Claims
- 1. A dicyanovinylsubstituted furan compound of the formula ##STR18## wherein A.sub.1 is CH.sub.2 OR.sup.1, and wherein R.sup.1 is H or a C.sub.1 -C.sub.8 alkyl, phenyl, p-hydroxyphenyl, p-nitrophenyl, p-dimethylamino phenyl, naphthyl, 2-pyridyl, trimethylsilyl, triphenylsilyl, acetyl, palmitoyl, benzoyl, p-nitrobenzoyl, methanesulfonyl, p-toluenesulfonyl, phosphonyl, 2-methoxyethyl or 4-methoxybutyl group.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 3718917 |
Jun 1987 |
DEX |
|
Parent Case Info
This application is a continuation-in-part of application Ser. No. 195,754 filed May 19, 1988.
Dicyanovinyl substituted furan derivatives, process for obtaining them and their applications.
The present invention refers to novel furan derivatives according to the general formula I shown in claim 1, which, as a result of their properties, are suited in a special way among others for electro-optical applications.
Compounds, which are capable of producing a dye-stuff and therefore an image, by light-absorption, without any developing or washing processes, can be utilized in optical informational recording- or processing systems. Because it is possible with these substances to make grain-free layers, very great storage densities are reachable (Chemiker-Zeitung 96, 535 (1972)).
Spiropyranes as those like formula 1 ##STR2## (comp. JP 61 18 782 (86 18 782); Chem. Abstr. 105, 78 849 q (1986)) belong to substances, which can be changed by UV-exposure to coloured compounds and which can be discoloured by heat influence.
The applications and advantages of reversible photochromic substances are described in "Chemie in unserer Zeit" 9, 85 (1975), namely the high optical resolution (high storage density), the control of exposure during the "writing", and the possibility of erasure or changing of parts of a picture.
In Kirk-Othmer, Encyclopedia of chemical technology 3. Ed. Vol. 6, 122 (1979) are mentioned as disadvantages of organic photochromic materials: small spectral shifts, slow reversal times, fatigue, or any combination of the three.
As class of substances, where a valence tautomerism is responsible for the chromogenic behaviour spiropyranes and fulgides are mentioned. The former can be partly built in a polymer by co-polymerisation with a suitable monomer. Fulgide belong also to the more intensely studied photochromic systems (comp. e.g. Chem. Abstr. 102, 229 304z (1985), GB 2 142 011 cited in Chem. Abstr. 103, 79 543 f (1985) with compounds of formula 2). ##STR3## In Angew. Chem. 96, 980 (1984) a system is described, in which a dihydroazulene derivative via light absorption is transformed in a coloured heptafulvene derivative which cyclizes by heat treatment again to the dihydroazulene. In contrast to R.dbd.NO.sub.2 the system 3 A.revreaction.3 B ##STR4## is chemically stable for R.dbd.OCH.sub.3, i.e. an at least 15-fold fore- and backreaction doesn't change the extinction coefficient. No side reactions or irreversible degradation takes place.
The above described photochromic system is synthesized according to the following reaction sequence: ##STR5## 8-Methoxyheptafulvene is accessible in two steps and good yield starting from cyclooctatetraene. A disadvantage of the applied p-anisaldehyde (R.dbd.OCH.sub.3) is the absence of a functional group, which would allow to connect the photochromic product in a suitable manner e.g. covalently to polymers.
1. The electronic influence of a furan ring on bound substituents is comparable with this of an O-alkylbenzene ring, i.e., that furfuraldehyde reacts similarly as anisaldehyde (p-methoxybenzaldehyde).
2. The hydroxymethyl group in HMF enables, as additional functional group, a coupling to an oligo- or polymer. Such a bonding is mentioned clearly as an advantage in the case of spiropyranes ( Kirk-Othmer, Encyclopedia of chemical technology 3. Ed. Vol. 6, 122 (1979). A derivatization at the hydroxymethyl group allows also a systematic control of the solubility.
3. Typical carbonyl reactions allow too, through a condensation with amines and a following oxidation of the hydroxymethyl group to the aldehydic state, to prepare e.g. compounds with formula 5, ##STR7## which are obtained via Knoevenagel-reaction with malononitrile.
4. The possibility to "build" different bridges between two furans, allows a perturbation of the dicyanovinyl groups and so a variation of the electron acceptor ability or of the di- or polyeneophilic properties.
5. 5-Hydroxymethylfurfuraldehyde has as starting component additionally the great advantage to be prepared in a single reaction step from renewable raw material (carbohydrate) and moreover on large-scale with water as sole solvent. Especially, the utilization of agricultural, (occasionally) on surplus produced carbohydrates e.g. sucrose, in technical fields via the intermediate HMF shows the advantage of the inventive dicyanovinylsubstituted furans.
