Hydrogenation of resorcinol

Palladium may not be preferred for dihydric aromatics. Dihydroresorcinol was obtained in 87% yield by alkaline hydrogenation of resorcinol over 5% Rh-on-C (65) and in only 50-60% yield over Pd-on-C 15). A 77% yield of the dione was obtained by alkaline hydrogenation of 3,5-dihydroxyphenylacetic acid over a 10% loading of 5% Rh-on-AljOj at 55"C and 55 psig (39a). 

Neopentyl alcohol, 40, 76 Nickel catalyst for hydrogenation of resorcinol, 41, 56, 57 Nitramines from amines and acetone cyanohydrin nitrate, 43, 84 Nitration, of amines to nitramines by acetone cyanohydrin nitrate, 43, 83... 

Partial reduction of phenols affords mixtures of allylic and vinylic alcohols. From the generality derived for aliphatic systems, the most hydrogenolysis of this mixture is expected with platinum, palladium, and iridium catalysts, and much less with rhodium and ruthenium, an expectation substantiated in practice. For example, hydrogenation of resorcinol in neutral medium affords 20, 19, and 70% cyclohexanediol over palladium-, platinum-, and rhodium-on-carbon, respectively (29). Many examples attest to the value of rhodium and ruthenium at elevated pressure in avoiding hydrogenolysis. 

Rylander and Himelstein studied the hydrogenation of resorcinol over supported platinum, palladium, rhodium, and palladium-rhodium as catalysts in ethanol at 65°C and an initial hydrogen pressure of 0.34 MPa. Extensive hydrogenolysis to give cyclohex -anol took place over 5% Pt-C, 5% Pd-C, and 2.5% Pd-2.5% Rh-C, and the yields of cyclohexane-1,3-diol were only 18.7-26.2%. Rhodium catalysts caused hydro-... 

Phenols can be partially hydrogenated in the presence of alkali to cyclohexanones. An example is the synthesis of dihydroresorcinol, or l,>cyclohexanedione, by hydrogenation of resorcinol in the presence of Raney nickel and an equimolar quantity of sodium hydroxide (95%). Under these same conditions, pyrogallol furnishes a stable enediolone. ... 

The C-methylation of dihydrorcsorcinol (2) is carried out with unisolated material obtained by hydrogenation of resorcinol (2 moles) in alkaline solution. The solution is filtered from catalyst and treated with dioxane and 2.64 moles of methyl iodide. 

Low-temperature hydrogenation of resorcinol over rhodium-alumina in alkaline solution affords a convenient procedure for the preparation of 1,3-cyclohexanedione. ... 

Cyclohexane-1,3-diones generally, for example the parent compound, dihydroresorcinol, available from rhe hydrogenation of resorcinol, have been aromatised by various techniques including the use of mercuric acetate in the presence of secondary amines to afford yields of 3-substituted aminophenols in the range 32-79% (ref.84). 

A heat-exchange single-channel reactor was used for the hydrogenation of resorcinol (as the phenate sodium salt, see Scheme 9.10) [52]. The advantage of such a HEx reactor is the facility to scale up to production units while keeping the advantages of... 

S. Raymahasay, J. M. Winterbottom, M. D. Mantle, A. J. Sederman, L. F. Gladden, C. Chatwin, K. T. Symonds, E. H. Stitt, Multiphase hydrogenation of resorcinol in structured and heat exchange reactor... 

On partial hydrogenation of resorcinol to 1,3-cyclohexanedione, C-methylation of enol is performed under standard conditions. In the next two steps, Robinson annelation is completed. Michael addition of methyl vinyl ketone affords an intermediate that spontaneously enters intramolecular aldol condensation to a stable six-membered ring in TM 4.10. 

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). 

A solution of resorcinol (11 g) in sodium hydroxide solution (4.8 g of sodium hydroxide in 20 ml of water) is hydrogenated in the presence of 1.1 g of 5 % rhodium on alumina for 16-18 hours at 50 psi initial pressure in a Parr apparatus. The reduction stops after the absorption of 1 equivalent of hydrogen. The catalyst is removed by filtration through celite, and the aqueous solution is carefully acidified with concentrated hydrochloric acid at 0°. The crude product is collected by filtration, dried in air, and recrystallized from benzene to give 1,3-cyclohexanedione, mp 105-107. ... 

Elsewhere, in a series of Japanese patents, mixtures of resorcinol + sodium nitrate, glycerine + sodium nitrate, lithium hydroxide + tungstate, etc., have been claimed to be effective. An example of the use of inhibited cooling mixtures of low toxicity is provided by a patent which describes a mixture of silicate-I- polyphosphate -I- a saccharide, e.g. sucrose or fructose, as the inhibitor formulation in a propylene glycol -I- potassium-hydrogen-carbonate mixture used in aluminium cooler boxes for ice-cream. 

Hydrogenation, of gallic add with rhodium-alumina catalyst, 43, 62 of resorcinol to dihydroresorcinol, 41,56 Hydrogen peroxide, and formic acid, with indene, 41, 53 in oxidation of benzoic add to peroxy-benzoic add, 43, 93 in oxidation of ieri-butyl alcohol to a,a/r, a -tetramcthyltetra-methylene glycol, 40, 90 in oxidation of teri-butylamine to a,<, a, a -tetramethyltetra-methylenediamine, 40, 92 in oxidation of Crystal Violet, 41, 2, 3—4... 

Our task was to develop a feasible synthesis for diamino resorcinol. From several possibilities [1-4] the resorcinol and anihne were chosen as starting materials. The diazotated aniline was coupled with resorcinol among basic conditions giving 4,6-bisphenylazo resorcinol. Hydrogenation of the latter resulted in diamino resorcinol and aniline, which could be recycled (scheme 14.2). This chemistry is well known [5-13] therefore, the research work focused on finding the optimal parameters and catalyst and finally on elaborating a process for scale-up. 

Finely powdered anhydrous zinc chloride (2 g.) is added to a solution of 5-5 g. of resorcinol and 3 g. of acetonitrile in 25 c.c. of absolute ether, the mixture is kept cool in ice and saturated with hydrogen chloride. After standing for some hours in a closed vessel... 

The effect of the weak hydrogen bond on the boiling point of catechol is noticeable. The substance boils at 245 C, whereas the boiling point of resorcinol is 277° and that of hydroquinone 285°. v... 

The preparation of various phenolic compounds has been accomplished from metbyl-enediisoxazole systems (74TL2793). Hydrogenation of (454) followed by acid treatment afforded a linear polyketone (456) which cyclized to the resorcinols (457) in good yield (55-80%) (Scheme 102). 

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