The present invention relates to photochromatic com- pounds.

More specifically, the present invention relates to photochromatic compounds bound to a triazine nucleus, a process for their preparation and their use in polymeric materials.

A further object of the present invention relates to polymeric compositions containing said photochromatic com- pounds and to photochromatic articles obtained from their processing.

Photochromatic compounds are substances which have the characteristic of reversibly changing colour and/or degree of light transmission when exposed to solar or artificial light in the band ranging from UV to visible, or to some types of electromagnetic radiation, returning to their original state of colour and transmission when the initial light source is removed.

There are numerous substances with photochromatic char- acteristics, which belong to various groups of both organic and inorganic compounds such as, for example, those de- scribed in the texts"Photochromism", by G. H. Brown (Ed.), Vol. III of the Weissberger series"Techniques of Organic Chemistry", Wiley Interscience, New York (1971) and in"Pho- tochromism: Molecules and Systems", by H. Durr and H. Bouas- Laurent (Ed.), Vol. 40 of the series"Studies in Organic Chemistry", Elsevier (1990).

Among organic photochromatic compounds, those belonging to the groups of spiro-indolino-oxazines, spiro-pyrans and chromenes, are particularly known and used.

The above compounds are capable of giving photo- chromatic characteristics to polymerized organic materials used, for example, in the production of photochromatic lenses for eye-glasses, special inks, toys, and in many other applications.

As an example, the following patents can be mentioned: USA 3,562,172, USA 3,578,602, USA 4,215,010, USA 4,342,668, USA 5,055,576, USA 5,110,922, USA 5,186,867, EP 146,135, EP 134,633, EP 141,407, EP 245,020, IT 1,233,348 and IT 1,238,694.

The Applicant has now found photochromatic compounds bound to a triazine nucleus which have good photochromatic characteristics, good fatigue resistance and good coloura- bility characteristics.

The present invention therefore relates to photochro- matic compounds having general formula (I):

wherein: -R', represents a hydrogen atom; an OH group; or a pho- tochromatic compound having general formula (II).

R'represents a linear or branched Cl-Cl0 alkyl group; a linear or branched C2-Clo acyl group; a hydroxyl group; a linear or branched Cl-C6 alkoxyl group; an amine group, said amine group optionally substituted with a linear or branched Cl-C6 alkyl group; an N-alkyl (Cl-C6) amine group; an N, N-dialkyl (Cl-C6) amine group; a pi- peridine, piperazine or morpholine group; a carboxylic acid group; a chloro carbonyl (CO-C1) group; an amide group; a COOR'a ester group wherein R'a represents a linear or branched Cl-Cl0 alkyl group; a linear or branched C2-Clo heteroalkyl group in which the heteroa-

tom is selected from nitrogen, oxygen, sulfur and sele- nium; a vinyl group; a (meth) allyl group; a (meth) acrylic group; a C3-Cg 1-alkenyloxyl group; R''represents a hydrogen atom; a halogen atom selected from fluorine, chlorine and bromine; a linear or branched C1-C6 alkyl group; a linear or branched C1-C6 alkoxyl group; a phenyl group; a phenoxyl group; P'represents one of the following groups having gen- eral formula (III), (IV) or (V): -R and R7, the same or different, represent a linear or branched Ci-Cio alkyl group, said alkyl group optionally

substituted with 1-10 halogen atoms selected from fluo- rine, chlorine and bromine, or with C (X') 3 groups wherein X'is selected from fluorine, chlorine and bro- mine, hydroxyl groups, linear or branched Cl-C6 alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6-tetramethylpiperidine group; a vinyl group; an allyl or methallyl group; a linear or branched C2-C6 alkenyl group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally sub- stituted with linear or branched Cl-C6 alkoxyl groups, carboxyl groups, amine groups, N, N-dialkyl (Cl-C6) amine groups; a 4-N, N-dialkyl (Cl-C6) aminoaniline group; an OH group; an NH2 or NHRa group wherein Ra rep- resents a linear or branched Cl-Cl0 alkyl group; a ben- zyl group, said benzyl group optionally substituted with 1-5 halogen atoms selected from fluorine, chlorine and bromine, or with C (X') 3 groups wherein X'is se- lected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Cl-calo alkyl groups, linear or branched C1-C6 alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6-tetramethylpiperidine group; a carboxylic acid group; a chloro carbonyl group; an amide group; a COOR'a ester group wherein R'a represents a linear or branched Cl-calo alkyl group; a benzyl group, said benzyl group optionally substituted

