1. Field of the Invention
This invention relates to a catalyst for the production of a substituted benzaldehyde, a method for the production of the catalyst, and a method for the production of a substituted benzaldehyde. More particularly, it relates to a catalyst for the production of a substituted benzaldehyde by catalytic vapor-phase oxidation of a corresponding substituted toluene with a molecular oxygen-containing gas and consequent selective oxidation of the methyl group of the substituted toluene, a method for the production of the catalyst, and a method for the production of the substituted benzaldehyde.
2. Description of the Prior Art
The substituted benzaldehydes are highly useful intermediates for the production of medicines, agricultural pesticides, and perfumes in the organic chemical industry.
As methods for the production of such substituted benzaldehydes as tert-butyl benzaldehyde and methoxy benzaldehyde, liquid-phase oxidation and electrolytic oxidation have been known to the art (as disclosed in JP-A-52-125,137(1977), JP-A-54-109,937(1979), JP-A-55-85,682(1980), and) JP-A-56-127,327(1981), for example). These methods, however, do not deserve to be called as economically advantageous measures because they require an extra step of treatment for disposal of water in order form them to be carried out on a commercial scale, necessitate an unduly high power cost, and entail a complicate process. For the solution of these problems, a desire is expressed for a method which attains the production of a substituted benzaldehyde by economically advantageous vapor-phase oxidation.
As respects the production of tert-butylbenzaldehyde by catalytic vapor-phase oxidation of corresponding tert-butyltoluene, a method which uses a molybdenum-bismuth-iron-nickel type catalyst (DE-A. 2,841,712) and a method which uses a molybdenum-copper-tin type catalyst (U.S. Pat. No. 4,700,009) have been known to the art. These catalysts are both extremely deficient in activity and selectivity.
A method which uses a vanadium-alkali metal type catalyst has been also known to the art (JP-B.2-9,014(1990)). Though the catalyst used in this method exhibits fairly high activity and selectivity, it cannot be safely called fully satisfactory for commercialization of this method.
As respects the production of methoxybenzaldehyde by catalytic vapor-phase oxidation of corresponding methoxy toluene, a method which uses a vanadium-alkali metal type catalyst (JP-B.63-12,857(1988) and JP-B-63-12,858(1988)), a method which uses a vanadium-thallium type catalyst (JP-B.-63-47,697(1988)), and a method which uses a vanadium-silver type catalyst (JP-A.2-53,750(1990)) have been known to the art. Though these catalysts exhibit fairly high activity and selectivity, their qualities have room for more improvement.
The production of other substituted benzaldehydes by catalytic vapor-phase oxidation is still inferior in technical level to the production of tert-butylbenzaldehyde and methoxybenzaldehyde.
The conventional catalysts disclosed for use in the production of substituted benzaldehydes by selective catalytic vapor-phase oxidation of the methyl group of corresponding substituted toluenes having tert-butyl group, methoxy group, phenoxy group, isopropyl group, and hydroxyl group as a substituent cannot be safely said to possess fully satisfactory quality suitable for actual use.
One object of this invention, therefore, is to provide a catalyst suitable for the production of substituted benzaldehydes by catalytic vapor-phase oxidation of corresponding substituted toluenes having tert-butyl group, methoxy group, phenoxy group, isopropyl group, and hydroxyl group as a substituent.
Another object of this invention is to provide a method for the production of the aforementioned catalyst for use in the production of the substituted benzaldehydes.
Yet another object of this invention is to provide a method for producing a substituted benzaldehyde in a high yield with high selectivity by catalytic vapor-phase oxidation of a corresponding substituted toluene having tert-butyl group, methoxy group, phenoxy group, isopropyl group, and a hydroxyl group as a substituent.