Process for Preparing Triarylmethane Derivatives

This invention relates to a process for preparing colourless chromogenic compounds which form coloured markings upon contact with acidic materials by electron donor-acceptor colour-forming reaction.

Particularly, this invention relates to a novel process for preparing triarylmethane derivatives represented by the following general formulae (I), (II), (III) and (IV): ##STR1## wherein each of R.sub.1 and R.sub.2 is at least one of hydrogen, halogen, nitro group, alkyl group, substituted alkyl group, amino group, substituted amino group, hydroxyl group, substituted hydroxyl group, thiohydroxyl group, or substituted thiohydroxyl group; each of R.sub.3 and R.sub.4 is hydrogen, substituted or unsubstituted alkyl group, cycloalkyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryl group, or substituted or unsubstituted unsaturated alkyl group, or one or both of R.sub.3 and R.sub.4 together with the adjacent nitrogen atom may form a heterocyclic ring; R.sub.5 is at least one of hydrogen, halogen, alkyl group, nitro group, substituted or unsubstituted amino group, substituted or unsubstituted hydroxyl group, substituted or unsubstituted thiohydroxyl group; R.sub.6 is at least one of hydrogen, halogen, lower alkyl group, lower alkoxyl group, amino group, lower alkylamino group, nitro group, phenyl group or phenoxy group; R.sub.7 is hydrogen, alkyl group, aralkyl group or phenyl group; and R.sub.8 is lower alkyl group or substituted or unsubstituted phenyl group.

There are known several methods for preparing triarylmethane derivatives represented by the general formula (I), for example, U.S. Pat. No. Re. 23,024 discloses a method in which the triarylmethane derivative is prepared from m-dimethylamino-benzoic acid and Michler's hydrol by condensation reaction. Another method for preparing triarylmethane derivative by condensation reaction of dimethylaniline with o-phthalaldehydric acid is described in "Beilsteins Handbuch der Organische Chemie", Vol. 14, page 549. However, these methods give triarylmethane derivative in low yields because a large amount of by-products is produced. Furthermore, these methods give only limited compound having a symmetrical structure.

The triarylmethane derivatives having the general formula (II) are novel compounds which are synthesized for the first time by this invention.

The known method for preparing triarylmethane derivatives represented by the general formula (III) and (IV) is disclosed in U.S. Pat. Nos. 2,443,092 and 2,597,965, "Beilsteins Handbuch der Organische Chemie", vol. 18, page 617 and Moriga & Oda, "Kogyo Kagaku Zasshi", vol. 64, page 1226, (1961), in which triarylmethane derivatives are prepared from dimethylaniline and phthalic anhydride by condensation. Another method is described in U.S. Pat. Nos. 3,491,112 and 3,491,116 and in "Beilsteins Handbuch der Organische Chemie", vol. 18, pages 618-619, in which benzophenone-2-carboxylic acid is first prepared from dimethylaniline and phthalic anhydride and then triarylmethane derivative is prepared from the resultant benzophenone-2-carboxylic acid and either dimethylaniline derivative or indole derivative.

However, these methods also give triarylmethane derivatives in low yields because of the production of a large amount of by-products. Particularly when substituted phthalic anhydride is used, a large amount of isomers is produced as well, therefore, the yield is more lowered. In addition, substituted phthalic anhydride has such a disadvantage that it is not suitable for industrial production because the process for the production thereof is complicated.

An object of the invention is to provide a novel process for preparing triarylmethane derivatives of a high purity in an extremely high yield.

Other objects and advantages of the invention will become apparent from the following description.

According to the invention, triarylmethane derivatives represented by the following general formula (I) or (II) are prepared by making 3-phenylphthalide derivatives represented by the general formula (V) react with anilic derivatives represented by the general formula (VI) or with indole derivatives represented by the general formula (VII) in the presence of Friedel-Crafts Type Catalysts: ##STR2## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are the same as described above. Further, triarylmethane derivatives represented by the general formula (III) or (IV) are prepared by oxidizing the above obtained triarylmethane derivatives represented by the general formula (I) or (II) with use of oxidizing agents: wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are the same as described above.

3-phenylphthalide derivative represented by the above described general formula (V) which is used in this invention is prepared, as shown as follows, from benzene derivative (VIII) and o-phthalaldehydic acid derivative (IX) by dehydration condensation, or from benzaldehyde derivative (X) and benzoic acid derivative (XI) by dehydration condensation: ##STR3## wherein R.sub.1 and R.sub.2 are the same as described above.

