Synthesis of Hydroquinones

Hydroquinone derivatives are prepared by hydrocarbonylation of acetylenic compounds  

Starting Material Product Catalyst C Conditions bar Yield % Ref. 

Hydroquinone has thus been obtained with a 73% yield at 250 C under 200 bar of carbon monoxide using a ruthenium catalyst [138]. 

The reaction stoichiometry imposes the presence of hydrogen but it is very often conducted with CO/water mixtures instead of COfR - 

Once again, everything behaves as if an initial water-gas-shift reaction were taking place. 

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Shindo H, Huang PM (1985a) The catalytic power of inorganic components in the abiotic synthesis of hydroquinone-derived humic polymers. Appl Clay Sci 1 71-81... 

Hessel V, Lowe H, Muller A, Kolb G (2005d) Chemical micro process engineering—processing and plants. Wiley-VCH, Weinheim Hessel V, Hofmann C, Lob P, Lowe H, Parals M (2007) Micro-reactor processing for the aqueous Kolbe-Schmitt synthesis of hydroquinone and phloro-glucinol. Chem Eng Technol 31, (in press)... 

Fig. 11. Hydro Quebec electrochemical plant for the synthesis of hydroquinone, using an Electro Prod Cell (photograph supplied by Hydro-Quebec)...

The use of a fixed-bed cell with Cu particles as the cathode 576 has been suggested for the synthesis. p-Aminophenol, produced by electrochemical reduction of nitrobenzene, was used for the synthesis of hydroquinone 577). According to recent work, the addition of emulsifiers, for example, trialkylamine oxides 578), is supposed to suppress the formation of aniline as a byproduct. The electrosynthesis of p-amino-phenol from nitrobenzene is carried out industrially in India 276). 

Carbonylation of the parent acetylene via stoichiometric or catalytic reactions involving transition-metal carbonyl complexes has been extensively studied. Various types of carbonylation reactions of acetylene were discovered. In 1968, Pino et al. [30] reported on the synthesis of hydroquinone via a Ru3(CO)12-cat-alyzed carbonylation of acetylene with H2 or H20. The product formally consisted of two molecules of acetylene and CO, and one molecule of H2 (Eq. 14). To achieve a good yield of hydroquinone, the H2 pressure must be kept under... 

Improvements of already existing oxidation processes are continuously made (in MAA manufacture, with the riser reactor by DuPont, or in oxychlorination, by Montecatini Technologic and ICI). In addition, and still more clearly demonstrating the dynamism of industrial catal5rtic oxidation, completely new catalysts are discovered, especially with the titanium silicalite which permits the synthesis of hydroquinone from phenol, selective epoxidations, oxidations of alcohols to aldehydes, and the manufacture of cyclohexanoneoxime. 

Most (97% to 98%) of the nitrobenzene produced is retained in closed systems for use in synthesizing aniline and other substituted nitrobenzenes and anilines (Dorigan and Hushon 1976 Chemical Marketing Reporter 1987). Most of these products go into the manufacture of various plastic monomers and polymers (50%) and rubber chemicals (27%) a smaller proportion goes into synthesis of hydroquinones (5%), dyes and intermediates (6%), drugs (3%), and pesticides and... 

HC=CH -t- 2CO -f- 2HaO the synthesis of hydroquinone in the presence of iron and ruthenium catalysts ... 

Lowe, H., Parals, M., Micro-reactor processing for the aqueous Kolbe-Schmitt synthesis of hydroquinone and phlorogludnol, Chem. Eng. Technol. 30(3)... 

Scheme 1.8 Ruthenium-catalyzed carbonylative synthesis of hydroquinones.

In 2005, Sweigart and coworkers [22] reported the synthesis of hydroquinone-type rhodium complexes, which by easy deprotonation and oxidation to quinone afford an anionic rhodium... 

FIGURE 12.5 Combined microbial and chemical synthesis of hydroquinone. 

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