EP1119572A1 - Photochromatic compounds, preparation, use in polymeric materials - Google Patents

Abstract

Photochromatic compounds having general formula (I). The above photochromatic compounds can be used in polymeric materials, obtaining photochromatic articles.

Description

PHOTOCHROMATIC COMPOUNDS, PREPARATION, USE IN POLYMERIC MATERIALS

The present invention relates to photochromatic compounds .

More specifically, the present invention relates to silylated photochromatic compounds, 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 compounds and the 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 characteristics, which belong to various groups of both organic and inorganic compounds such as, for example, those described in the texts "Photochromism", by G.H. Brown (Ed.), Vol. Ill of the Weissberger series "Techniques of Organic Chemistry", Wiley Interscience, New York (1971) and in "Photochromism: Molecules and Systems", by H. Dϋrr 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 photochromatic 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 new silylated photochromatic compounds which have good photochromatic characteris- tics , good fatigue resistance and good colourability char- acteristics .

The present invention therefore relates to photochromatic compounds having general formula ( I ) :

R-_{2 Rl ι} wherein:

X represents an oxygen atom; a sulfur atom; a selenium atom; an NH group; or an NR_a group wherein R_a represents a linear or branched Ci-Cio 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched Ci-Cβ alkoxyl groups, carboxyl groups, cyano groups, or with a 2, 2, 6, 6-tetramethylpiperidine group;

R'ι represents a linear or branched Ci-Cio alkyl group, said alkyl group optionally substituted with 1-10 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 Cι-C₃ 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-C₈ 1-alkenyloxyl group; a linear or branched C₂-C₆ alkenyl group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally substituted with linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, amine groups, N,N-dialkyl (Cι~C₆) amine groups; a COOR'_a ester group wherein R'_a represents a linear or branched Ci-Cio 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched Ci-Cε alkoxyl groups, carboxyl groups, cyano groups, or with a 2, 2, 6, 6-tetramethylpiperidine group; R' represents a hydrogen atom; an OH group; or a photochromatic compound having general formula (II) :

R' represents a linear or branched Ci-Cio alkyl group; a linear or branched C₂-Cι₀ acyl group; a linear or branched C₂-Cχo heteroalkyl group in which the heteroa- tom is selected from nitrogen, oxygen, sulfur and selenium; a vinyl group; a (meth) ally1 group; a (meth) acrylic group; a C₃-C₈ 1-alkenyloxyl group; R¹ ' represents a hydrogen atom; a halogen atom selected from fluorine, chlorine and bromine; a linear or branched Ci-Cβ alkyl group; a linear or branched Ci-Cβ alkoxyl group; a phenyl group; a phenoxyl group; P' represents one of the following groups having general 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 fluorine, chlorine and bromine, or with C(X')₃ groups wherein X' is selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cβ alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2, 6, 6-tetramethylpiperidine group; a vinyl group; a (meth)allyl group; a linear or branched C₂-C6 alkenyl group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally substituted with linear or branched Ci-Cε alkoxyl groups, carboxyl groups, amine groups, N,N-dialkyl (Ci-Cβ) amine groups; a COOR'_a ester group wherein R'_a represents a linear or branched Ci-Cio 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched Ci-Cβ 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 Cj-Cio alkyl group, said alkyl group optionally substituted with 1-10 halogen atoms selected from fluo-

G rine, chlorine and bromine, or with C(X')₃ groups wherein X' is selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Cι-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-C₈ 1- alkenyloxyl group; a linear or branched C₂-Cι₀ alkenyl group; a COOR'_a ester group wherein R'_a represents a linear or branched Ci-Cio 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched Ci-Cβ alkoxyl groups, carboxyl groups, cyano groups, or with a 2, 2, 6, 6-tetramethylpiperidine group; a linear or branched Ci-Cβ alkoxyl group; an N-alkyl (Ci-Cβ) amine group; an N,N-dialkyl (Cι-C₆) amine group; or Rj. and R₂, considered jointly with the carbon atom to which they are bound, represent a C₄-Cι₀ cycloalkyl group, said cy- cloalkyl group optionally substituted with halogen atoms selected from fluorine, chlorine and bromine, or with hydroxyl groups, linear or branched Ci-Cβ alkoxyl groups, carboxyl groups, cyano groups, amine groups, N- alkyl (Cι-C₃) amine groups, N,N-dialkyl (Cι-C₆) amine groups; an N,N-dialkyl (Cι-C₆) amide group; an aryl group selected from phenyl and biphenyl; a cyano group; R₃, R, R5 and Re, the same or different, represent a hydrogen atom; a halogen atom selected from fluorine, chlorine, bromine and iodine; a linear or branched C₁-C₆ alkyl group, said alkyl group optionally substituted 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 C_I-C_Θ alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6- tetramethylpiperidine 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched C1-C₁₀ alkyl groups, linear or branched Ci-Cε alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2, 6, 6-tetramethylpiperidine group; a hydroxyl group; a linear or branched Cι-C₆ alkoxyl group; an amine group; an N-alkyl (Ci-Cε) amine group; an N,N- dialkyl (Cι-C₆) amine group; a piperidine, piperazine or morpholine group; a Ci-Cβ carboxyalkyl group; a C₂-C₆ carboxyalkenyl group; a carboxyamide group; an N-alkyl (Cι-C₆) carboxyamide group; an N,N-dialkyl (Ci-Cβ) car-

