DK143654B - PROCEDURE FOR PREPARING A FLUORANDY DERIVATIVE OF TRIPHENYLMETHAN - Google Patents

Description

(19) DENMARK

| J | (12) SUBMISSION WRITING au 14365 ^ B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 4262/72 (51) IrrtCI.3 C 09 B ^ 11 ^ 2A

(22) Submission day 29 · Aug. 1972 ® M 5/12 (24) Running Day Aug 29 1972 ® (41) Aim. available March 1 1975 (44) Presented 21. s ep. 1981 (86) International application # - (86) International filing day (85) Continuation day - (62) Master application no -

(30) Priority 50 · Aug. 1971, 176296, US

(71) Applicant APPLETON PAPERS INC., Appleton, US.

(72) Inventor of Sheldon Father here, US: Troy Eugene Hoover, US: David

Bryan McQuain, US: Arthur John Wright, US.

(74) Associate Engineer Hofman-Bang & Boutard.

(54) Procedure for the preparation of a fluorane derivative of triphenyl = me than.

The invention relates to a particular process for the preparation of a fluorane derivative of triphenylmethane.

Fluorane derivatives of triphenylmethane are known as essentially colorless, chromogenic materials that react with large materials, such as phenolic polymers in the color-forming systems of pressure sensing recording media to form colored markings on J such media.

Known processes for preparing these derivatives include the reaction between β-carboxy-α-amino-benzophenone and an amino-phenol in concentrated sulfuric acid at high temperatures for a period of between 6 and 2 hours and 48 hours. In addition to any general drawbacks associated with the requirements for such a reaction, the known processes have the disadvantage that they tend to produce relatively low yields of the desired compounds, apparently due to excessive sulfonation of the phenol.

It is the object of the invention to provide a process of the kind set forth in the preamble to the claim, in which a significantly higher yield of the desired fluorane derivative is obtained than the yields obtainable using prior art.

The method according to the invention, which is of the kind specified in the preamble of the claim, is peculiar to that of the characterizing part of the claim.

It is admittedly known from English Patent No. 1,182,743 to a process for the preparation of fluorane derivatives which are closely related to the fluorane derivatives prepared by the process of the invention in which the reaction between benzophenone and phenol in concentrated sulfuric acid takes place at room temperature.

However, in this known method, equimolar ratios of benzophenone to phenol or a molar excess of phenol are used. In contrast, in the process of the invention, a molar excess of benzophenone is used. The yield of the desired fluorane derivatives is considerably higher in the process according to the invention than in the known method. Reference can be made in this connection to Example 1 (according to the invention) and the comparative example (according to the prior art).

It has been found that the process of the invention results in an improved yield of the desired fluorane derivatives of triphenylmethane, and it is believed that a factor contributing to this higher yield may be that the presence of the excess benzophenone tends to increase the probability for the benzophenone to react with the phenol, and not the sulfuric acid.

In the reaction between the benzophenone and the phenol in concentrated sulfuric acid, the concentration of sulfuric acid is preferably 96 to 9T / °, the temperature 3Η3B * tvir is preferably 20 to 25 ° C, and the reaction time is between 2 and 5 hours, preferably between 3 and 4.5. hours. The second step of the synthesis is carried out at a temperature between 80 and 100 ° C, at an alkaline pH, namely in the range of 10.0 to 11.5 ° and for a period of between 1.5 and 5 hours. Preferably, the temperature is approx. 90 ° C, the pH is in the range of 10.5 to 11.0, and the time span is 4 hours. The fluorane derivative is isolated by dilution with water and filtration, and the fluorane derivative is preferably washed with small portions of water, followed by a minor hexane wash, and dried using air or heat.

The fluorane derivatives have previously been described in German Patent Application No. P 20 01 864.

The pH settings are preferably carried out by adding a 259 aqueous solution of sodium hydroxide and the whole process is preferably carried out under atmospheric pressure, although this is not a critical aspect.

