/Pb02 electrodes in sulfuric acid. This reaction was worked out on a semitechnical scale for quinone/ hydroquinone production (792) ... 

Using the principles of green chemistry, researchers have improved this process. The new process for hydroquinone production uses a new starting material. Two of the byproducts of the new reaction (shown in green) can be isolated and used to make the new starting material. 

Hydroquinone production is feasible via the copper-catalyzed oxidation of phenol with dioxygen to p-benzoquinone, with subsequent reduction [105,106], which can be effected using the same CuCl/acetonitrile catalyst under hydrogen. 

Where might there be room to make changes in this process that would make hydroquinone production even greener ... 

Reaction conditions in hydroquinone production are selected to ensure the most selective hydrogenation possible of the oxygen of quinone to the hydroquinone. 

To help evaluate this, yield was studied as a function of pH using buffered aqueous systems with hydroquinone over a pH range of 8 to 13. There is a direct correlation between pH and product yield and between product yield and the percentage of monoionized and diionized hydroquinone. Product was formed only when a large amount of the hydroquinone is at least monoionized. This is consistent with the active diol species being the deprotonated diol in the aqueous solution systems. 

Ruthenium-catalyzed ring-opening annulations of cyclobutenediones with norbornene have been reported (Scheme 3.54) [63]. The reaction with 3-alkyl-4-alkoxycyclobutenediones 95a under 3 atm CO gave cyclopentenone 96 via [4-1+2]-type annulation. On the other hand, 3,4-dialkylcyclobutenedione 95b produced a hydroquinone product 97. 

Hydroperoxidative synthesis 4 (Figure 12.4, middle) accounts for approximately 2.5 x 10 kg of hydroquinone production per year. p-Diisopropylbenzene is synthesized by zeolite-catalyzed Friedel-Crafts reaction of benzene or cumene with propylene or isopropanol. Air oxidation of p-diisopropyl-benzene proceeds at 90-100°C in an aqueous NaOH solution containing organic bases along with cobalt... 

Reaction of phenol with hydrogen peroxide (H2O2) in the presence of strong acids leads to a mixture of hydroquinone and catechol (Figure 12.4, bottom).This hydroxylation process accounts for approximately 1.4 x 10 kg of hydroquinone production per year. The ratio of hydroquinone to catechol is controlled to a finite extent by the acidity of the catalyst. ZSM zeolites, an aluminosilicate zeolite with high silica and low aluminum content, such as TS-1 are also used as the acid catalyst. 

CH(CH0H)4C0 ) -I- hydroquinone — products -I- "0C6H40 Pulse rad. of meso-inositol -f N2O + H2O... 

Iwasuwa et al. [14] treated l-(l,2-propadienyl)cyclopropa-nols with octacarbonyldicobalt, and got hydroquinone derivatives in moderate to good yields (Scheme 17.10). Acetic anhydride and triethylamine were added to retard the formation of the benzoquinone compound 50 from oxidation of the original hydroquinone product 49, otherwise a mixture of 49 and 50 was produced. Even a half equivalent of Co2(CO)g was sufficient to promote the reaction, although usually a stoichiometric amount of Co2(CO)g was used in the [5-fl] cycloaddition. 

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