I boxyamide group; a cyano group; a nitro group; a sul- fonic group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally substituted with N,N-dialkyl (Cι-C₆) amine groups, linear or branched Ci-Cβ alkoxyl groups, hydroxyl groups, linear or branched Ci-Cβ alkyl groups; an acyl group of the alkyl ketone, aryl ketone or benzyl ketone type; a vinyl group; a (meth)allyl group; a (meth) acrylic group; a C3-C8 1-alkenyloxyl group; a linear or branched C₂-C₆ alkenyl group, said alkenyl group optionally substituted with one or two N,N-dialkyl- (d- Cβ) -4-aniline groups; an N-2, 3-dihydroindoline group; a linear or branched Cι-C₆ thioether group; two consecutive substituents between R₃ and Rε can rep- resent the condensation points with other aromatic, heterocyclic or quinonic rings;

P represents a monocyclic or polycyclic aromatic nucleus, belonging to one of the following types: ben- zenic represented by general formula (VI); naphthalenic represented by general formula (VII); quinolinic represented by general formula (VIII); isoquinolinic represented by general formula (IX); cumarinic represented by general formula (X) ; quinazolinic represented by general formula (XI); phenanthrenic represented by gen- eral formula (XII); anthracenic represented by general

•j formula (XIII); or a group having general formula (XIV) :

TO

wherein: at least two consecutive substituents between R₈ and

Ri3, Ri4 and R_2i, R₂₂ and R₂₈, R29 and R₃₅, R₃e and R_i, R₂ and R₄ , R₄₈ and R₅ , R58 and R₆₇, Res and R₇₅, represent the condensation points with the oxazine or pyran ring, the other substituents having the meaning described for substituents R₃, R, R5 and Re;

Xi represents an oxygen atom; a sulfur atom; a selenium atom; an NH group; an NR_a group wherein R_a represents a linear or branched C1-C₁₀ alkyl group;

Y represents CH or a nitrogen atom; or R'₂ represents a compound having general formula

wherein R' ' ' , R'" If R' 2/ 3f R' 4/ R' S r R" 61

R^{, ,!} ₇, R'''₈, R'''9 and R' ' 'ιo , the same or different, represent a hydrogen atom; a linear or branched C1-C10 alkyl group, said alkyl group optionally substituted with 1-10 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 Ci-Cβ 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-C₈ 1- alkenyloxyl group; a linear or branched C₂-C₆ alkenyl group; an aryl group selected from phenyl, biphenyl and naphthyl, said aryl group optionally substituted with linear or branched Cχ-C₆ alkoxyl groups, carboxyl groups, amine groups, N,N-dialkyl (Ci-Cβ) amine groups; a COOR'_a ester group wherein R'_a represents a linear or branched Cχ-Cιo 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2, 6, 6-tetramethylpiperidine group; on the condition that at least one of the R'₂ substituents represents a photochromatic compound having general formula (II) and at least one of the R'₂ substituents represents a compound having general formula (XV) .

Preferred photochromatic compounds having general for- mula (I) for the purposes of the present invention, are those wherein:

X represents an oxygen atom; R'ι represents a methyl;

R'₂ represents an OH group; a photochromatic compound having general formula (II) ; a compound having general formula (XV) ;

R' represents a linear or branched C₁-C₄ alkyl group; a linear or branched C₂-C₄ acyl group; a linear or branched C₂-C₄ heteroalkyl group in which the heteroa- torn is selected from nitrogen, oxygen, sulfur and selenium; a (meth)allyl group; a (meth) acrylic group; a C₃- C₈ 1-alkenyloxyl group;

R' ' represents a hydrogen atom, a chlorine atom, a bromine atom, a methyl group, or a phenyl group; - Y represents a nitrogen atom; or CH;

P¹ 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-carbo- xymethyl, phenyl, 4-N,N-dimethylaminoaniline, 4- methoxybenzene, 4-cyanobenzene;

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, R , R5 and R5 , the same or different, represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or one of the following groups: methyl, isopropyl, hydroxyl, methoxyl, N,N-di- methylamine, piperidine, morpholine, carboxyl, carboxymethyl, N,N-dimethylcarboxyamide, cyano, nitro, methylketone, phenylketone, phenyl;

P represents one of the groups having general formula from (VI) to (XIV), wherein:

(a) two consecutive substituents between R₈ and R₃.₃, R_3.4 and R₂χ, R₂ and R₂₈, R₂₉ and R₃₅, R₃₆ and R₄₁, R₄₂ and R₄₇, R₄₈ and R₅₇, R₅₈ and R₆ , Ree and R₇₅, independently represent the condensation points with the oxazine or pyran ring; and the other substituents each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or one of the following groups: methyl, isopropyl, hydroxyl, methoxyl, 2-hydroxyethyl, 2- (meth) allyl, (meth)acryl, piperidine, morpholine, N,N-dime- thylamine, carboxyl, carboxymethyl, N,N-dime- thylcarboxyamide, cyano, nitro, methylketone, eth- ylketone, phenylketone, methylthiol;

(b) two consecutive substituents between R₈ and R13, R₁₄ and R₂₁, R₂₂ and R₂₈, R₂₉ and R₃₅, R₃6 and R41, R₄₂ and R₄₇, R₄₈ and R₅ , R₅₈ and R₆ , Res and R₇₅, different from those indicated under point (a) , represent the condensation points with the benzene or quinone ring;

Xi represents an oxygen atom; a sulfur atom; a selenium atom; an NH group;

R' ' ' represents a hydrogen atom; a methyl;

R* "ι, R' "2/ R'''3 and R'''₄ represent a methyl;

R"'s, R'"₆, R' "₇, R'''9 and R'''ιo represent a hydrogen atom;

R'''₈ represents a C₃-C₈ 1-alkenyloxyl group.

Specific examples of preferred compounds according to the present invention are:

Compound having formula (la)

f Compound having formula (lb)

Compound having formula (Ic⁾

<7 A further object of the present invention relates to a process for the preparation of 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, and compounds having general formula (XV) :

wherein R' ' ' R' I t R' 2/ R' 3f R' t R' 5 R' 6

R'''₇, R'''₈, R'''9 and R'''ιo have the same meanings described above, with silylated tetramers having general formula (I 'a) :

1& wherein the substituents R'ι and X have the same meanings described above, in the presence of an inert organic solvent such as, for example, acetone, acetonitrile, ethyl alcohol, isopropanol, toluene, dioxane, xylene, or a mixture of these solvents, at a temperature ranging from 50°C to 100°C, preferably from 60°C to 80°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 column, with subsequent crystallization from a solvent such as, for example, acetone, toluene, pentane, heptane, diethyl ether, or by repeated precipitations with methanol and dried with toluene. The photochromatic compounds having general formula (II) are obtained by the condensation of isoindoline compounds having general formula (XVI), or of indoline compounds having general formula (XVII), or of compounds deriving from propargyl alcohol having general formula (XVIII), or of compounds deriving from α, β-unsaturated aldehydes hav-

«5 ing general formula (XIX) , with nitroso compounds or aldehyde compounds having general formula (XX) , or with hydroxy- aryl compounds having general formula (XXI), to give the respective photochromatic compounds having general formula (XVIa), (XVIIa) and (XVIIIa) , indicated in Schemes 1-4:

SCHEME 1

SCHEME 2

SCHEME 3

(XXI)

(XVIII) (XVIIIa)

J2.0 SCHEME 4

(XVIIIa)

wherein the substituents R, from Ri to R₇, R¹', Y and P have the same meanings described above and Y' represents an NO or CHO group.

Said condensation reaction is carried out in the presence of an inert organic solvent such as, for example, ethyl alcohol, isopropanol, toluene, acetonitrile, or a mixture of said 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, titaniu (IV) tetra-ethoxide, at a temperature ranging 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 generally purified by elution on a silica column and subsequent crystallization from a solvent such as, for example, acetone, toluene, hexane, heptane, pentane, diethyl ether, di- chloromethane .

2.1 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, chlorides, 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 USA patents 5,585,042 and 5,238,981.

The compounds deriving from α, β-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.

2.2. 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, followed 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, β-naphthol or phenol.

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

Specific examples of nitroso compounds having general formula (XX) are the following:

The compounds having general formula (XV) can be prepared according to processes known in the art and de- scribed, for example, in patents USA 4,684,726, USA

2 + 4,946,880 and USA 5,051,458.

A specific example of a compound having general formula (XV) is the following:

CH₀

CH

CH,

O

The photochromatic compounds having general formula (I) of the present invention are colourless or yellow/brown col- oured, oily or crystalline products.

Their solutions in common organic solvents such as, for example, benzene, toluene, methanol, ethanol, when not exposed to light sources, are colourless or slightly yellow- coloured. These solutions, if exposed to a light source, ei- ther visible or ultraviolet, become blue. The colouring quickly decays 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.