with 1-5 halogen atoms selected from fluorine, chlorine and bromine, or with C (X') 3 groups wherein X'is se- lected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Cl-Cl0 alkyl groups, linear or branched C1-C6 alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6-tetramethylpiperidine group; Ri and R2, the same or different, represent a linear or branched Ci-Cio alkyl group, said alkyl group optionally substituted with 1-10 halogen atoms selected from fluo- rine, chlorine and bromine, or with C (X') 3 groups wherein X'is selected from fluorine, chlorine and bro- mine, hydroxyl groups, linear or branched Cl-C6 alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6-tetramethylpiperidine group; a vinyl group; a (meth) allyl group; a (meth) acrylic group; a C3-Cg 1- alkenyloxyl group; a linear or branched C2-Clo alkenyl group; a COOR'a ester group wherein R'a represents a linear or branched Cl-calo alkyl group; a benzyl group, said benzyl group optionally substituted with 1-5 halo- gen atoms selected from fluorine, chlorine and bromine, or with C (X') 3 groups wherein X'is selected from fluo- rine, chlorine and bromine, hydroxyl groups, linear or branched Cl-Cl0 alkyl groups, linear or branched Cl-C6 alkoxyl groups, carboxyl groups, cyano groups, or with

a 2,2,6,6-tetramethylpiperidine group; a linear or branched Cl-C6 alkoxyl group; an N-alkyl (C1-C6) amine group; an N, N-dialkyl (C1-C6) amine group; or Rl and R2, considered jointly with the carbon atom to which they are bound, represent a C4-Clo cycloalkyl group, said cy- cloalkyl group optionally substituted with halogen at- oms selected from fluorine, chlorine and bromine, or with hydroxyl groups, linear or branched Cl-C6 alkoxyl groups, carboxyl groups, cyano groups, amine groups, N- alkyl (Cl-C6) amine groups, N, N-dialkyl (Cl-C6) amine groups; an N, N-dialkyl (Cl-C6) amide group; an aryl group selected from phenyl and biphenyl; a cyano group; R3, R4, R5 and R6, the same or different, represent a hydrogen atom; a halogen atom selected from fluorine, chlorine, bromine and iodine; a linear or branched Cl-C6 alkyl group, said alkyl group optionally substi- tuted with 1-6 halogen atoms selected from fluorine, chlorine and bromine, or with C (X') 3 groups wherein X' is selected from fluorine, chlorine and bromine, hy- droxyl groups, linear or branched Cl-C6 alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6- tetramethylpiperidine group; a benzyl group, said ben- zyl group optionally substituted with 1-5 halogen atoms selected from fluorine, chlorine and bromine, or with C (X') 3 groups wherein X'is selected from fluorine,

chlorine and bromine, hydroxyl groups, linear or branched Cl-Cl0 alkyl groups, linear or branched C1-C6 alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6-tetramethylpiperidine group; a hydroxyl group; a linear or branched C1-C6 alkoxyl group; an amine group; an N-alkyl (C1-C6) amine group; an N, N- dialkyl (C1-C6) amine group; a piperidine, piperazine or morpholine group; a carboxylic acid group; a chloro carbonyl (CO-C1) group; an amide group; a COOR'a ester group wherein R'a represents a linear or branched Cl-calo alkyl group; a benzyl group, said benzyl group option- ally substituted with 1-5 halogen atoms selected from <BR> <BR> <BR> <BR> <BR> fluorine, chlorine and bromine, or with C (X'3) groups wherein X'is selected from fluorine, chlorine and bro- mine, hydroxyl groups, linear or branched Cl-Cl0 alkyl groups, linear or branched Cl-C6 alkoxyl groups, car- boxyl groups, cyano groups, or with a 2,2,6,6- tetramethylpiperidine group; a Cl-C6 carboxyalkyl group; a C2-C6 carboxyalkenyl group; a carboxyamide group; an N-alkyl (C1-C6) carboxyamide group; an N, N- dialkyl (C1-C6) carboxyamide group; a cyano group; a nitro group; a sulfonic group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally substituted with N, N-dialkyl (Cl-C6) amine groups, linear or branched Cl-C6 alkoxyl groups, hy-