6. Another surprising advantage of furylidenemalononitriles compared with phenylanaloga is e.g. the full reversibility of the reduction of compound 6, as shown by cyclovoltammatry. Compound 7 is under the same conditions not reversibly reducible. This is also to see in connection with the substituent effect mentioned in 1. ##STR8## This means, that the compound 6 similar to tetracyanoquinodimethane (TCNQ) (formula 8) ##STR9## which can be reversibly reduced also in a twofold one-electron reaction, can be used as component of so-called "organic metals", or an electron-storage system or electron-transfer-catalyst.
The spectroelectrochemistry of 6 shows reversible electrochromic behaviour. An application in displays is possible because of the good reversibility of the electron absorption.
A combination of photochromic and electrochromic behavior is observed with the cycloadduct of compound 6 with 8-methoxyheptafulvene (CH.sub.3 OH is eliminated) prepared in Example 4. The different electrochemical reactivities of the dihydroazulene form 13A and the heptafulvene form 13B make the cycloadduct useful in opto-electronic devices.
When compound 13A (in solution) is exposed to light, it is converted into 13B. The reverse reaction of 13B to 13A is so fast at ambient temperature that a change in color is not observed. If there is a potential difference of -1050 mV (vs. ferrocene as the standard) between a transparent electrode containing a solution of the cycloadduct and a counter-electrode, an electron transition takes place and current will flow, when form 13B is generated by exposure to pulses of light. When the exposure to the light pulses is ended, the current ceases to flow.
A cell of the type described above is suitable for use in information processing because a sequence of light pulses can be converted into a sequence of current pulses. It is also suitable for use in modulating an electric current by variable light irradiation (photomodulation of an electric current by light). It can also be used as "light switch", since a unit (machine, lamp or the like) can be switched on or off by a light pulse after its conversion into an electric pulse by means of a appropriate electronic circuit.
Details due to the reduction of 6, as determined by cyclovoltammetry under aprotic conditions under formation of 6.sup..-, respectively 6.sup.2- as well as to the absorption spectrum of the radical anion and the dianion formed and obtained by spectroelectrochemistry are shown in FIG. 1 and 2. Radical anion 6.sup..- displays a rather narrow absorption band at .lambda.=599 nm (dark blue solution) with a high extinction coefficient. Thus, contrarily to the radical anion 8.sup..- of TCNQ with an absorption at .lambda.=840 nm, radical anion 6.sup..- absorbs in the visible part of the spectrum.
The reversible reducibility of alkylidene malononitriles is mentioned in Angew. Chem. 88, 311 (1976). The formation of radical anions of tetracyanoethylene or TCNQ is also described in Kirk-Othmer, Encyclopedia of chemical technology 3. Ed. Vol. 7, 359, 362 (1979).
A correlation between reversible redox properties (electrochemistry) and chromogenic features (photochemistry) appears too in the long-known class of fulgides. Thus, in J. Amer. Chem. Soc. 106, 7626 (1984) is described, that the reversible generated radical anion of formula 9 reacts in an electro-cyclic reaction to a structure similar to the ring-closed, photochemically produced of chromogenic fulgides. ##STR10## In Angew. Chem. 90, 927 (1978) tetracyano compounds are mentioned among others too, and applications of these two-step redox systems as redox indicators, electron acceptors, catalyst for electron transfer, light-sensitive systems and electron conducting materials are mentioned.
The furylidenmalononitriles described in this invention can therefore be characterized as important new substance class for electro-optical applications.
7. An advantage of furanic substituents at the dihydroazulene residue is also the rapid back-reaction of the coloured heptafulvene structure after light exposure, which is favoured in addition to electron withdrawing substituents for A, e.g. A.dbd.A.sup.1 .dbd.CH.dbd.C(CN).sub.2, NO.sub.2. A slow back-reaction is mentioned in Kirk-Othmer, Encyclopidia of chemical technology 3. Ed. Vol. 6, 124 (1979), as an explicit disadvantage of organic photochronic materials. For a fast optical information-storing and -processing, furylidenmalononitrile-derivatives, analogous to 5 , meet ideal preconditions.
8. Another advantage of the dihydroazulene-heptafulvene-systems 3A.revreaction.3B (R.dbd.OCH.sub.3) is also the relatively great shift from about 380 nm to about 470 nm with a simultaneous increase of the extinction coefficient. Processes for producing 3- and/or 4-substituted HMF-derivatives are described e.g. in Carbohydr. Res. 155, 99 (1986), where via the oxidation of 1,2; 4,5-diisopropylidenfructose followed by a Grignard-reaction und dehydratisation several 3-substituted HMF-derivatives are synthesized e.g. formula 10 ##STR11##
Other substituents can be introduced in the furan ring according to the rules of the chemistry of aromatic compounds. The 3- or 4-substituted HMF-derivatives are further reacted as the unsubstituted HMF.
The preparation of compounds with n=0 and A.dbd.A.sub.1 .dbd.CH.sub.2 OR.sup.1 is achieved by an etherification or esterification e.g. with acetic anhydride of HMF followed by a Knoevenagel-condensation. ##STR12## one starts from HMF and a suitable ortho-disubstituted phenyl derivative and makes first the aminal or O, N- or S, N-acetal, which is oxidized in one step e.g. with BaMnO.sub.4 to the aromatic (e.g. Benzimidazol) and at the same time to the aldehydic stage (from the hydroxymethyl group).