2.5 Some polymeric photochromatic end-articles can be obtained with moulding techniques such as, for example, injection 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 general 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 transparent 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 met (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-

*T pregnation obtained by putting the substrate in contact, at a suitable temperature, with a solution or dispersion containing one or more of the photochromatic compounds having general formula (I), operating according to a method de- scribed, for example, in USA 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 techniques described above, into various organic polymers such as, for example, high density polyethylene (HDPE) , low density 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 relates to polymeric compositions comprising the above poly- meric materials and the above photochromatic compounds having general formula (I) and the photochromatic articles obtained 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

7 weight, preferably between 0.1% and 2% by weight, with respect 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 compositions, 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. Noga i, 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 conventional methods such as, for example, brushing, spraying, pouring, dipping or electrophoresis.

2Θ The photochromatic compounds having general formula (I) of the present invention can optionally be used in the presence 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 yellow/brown 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 belonging to the group of spiro-indolino-oxazines or spiro-pyrans described in the art such as, for example, in USA 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 itself. EXAMPLE 1

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

16 g of 2, 7-dihydroxynaphthalene, 7.0 g of sodium nitrate, 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 reaction temperature is maintained at 0°C to 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-l-nitroso-naph- thalene, are obtained.

18.6 g of 2, 7-dihydroxy-l-nitroso-naphthalene are mixed with 17 g of 1, 3, 3-trimethyl-2-methylene-indoline and 30 ml of isopropyl alcohol: the mixture obtained is maintained for 3 hours at reflux 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 a solid white product corresponding to the Compound having formula (XVIIa) -1 which is identified by gas-mass (molecular weight = 344) . EXAMPLE 2 Preparation of the compound having formula (XVIIa) -2 :

6.9 g of Compound (XVIIa) -1 obtained as described in Example 1, 25 ml of toluene, 25 ml of acetonitrile and 4 ml of triethylamine are charged into a 250 ml flask, equipped with a reflux cooler and mechanical stirrer, obtaining a so- lution which is not completely homogeneous. This solution is maintained under a stream of nitrogen to prevent the product from oxidation.

The above mixture is heated to 20 °C and a solution of 1.8 g of acryloyl chloride in 10 ml of toluene are added dropwise, obtaining a crystalline precipitate. After 10 minutes, 50 ml of water and 5.0 g of sodium carbonate are added; the mixture is stirred and the two phases are separated. The organic phase is concentrated under vacuum obtaining a dark oil which is cooled.

The precipitated raw product is filtered, obtaining 6.3 g of a solid white product corresponding to the Compound having formula (XVIIa) -2 which is identified by gas-mass (molecular weight = 398) . EXAMPLE 3

Preparation of 3 , 3-dimethyl-N-methyl-allyl-2-methylene-ind- oline iodide having formula (XVII¹) -A:

7,2 g of 2, 3, 3-trimethylindolenine, 8.1 g of potassium iodide, 5.4 g of allylamine hydrochloride, 20 ml of water and 12 ml of acetonitrile are charged into a 100 ml closed test-tube.

The above mixture is heated to 90°C for 8 hours. At the end, the raw product obtained is washed with water, with toluene and with hydrochloric acid until pH 7.

The aqueous phase is further washed with toluene, treated with aqueous sodium hydroxide (solution at 30%) until pH 14 is reached and with toluene. The organic phases obtained are concentrated and dried.

A pinkish-brown oil is obtained (yield: 8.3 g) , corresponding to 1, l-dimethyl-N-methyl-allyl-2-methylene-indoline iodide having formula (XVII¹) -A. The free base, corresponding to the compound having formula (XVII'), is identified by gas-mass (molecular weight = 213) . EXAMPLE 4 Preparation of the compound having formula (XVIIa) -3 :

(XVIIa)-3

1.7 g of 1, l-dimethyl-N-methyl-allyl-2-methylene-indol- ine iodide obtained as described in Example 3, 1.04 g of 1- nitroso-2-naphthol, 1 g of triethylamine and 8 ml of toluene, are charged into a 250 ml flask equipped with a reflux cooler and mechanical stirrer.

The above mixture is heated to 90°C and maintained at this temperature, under stirring, under a nitrogen atmosphere, for 6 hours. The raw reaction product obtained, is dried and repeatedly extracted with boiling heptane to which 1 g of activated carbon has been added. The heptane extracts are concentrated and boiled with an additional 0.6 g of activated carbon.

The reaction raw product obtained is filtered and subsequently purified by passage on a silica column eluating with a mixture of toluene/hexane in a ratio of 1/1.

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

After crystallization, 1.2 g of a solid white product are obtained, corresponding to the compound having formula (XVIIa) -3 which is identified by gas-mass (molecular weight = 368) . EXAMPLE 5

Preparation of 1,1,4, 7-tetramethyl-N-allyl-3-methylene-iso- indoline iodide having formula (XVI') -A:

40 g of acetonylacetone, 16 g of allylamine hydrochloride, 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 aqueous phase obtained is treated with aqueous sodium hydroxide (solution at 30%) until pH 14 is reached: a yellow-white precipitate is thus formed which is rapidly filtered 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 31.5 g. This product is identified as 1, 3, 4,7-tetramethyl-N-allyl-isoindoline, by gas-mass (molecular weight = 213) .