As the typical compounds of 3-phenylphthalide derivatives represented by the above general formula (V) which are used in this invention, the following compounds may be exemplified;

3-(4'-dimethylaminophenyl)phthalide,

3-(4'-dimethylamino-2'-methylphenyl)phthalide,

3-(4'-dimethylamino-2'-methoxyphenyl)phthalide,

3-(4'-dimethylamino-2'-methylthiophenyl)phthalide,

3-(4'-dimethylamino-2'-chlorophenyl)phthalide,

3-(4'-dimethylamino-2'-diethylaminophenyl)phthalide,

3-(4'-diethylaminophenyl)phthalide,

3-(4'-diethylamino-2'-chlorophenyl)phthalide,

3-(4'-diethylamino-2'-methoxyphenyl)phthalide,

3-[4'-(N-ethyl-N-benzyl)aminophenyl]phthalide,

3-[4'-(N-methyl-N-P-tolyl)aminophenyl]phthalide,

3-(4'-pyrrolidinophenyl)phthalide,

4-(julolidine-6'-yl)phthalide,

3-phenyl-6-dimethylaminophthalide,

3-phenyl-6-diethylaminophthalide,

3-[2'(or 3', or 4')-methylphenyl]-6-dimethylaminophthalide,

3-[2'(or 3', or 4')-methyoxyphenyl]-6-dmethylaminophthalide,

3-[2'(or 3', or 4')-methoxyphenyl]-6-diethylaminophthalide,

3-[2'-(or 3', or 4')-chlorophenyl]-6-dimethylaminophthalide,

3-[2'(or 3', or 4')-nitrophenyl]-6-dimethylaminophthalide,

3-[2'-(or 3', or 4')-nitrophenyl]-6-diethylaminophthalide,

3-[2', 3' (or 2', 4')-dimethylphenyl]-6-dimethylaminophthalide,

3-[2', 3' (or 2', 4')-dimethoxyphenyl]-6-dimethylaminophthalide,

3-[2', 3'(or 2', 4')-dimethoxyphenyl]-6-diethylaminophthalide,

3-[2', 3'(or 2', 4')-dichlorophenyl]-6-dimethylaminophthalide,

3-(2'-methyl-4'-methoxyphenyl)-6-dimethylaminophthalide,

3-(2'-methoxy-4'-methylphenyl)-6-dimethylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-dimethylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-diethylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-N-methyl-N-P-tolylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-N-ethyl-N-benzylaminophthalide,

3-[2'(or 3', or 4')-diethylaminophenyl]-6-dimethylaminophthalide,

3-[2'(or 3', or 4')-diethylaminophenyl]-6-diethylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-5-chloro-6-dimethylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-5-chloro-6-diethylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-diallylaminophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-dipropargylamino-phthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-pyrrolidinophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-pyrimidinophthalide,

3-[2'(or 3', or 4')-dimethylaminophenyl]-6-morpholinophthalide,

3-(4'-pyrrolidinophenyl)-6-dimethylaminophthalide,

3-(4'-pyrimidinophenyl)-6-dimethylaminophthalide,

3-(julolidine-6'-yl)-6-dimethylaminophthalide,

3-(4'-morpholinophenyl)-6-dimethylaminophthalide,

3-[4'-(N-methyl-N-benzyl)aminophenyl]-6-dimethylaminophthalide,

3-[4'-(N-methyl-N-benzyl)aminophenyl]-6-diethylaminophthalide,

3-[4'-(N-ethyl-N-benzyl)aminophenyl]-6-dimethylaminophthalide,

3-[4'-(N-methyl-N-para-tolyl)aminophenyl]-6-dimethylamino-phthalide,

3-[4'-(N-ethyl-N-para-tolyl)aminophenyl]-6-dimethylaminophthalide,

3-[4'-(N-ethyl-N-para-tolyl)aminophenyl]-6-diethylaminophthalide,

3-(4'-diallylaminophenyl)-6-dimethylaminophthalide,

3-(4'-dipropargylaminophenyl)-6-dimethylaminophthalide,

3-(4'-dimethylamino-2'-methylphenyl)-6-dimethylaminophthalide,

3-(4'-diethylamino-2'-methylphenyl)-6-dimethylaminophthalide,

3-(4'-dimethylamino-2'-chlorophenyl)-6-dimethylaminophthalide,

3-(4'-diethylamino-2'-chlorophenyl)-6-dimethylaminophthalide,

3-(4'-dimethylamino-2'-methoxyphenyl)-6-dimethylaminophthalide,

3-(4'-diethylamino-2'-methoxyphenyl)-6-dimethylaminophthalide,

3-(4'-dimethylamino-2'-methylthiophenyl)-6-dimethylaminophthalide,

3-(4'-diethylamino-2'-methylphenyl)-5-chloro-6-dimethylaminophthalide,

3-(4'-diethylamino-2'-methylphenyl)-5-chloro-6-diethylaminophthalide,

3-(4'-diethylamino-2'-methoxyphenyl)-5-chloro-6-dimethylaminophthalide,

3-(4'-diethylamino-2'-methoxyphenyl)-5-chloro-6-diethylaminophthalide,

3-(4'-dimethylaminophenyl)-6-methoxyphthalide,

3-(4'-diethylaminophenyl)-6-ethoxyphthalide,

3-(4'-diethylaminophenyl)-6-methoxyphthalide and

3-(4'-diethylamino-2'-methoxyphenyl)-6-methoxyphthalide.

Among the above mentioned 3-phenylphthalide derivatives, those having R.sub.2 at the 6 position are preferably used and preferably R.sub.2 is an substituted amino group.

