Disclosed is a photochromic compound having a diaryl-3H-napthopyran structure, which has at the 8-position a nitrogen atom-linked hetercyclus, in which the heterocylcus can also have a HALS compound as a substituent or the heterocyclus itself can be formed as a HALS compound. Furthermore a photochromic compound is described having a diaryl-3H-naphtopyran structure which has at the 8-position an N-atom linked and an alkyl-bridge linked HALS compound.

This application is a national stage application (371) of PCT/DE96/02049, 
filed on Oct. 28, 1996. 
TECHNICAL FIELD 
The present invention relates to photochromic diaryl-3H-naphthopyrans. 
STATE OF THE ART 
Photochromic compounds possess the property that they change color 
reversibly under the influence of light containing a certain amount of 
ultra-violet radiation, such as for instance sunlight or the light from a 
mercury vapor lamp. This coloring is due to a bond opening in the pyran 
ring of the photochromic naphthopyran induced by the high-energy 
ultra-violet light. After removing the ultraviolet radiation source, the 
compound returns to its original closed state. 
A variety of classes of photochromic compounds have been known for some 
time and are used in various applications requiring reversible 
light-dependent coloring, by way of illustration by means of the 
ultraviolet part of the sunlight. 
A variety of methods for coloring plastic articles using photochromic 
compounds are described in the state of the art. With regard to this 
reference is made , by way of example, to U.S. Pat. No. 4,286,957, DE-A 35 
16 568 and EP 0 227 337 B1. 
The basic chemical structure of benzopyrans and naphthopyrans is described 
by Becker in U.S. Pat. No. 3,567,605. However these compounds, which were 
patented as early as in 1971, are hardly of significance for use in the 
production of photochromic articles, because their color is dependent on 
irradiation with ultraviolet light only at temperatures in the -40.degree. 
C. range. 
Moreover, U.S. Pat. No.: 5,066,818 discloses that photochromic compounds 
that are suited for use at normal temperatures are obtained by introducing 
at least one ortho-substituted phenyl group in the 3H-position of the 
pyran ring. These compounds can be employed, by way of illustration, in 
optical lenses or other transparent plastic articles. 
A further development of the general naphthopyran compounds known from U.S. 
Pat. No. 5,066,818 is described in U.S. Pat. No. 5,369,158. According to 
this printed publication, the photochromic naphthopyrans possess 
particularly advantageous properties if they are substituted at the 
8-position of the naphthalene portion. Compared to other naphthopyrans 
with substitutents in the 5-, 7- or 9- position, these photochromic 
compounds exhibit a considerable bathochromic shift of the absorption 
maximum in the activated as well as in the non-activated state. 
Furthermore, this shift leads to increased darkening velocity and greater 
optical density in the photochromic compound. 
The naphthopyrans of U.S. Pat. No. 5,369,158 have the following structure: 
##STR1## 
with R5 and R9 being H, C.sub.1 -C.sub.4 alkoxy or C.sub.1 -C.sub.4 alkyl, 
R8 being halogen, C.sub.1 -C.sub.5 acyloxy, benzoyloxy, methoxybenzoyloxy 
or di(C.sub.1 -C.sub.5)alkylamino or LO-, wherein L is C.sub.1 -C.sub.12 
alkyl, C.sub.6 -C.sub.9 aryl (C.sub.1 -C.sub.3) alkyl, C.sub.5 -C.sub.7 
cycloalkyl or C.sub.5 -C.sub.7 cycloalkyl substituted by C.sub.1 -C.sub.4 
alkyl and B and B' are substituted or unsubstituted phenyl or naphthyl, 
pyridyl, thienyl, benzothienyl, furyl or benzofuryl, with the substituent 
or substituents being C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 halogen 
alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 -alkoxy(C.sub.1 -C.sub.4) 
alkyl, di (C.sub.1 -C.sub.5) alkylamino or halogen provided that at least 
one of the residues B or B' is substituted or unsubstituted phenyl or B 
and B' together form an adamantane residue. 
Furthermore this printed publication mentions that ultra-violet absorbers 
or stabilizers like hindered amine functions (HALS) or singulet oxygen 
removers can be added to the photochromic compounds in order to improve 
the stability and the lifetime. 
Photochromic naphthopyrans having an amide substituent, which can be a 
acyclic amide, at the 9-position of the basic naphthopyran structure are 
known from PCT/WO 95/00867. This substitution causes the absorption 
maximum to shift into the longwave range but also results in diminished 
maximum darkening and slower darkening velocity.

DESCRIPTION OF THE INVENTION 
The object of the present invention is the description and the synthesis of 
photochromic compounds which possess improved properties compared to the 
compounds known from the state of the art, such as a good photochromic 
effect, a high darkening velocity, intense maximum darkening, a longwave 
absorption in the activated state, a rapid lightening velocity and a long 
lifetime. 
An element of the present invention was understanding that suited for 
solving this object :is a photochromic compound, which has a 
diaryl-3H-naphthopyran structure having at the 8-position a cyclic 
nitrogen base linked via a nitrogen atom, having the following structure: 
##STR2## 
with R1 and R2: hydrogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 
alkoxy 
B and B': 
##STR3## 
with R and R': C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 halogen alkyl, 
C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkoxy (C.sub.1 -C.sub.4) alkyl, 
di(C.sub.1 -C.sub.5, alyklamino, halogen, with halogen=F, Cl, Br 
and p, q: 0, 1, 2 
Y: --O--, --S--, N--R" with R"=C.sub.1 -C.sub.6 alkyl, phenyl, benzyl 
--(CZ.sub.2)--, 
with Z.dbd.H, C.sub.1 -C.sub.6 alkyl, and two Z also together C.sub.5 
-C.sub.7 cycloalkyl 
and m being an integer from 3 to 7 
with at least (m-1) residues Y being --(CZ.sub.2)--. 