droxyl groups, linear or branched Cl-C6 alkyl groups; an acyl group of the alkyl ketone, aryl ketone or ben- zyl ketone type; a vinyl group; a (meth) allyl group; a (meth) acrylic group; a C3-C8 1-alkenyloxyl group; a li- near or branched C2-C6 alkenyl group, said alkenyl group optionally substituted with one or two N, N-di- alkyl- (Cl-C6)-4-aniline groups; an N-2,3-dihydroindo- line group; a linear or branched Cl-C6 thioether group; two consecutive substituents between R3 and R6 can rep- resent the condensation points with other aromatic, heterocyclic or quinonic rings; P represents a monocyclic or polycyclic aromatic nu- cleus, belonging to one of the following types: ben- zenic represented by general formula (VI); naphthalenic represented by general formula (VII); quinolinic repre- sented by general formula (VIII); isoquinolinic repre- sented by general formula (IX); cumarinic represented by general formula (X); quinazolinic represented by ge- neral formula (XI); phenanthrenic represented by gener- al formula (XII); anthracenic represented by general formula (XIII); or a group with general formula (XIV):

wherein: at least two consecutive substituents between R8 and andR21,R22andR28,R30andR35,R36andR41,R42R13,R14 and R47, R48 and R57, R58 and R67, R68 and R75, represent the condensation points with the oxazine or pyran ring, the other substituents having the meaning described for substituents R3, R4, R5 and R6; Xi represents an oxygen atom; a sulfur atom; a selenium

atom; an NH group; an NRa group wherein Ra represents a linear or branched Cl-calo alkyl group; Y represents CH or a nitrogen atom.

Preferred photochromatic compounds having general for- mula (I) for the purposes of the present invention, are those wherein: R'l represents an OH group; or a photochromatic com- pound having general formula (II); R'represents a linear or branched Cl-C4 alkyl group; a linear or branched C2-C4 acyl group; a hydroxyl group; a linear or branched Cl-C6 alkoxyl group; an amine group; an N-alkyl (Cl-C6) amine group; an N, N-dialkyl (C1-C6) amine group; a piperidine, piperazine or mor- pholine group; a carboxylic acid group; a chloro car- bonyl (CO-C1) group; a (meth) allyl group; a (meth)- acrylic group; a C3-C8 1-alkenyloxyl group; R''represents a hydrogen atom, a chlorine atom, a bro- mine atom, a methyl group, or a phenyl group; Y represents a nitrogen atom; or CH; P'represents one of the groups having general formula (III), (IV) or (V) wherein: R and R7, the same or different, represent one of the following groups: methyl, ethyl, isopropyl, 2- allyl, 2-methallyl, 2-hydroxyethyl, 2- carboxymethyl, phenyl, 4-N, N-dimethylaminoaniline,

4-methoxybenzene, 4-cyano-benzene; a linear or branched C1-C6 alkoxyl group; a linear or branched C2-C6 amine group; an N, N-dialkyl (Cl-C6) amine group; Ri and R2, the same or different, represent a methyl or phenyl group; or considered jointly with the carbon atom to which they are bound, represent a cyclohexyl group; -R3, R4, R5 and R6, the same or different, rep- resent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or one of the following groups: methyl, isopropyl, hy- droxyl, methoxyl, N, N-dimethylamine, piperi- dine, morpholine, carboxyl, carboxymethyl, N, N-dimethylcarboxyamide, cyano, nitro, meth- ylketone, phenylketone, phenyl; a linear or branched C1-C6 alkoxyl group; an amine group; an N-alkyl (Cl-C6) amine group; an N, N- dialkyl (Cl-C6) amine group; a piperidine, piperazine or morpholine group; a carboxylic acid group; an amide group; a chloro carbonyl (CO-C1) group; a COOR'a ester group wherein R'a represents a linear or branched Cl-Cl0 al- kyl group; -P represents one of the groups having general formula