Among the typical compounds of aniline derivatives represented by the above described general formula (VI) which are used in this invention there may be included the following compounds:

aniline, N-methylaniline, N-ethylaniline, o-toluidine, m-toluidine, m-nitroaniline, m-phenylenediamine, m-chloroaniline, m-bromoaniline, o-anisidine, o-phenetidine, 2.5-dichloroaniline, N,N-dimethylaniline, N,N-diethylaniline, N-(2-ethylhexyl)-N-methylaniline, N,N-dibutylaniline, N-dodecyl-N-ethylaniline, N,N-diethyl-m-toluidine, N,N-diethyl-o-toluidine, N,N-dibenzylaniline, N-methyl-N-benzylaniline, N-ethyl-N-benzylaniline, diphenylamine, N-benzyldiphenylamine, 4-benzyloxydiphenylamine, N-ethyl-4-ethoxydiphenylamine, N-methyldiphenylamine, N-ethyldiphenylamine, N,N-diethyl-o-anisidine, N,N-dimethyl-o-phenetidine, N,N-diethyl-m-acetoxyaniline, N,N-dimethyl-m-nitroaniline, N,N-diethyl-m-nitroaniline, N,N-dimethyl-o-chloroaniline, N,N-dimethyl-m-chloroaniline, N,N-diethyl-m-chloraniline, N,N-dimethyl-o-bromoaniline, N,N-dimethyl-m-bromoaniline, N,N-diethyl-o-bromoaniline, N,N-diethyl-m-bromoaniline, N,N-diethyl-m-hydroxyaniline, N,N-bis (.beta.-cyanoethyl)aniline, N,N-bis(.beta.-chloroethyl)aniline, N,N-bis(.beta.-bromoethyl)aniline, N,N-bis(.beta.-ethoxyethyl)aniline, N,N-bis(.beta.L-cyanoethyl)-m-toluidine, N,N-bis(.beta.-chloroethyl)-m-toluidine, N,N-bis(.beta.-bromoethyl)-m-toluisine, N-ethyl-N-(.beta.-chloroethyl)-m-toluidine, N,N-bis(.beta.-ethoxyethyl)-m-toluisine, N-ethyl-N-phenethylaniline, N-ethoxycarbonylmethyl-N-cyclohexylaniline, N,N-diethyl-m-phenylenediamine, N,N-diethyl-o-phenylenediamine, N, N, N', N', -tetraethyl-m-phenylenediamine, N, N, N', N', -tetraethyl-o-phenylenediamine, N-cyclohexyl-N-methylaniline, N-phenylmorpholine, N-phenylpiperidine, N-phenylpyrrolidine, N-phenylimidazoline, N-phenylpyrazolidine, N-phenylpiperazine, julolidine, 1-naphthylamine, N-methyl-1-naphthylamine, N-ethyl-1-naphthylamine, N-phenyl-1-naphthylamine, N,N-dimethyl-1-naphthylamine, N,N-diethyl-1-naphthylamine, 5-chloro-N, N-dimethyl-1-naphthylamine, 5-bromo-N,N-dimethyl-1-naphthylamine, 5-ethoxy-N,N-diethyl-1-naphthylamine, 5-benzyloxy-N,N-dimethyl-1-naphthyla mine, N-ethyl-N-benzyl-1-naphthylamine, N,N-bis(.beta.-chloroethyl)-1-naphthylamine, N,N-bis(.beta.-bromoethyl)-1-naphthylamine, N,N-bis(.beta.-cyanoethyl)-1-naphthylamine, N,N-bis(.beta.-methoxyethyl)-1-naphthylamine, N,N-bis(.beta.-ethoxyethyl)-1-naphthylamine and N-phenyl-N-methyl-1-naphthylamine.

Among the typical compounds of indole derivatives represented by the above mentioned general formula (VII) which are used in this invention there may be included the following compounds:

2-methylindole, 2-ethylindole, 2-phenylindole, 2-(2'-methylphenyl)indole, 2-methyl-5-chloroindole, 2-methyl-5-ethoxyindole, 2-methyl-7-phenylindole, 2-methyl-5-aminoindole, 1,2-dimethylindole, 1-methyl-2-phenylindole, 1.2.5-trimethylindole, 1.2-dimethyl-5-methoxyindole, 1.2-dimethyl-5-phenoxyindole, 1.2-dimethyl-5-nitroindole, 1-methyl-2-(4'-chlorophenyl)indole, 1-methyl-2-(4'-ethoxyphenyl)indole, 1-methyl-2-(4'-ethoxyphenyl)-5-dimethylaminoindole, 1-benzyl-2-methylindole, 1-benzyl-2.5-dimethylindole 1-benzyl-2-methyl-5-methoxyindole, 1.2-dimethyl-7-phenylindole, 1-phenyl-2.5-dimethylindole, 1-phenyl-2.5-diethylindole and 1.2-dimethyl-5.6-dichloroindole.

In the practice of the invention, 3-phenylphthalide derivative is made to react with aniline derivative or indole derivative in the presence of Friedel-Crafts type catalyst, if necessary, with use of a suitable solvent, at the temperature of 0 to 180.degree. C for the period between several minutes and several decades of hours.