A quantity equal to 31.5 g of the above product is placed in a 100 ml inox steel autoclave together with 20 ml of toluene and 23.8 g of methyl-iodide. The autoclave is heated to 85°C and is maintained at this temperature, under a nitrogen atmosphere, for 6 hours. At the end, the autoclave is cooled to room temperature and the raw product is filtered obtaining a crystalline precipitate which is washed with 20 ml of ethyl acetate and finally with 20 ml of hexane.

43.6 g of product are obtained, corresponding to 1,1,- 4, 7-tetramethyl-N-allyl-3-methylene-isoindoline iodide having formula (XVI') -A. The free base, corresponding to Com- pound (XVI'), is identified by gas-mass (molecular weight = 227) . EXAMPLE 6 Preparation of the compound having formula (XVIa) -4 :

4 g of 1, 1, 4,7-tetramethyl-N-allyl-3-methylene-isoind- oline iodide obtained as described in Example 5, 2.6 g of l-nitroso-2-naphthol-6-propan (1) one, 2.3 g of triethylamine and 60 ml 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 atmosphere, for 1 hour. The reaction raw product obtained is filtered 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 (yellow solid) is obtained which is further purified by crystallization from toluene.

After crystallization, 2 g of a solid, white product are obtained, corresponding to the compound having formula (XVIa) -4 which is identified by gas-mass (molecular weight = 438) .

EXAMPLE 7 Preparation of the compound having formula (la)

0.20 g of 2, 4, 6, 8-tetramethylcyclotetrasiloxane of Al- drich (95%), a catalytic quantity of the complex platinum- divinyltetramethyl-disiloxane and 10 ml of anhydrous toluene are charged into a 100 ml flask, equipped with a reflux cooler and mechanical stirrer. The mixture is maintained at 80°C, under stirring and in a nitrogen atmosphere, for 5 minutes.

0.36 g of the Compound having formula (XV) dissolved in 10 ml of anhydrous toluene are then added: the mixture obtained is maintained at 100°C for 1 hour.

0.7 g of the Compound (XVIIa) -2, obtained as described in Example 2, dissolved in 30 ml of anhydrous toluene are then added: the mixture obtained is maintained at 80°C for 4 hours. At the end the solvent is eliminated by evaporation under vacuum.

The reaction raw product obtained is purified by repeated precipitations with methanol and dried with toluene.

0.60 g of a product (yellow/brown solid) are obtained, corresponding to the Compound having formula (la), which is identified by liquid chromatography coupled with a mass spectrometer (molecular weight = 1456.5) and NMR spectrum. The NMR data obtained are specified below: ²⁹Si-NMR: OSi(CH_n)₂0- at -20 ppm. EXAMPLE 8 Preparation of the compound having formula (lb) :

28 CH,

H₃ C , CH,

H₃ C CH,

0

0.20 g of 2, 4, 6, 8-tetramethylcyclotetrasiloxane of Al- drich (95%), a catalytic quantity of the complex platinum- divinyltetramethyl-disiloxane and 10.0 ml of anhydrous toluene are charged into a 100 ml flask, equipped with a reflux cooler and mechanical stirrer. The mixture is maintained at 80°C, under stirring and in a nitrogen atmosphere, for 5 minutes.

0.36 g of the Compound having formula (XV) dissolved in 10 ml of anhydrous toluene are then added: the mixture obtained is maintained at 100°C for 1 hour. 0.60 g of the Compound (XVIIa) -3, obtained as described

^ in Example 4, dissolved in 40 ml of anhydrous toluene are then added: the mixture obtained is maintained at 80°C for 5 hours. At the end the solvent is eliminated by evaporation under vacuum.

The reaction raw product obtained is purified by repeated precipitations with methanol and dried with toluene.

0.48 g of a product (yellow/brown oil) are obtained, corresponding to the Compound having formula (lb), which is identified by liquid chromatography coupled with a mass spectrometer (molecular weight = 1238.5) and NMR spectrum. The NMR data obtained are specified below: ²⁹Si-NMR: OSi(CH_n)₂0- at -20 ppm. EXAMPLE 9

Preparation of the compound having formula (Ic)

^< 0.26 g of 2, 4, 6, 8-tetramethylcyclotetrasiloxane of Al- drich (95%), a catalytic quantity of the complex platinum- divinyltetramethyl-disiloxane and 20 ml of anhydrous toluene are charged into a 250 ml flask, equipped with a reflux cooler and mechanical stirrer. The mixture is maintained at 80°C, under stirring and in a nitrogen atmosphere, for 5 minutes.

0.65 g of the Compound having formula (XV) dissolved in 25 ml of anhydrous toluene are then added: the mixture obtained is maintained at 100°C for 1 hour.

0.45 g of the Compound (XVIa) -4, obtained as described in Example 6, dissolved in 40 ml of anhydrous toluene are then added: the mixture obtained is maintained at 70°C for 4 hours . At the end the solvent is eliminated by evaporation under vacuum.