from (VI) to (XIV), wherein: (a) two consecutive substituents between R8 and R13, R14 and R21, R22 and R28, R30 and R35, R36 and R41, R42 and R47, R49 and R57, R58 and R67, R68 and R75, in- dependently represent the condensation points with the oxazine or pyran ring; and the other substitu- ents each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or one of the following groups: methyl, isopropyl, 2- (meth) allyl, (meth) acryl, hydroxyl, methoxyl, 2- hydroxyethyl, amine, N-methylamine, N-ethylamine, N, N-dimethylamine, piperidine, morpholine, car- boxyl, carboxymethyl, N, N-dimethylcarboxyamide, cyano, nitro, methylketone, ethylketone, phenylke- tone, methylthiol; (b) two consecutive substituents between R8 and R13, R14 and R21, R22 and R28, R30 and R35, R36 and R41, R42 and R47, R48 and R57, R58 and R67, R68 and R75, dif- ferent from those indicated under point (a), rep- resent the condensation points with a benzene or a quinone ring; -X1 represents an oxygen atom; a sulfur atom; a selenium atom; an NH group.

Specific examples of preferred compounds according to the present invention are: - Compound having formula (Ia):

- Compound having formula (Ib):

- Compound having formula (Ic):

A further object of the present invention relates to a process for the preparation of the photochromatic compounds having general formula (I).

The photochromatic compounds having general formula (I) can be prepared by the condensation of photochromatic compounds having general formula (II): wherein the substituents R', R'', P, P'and Y have the same meanings described above, with a cyanuryl halide having gen- eral formula (XV): wherein X represents a halogen atom such as fluorine, chlo- rine, bromine or iodine, in the presence of an inert organic solvent such as, for example, acetone, ethyl alcohol, iso- propanol, toluene, dioxane, or of a mixture of these sol- vents, at a temperature ranging from 20°C to 100°C, prefera- bly from 20°C to 40°C, for a time ranging from 1 hour to 10 hours, preferably from 2 hours to 5 hours. The reaction product thus obtained is generally purified on a silica col-

umn, with subsequent crystallization from a solvent such as, for example, acetone, toluene, pentane, heptane, diethyl ether.

The photochromatic compounds having general formula (II) are obtained by the condensation of isoindoline com- pounds having general formula (XVI), or of indoline com- pounds having general formula (XVII), or of compounds deriv- ing from propargyl alcohol having general formula (XVIII), or of compounds deriving from a, p-unsaturated aldehydes hav- ing general formula (XIX), with nitroso compounds or alde- hyde compounds having general formula (XX), or with hydroxy- aryl compounds having general formula (XXI), to give the re- spective photochromatic compounds having general formula (XVIa), (XVIIa) and (XVIIIa), indicated in Schemes 1-4: Scheme 1 Scheme 2

Scheme 3 Scheme 4 wherein the substituents R, from Ri to R7, R'', Y and P have the same meanings described above and Y'represents an NO or CHO group.

The condensation reaction is carried out in the pres- ence of an inert organic solvent such as, for example, ethyl

alcohol, isopropanol, toluene, acetonitrile, or of a mixture of these solvents, and in the presence of an amine such as, for example, triethylamine, morpholine, piperidine, or of an acid such as, for example, paratoluenesulfonic acid, sulfu- ric acid, acid alumina, or of a metal complex such as, for example, titanium (IV) tetra-ethoxide, at a temperature rang- ing from 50°C to 100°C, preferably from 60°C to 75°C, for a time ranging from 1 hour to 10 hours, preferably from 2 hours to 3 hours. The reaction product thus obtained is gen- erally purified by elution on a silica column and subsequent crystallization from a solvent such as, for example, ace- tone, toluene, hexane, heptane, pentane, diethyl ether, di- chloromethane.

The isoindoline compounds having general formula (XVI) can be prepared according to processes known in the art and described, for example, in:"Tetrahedron" (1966), Vol. 22, page 2481 ;"Journal of Organic Chemistry" (1979), Vol. 44, page 1519 ;"Angewandte Chemie International (1968), Vol. 7, page 373.

The indoline compounds having general formula (XVII) can be prepared by the reaction of 2,3,3-trimethylindolenine compounds with an alkyl or (meth) allyl halide as described, for example, in Japanese patent application JP 03/176467.

The isoindoline compounds having general formula (XVI) and the indoline compounds having general formula (XVII),

are usually kept in the form of salts such as, for example, iodides, bromides, chlqrides, as the free base is very oxidable in air.