As a Friedel-Crafts type catalyst, acidic halide Lewis acid catalysts such as AlCl.sub.3, AlBr.sub.3, BeCl.sub.2, CdCl.sub.2, ZnCl.sub.2, BF.sub.3, BCl.sub.3, GaCl.sub.3, GaBr.sub.3, TiCl.sub.4, TiBr.sub.4, ZnCl.sub.4, SnCl.sub.4, SnBr.sub.4, SbCl.sub.5, SbCl.sub.3, BiCl.sub.3, FeCl.sub.3, UCl.sub.4, PF.sub.5, SbF.sub.5, AsF.sub.5 and mixed pentafluorides of Nb and Ta; metal alkyl Lewis acid catalysts such as Al.sub.2 Cl.sub.3 (CH.sub.3).sub.3 +HCl, AlCl.sub.2 (C.sub.2 H.sub.5), AlCl(C.sub.2 H.sub.5).sub.2, AlBr.sub.3 (C.sub.2 H.sub.5).sub.3, Al(C.sub.2 H.sub.5).sub.2 Br, Al(C.sub.2 H.sub.5)Br.sub.2, Al(C.sub.2 H.sub.5).sub.3, Al(t-C.sub.4 H.sub.9).sub.3, Al(i-C.sub.4 H.sub.9).sub.3, AuBr.sub.2 C.sub.2 H.sub.5, Be(C.sub.2 H.sub.5).sub.2, BRx.sub.3, MgRx.sub.2 R.sub.2 Mg.MgX.sub.2, TiCl.sub.3 CH.sub.3, TiCl.sub.3 (C.sub.2 H.sub.5) and Zn(C.sub.2 H.sub.5).sub.2, wherein Rx is alkyl group and X is halogen; metal alkoxide Lewis acid catalysts such as Al(OC.sub.6 H.sub.5).sub.3, aluminum alkoxides, AlCl.sub.2 ORx, AlCl.sub.3.Ti(ORx).sub.4, Ti(BuO).sub.4 and Ti(i-PrO).sub.4, wherein Rx is alkyl group; Bronsted acid catalysts such as, phosphoric acid, polyphosphoric acid, perchloric acid, chlorosulfonic acid, fluosulfonic acid, alkane sulfonic acids such as ethane sulfonic acid, p-toluenesulfonic acid, acetic acid, chloroacetic acids, trifluoroacetic acid, sulfuric acid, hydrogen halides and alkyl halides; acidic oxide and sulfide (acidic chalcide) catalysts such as alumina, Al.sub.2 O.sub.3.CaO, Al.sub.2 O.sub.3. Cr.sub.2 O.sub.3, Al.sub.2 O.sub.3. Fe.sub.2 O.sub.3, Al.sub.2 O.sub.3. V.sub.2 O.sub.3, alumino-silicates (natural), bauxite, bentonite clay, BeO, acid activated clay, chromia (with silica-alumina), Cr.sub.2 O.sub.3 (synthetic), Cr.sub.2 O.sub.3, Fe.sub.2 O.sub.3, floridin, Georgia clay, Gumbrin clay, magnesia (with silica-alumina), molybdenum oxide-alumina, MoS.sub.2, MoS.sub.3, MoS.sub.2. CoS, montmorillonite clay, nickel-alumina, P.sub.2 O.sub.5, silica-alumina, thoria (with silica-alumina), ThO.sub.2 (synthetic), TiO.sub.2, WO.sub.3 (with silica-alumina) and zirconia (with silica-alumina); acidic cation exchanger catalysts such as sulfonated coals, sulfonated phenol-formaldhyde resins, sulfonated divinylbenzene cross linked polymers and exchangers with carboxyl group, phenol group or alumina-silicate skeleton; metathetic cation forming substances such as AgAsF.sub.6, AgClO.sub.4, AgBF.sub.4, AgNO.sub.3, AgOOCCF.sub.3, AGPO.sub.4, AgPF.sub.6, AgSbF.sub.6, Ag.sub.2 SO.sub.4, AgNbF.sub.6, AgTaF.sub.6 and AgTi.sub.2 F.sub.9 ; and the mixtures thereof may be used.

Among the above Friedel-Crafts type catalyst acidic halide Lewis acid catalysts, Bronsted acid catalysts, acidic oxide catalysts, metal alkyl Lewis acid catalysts and metal alkoxide acid catalysts are preferably used because they are highly reactive and economical. Particularly, acidic halide Lewis acid catalysts, Bronsted acid catalysts and acidic oxide catalysts are most preferable.

Referring to the amount of such Friedel-Crafts type catalysts, it may be controlled properly according to the kinds of the starting materials, but it is preferable to use them in amounts equimolar with respect to 3-phenylphthalide derivative or more.

As a solvent, benzene, toluene, alkylbenzene, chlorobenzene, dichlorobenzene, bromobenzene, nitrobenzene, alkylnaphthalene, ethylene chloride, chloroform, tetrachloromethane, tetrachloroethane, nitromethane, nitroethane, nitropropane, carbon disulfide, kerosene, high-boiling naphtha, etc. are preferably used. In order to increase the rate of reaction and to minimize the amount of catalyst, it is preferable that such a solvent should not be used or the amount of the solvent should be minimized even when it is used. On the other hand, the excess amount of solvent is preferably used for the purpose of control of the reaction temperature, homogenization of reaction, extraction or the resultant product, etc. Therefore, the solvent should be used as occasion demands.