The reaction raw product obtained is purified by repeated precipitations with methanol and dried with toluene.

0.81 g of a product (yellow/brown oil) are obtained, corresponding to the Compound having formula (Ic), which is identified by liquid chromatography coupled with a mass spectrometer (molecular weight = 1308.5) and NMR spectrum. The NMR data obtained are specified below: ²⁹Si-NMR: OSi(CH_n)₂0- at -20 ppm. EXAMPLE 10 Evaluation of the photochromatic activity. The photochromatic activity is evaluated in ethanol, at 10°C, of Compounds (Ia)-(Ic) obtained as described in Examples 7-9.

Solutions are prepared at a concentration equal to 10^~4 M of the various Compounds (Ia)-(Ic) in ethanol and subsequently 2 ml of each solution is 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 deactivated 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 wavelengths. The following parameters are determined using the measurements obtained as described above and with a calculation effected with the GRAFit program of Erithaeus Software Ltd. for the mathematical treatment of the graphs: tι_/2 (s) : time in which the absorbance of the merocya- nine open form is equal to half of the initial absorb- ance value;

k_Δ (s^_1) : constant of the thermal reaction rate of the oxazine ring closing;

λ^PMC (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 (XVIIa) -2, (XVIIa) -3 and (XVIa) -4: Compounds (Ia)-(Ic) show an increase in the value of tι_/2 (s) .

The data obtained are indicated in Table 1.

TABLE 1

^3

Claims

1. Photochromatic compounds having general formula (I):

wherein :

X represents an oxygen atom; a sulfur atom; a selenium atom; an NH group; or an NR_a group wherein R_a represents a linear or branched Ci-Cio alkyl group; a benzyl group, said benzyl group option- ally 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 Ci-Cio alkyl groups, linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2, 2, 6, 6-tetramethylpiperidine group;

R'ι represents a linear or branched Ci-Cio alkyl group, said alkyl group optionally substituted with 1-10 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 Ci-Cβ 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-C₈ 1-alkenyloxyl group; a linear or branched C₂-C₆ alkenyl group; an aryl group selected from phenyl, diphenyl and naphthyl, said aryl group optionally substituted with linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, amine groups, N,N-dialkyl (Ci-Cβ) amine groups; a COOR'_a ester group wherein R'_a represents a linear or branched Ci-Cio 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-C-io alkyl groups, linear or branched Cχ-C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6- tetramethylpiperidine group;

R'₂ represents a hydrogen atom; an OH group; or a photochromatic compound having general formula (II):

R¹ represents a linear or branched Ci-Cio alkyl group; a linear or branched C₂-Cι₀ acyl group; a linear or branched C₂-Cιo heteroalkyl group in which the heteroatom is selected from nitrogen, oxygen, sulfur and selenium; a vinyl group; a (meth) allyl group; a (meth) acrylic group; a C₃-Cs 1-alkenyloxyl group; R' ' represents a hydrogen atom; a halogen atom se- lected from fluorine, chlorine and bromine; a linear or branched Cι-C₆ alkyl group; a linear or branched Ci-Cβ alkoxyl group; a phenyl group; a phenoxyl group; P' represents one of the following groups having general formula (III), (IV) or (V):

R

4^

₇ ,R

( 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 fluorine, chlorine and bromine, or with C(X')₃ groups wherein X' is selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2, 6, 6-tetramethylpiperidine group; a vinyl group; a (meth) allyl group; a linear or branched C₂-C₆ alkenyl group; an aryl group selected from phenyl, diphenyl and naph- thyl, said aryl group optionally substituted with linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, amine groups, N,N-dialkyl (Cι-C₆) amine groups; a COOR'_a ester group wherein R'_a represents a linear or branched Ci-Cio 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched Cι-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 fluorine, chlorine and bromine, or with C(X')₃ groups wherein X' is selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Cι-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-Cs 1-alkenyloxyl group; a linear or branched C₂-Cι₀ alkenyl group; a COOR'_a ester group wherein R'_a represents a linear or branched Cι-Cι₀ 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, lin-

H ear or branched Cι-C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2, 2, 6, 6-tetramethylpiperidine group; a linear or branched Cι-C₆ alkoxyl group; an N-alkyl (Cχ-C₆) amine group; an N,N-dialkyl (Cι-C₆) amine group; or Ri and R₂, considered jointly with the carbon atom to which they are bound, represent a C₄-Cι₀ cycloalkyl group, said cycloalkyl group optionally substituted with halogen atoms selected from fluorine, chlorine and bro- mine, or with hydroxyl groups, linear or branched

Ci-Ce alkoxyl groups, carboxyl groups, cyano groups, amine groups, N-alkyl (Ci-Cβ) amine groups, N,N-dialkyl (Ci-Cδ) amine groups; an N,N-dialkyl (Ci-Cε) amide group; an aryl group selected from phenyl and diphenyl; a cyano group;