The compounds deriving from propargyl alcohol having general formula (XVIII) can be prepared by the reaction of ketone compounds with sodium acetylide in xylene or with a lithium acetylide/ethylenediamine complex as described, for example, in U. S. patents 5,585,042 and 5,238,981.

The compounds deriving from a, ß-unsaturated aldehydes having general formula (XIX) can be prepared according to the processes known in the art as described, for example, in Japanese patent application JP 48/016481; or in"Organic Synthesis" (1970), Vol. 50, page 66.

The nitroso compounds having general formula (XX) can be prepared by the reaction of phenol compounds with nitrous acid or butyl nitrite, as described, for example, in Italian patent IT 1,176,858.

The aldehyde compounds having general formula (XX) can be prepared by the reaction of phenol compounds with para- formaldehyde, hexamethylenetetramine, or acetic acid, fol- lowed by the addition of an aqueous solution of sulfuric acid at 60%-70%, as described, for example, in German patent DE 2,425,430.

The hydroxy-aryl compounds having general formula (XXI) are normally products which are commercially available such as, for example, P-naphthol or phenol.

Specific examples of isoindoline compounds having gen- eral formula (XVI), or indoline compounds having general formula (XVII), are the following:

A specific example of a nitroso compound having gen- eral formula (XX) is the following: A specific example of an aldehyde compound having general formula (XX) is the following:

The compounds having general formula (XV) are gener- ally products which are commercially available.

A specific example of a compound having general for- mula (XV) is the following: The photochromatic compounds having general formula (I) of the present invention are colourless or slightly yellow- coloured, crystalline products.

Their solutions in common organic solvents such as, for example, benzene, toluene, methanol, ethanol, when not ex- posed to light sources, are colourless or slightly yellow- coloured. These solutions, if exposed to a light source, either visible or ultraviolet, become blue or orange-red coloured. The colouring quickly fades when the light source is removed.

The photochromatic compounds having general formula (I) can be applied to the surface or incorporated in mass into the desired articles, using techniques already known in the

art and described hereunder.

Some polymeric photochromatic end-articles can be ob- tained with moulding techniques such as, for example, injec- tion or compression moulding, starting from polymers in which one or more of the photochromatic compounds having formula (I) are homogeneously dispersed in mass.

Alternatively, the photochromatic compounds having gen- eral formula (I) can be dissolved in a solvent, together with the polymeric material such as, for example, polymethyl methacrylate, polyvinyl alcohol, polyvinyl butyral, cellu- lose acetate butyrate or epoxy, polysiloxane, urethane resin. The mixture thus obtained is deposited on a transpar- ent support to form, after evaporation of the solvent, a photochromatic coating.

The photochromatic compounds having general formula (I) can also be added to a polymerizable monomer such as, for example, a meth (acrylic) or allyl carbonate monomer, so that, after polymerization carried out in the presence of a suitable initiator such as, for example, azo-bis (isobutyro- nitrile) in the case of the meth (acrylic) monomer or a per- oxyketal in the case of the allyl carbonate monomer, they are uniformly incorporated in the resin formed.

Finally, the photochromatic compounds having general formula (I) can be applied to a transparent substrate such as, for example, polycarbonate, polymethyl methacrylate or

polydiethyleneglycol bis (allyl carbonate), by surface im- pregnation obtained by putting the substrate in contact, at a suitable temperature, with a solution or dispersion con- taining one or more of the photochromatic compounds having general formula (I), operating according to a method de- scribed, for example, in U. S. patent 5,130,353.

The photochromatic compounds having general formula (I) of the present invention have the characteristic of being able to be incorporated in mass or using one of the tech- niques described above, into various organic polymers such as, for example, high density polyethylene (HDPE), low den- sity polyethylene (LDPE), ethylene-vinylacetate copolymer, polyether amides, polypropylene, polymethyl methacrylate, polyvinyl alcohol, polyvinyl butyral, cellulose acetate bu- tyrate, epoxy, polysiloxane or urethane resins, polycarbon- ate, polydiethylene glycol bis (allyl carbonate), polyamides, polyesters, polystyrene, polyvinylchloride, polyethy- lacrylate, siliconic polymers.

