DE1135465B - Process for the preparation of 2, 2-bis (p-hydroxyphenyl) -3-oxo-dihydrobenzoxazines- (1, 4) and their O-acyl or O-alkyl derivatives - Google Patents

Description

Process for the preparation of 2,2-bis- (p-hydroxyphenyl) -3-oxo-dihydrobenzoxazinen- (1,4) and their O-acyl or O-alkyl derivatives. The subject of patent 1097 993 is a process for the preparation of 2, 2-bis- (p-hydroxyphenyl) -3-oxo-dihydrobenzoxazinen- (1,4) and their O-acyl or O-alkyl derivatives of the general formula in which R is a hydrogen atom or a low molecular weight alkyl radical, R1 is a hydrogen atom, a low molecular weight alkyl radical or a low molecular weight alkoxy group and R2 is a hydrogen atom, an acyl group or a low molecular weight alkyl radical, which is characterized in that 2,2-dihalo-3-oxo -dihydrobenzoxazine- (1,4) of the general formula in which R has the meaning given and Hal is a halogen atom, with a phenol of the general formula which is not substituted in the p-position to the R20 group, where R1 and R2 are as defined above.

It has now been found that the compounds of the formula (I) can also be prepared by the process described below. According to the invention, α, α-diphenyl glycolic acids of the general formula are used in which R 1 has the meaning given above and R 3 is a group which can be subsequently replaced by hydrogen, for example an alkyl or aralkyl group, or their reactive esters with o-aminophenols of the formula wherein R has the meaning given above, reacted at elevated temperatures.

In the 2,2-di-phenyl-3-oxo-dihydrobenzoxazinen- (1,4) of the general formula obtained in this way in which R, R1 and R3 have the meaning given above, the radical R3 is optionally converted into the radical R2 by methods known per se. The reaction is carried out at elevated temperatures, preferably between 150 and 220 ° C. You can also in an inert solvent such as a hydrocarbon, for. B. cumene or tetralin, or a chlorinated hydrocarbon, e.g. B. dichlorobenzene, work. It is also advantageous to work in the presence of a dehydrating catalyst, such as arylsulfonic acids, zinc chloride or aluminum chloride.

Instead of the free α, α-diphenyl-glycolic acids, their reactive esters, for example the lower alkyl esters, are used, however, the yields here are somewhat less good.

When a compound according to the above general formula (1) is desired is, in which R2 is a hydrogen atom, then if the radical R3 is, for example an alkyl radical means this by treatment with the for the cleavage of ether usual means, e.g. B. by heating. with pyridine hydrochloride, in the appropriate Hydroxyl compound are converted; if R3 is an aralkyl group, preferably denotes a benzyl group, this can easily be hydrogenated off in the usual way.

If compounds according to the general formula (I) are desired, in which R2 denotes an alkyl or acyl radical, then the one obtained as described above can Hydroxyl compound can be alkylated or acylated by methods known per se.

When compounds according to the general formula (I) are prepared where R2 is an alkyl radical are preferred in the reaction such a, a-di-phenyl-glycolic acids of the above general formula (1I) are used, where R3 already denotes this alkyl radical.

The following examples are intended to explain the invention in more detail. Example 1 A mixture of 2 g of anisilic acid and 0.5 g of o-aminophenol is heated in an oil bath at 180 ° C. for 3 hours. After cooling, the reaction mixture is treated several times with warm, dilute hydrochloric acid and then with water. The remaining solid residue is extracted several times with ether, the ether solutions are combined and evaporated until crystallization begins. The crystals (0.5 g) of 2,2-bis- (p-methoxy phenyl) -3-oxo-dihydrobenzoxazine- (1,4) which separate out after standing for a while melt. After recrystallization from dilute ethanol at 1550 C. Example 2 The mixture of 1.5 g of anisilic acid, 1 g of o-aminophenol and 0.5 g of zinc chloride is heated in an oil bath at 150 to 160 ° C for 1 hour. Working up as described above, 0.4 g of 2,2-bis- (p-methoxyphenyl) -3-oxo-dihydrobenzoxazine- (1,4) with a melting point of 154 ° C. is obtained. If the same amount of aluminum chloride is used instead of Zinc chloride gives the same result. Example 3 3 g of anisilic acid, 3 g of o-aminophenol and 0.5 g of p-toluenesulfonic acid in 50 ml of o-dichlorobenzene are heated in an oil bath at 180 to 190 ° C. for 4 hours using a descending condenser. After cooling, the mixture is filtered off with suction, the filtrate is concentrated to dryness and the residue is treated a few times with warm dilute hydrochloric acid and then with water. The remaining crude 2,2-bis- (p-methoxyphenyl) -3-oxo-dihydrobenzoxazine- (1,4) is recrystallized from dilute ethanol. 1.5 g of crystals with a melting point of 157 ° C. are obtained.