R₃, R₄, R₅ and Re, the same or different, represent a hydrogen atom; a halogen atom selected from fluorine, chlorine, bromine and iodine; a linear or branched Cι-C₆ alkyl group, said alkyl group op- tionally substituted 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, hydroxyl groups, linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2, 2, 6, 6-tetramethylpiperid-

^ ine 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched d_.- C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2, 6, 6-tetramethylpiperidine group; a hydroxyl group; a linear or branched Ci-Cβ alkoxyl group; an amine group; an N-alkyl (Cι-C₆) amine group; an N,N-dialkyl (Ci-Cβ) amine group; a piperidine, piperazine or morpholine group; a ι-Cζ carboxyalkyl group; a C₂-C₆ carboxyalkenyl group; a carboxyamide group; an N-alkyl (Cι-C₆) carboxyamide group; an N,N-dialkyl (Ci-Cβ) carboxyamide group; a cyano group; a nitro group; a sulfonic group; an aryl group selected from phenyl, diphenyl and naph- thyl, said aryl group optionally substituted with N,N-dialkyl (Ci-Cβ) amine groups, linear or branched Ci-Cβ alkoxyl groups, hydroxyl groups, linear or branched Cι-C₆ alkyl groups; an acyl group of the alkyl ketone, aryl ketone or benzyl ketone type; a vinyl group; a (meth) allyl group; a (meth) acrylic group; a C₃-C₈ 1-alkenyloxyl group; a linear or branched C₂-C₆ alkenyl group, said

0 alkenyl group optionally substituted with one or two N,N-dialkyl- (Ci-Ce) -4-aniline groups; an N-2,3- dihydroindoline group; a linear or branched Cι-C₆ thioether group; two consecutive substituents between R₃ and Re can represent the condensation points with other aromatic, heterocyclic or quinonic rings; P represents a monocyclic or polycyclic aromatic nucleus, belonging to one of the following types: benzenic represented by general formula (VI); naph- thalenic represented by general formula (VII) quinolinic represented by general formula (VIII) isoquinolinic represented by general formula (IX) cumarinic represented by general formula (X) quinazolinic represented by general formula (XI) phenanthrenic represented by general formula (XII) anthracenic represented by general formula (XIII) or a group having general formula (XIV) ;

wherein:

at least two consecutive substituents between R₈ and R₁₃, R₁ and R₂ι, R₂ and R₂₈, R₂₉

and R₃s, R₃e and R_4i, R₄₂ and R₄₇, R₈ and R₅₇, R₅₈ and R₆₇, Res and R7₅, represent the condensation points with the oxazine or pyran ring, the other substituents having the meaning described for substituents R₃, R , R5 and Re; Xi represents an oxygen atom; a sulfur atom; a selenium atom; an NH group; an NR_a group wherein R_a represents a linear or branched Cχ-Cιo alkyl group;

Y represents CH or a nitrogen atom; or R'₂ represents a compound having general formula (XV) :

wherein R¹ R' I t R' 2 , R' 3, R' 4, R" S i

R'''₆, R'''₇, R'''₈, R'''₉ and R'''ιo , the same or different, represent a hydrogen atom; a linear or branched Ci-Cio alkyl group, said alkyl group optionally substituted with 1-10 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 Cι-C_δ 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-C₈ 1-alkenyloxyl group; a linear or branched C₂-C₆ alkenyl group; an

⁵^- aryl group selected from phenyl, diphenyl and naph- thyl, said aryl group optionally substituted with linear or branched Ci-Cβ alkoxyl groups, carboxyl groups, amine groups, N,N-dialkyl (Cι-C₆) amine groups; a COOR'_a ester group wherein R'_a represents a linear or branched Ci-Cio 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 selected from fluorine, chlorine and bromine, hydroxyl groups, linear or branched Ci-Cio alkyl groups, linear or branched Cι-C₆ alkoxyl groups, carboxyl groups, cyano groups, or with a 2,2,6,6- tetramethylpiperidine group; on the condition that at least one of the R'₂ substituents represents a photochromatic compound having general formula (II) and at least one of the R'₂ substituents represents a compound having general formula (XV) . 2. The photochromatic compounds having general formula (I) according to claim 1, wherein:

X represents an oxygen atom; R'ι represents a methyl;

R^f ₂ represents an OH group; a photochromatic compound having general formula (II); a compound hav- ing general formula (XV) ; R' represents a linear or branched Cχ-C₄ alkyl group; a linear or branched C₂~C₄ acyl group; a linear or branched C₂-C₄ heteroalkyl group in which the heteroatom is selected from nitrogen, oxygen, sulfur and selenium; a (meth) allyl group; a (meth) acrylic group; a C₃-C₈ 1-alkenyloxyl group;

R' ' represents a hydrogen atom, a chlorine atom, a bromine atom, a methyl group, or a phenyl group; Y represents N 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-hydroxy- ethyl, 2-carboxymethyl, phenyl, 4-N,N-dime- thylaminoaniline, 4-methoxybenzene, 4-cy- anobenzene;