A further object of the present invention therefore re- lates to polymeric compositions comprising the above poly- meric materials and the above photochromatic compounds hav- ing general formula (I) and the photochromatic articles ob- tained from their processing.

The photochromatic compounds having general formula (I) of the present invention, are added to the above polymeric

compositions in a quantity ranging from 0.01% to 5% by weight, preferably between 0.1% and 2% by weight, with re- spect to the weight of said polymeric compositions.

The photochromatic compounds having general formula (I) of the present invention can also be added to coating compo- sitions, such as for example, paints, lacquers, paints or lacquers based on hybrid polysiloxanes and/or silica gel, compositions based on plastic materials. A further object of the present invention consequently relates to coating compo- sitions, such as for example, paints, lacquers, paints or lacquers based on hybrid polysiloxanes and/or silica gel, compositions based on plastic materials, comprising said photochromatic compounds.

The photochromatic compounds having general formula (I) of the present invention are added to the above coating com- positions in a quantity ranging from 0.01% to 5% by weight, preferably between 0.1% and 2% by weight, with respect to the weight of said coating compositions.

Paints or lacquers based on hybrid polysiloxanes and/or silica gel are obtained by means of the"sol-gel"process described, for example, by M. Nogami, Y. Abe in:"Journal of Materials Science" (1995), Vol. 30, pages 5789-5792.

The above coating compositions can be applied to the substrate (metal, plastic, wood, etc.) using the conven- tional methods such as, for example, brushing, spraying,

pouring, dipping or electrophoresis.

The photochromatic compounds having general formula (I) of the present invention can optionally be used in the pres- ence of usual additives for organic polymers such as, for example, phenolic antioxidants, sterically hindered amines, benzotriazoles, benzophenones, phosphites or phosphonites.

The photochromatic compounds having general formula (I) of the present invention which, as already mentioned above, are colourless or slightly yellow-coloured, can be used as such, mixed with each other, or combined with other suitable organic photochromatic compounds, in order to obtain, after activation, the formation of other colourings such as brown and grey. For this purpose, photochromatic compounds belong- ing to the group of spiro-indolino-oxazines or spiro-pyrans described in the art such as, for example, in U. S. patent 5,066,818, are particularly useful for the purpose.

Some illustrative examples are provided hereunder for a better understanding of the present invention and for its embodiment but in no way limit the scope of the invention.

EXAMPLE 1 Preparation of 1,1,2,4,7-pentamethyl-3-methylene-isoindol- ine iodide having formula (XVI')-A:

40 g of acetonylacetone, 12 g of methylamine hydro- chloride, 20 ml of water and 12 ml of ethyl alcohol are charged into a 100 ml flask, equipped with a reflux cooler and mechanical stirrer.

The above mixture is heated to 80°C, under a nitrogen atmosphere, for 24 hours. At the end, the mixture is cooled and subsequently extracted with 30 ml of hexane. The aque- ous phase obtained is treated with aqueous sodium hydrox- ide (solution 30%) until a pH of 14 is reached: a yel- low-white precipitate is thus formed, which is rapidly fil- tered and washed with 30 ml of water and 10 ml of hexane.

The product is dried under vacuum and conserved in a nitrogen atmosphere: the yield is 23.5 g. This product is identified as 1,2,3,4,7-pentamethyl-isoindoline by means of gas-mass (molecular weight = 187).

A quantity equal to 23.5 g of the above product is charged into a 100 ml stainless steel autoclave together with 20 ml of toluene and 16 g of methyliodide. The auto- clave is heated to 85°C and the whole mixture is maintained at this temperature, under a nitrogen atmosphere, for 6

hours. At the end, the autoclave is cooled to room tempera- ture and the raw product is filtered obtaining a crystal- line precipitate which is washed with 20 ml of ethyl ace- tate and finally with 20 ml of hexane.

35 g of product are obtained, corresponding to 1, 1,2,4,7-pentamethyl-3-methylene-isoindoline iodide having formula (XVI')-A. The free base, corresponding to Compound (XVI'), is identified by means of gas-mass (molecular weight = 201).

EXAMPLE 2 Preparation of the compound having formula (XVIa)-1 16 g of 2,7-dihydroxynaphthalene, 7.0 g of sodium ni- trate, 100 ml of water and 4.0 g of sodium hydroxide are charged into a 250 ml flask, equipped with a reflux cooler and mechanical stirrer.