In this invention, triarylmethane derivatives represented by the general formula (III) or (IV) are obtained by oxidation of the above obtained triarylmethane derivatives represented by the general formula (I) or (II) with use of an oxidizing agent. Triarylmethane derivative represented by the general formula (I) or (II) is dissolved in acidic aqueous solutions such as hydrochloric acid solution and sulfuric acid solution, alkaline aqueous solutions such as caustic soda solution and caustic potash solution, or organic solvents such as alcohols, lower aliphatic carboxylic acids, ethers, ketones, aromatic hydrocarbons, and thereafter an oxidizing agent is added to the solution, and then the oxidation is carried out at the temperature of 0.degree. to 500.degree. C for the period between several minutes and several decades of hours.

As an oxidizing agent, manganese compounds such as permanganates, manganates, managanese dioxide, manganese (III) salts and manganese acetate; chromic acid compounds such as chromic anhydride, chromic acid, perchromates, alkyl esters of chromic acid and chromyl chloride; lead compounds such as PbO, PbO.sub.2 and Pb(CCOCH.sub.3).sub.4 ; copper compounds such as CuO, Cu(OH).sub.2, CuSO.sub.4, Cu(OCOCH.sub.3).sub.2, CuCl.sub.2 and CuBr.sub.2 ; cobalt compounds such as Co.sub.2 (SO.sub.4).sub.3 and Co.sub.3 O.sub.4 ; cerium compounds such as CeO.sub.2, Ce(SO.sub.4).sub.2 and Ce(SO.sub.4).sub.3 ; bismuth compounds such as NaBiO.sub.3, BiO and Bi(OCOCH.sub.3).sub.2 ; silver compounds such as Ag.sub.2 O, AgOCOCH.sub.3 and AgNO.sub.3 ; iron compounds such as FeCl.sub.3, Fe.sub.2 (SO.sub.4).sub.3 and potassium ferricyanate; SeO.sub.2 ; RuO.sub.4 ; OsO.sub.4 ; inorganic peroxides such as hydrogen peroxide, Fenton's reagent, persulfuric acid and salts thereof; organic peroxides such as performic acid, peracetic acid, perpropionic acid, perbutyric acid, perbenzoic acid, monoperphthalic acid, monoperterephthalic acid, monopersuccinic acid and trifluoroperacetic acid; halides such as hypochlorites, chlorates, hypobromites and bromates; oxygen; ozone; ultraviolet ray; sulfoxides; amine oxides; and chloranil are preferably used. The amount of oxidizing agent may be controlled according to the kinds of oxidizing agent to be used, but it may be usually used in an excess of a stoichiometric amount based on the amount of said triarylmethane derivatives having the general formula (I) or (II).

When the compounds having an oxidizing function such as FeCl.sub.3, FeBr.sub.3, AgNO.sub.3, CuCl.sub.2 and peracetic acid are used as a Friedel-Crafts type catalyst in the preparation of triarylmethane derivatives represented by the general formula (I) or (II) from 3-phenylphthalide derivatives and aniline derivatives or indole derivatives, the resultant triarylmethane derivatives represented by the general formula (I) or (II) are instantaneously oxidized to form triarylmethane derivatives represented by the general formula (III) or (IV).

Namely, the reaction of a 3-phenylphthalide derivative with an aniline derivative or an indole derivative to form a triarylmethane derivative having the general formula (I) or (II) is immediately followed by and concurrently occurs with the oxidizing reaction to form said triarylmethane derivative having the general formula (III) or (IV). For this purpose Friedel-Crafts type catalysts may preferably be used in an excess of the total amount of an equimolar amount with respect to said 3-phenylphthalide derivative and a stoichiometric amount based on the amount of said triarylmethane derivative having the general formula (I) or (II).

The process of the invention for the preparation of triarylmethane derivatives from 3-phenylphthalide derivatives is a novel method which has never been described in any literature. The process of the invention gives triarylmethane derivatives at high purities and in extremely high yields. In addition, the process of the invention makes it possible to prepare the various novel triarylmethane derivatives which could not be synthesized by any conventional methods.

The triarylmethane derivatives obtained in this invention form coloured markings upon contact with acidic substances such as solid acids, e.g., acid clay, activated clay, attapulgite, zeolite, kaolin, bentonite and silicates; and organic acidic materials such as phenol-formaldehyde polymers, phenol-acetylene polymers, maleic acid rosin resin, ethylene-maleic acid anhydride polymers, salicylic acidaldehyde polymers, salicylic acid-acetylene polymers, polyvalent metal salts of those polymers mentioned above, aromatic carboxylic acids, e.g., salicylic acid and salicylic acid derivatives, and polyvalent metal salts of aromatic carboxylic acids by an electron donor-acceptor colour-forming reaction, therefore, they may be utilized as colourless chromogenic compounds (i.e. electron donor) in various fields which utilize such a reaction. For example, triarylmethane derivatives of the invention can be utilized for the production of pressure sensitive copying sheet which is disclosed in U.S. Pat. Nos. 2,730,456 and 2,730,457 and Japanese Pat. No. 511,757, heat sensitive copying sheet which is disclosed in U.S. Pat. Nos. 3,451,338 and 3,539,375, hectographic copying sheet, electron beam sensitive recording sheet, photosensitive sheet, electrographic heat sensitive recording sheet, ultrasonic recording sheet, toner for Xerox type copying sheet, and leuco ink.