The same result is achieved when using tetralin as the solvent and benzenesulfonic acid as the cyclizing agent. Example 4 In 50 ml of o-dichlorobenzene is added 3- _ g Anisilsäuremethylester, 3 g o-aminophenol and 0.5 g of p-toluenesulfonic acid and the mixture heated descending condenser in an oil bath for 4 hours at 180 to 190 ° C. After the Cooling is suctioned off and, as described in Example 3, worked up. 0.8 g of 2,2-bis- (p-methoxyphenyl) -3-oxo-dihydrobenzoxazine- (1,4) with a melting point of 154 to 156 ° C. are obtained Use of 2 g of anisilic acid, 2 g of 1-hydroxy-2-amino-4-methylbenzene and 0.3 g of benzenesulfonic acid in 35 ml of o-dichlorobenzene. 0.9 g of 2,2-bis- (p-methoxyphehyl) -3-oxo-6-methyl-dihydrobenzoxazine- (1,4) with a melting point of 230 to 231 ° C. are obtained. EXAMPLE 6 1 g of 2,2-bis- (p-methoxyphenyl) -3-oxodihydrobenzoxazine- (1,4) with 5 g of pyridine hydrochloride is heated in an oil bath at 180 ° C. for 4 hours and, after cooling, the mixture is poured into water. The 2,2-bis- (p-hydroxyphenyl) -3-oxo-dihydrobenzoxazine- (1,4) separates out, which is converted into the O-acetyl derivative with 5 cc of acetic anhydride and 0.3 g of sodium acetate in 2 hours warmed up in a boiling water bath for a long time. will. After adding water, the 2,2-bis- (p-acetoxyphenyl) -3-oxo-dihydrobenzoxazine- (1,4) which has separated out is sucked off, washed with water and recrystallized from ethanol. F. = 190 ° C. Example 7 25 ml of o-dichlorobenzene are added to a mixture of 3 g of anisilic acid and 1 g of o-aminophenol and the mixture is refluxed for 4 hours. The o-dichlorobenzene is then distilled off under reduced pressure and the solid residue is triturated with ether. This gives almost colorless crystals, which are filtered off with suction and recrystallized from ethanol.

The yield of 2,2-bis (p-methoxyphenyl) -3-oxodihydrobenzoxazine- (1,4) from melting point 156 to 157 ° C is 2.0 g.

Claims (3)

PATENT CLAIMS: 1. Modification of the process for the preparation of 2,2-bis- (p-hydroxyphenyl) -3-oxo-dihydrobenzoxazines- (1,4) and their O-acyl or O-alkyl derivatives of the general formula where R is a hydrogen atom or a low molecular weight alkyl radical, R1 is a hydrogen atom, a low molecular weight alkyl radical - or a low molecular weight alkoxy group and R2 is a hydrogen atom, an acyl group or a low molecular weight alkyl radical, according to patent 1097 993, characterized in that a, a-di- phenyl glycolic acids of the general formula in which R1 has the meaning given above and R3 denotes a group which can be subsequently replaced by hydrogen, or its reactive esters with o-aminophenols of the general formula in which R has the meaning given above, is reacted at elevated temperatures and, if appropriate, in the compounds thus obtained, converts the radical R3 into the radical R2 by methods known per se. 2. The method according to claim 1, characterized in that that the reaction is carried out in a high-boiling, inert solvent. 3. Process according to Claims 1 and 2, characterized in that the reaction is carried out executes in the presence of a dehydrating catalyst.