The above mixture is stirred, under a nitrogen atmos- phere, until dissolution. 10.7 g of sulfuric acid diluted in 30 ml of water are subsequently added dropwise and the reac- tion temperature is maintained between 0°C and 5°C. After

30 minutes at this temperature, the reaction raw product is filtered, washed with water and dried in air. 18.6 g of a dark brown powder corresponding to 2,7-dihydroxy-1-nitroso- naphthalene, are obtained.

4 g of 1,1,2,4,7-pentamethyl-3-methylene-isoindoline iodide obtained as described in Example 1,2.8 g of 2,7- dihydroxy-1-nitroso-naphthalene, 2.5 g of triethylamine and 60 g of toluene are charged into a 250 ml flask, equipped with a reflux cooler and mechanical stirrer.

The above mixture is heated to 70°C and maintained at this temperature, under stirring, under a nitrogen atmos- phere, for 1 hour. The reaction raw product obtained is fil- tered and subsequently purified by passage on a silica gel column, eluating with a mixture of heptane/ethyl acetate in a ratio of 1/1.

An almost pure photochromatic product is obtained yellow solid), which is further purified by crystallization from toluene.

After crystallization, 2.5 g of a solid white product are obtained, corresponding to the compound having formula (XVIa)-1 which is identified by means of gas-mass (molecular weight 372).

EXAMPLE 3 Preparation of the compound having formula (XVIIa)-1:

18.6 g of 2,7-dihydroxy-l-nitroso-naphthalene, obtained as described in Example 2, are mixed with 17 g of 1,3,3- trimethyl-2-methylene-indoline and 30 ml of isopropyl alco- hol: the mixture obtained is maintained for 3 hours at re- flux temperature.

At the end of the reaction, the solvent is eliminated by distillation under vacuum and 40 ml of toluene and 2.0 g of activated carbon are subsequently added. This mixture is heated to 70 C for 15 minutes: the reaction raw product is filtered, concentrated and cooled.

The precipitated raw product is filtered obtaining 7.0 g of. raw product which is further crystallized from toluene obtaining a white solid corresponding to the Compound having formula (XVIIa)-1 which is identified by means of gas-mass (molecular weight = 344).

EXAMPLE 4 Preparation of the compound having formula (XVIIIa)-1:

1.66 g of 2,7-dihydroxynaphthalene diluted in 20 ml of anhydrous toluene are charged into a 250 ml flask, equipped with a reflux cooler and mechanical stirrer.

2.4 g of titanium (IV) tetra-ethoxide in 10 ml of anhy- drous toluene and 2.16 g of P-phenyl-cinnamaldehyde in 20 ml of anhydrous toluene are then added, under an inert atmos- phere: at the end of the additions, the mixture obtained is heated to 100°C for 5 hours.

This mixture is subsequently cooled to room temperature and the reaction raw product obtained is poured into an aqueous solution 2M of NH4Cl (100 ml) and heated to 80°C for an hour. At the end, the mixture is cooled again to room temperature and, after filtration of the titanium (IV) tetra- ethoxide, the organic phase is separated, washed with water and dried on magnesium sulfate. The solvent is partially re- moved at reduced pressure and the resulting solution is cooled to 0°C.

The crystallized product obtained is filtered and washed with heptane: a photochromatic product (yellow solid) is obtained.

After further crystallization, 2.1 g of a solid white product are obtained, corresponding to the compound having formula (XVIIIa)-1 which is identified by means of gas-mass (molecular weight = 350).

EXAMPLE 5 Preparation of the compound having formula (Ia): 2.2 g of triethylamine and 1 g of the compound having formula (XVIa)-1 obtained as described in Example 2 dis- solved in 45 ml of anhydrous toluene and 45 ml of acetoni- trile, are charged into a 250 ml flask, equipped with a re- flux cooler and mechanical stirrer.

0.2 g of cyanuryl chloride diluted in 10 ml of anhy-

drous toluene are subsequently added dropwise, at room tem- perature and under an inert atmosphere.

After 2 hours at room temperature, the reaction raw product is filtered and the solvent is eliminated by evapo- ration under vacuum. A light blue solid is obtained which is purified by repeated washings with 10 ml of diethyl ether and dried by evaporation under vacuum.