The following examples serve to illustrate the invention in more detail although the invention is not limited to the examples.

30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline were dissolved in 250 cc of tetrachloroethane. 14g of anhydrous aluminum chloride was added to the solution and the resultant mixture was heated at 50.degree. C for 3 hours with stirring. After the termination of reaction, 30% aqueous solution of caustic soda was added to dissolve aluminum chloride while cooling the mixture with ice. Then, the tetrachloroethane phase was separated with the aid of a separatory funnel, and then steam distilled to remove the unreacted dimethylaniline and tetrachloroethane. The remaining aqueous phase was neutralized with acetic acid to obtain a pale yellow solid. The yield was 42g. This solid was recrystallized from benzene to obtain colourless crystals having a melting point (hereinafter referred to as m.p.) of 201.degree. C. The obtained crystal results in a blue colouration when it is subjected to light on silica gel. This compound is triarylmethane represented by the following formula: ##STR4##

30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide and 17g of N,N-diethyl-m-toluidine were dissolved in 300cc of benzene. After the addition of 14g of zinc chloride, the mixture was heated at 80.degree. C for 5 hours with stirring. After cooling, the resultant precipitate was filtered and then dried. The obtained precipitate was dissolved in dilute hydrochloric acid, and then the pH of the solution was adjusted at 4.0 with an aqueous solution of caustic soda to form a yellow precipitate. This precipitate was filtered and then dried. The yield was 45g. Recrystallization from benzene gave triarylmethane represented by the following formula in the form of colourless crystals whose m.p. was 255.degree.-260.degree. C. This compound turns in blue colour upon exposure to light on TCL. ##STR5##

Example 1 was repeated except that 26g of 3-(p-dimethylaminophenyl)phthalide was used instead of 30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide to obtain 32g of triarylmethane represented by the following formula whose m.p. was 194.degree.-195.degree. C in the form of colourless crystals. This compound becomes bluish green upon exposure to light on silica gel. ##STR6##

Example 1 was repeated except that 29g of 3-(o-methoxyphenyl)-6-dimethylaminophthalide was used instead of 30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide to obtain 38g of triarylmethane represented by the following formula whose m.p. was 237.degree.-238.degree. C in the form of colourless crystals (Recrystallized from acetic acid-methanol). This compound becomes bluish green upon exposure to light on silica gel. ##STR7##

Example 1 was repeated except that 13.5g of 2-methylindole was used instead of 13g of dimethylaniline to obtain 34g of triarylmethane having the following formula in the form of colourless crystals. This compound becomes violet upon exposure to light on silica gel. ##STR8##

Example 1 was repeated except that 29g of 3-(o-methoxyphenyl)-6-dimethylaminophthalide and 13.5g of 2-methylindole were used instead of 30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline, respectively, to obtain 29g of triarylmethane having the following structure whose m.p. was 203.degree.-205.degree. C in the form of colourless crystals (Recrystallized from methanol). This compound becomes blue black upon exposure to light on silica gel. ##STR9##

Example 1 was repeated except that 32g of 3-(3', 4'-dimethoxyphenyl)-6-dimethylaminophthalide and 13.5 g of 2-methylindole were used, respectively, instead of 30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline to obtain 33g of triarylmethane having the following structure whose m.p. was 230.degree.-232.degree. C in the form of colourless crystals (Recrystallized from methanol). This compound becomes bluish violet upon exposure to light on silica gel. ##STR10##

Example 1 was repeated except that 19.5g of 2-phenylindole was used instead of 13g of dimethylaniline to obtain 34g of triarylmethane having the following structure in the form of colourless crystals. This compound becomes blue upon exposure to light on silica gel. ##STR11##

Example 1 was repeated except that 32g of 3-(2',4'-dimethoxyphenyl)-6-dimethylaminophthalide and 13.5g of 2-methylindole were used, respectively, instead of 30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline to obtain 27g of triarylmethane having the following structure whose m.p. was 202.degree.-203.degree. C in the form of colourless crystals (Recrystallized from methanol). This compound becomes bluish violet upon exposure to light on silica gel. ##STR12##

Example 1 was repeated except that 30g of 3-(p-dimethylaminophenyl)-6-ethoxyphthalide was used instead of 30g of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide to obtain 39g of triarylmethane having the following structure whose m.p. was 197.degree.-198.degree. C in the form of colourless crystals. This compound becomes bluish green upon exposure to light on silica gel. ##STR13##

Example 1 was repeated with use of the various starting materials and catalysts shown in the following table instead of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide, dimethylaniline and anhydrous aluminum chloride to obtain the various triarylmethane compounds shown in the following table. The colours formed upon exposure to light on silica gel are shown in the following table as well.