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, represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, or one of the

;f following groups: methyl, isopropyl, hydroxyl, methoxyl, N,N-dimethylamine, piperidine, morpholine, carboxyl, carboxymethyl, N,N-dimethylcarboxyamide, cyano, nitro, meth- ylketone, phenylketone, phenyl;

P represents one of the groups having general formula from (VI) to (XIV), wherein:

(a) two consecutive substituents between R₈ and R13, i4 and R₂ι, R₂₂ and R₂₈, R₂₉ and R₃₅, R₃e and R₄ι, R₂ and R₄₇, R₄₈ and R₅₇, Rss and Rβη,

Res and R₇₅, independently represent the condensation points with the oxazine or pyran ring; and the other substituents each independently represent a hydrogen atom, a fluo- rine atom, a chlorine atom, a bromine atom, or one of the following groups: methyl, isopropyl, hydroxyl, methoxyl, 2-hydroxyethyl, 2- (meth) allyl, (meth)acryl, piperidine, morpholine, N,N-dimethylamine, carboxyl, car- boxymethyl, N,N-dimethylcarboxyamide, cyano, nitro, methylketone, ethylketone, phenylketone, methylthiol;

(b) two consecutive substituents between R₈ and R₁₃, Ri4 and R₂₁, R₂₂ and R₂₈, R₂₉ and R₃₅, R₃e and R₄ι, 42 and R₄₇, R₄₈ and R57, 58 and Rό7,

⁵f R_S8 and R₇₅, different from those specified under point (a) , represent the condensation points with the benzene or quinone ring; Xi represents an oxygen atom; a sulfur atom; a selenium atom; an NH group; R' ' ' represents a hydrogen atom; a methyl; R'''ι, R'^{, !} ₂, R^,!,3 and R'''₄ represent a methyl; R'''₅, R'''₆, R'"7, R'"9 and R'''ιo represent a hydrogen atom;

R'''s represents a C₃-C₈ 1-alkenyloxyl group. The photochromatic compound having general formula (I) according to claim 1 or 2, consisting of the compound having formula (la) :

CH₃

I

H, C CH,

H, C CH,

0

CH₂ 0

5S> The photochromatic compound having general formula (I) according to claim 1 or 2, consisting of the compound having formula (lb):

5. The photochromatic compound having general formula (I) according to claim 1 or 2, consisting of the compound having formula (Ic) :

") ,

6. A process for the preparation of the photochromatic compounds having general formula (I) according to any of the previous claims, comprising the condensation of photochromatic compounds having general formula (II):

wherein the substituents R', R'¹, P, P' and Y have the same meanings described above, and compounds having general formula (XV) : wherein R'", R"'ι, R' ' '₂, R'"₃, R' ' ' , R^{, M} ₅, R'''Θ, R'''₇, R'''s, R'''₉ and R'''ιo have the same meanings described above, with silylated tetramers having general formula (I 'a):

wherein the substituents R'ι and X have the same meanings described above, in the presence of an inert organic solvent, at a temperature ranging from 50°C to 100°C, for a time ranging from 1 hour to 10 hours. The process according to claim 6, wherein the inert organic solvent is selected from: acetone, acetonitrile, ethyl alcohol, isopropanol, toluene, dioxane, xylene, or from mixtures of these solvents. The process according to claim 6 or 7, wherein the re-

4 action temperature ranges from 60°C to 80°C.

9. The process according to claim 6, 7 or 8, wherein the reaction time ranges from 2 hours to 5 hours.

10. Polymeric compositions comprising at least one photo- chromatic compound according to any of the claims from

1 to 9, and at least one organic polymer selected from high density polyethylene, low density polyethylene, ethylene-vinylacetate copolvmer, polyether amides, polypropylene, polymethyl methacrylate, polyvinyl alco- hoi, polyvinyl butyral, cellulose acetate butyrate, epoxy, polysiloxane or urethane resins, polycarbonate, polydiethylene glycol bis (allyl carbonate), polyamides, polyesters, polystyrene, polyvinyl chloride, polyethyl- acrylate, siliconic polymers. 11. Coating compositions, such as paints, lacquers, paints or lacquers based on hybrid polysiloxanes and/or silica gel, compositions based on plastic materials, comprising one or more of the photochromatic compounds having general formula (I) according to any of the claims from 1 to 9.

12. The compositions according to claim 10 or 11, comprising additives for organic polymers selected from phenol antioxidants, sterically hindered amines, benzotriazoles, benzophenones, phosphites or phosphonites. 13. Photochromatic articles obtained from the processing of

%. the compositions according to any of claims 10, 11 or 12. 14. Mixtures comprising at least one photochromatic compound having general formula (I) according to any of the claims from 1 to 9 and at least one photochromatic compound belonging to the group of spiro-indolino- oxazines or spiro-pyrans.

ώ