Resorcinol diols

Resorcinol diols represent a new class of aromatic dihydroxylic compounds with the general formula (15.33) ... 

Resorcinol diols are obtained by the reaction of resorcinol with ethylene carbonate or propylene carbonate (reaction 15.34), in the presence of basic catalysts (K2COs, KOH, NaOH, tertiary amines), or even in the absence of catalysts, at higher temperatures (150-170 °C) ... 

A resorcinol diol based on 1 mol of resorcinol and 2 EO units is a solid with a melting point of 87-89 °C and an hydroxyl number of 555 mg KOH/g [34]. All the resorcinol diols having PO units or PO and EO units are liquids at room temperature, with a viscosity of between 3,900 -20,000 mPa-s at 25 °C and hydroxyl numbers between 345-485 mg KOEl/g [34]. The resorcinol diols based on resorcinol and more than 2 EO units are liquid at room temperature, with a viscosity of around 2000 mPa-s at 25 °C and 375-385 mg KOH/g [34]. 

It is very interesting that a resorcinol diol based on propylene carbonate has 85% secondary hydroxyl groups and 15% primary hydroxyl groups. In the resorcinol diols based on propylene carbonate and ethylene carbonate (terminal units), the terminal primary hydroxyl is around 50% [33, 34]. 

Resorcinol diols are superior to the well known hydroquinone di(beta-hydroxyethyl) ether (HQEE), which is a solid with a melting point of 100 °C ... 

The resorcinol diols are used successfully in high durability and thermal stability PU adhesives, PU elastomers (cast and thermoplastic PU elastomers), sealants and coatings. 

The approach used Involved a four step sequence to obtain the desired product. A number of low cost diols and bis-diols were studied, including bisphenol A, resorcinol and hydroquinone. 

The variation in the initial Tg s show the effect on processability of the structures of the diol and the dibromobenzene. Two of the systems, those based on thiodiphenol and dihydroxybiphenyl, gave crystalline products which could not be made amorphous upon heat treatment. The effect on chain flexibility of dibromobenzene structure could be seen with the two hydroquinone systems. In this case, the meta isomer gave an initial Tg of 12°C while the more rigid para system had a Tg of 59°C. Variation of diol structure shows a parallel effect as shown with the resorcinol/j>-dibromobenzene system. This material has a softening temperature of 20°C. 

Thus, by employing resorcinol to juxtapose, by way of hydrogen bonds, two bipyridines within a solid-state molecular assembly for reaction, the diol served... 

The hydrogenation of phenols may proceed more readily than other aromatic compounds under proper use of catalyst and conditions. Over Ni-kieselguhr, hydroxyben-zenes such as phenol, catechol, and resorcinol are hydrogenated rapidly at 120-150°C under high pressure. Usually, the yields of the corresponding cyclohexanols are quantitative except for resorcinol, which gave only a 90% yield of cyclohexane-1,3-diol.70 An example is shown in eq. 11.11 for the hydrogenation of phenol. 

On the other hand, resorcinol is liable to hydrogenolysis and tends to give decreased yields (65-89%) of cyclohexane-1,3-diol over Ni-kieselguhr, together with 8-22%... 

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-... 

The reaction of catechol with N4P4C18 does not give the tetrameric analog of 18 but leads to the degradation of the phosphazene skeleton (17). With diols, such as hydroquinone or resorcinol, cyclolinear and cyclomatrix polymers are formed (21). 

DIHYDROXY-l,3,5-TRINITROBENZENE 3-HYDROXY-2,4,6-TRINITROPHENOL 2,4,6-TRINITRO-BENZENE-l,3-DIOL 2,4,S-TRINITRO-l,3-BENZENEDI-OL 2,4,6-TRINITRORESORCINOL TRINITRO-RESORCINOL pOT) TRINITRORESORCINOL, DRY pOT) TRINITRORESORCINOL, wetted with less than 20% water (DOT)... 

Fluoride-induced fragmentation reactions were used in two stages of a synthesis of hexahydrocannabi-nol methyl ether (144 Scheme 52). One of the phenolic hydroxy functions in the resorcinol derivative (140) was selectively liberated from the SEM ether to give the diol (141), which was converted to the bis (trimethylsilyl) ether (142). Subsequent treatment with CsF resulted in a 1,4-elimination to the o-quinone methide (143) intermediate, which underwent an intramolecular [4 -i- 2] cycloaddition to give the product in good yield. 

As hereinbefore pointed out, the 5-(tertiary alkyl)resorcinols thus prepared in accordance with this invention are important intermediates in the preparation of useful drugs. For example, 5-(l,l-dimethyl-heptyl)resorcinol is utilized in the preparation of l-hydroxy-3-(l,l-dimethylheptyl)-6,6a,7,8,9,l 0,10a-hexahydro-6,6-dimethyl-9H-dibenzo[b,d]pyran-9-one, which compound is extremely useful in the treatment of depression in humans, as described in U.S. Pat. Nos. 3,928,598, 3,944,673, and 3,953,603. Similarly, 5-(l,l-dimethyl-heptyl)resorcinol is required in the synthesis of3-(l,l-dimethylheptyl)-6a,7,8,9,10,10a-hexahydro-6,6-dimethyl-6H-dibenzo[b,d]pyran-l,9-diol, which compound is useful as a blood-pressure lowering agent. It can thus be seen that a commercially feasible process for preparing 5-(tertiary alkyl)resorcinols in high yield is desirable. 

Although there are ten isomeric naphthalenediols, there are enthalpy of formation data for only five of them. The enthalpy of formation data for the 1,4-isomer from two sources are disparate, as are the data from the two sources for the 2,3-isomer. The 1,3-naphthalenediol is more stable than either the 1,2- or the 1,4-diols for the same reason that the m-benzenediol, resorcinol, is more stable than its isomers more stable resonance structures for 1,3-dihydroxy substitution on an aromatic ring. From the appropriate OH/H increment exchange energies and the enthalpy of formation of naphthalene, we would have predicted a value of —329 kJ moE and —208 kJ mol for any solid and gaseous naphthalenediol, respectively. Only for 1,3- and 2,7-naphthalenediol is the expectation confirmed the others with their less stable ortho- and para-type substitution are less negative. 

Cannabinoids.—New compounds (259 OH at C-8 or at C-10)847 and (259 OH at both C-9 and C-10)848 have been isolated from Cannabis sativa. p-Menth-2-ene-1,8-diol is an excellent synthon for the A9-tetrahydrocannabinol (THC) skeleton, coupling (ZnCl2-catalysed) with olivetol (3-n-pentylresorcinol) to form the (—)-parent compound, and forming the biologically potent 3-OH metabolite by appropriate modification of the reaction.849 The structurally equivalent substrate p-menth-1,8-dien-1 -ol reacted with other substituted resorcinols and led to A8- and A9-THC analogues differing in the side-chain attached at C-3.850-851 Use of the synthon (260) in a similar manner gave 2, 1 l-dihydroxy-A9-THC this was claimed... 

Flavans. - New tannins have been synthesized by stereoselective condensation of flavan-3,4-diols with resorcinols, and their stereochemistry has been correlated, using circular dichroism, but the general rule thus demonstrated had exceptions among some 2,3-c/s-3,4-c/s-diastereoisomers, e.g. (163), which... 

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