Example 1 was repeated except that 33g of anhydrous ferric chloride was used instead of 14g on anhydrous aluminum chloride to obtain 16g of compound having the following structure whose m.p. was 180.degree. C in the form of colourless crystals (Recrystallized from benzene-methanol). This compound becomes blue upon contact with silica gel. ##STR59##

Example 12 was repeated with use of the various starting materials and catalysts shown in the following table instead of 3-(p-dimethylaminophenyl)-6-dimethylaminophthalide, dimethylaniline and anhydrous ferric chloride to obtain the various triarylmethane compounds shown in the following table. Those compounds produce the various colours shown in the following table immediately upon contact with silica gel.

33g of 3-(m-diethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline were dissolved in 300cc of tetrachloroethane. 14g of anhydrous aluminum chloride was added to the solution, and then the mixture was heated at 50.degree. C for 3 hours with stirring. After the termination of reaction, 30% aqueous solution of caustic soda was added to the mixture to dissolve aluminum chloride while cooling with ice. Tetrachloroethane phase was steam distilled to remove unreacted dimethylaniline and tetrachloroethane. The remaining aqueous phase was neutralized with acetic acid to obtain a white solid. This solid was dissolved in 600cc of 2.5% aqueous solution of caustic soda, and then heated at 50.degree. C. 600cc of 5% aqueous solution of potassium persulfate was added dropwise to the above solution, and then the mixture was heated at 60.degree. C for 3 hours. After the termination of reaction, the resultant precipitates were filtered and recrystallized from methanol to obtain 31g of 3-(m-diethylaminophenyl)-3-(p-dimethylaminophenyl)-6-dimethylaminophthalid e having the following structure whose m.p. was 177.degree.-178.degree. C in the form of colourless crystals. This compound become green on contact with silica gel. ##STR72##

Example 14 was repeated except that 29g of 3(p-methoxyphenyl)-6-dimethylaminophthalide and 19.5g of 2-phenylindole were used, respectively, instead of 33g of 3-(m-diethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline to obtain 24g of 3-(p-methoxyphenyl)-3-(2-phenylindole-3-yl)-6-dimethylaminophthalide having the following structure whose m.p. was 224.degree.-225.degree. C in the form of colourless crystals (Recrystallized from benzene-methanol). This compound becomes blue black on contact with silica gel. ##STR73##

Example 14 was repeated except that 32g of 3-(3,4-dimetoxyphenyl)-6-dimethylaminophthalide and 19.5g of 2-phenylindole were used instead of 33g of 3-(m-diethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline to obtain 21g of 3-(3',4'-dimetoxyphenyl)-3(2'-phenylindole-3'-yl)-6-dimethylaminophthalide having the following structure whose m.p. was 235.degree.-236.degree. C in the form of colourless crystals (Recrystallized from benzene-methanol). This compound becomes blue black upon contact with silica gel. ##STR74##

Example 14 was repeated except that 32g of 3-(2',4'-dimethoxyphenyl)-6-dimethylaminophthalide and 19.5g of 2-phenylindole were used instead of 33g of 3-(m-diethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline to obtain 30g of 3-(2',4'-dimethoxyphenyl)-3-(2'-phenylindole-3'-yl)-6-dimethylaminophthali de having the following structure whose m.p. was 239.degree.-240.degree. C in the form of colourless crystals (Recrystallized from benzene-methanol). This compound becomes blue black upon contact with silica gel. ##STR75##

Example 14 was repeated except that 35g of 3-(julolidine-6'-yl)phthalide and 15g of 1,2-dimethylindole were used instead of 33g of 3-(m-diethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline to obtain 28g of 3-(julolidine-6'-yl)-3-(1',2'-dimethylindole-3'-yl)phthalide having the following structure whose m.p. was 259.degree.-260.degree. C in the form of colourless crystals (Recrystallized from alcohol). This compound becomes violet upon contact with silica gel. ##STR76##

Example 14 was repeated except that 38g of 3-{p-di(n-butyl)aminophenyl}phthalide and 15g of 1,2-dimethylindole were used instead of 33g of 3-(m-diethylaminophenyl)-6-dimethylaminophthalide and 13g of dimethylaniline to obtain 33g of 3-{p-di(n-butyl)aminophenyl}-3-(1',2'-dimethylindole-3'-yl)phthalide having the following structure whose m.p. was 140.degree.-142.degree. C in the form of colourless crystals (Recrystallized from benzene-methanol). This compound becomes violet on contact with silica gel. ##STR77##