The crossed benzoin addition with HMF or derivatives thereof as e.g. 5-acetoxymethylfurfuraldehyde followed by oxidation leads to compounds e.g. of formula 11 ##STR13## The oxidation of the deacetylated compound and Knoevenagel-condensation with malononitrile yields compounds according to formula ##STR14## General manufacturing method for n=1 and A.dbd.A.sub.2 .dbd.--CH.dbd.N----Z----N.dbd.CH--:
The diamino compound is dissolved in a suitable solvent optionally as hydrochloride or a similar salt, e.g. hydrazine hydrochloride or -hydrogenesulfate in water or ethylenediamine, 1,12-diaminododecane or p-phenylenediamine in methylene chloride. To the stirred solution two mol equivalents of HMF, is dropped slowly at room temperature dissolved in a suitable solvent, e.g. water or methylene chloride.
Either a solid precipitates in a short time, which is optionally recrystallized but also can be used often directly in the following oxidation step, or it has to be heated for the formation of the Schiff base and/or water removing agents had to be added. The conditions for the formation of Schiff bases are described e.g. in J. March, Advanced Organic Chemistry 3. Ed., 1985 J. Wiley & Sons, Inc., New York, S. 796-798.
The oxidation of the both hydroxymethyl groups in these amine-HMF-condensation products can be achieved e.g. with active manganese dioxide or barium manganate. In contrast to the literature, Synthesis 1976, 133, where it is started that azines are unstable in the presence of manganese dioxide, the oxidation of the HMF-azine is possible. In the inventive process other oxidants (besides the mentioned manganese compounds), which are able to oxidize hydroxymethyl groups to the aldehydic stage, are not excluded. Thin layer chromatographically the oxidation progress can be followed. The oxidation can be made in benzene, toluene or trichloroethane eventually with concomitant azeotropic destillative removing of the reaction water.
The obtained dialdehydes are reacted with malononitrile according the common procedures, optionally with TiCl.sub.4 catalysis, and the dicyanovinylsubstituted furan derivatives are received as good crystallizing solids.
Examples of compounds with n=0
Examples of compounds with n=1 and
A.dbd.A.sub.2 .dbd.--CH.dbd.N--Z--N.dbd.CH--:
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 0293651 |
Dec 1988 |
EPX |
Non-Patent Literature Citations (30)
| Entry |
| Chemiker-Zeitung 96, 535 (1972). |
| Chem. Abstr. 105, 78 849 q (1986). |
| "Chemie in unserer Zeit" 9, 85 (1975). |
| Kirk-Othmer, Encyclopedia of Chemical Technology 3. Ed. vol. 6, 122 (1979). |
| Chem. Abstr. 102, 299 304z, (1985). |
| Chem. Abstr. 103, 79 543 f (1985). |
| Angew. Chem. 96, 980 (1984). |
| Angew. Chem. 88, 311 (1976). |
| Kirk-Othmer, Encyl. of Chemical Technology 3. Ed. vol. 7, 359, 362 (1979). |
| J. Amer. Chem. Soc. 106, 7626 (1984). |
| Angew. Chem. 90, 927 (1978). |
| Kirk-Othmer, Encyl. of Chemical Technology 3. Ed. vol. 6, 124 (1979). |
| Carbohydr. Res. 155, 99 (1986). |
| J. March, Advanced Organic Chemistry 3. Ed., 1985 J. Wiley & Sons, Inc., New York, pp. 796-798. |
| Synthesis 1976, 133. |
| Chemiker-Zeitung 96, 535 (1972). |
| Chem. Abstr. 105, 78 849 q (1986). |
| "Chemie in unserer Zeit" 9, 85 (1975). |
| Kirk-Othmer, Encyclopedia of Chemical Technology 3. Ed. vol. 6, 122 (1979). |
| Chem. Abstr. 102, 299 304z, (1985). |
| Chem. Abstr. 103, 79 543 f (1985). |
| Angew. Chem. 96, 980 (1984). |
| Angew. Chem. 88, 311 (1976). |
| Kirk-Othmer, Encyl. of Chemical Technology 3. Ed. vol. 7, 359, 362 (1979). |
| J. Amer. Chem. Soc. 106, 7626 (1984). |
| Angew. Chem. 90, 927 (1978). |
| Kirk-Othmer, Encyl. of Chemical Technology 3. Ed. vol. 6, 124 (1979). |
| Carbohydr. Res. 155, 99 (1986). |
| J. March, Advanced Organic Chemistry 3. Ed., 1985 J. Wiley & Sons, Inc., New York, pp. 796-798. |
| Synthesis 1976, 133. |
Continuation in Parts (1)
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Number |
Date |
Country |
| Parent |
195754 |
May 1988 |
|
Patent Grant
5091538