The molar ratio of benzophenone to aminophenol is in the range of 1.1: 1 to 2: 1, with a ratio of 1.3: 1 being preferred.

The mole ratio of sulfuric acid to benzophenone can vary widely, with a ratio of 18: 1 being preferred, and the benzophenone is preferably dissolved in a preceding step in the sulfuric acid with heating up to 50 ° C to support the dissolution process if desired. The phenolic amine is slowly added to the cold reaction mixture over a period of time.

The following example describes in more detail an embodiment of the invention.

EXAMPLE 1

At 40-50 ° C, 3.44 g (0.011 mol) of 2β-carboxy-4-diethylamino-2-hydroxy-benzophenone (A) was dissolved in 8.0 ml (0.147 mol) of concentrated sulfuric acid. The solution was cooled to 20 ° C and over a period of 70 minutes, the following alternate additions of 4-methoxy-2-methyl-diphenylamine (P) (0.0095 mol) and additional benzophenone (A) (0.002 mol) were made: 4 163654

Time (P) (A) 0-20 minutes 1.03 g 0 20-25 minutes 0 0.31 g 25-45 minutes 0.60 g 0 45-50 minutes 0 0.31 g 50-70 minutes 0.40 g 0

After reaction for a further 2.5 hours at 20-25 ° C, the highly viscous reaction solution was poured into a mixture of 35 g of ice and 25 ml of water, which mixture was stirred well. To the slurry of the light pink precipitate was added 50 ml of 25% NaOH (0.3 mol) and 30 ml of acetone. The pH was then adjusted to a value in the range of 10.5 to 11.0 and maintained at such a value that the reaction continued and the temperature was raised to 90 ° C for a period of 1.5 hours.

When substantially all of the acetone was removed, the reaction mixture was cooled to room temperature and filtered. The solid was washed with 25 ° C hot water (until the filtrate was no longer colored pink), then with 15 ml of 60 ° C hot water and 10 ml of hexane.

The solid, 2'-anilino-6'-diethylamino-3 * -methylfluorane, was dried in air in an oven (1 hour at 100 ° C). The yield was 3.67 g (85% by weight) and the melting point was 186-188 ° C.

94% by weight of the unused benzophenone (A) was recovered from the combined aqueous filtrates.

Not only was the yield of the desired fluorane derivative very large, but the total reaction time was only 5 hours and 10 minutes.

Analogously, other fluorane derivatives can be prepared within the scope of the claim, e.g. 2'-amino-6'-diethylaminofluorane and 2'-diethylamino-6'-diethylaminofluorane. The melting points of these two compounds were, after recrystallization of benzene, 176 and 172-174 ° C, respectively. The yields were of the same order of magnitude as for the compound given in this example.

Claims (1)

Comparative Example An experiment with the same reactants as used in Example 1 was performed except that the molar ratio of (A) to (p) was 1: 1. In 30 ml of concentrated sulfuric acid at 45 ° C was dissolved 6.27 g (0.02 mol) of (A) and at 20 ° C 4.27 g (0.02 mol) was added over a period of 2.5 hours. ) of (P). After a total of 8 hours at 20 ° C, the reaction solution was poured into a mixture of water and ice. The solids were removed by filtration and treated with 95 ml of 25 # NaOH solution for 30 minutes at room temperature. After washing with water and 50 ml of 10 # benzene in hexane, 8.15 g of a solid, mp 187 DEG-5-189.0 ° C, were obtained. The initial acidic aqueous filtrate according to the above was treated in a similar manner to form an additional 0.60 g of the same melting point. Analysis of the product showed that it was the fluorane derivative as in Example 1, but the yield in this experiment was 52 #, substantially less than the yield obtained in Example 1 using an excess of (A) relative to ( P) within the limits specified in the claim. P_a t e_n_t_k_r_a_v: Process for the preparation of ec fluorane derivative of triphenylmethane, characterized in that a benzophenone of the general formula R R-COOH is reacted with a phenol of the general formula