At the end of the above treatment, 1 g of product (white solid) is obtained, corresponding to the Compound having formula (Ia) which is identified by liquid chromatog- raphy coupled with a mass spectrometer (molecular weight = 1191).

EXAMPLE 6 Preparation of the compound having formula (Ib):

3 g of triethylamine and 1 g of the Compound having formula (XVII-a)-1 obtained as described in Example 3, dis- solved in 45 ml of anhydrous toluene and 45 ml of acetroni- trile are charged into a 100 ml flask, equipped with a re- flux cooler and mechanical stirrer.

0.24 g of cyanuryl chloride diluted in 20 ml of anhy- drous toluene are subsequently added dropwise, at room tem- perature and under an inert atmosphere.

After 1 hour at room temperature, the reaction raw product is filtered and the solvent is eliminated by evapo- ration under vacuum. A light green solid is obtained, which is purified by repeated washings with 10 ml of diethyl ether and dried by evaporation under vacuum.

At the end of the above treatment, 1.32 g of a product (white solid) are obtained, corresponding to the Compound having formula (Ib) which is identified by liquid chromatog- raphy coupled with a mass spectrometer (molecular weight = 1107).

EXAMPLE 7 Preparation of the compound having formula (Ic):

1.9 g of triethylamine and 1 g of the compound having formula (XVIII-a)-1 obtained as described in Example 4, dis- solved in 30 ml of anhydrous toluene are charged into a 100 ml flask, equipped with a reflux cooler and mechanical stir- rer.

0.213 g of cyanuryl chloride diluted in 10 ml of anhy- drous toluene are subsequently added dropwise, at room tem- perature and under an inert atmosphere.

After 2 hours at room temperature, the reaction raw product is filtered and the solvent is eliminated by evapo- ration under vacuum. A light orange solid is obtained, which is purified by repeated washings with 10 ml of diethyl ether and dried by evaporation under vacuum.

At the end of the above treatment, 0.5 g of a product (beige solid) are obtained, corresponding to the Compound having formula (Ic) which is identified by liquid chromatog-

raphy coupled with a mass spectrometer (molecular weight = 1125).

EXAMPLE 8 Evaluation of the photochromatic activity.

The photochromatic activity is evaluated in ethanol, at 25°C, of Compounds (Ia)- (Ic) obtained as described in Exam- ples 5-7.

Solutions are prepared at a concentration equal to 3.5* 10-5 of the various Compounds (Ia)- (Ic) in ethanol and subsequently 2 ml of each solution are placed in a 1 cm quartz cell.

The quartz cell containing the solution is introduced into a temperature control system, equipped with a magnetic stirrer (the solution is maintained under stirring during the measurement). The spectrum of the activated and deacti- vated forms and the decolouring kinetics are registered with a UV/visible spectrophotometer with a diode battery (HP 8453) equipped with perpendicular optical fibres which give a continuous monochromatic irradiation. The light source is a high pressure Hg lamp and the irradiation wave length is determined by monochromatic filters. This system allows the absorbance to be contemporaneously monitored at all wave- lengths.

The following parameters are determined using the meas- urements obtained as described above and with a calculation

effected with the GRAFit program of Erithaeus Software Ltd. for the mathematical treatment of the graphs: -tl/2 (s): time in which the absorbance of the merocya- nine open form is equal to half of the initial absorb- ance value; -ka (s-1): constant of the thermal reaction rate of the oxazine or spirane ring closing; <BR> <BR> _ XPMC (nm) : wave-length of the maximum absorbance of the merocyanine open form; -colourability: difference between the final absorbance and initial absorbance of the merocyanine open form.

The data obtained analyzing Compounds (Ia)- (Ic) are compared with the data obtained using Compounds (XVIa)-1, (XVIIa)-1 and (XVIIIa)-l: the data are indicated in Table 1.

TABLE 1 k##PMCCOLOURABILITYCOMPOUNDt1/2 (s) (s-1) (nm) (XVIa)-1 40 1. 4x10-2 612 0.70 (Ia) 6100.702.4x10-3 0.146070.10(XVIIa)-15 (Ib) 6 0. 11 609 0.30 5x10-24340.40(XVIIIa)-116 (Ic) 4310.257x10-2