These compounds are superior in various respects to the compounds known 
from the state of the art. 
The invented introduction of a cyclic nitrogen base at the 8 position of 
the diaryl-3H-naphthopyran improves the electron stabilizing effect of the 
substituents known from the state of the art, such as by way of example 
--OR, due to a stronger electron donator effect of the cyclic nitrogen 
base. This increased stabilization surprisingly leads only to a small 
shift of the absorption maximum of the non-activated form of the 
photochromic compound but to a great bathochromic shift of the absorption 
maximum of the activated form of the photochromic compound. 
The introduction of a cyclic nitrogen base instead of analog compounds 
having an open amine structure known from the state of the art improves 
the lifetime of the photochromic compound. 
Especially advantageous is if, according to claim 2, a class of compounds 
known as hindered amine light stabilizer (HALS) is introduced at the 
8-position of the diaryl-3H-naphthopyran structure. These substances, 
whose effect is based on the capture and inactivation of radicals, are 
utilized as light protection means in polymer materials. The 
conventionally employed HALS have two essential structural features. 
First, they have a free amine function (N--H), and second they possess 
steric hindrance, greatly space-filling groups in the immediate vicinity 
of this free amine function. 
Recently, polymer substances of the HALS type have also been developed. 
These polymer substances of the HALS type no longer have a free amine 
function, but rather are polymerized via a substituent at the nitrogen. 
However, like the conventional HALS they possess steric hindrance groups 
at the ortho-position for the amine function. Although the light 
protective effect of these new substances does not attain the quality of 
conventional HALS having a free amine function, it suffices for using 
these substances in the embodiment of the present invention described in 
claim 2. 
The introduction of the HALS substances into the basic 
diaryl-3H-naphthopyran structure by means of the N-atom linked cyclic 
nitrogen base occurs according to the present invention in such a manner 
that the ring of the cyclic nitrogen base is provided with the HALS 
properties. In addition to the N-atom, which represents the linking point 
to the diaryl-3H-naphthopyran structure, the cyclic nitrogen base has an 
amine function and at the ortho-position to this amine group it has a 
greatly space-filling substituent, such as by way of illustration 
tetramethyl, tert.-butyl or other branched or long-chain groups. 
The use of these substances, which are known as HALS substances, for light 
stabilization is described for instance in EP 0313 941 A1 or in the 
journal "farbe+lack", 95. Jahrgang, 10/1989, pp. 715 ff. Das Taschenbuch 
der Kunststoff Additive by Gachter/Muller, 2nd edition, Carl Hanser 
Verlag, describes on pp. 144 ff. the use of these HALS as additives for 
polymer mixtures. 
However, on the basis of this literature, known is only to add the 
substances to the polymer materials. None of the documents, however, 
mentions entering these compounds in a modified form of a cyclic nitrogen 
base into other molecules, such as by way of illustration photochromic 
dyestuffs. 
The described HALS compounds, which for example are obtainable under the 
tradenames TINUVIN, CHIMASORB, CYASORB; SPINUVEX or HOSTAVIN, are usually 
added to the photochromic compounds in concentrations of 0.01 to 5% in 
order to increase their lifetime. 
Introducing these substances directly into the diaryl-3H-naphthopyran 
structure at the 8-position, an N-atom linked cyclic nitrogen base from 
the hindered amine light stabilizer (HALS) compound, obviates adding these 
stabilizers later, thereby facilitating the use of the invented compounds 
in the manufacture of plastic articles having photochromic properties. The 
lifetime of the photochromic compounds is also improved, because the 
stabilizer is entered directly into the molecule. Undesired effects such 
as wrong dosage or demixing are thus prevented. In this way it is always 
ensured that an active HALS is always located in the vicinity of the 
dyestuff molecule. In conventional addition, this requires very high 
concentrations, which are partly no longer soluble in the monomer. 
Just as advantageous is to add the HALS compounds not immediately into the 
cyclic nitrogen base, but rather link them as a substituent directly or 
via an alkyl bridge --(CX2)n--, with X.dbd.H, C.sub.1 -C.sub.6 alkyl, and 
n is an integer from 0 to 6, to the cyclic nitrogen base. 
Moreover, it was recognized that suited for solving the object of the 
present invention are also substances which have a cyclic nitrogen base 
like the type of the HALS compounds which is linked via an alkyl 
bridge--(CX.sub.2).sub.n, with X.dbd.H, C.sub.1 -C.sub.6 alkyl, and is an 
integer from 0 to 6, with one N-atom being linked at the 8-position of the 
diaryl-3H-naphthopyran structure. The third valence of the N-atom can be 
free or can be substituted by C1-C.sub.6 alkyl. 
Although in this way the electron stabilizing properties of the cyclic 
nitrogen base are slightly weakened by the greater distance to the 
diaryl-3H-naphthopyran structure, the invented compounds are superior to 
the state of the art compounds due to the simultaneously occurring 
light-stabilizing effect of the HALS compound. 
Furthermore, as described the cyclic nitrogen base can also have a 
condensated on aromatic or heteroaromatic system or a condensated-on 
cycloalkyl ring. 
Examples for the cyclic nitrogen bases, which are introduced at the 
8-position of the diaryl-3H-naphthopyran structure via the N-atom are 
azetidine, pyrrolidine, piperidine, hexahyroazepine, heptamethylimine, 
morpholine, thiomorpholine, N-methylpiperazine, N-phenylpiperazine, 
indoline, isoindoline, benzoindoline, tetrahydrochinoline, 
tetrahydroisochinoline and N-methylimidazolidine.