Example 14 was repeated with use of the following various 3-phenylphthalide derivatives instead of 3-(m-diethylaminophenyl)-6-dimethylaminophthalide, and the following various aniline or indole derivatives instead of dimethylaniline to obtain the triarylmethane derivatives shown in the following table. The colours which were formed on contact with silica gel are shown in the following table as well. aniline or 3-phenylphthalide indole de- resultant derivatives rivatives compound m.p. color ##STR78## ##STR79## ##STR80## 89-93.degree. C Blue " ##STR81## ##STR82## 147-149.degree. C " " ##STR83## ##STR84## 187-189.degree. C " " ##STR85## ##STR86## 68-70.degree. C " " ##STR87## ##STR88## -- " " ##STR89## ##STR90## -- " " ##STR91## ##STR92## 143-145.degree. C " " ##STR93## ##STR94## -- Green " ##STR95## ##STR96## -- Blue " ##STR97## ##STR98## -- " " ##STR99## ##STR100## -- " " ##STR101## ##STR102## -- " ##STR103## ##STR104## ##STR105## -- Bluishgreen ##STR106## " ##STR107## -- " ##STR108## " ##STR109## -- " ##STR110## ##STR111## ##STR112## -- " ##STR113## ##STR114## ##STR115## 180-182.degree. C Blue ##STR116## " ##STR117## 191-192.degree. C " ##STR118## " ##STR119## 215-216.degree. C " " ##STR120## ##STR121## 108-115.degree. C " ##STR122## ##STR123## ##STR124## 200-202.degree. C " ##STR125## ##STR126## ##STR127## 223-225.degree. C " ##STR128## ##STR129## ##STR130## 238-239.degree. C reddishviolet ##STR131## " ##STR132## 242-243.degree. C " ##STR133## ##STR134## ##STR135## 95-98.degree. C violet ##STR136## ##STR137## ##STR138## 102-105.degree. C bluishgreen ##STR139## ##STR140## ##STR141## 125-128.degree. C " ##STR142## ##STR143## ##STR144## 263-265.degree. C blueblack " ##STR145## ##STR146## 235-237.degree. C green ##STR147## ##STR148## ##STR149## 220-223.degree. C blue ##STR150## ##STR151## ##STR152## -- violet " ##STR153## ##STR154## -- " " ##STR155## ##STR156## -- " ##STR157## ##STR158## ##STR159## -- violet

10g of the triarylmethane derivative obtained in Example 2 was dissolved in 100cc of ethylene glycol monomethyl ether. 7g of chloranil was added to the solution, and then the mixture was heated at 50.degree. C for one hour with stirring. The reaction mixture was poured into 2000cc of water. After the adjustment of the pH of the mixture solution at less than 2 with dilute hydrochloric acid, the insoluble material was removed by filtration. The pH of the filtrate was adjusted at 4 with an aqueous solution of caustic soda to obtain a pale blue solid. After drying, the solid was recrystallized from benzenemethanol to obtain 3-(p-dimethylaminophenyl)-3-(2'-methyl-4'-diethylaminophenyl)-6-dimethylam inophthalide having the following structure whose m.p. was 212.degree.-214.degree. C in the form of colourless crystals. This compound immediately becomes blue on contact with silica gel. ##STR160##

Example 21 was repeated with use of the various triarylmethane derivatives obtained in Examples 3 to 11 and the various oxidizing agents and solvents as shown in the following table to prepare the various triarylmethane lactone derivatives. The colours which were formed on silica gel are shown in the following table as well. oxidiz- triarylmethane ing resultant derivatives solvents agents compounds m.p. color ##STR161## aqueoussolutionofcausticsoda KM.sub.n O.sub.4 ##STR162## 190-191.degree. C bluishgreen ##STR163## dilutehydro-chloricacid FeCl.sub.3 ##STR164## 208-210.degree. C " ##STR165## dilutesulfuricacid Fe.sub.2 (SO.sub.4).sub.3 ##STR166## 203-205.degree. C violet ##STR167## aqueoussolutioncausticsoda NaClO ##STR168## 235- 236.degree. C blueblack ##STR169## aceticacid CH.sub.3 COOOH ##STR170## 244-245.degree. C bluishviolet ##STR171## aqueoussolutionofcausticsoda AgNO.sub.3 ##STR172## 252-253.degree. C blue ##STR173## dilutehydro-chloricacid PbO.sub.2 ##STR174## 213-215.degree. C bluishviolet ##STR175## aqueoussolutionofcausticsoda K.sub.2 S.sub.2 O.sub.8 ##STR176## 167-168.degree. C bluishgreen ##STR177## dilutehydro-chloricacid PbO.sub.2 ##STR178## 172-175.degree. C blue ##STR179## dilutehydro-chloricacid PbO.sub.2 ##STR180## 80-85.degree. C " ##STR181## " CuCl.sub.2 ##STR182## -- " ##STR183## aqueoussolutionofcausticsoda Na.sub.2 S.sub.2 O.sub.8 ##STR184## -- " ##STR185## aqueoussolutionofcausticsoda Na.sub.2 S.sub.2 O.sub.8 ##STR186## -- " ##STR187## " " ##STR188## -- " ##STR189## dilutesulfuricacid K.sub.2 Cr.sub.2 O.sub.7 ##STR190## 186-187.degree. C bluishgreen ##STR191## aqueoussolutionofcausticsoda H.sub.2 O.sub.2 ##STR192## 218.degree. C bluishgreen ##STR193## " " ##STR194## 204-206.degree. Cblueblack ##STR195## " " ##STR196## -- bluishgreen ##STR197## " H.sub.2 O.sub.2 ##STR198## viscoussolid blue ##STR199## " " ##STR200## -- blueblack ##STR201## ethyleneglycolmono-methylether chlora-nil ##STR202## 151-152.degree. C bluishgreen ##STR203## " " ##STR204## 183-186.degree. C blue ##STR205## aqueoussolutionofcausticsoda K.sub.2 S.sub.2 O.sub.8 ##STR206## -- " ##STR207## " " ##STR208## -- " ##STR209## " " ##STR210## -- "