Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
2000-02-16
2000-12-12
Trinh, Ba K.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D30112
Patent
active
061601381
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
Epoxides such as ethylene oxide, propylene oxide, glycidol, etc, are intermediate products in the preparation of a wide range of products. For example, epoxides can be hydrolysed to yield glycols used in the formulation of antifreeze fluids or as monomers in the preparation of condensation polymers such as polyesters. Polyols, generated by epoxide ring cleavage polymerisation, are broadly used in the preparation of polyurethane foams, sealant elastomers, linings, etc. The reaction with alcohols yields glycolic ethers that are used as polar solvents in numerous applications.
The epoxidation of olefinic unsaturated compounds can be performed with a wide range of reactants. The epoxidation of olefins in the liquid phase with organic hydroperoxides is particularly interesting, which process is used industrially despite these reactions yielding as co-products the alcohols derived from the hydroperoxides used. On the other hand, the catalytic epoxidation with hydrogen peroxide has not been as successful due to economic factors and to the lack of efficient catalysts. However, in the eighties, an Italian group developed catalyst called titanium silicalytes, microporous solids with the MFI type structure, in which the titanium atoms hold places in the structure of the crystalline lattice, U.S. Pat. Nos. 4,410,501, 4,666,692, 4,701,428, 4,824,976 and 4,833,260. These titanium and silica compounds are known as TS-1, and are effective catalysts for the epoxidation of olefinic compounds with hydrogen peroxide in the presence or in the absence of solvents. Even though the specificity for epoxide is high when the epoxidation is effected in a protic medium such as an alcohol or water it is very important, both for kinetic and specificity reasons, the use of important amounts of methanol as solvent. This alcohol is considered as a co-catalyst (M. G. Clerici et al. J. Catal. 129, 159 (1991), M. G. Clerici et al. in Green Chemistry, ACS Pub. Services, 1996, p. 58). The use of this solvent posses a problem in the epoxidation of polypropylene, due to the fact that it hinders the subsequent purification stages of the product by means of the nearest boiling point between propylene and methanol (European Patent Application no. 673935 A2).
Even though the specificity for epoxide is relatively high, the non selective breaking of the oxiranic ring takes place during the epoxidation reaction. In order to increase the specificity for epoxide the catalyst may be treated with a neutralising agent for the superficial acid sites of the catalyst, responsible for the formation of these undesired byproducts (U.S. Pat. No. 4,824,296, European Patent no. 230949). Subsequently, the European Patent application no. 712852 Al indicates that this same effect may be achieved when the epoxidation is carried out in the presence of small amounts of non basic salts such as lithium chloride, sodium nitrate, etc.
On the other hand, as a consequence of the small pore size of the titanium silicalytes (5.6.times.5.3 .ANG.), there exists a wide range of olefins that cannot be epoxidated with these catalysts since voluminous olefins cannot reach the active sites. In order to be able to avoid these limitations several authors have proceeded to the synthesis of zeolytes of larger pore size with titanium in the lattice, such as for instance the beta zeolyte structure (Ti.beta.) (Spanish Patent application no. 9101798, Camblor et al. in J. Chem. Soc., Chem. Commun., page 589 (1992) and U.S. Pat. No. 5,412,122), but very low specificity for epoxide was obtained due to the presence of acid sites (aluminium) in the lattice which favour the breaking of the oxirane ring. Due to these problems certain authors claim the synthesis of Ti.beta. compounds without the presence of aluminium in the lattice (U.S. Pat. Nos. 5,374,747 and 5,621,122 and European Patent no. 659685 and Camblor et al. in Chem. Commun., page 1339 (1996)) despite of which, it still shows a very low specificity for epoxide.
The relatively high price of hydrogen peroxide in commercial aq
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Campos Martin Jose Miguel
De Frutos Escrig Pilar
McMahon John C.
Repsol Quimica S.A.
Trinh Ba K.
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