3, 3'(2H,2'H)-SPIROBIBENZOFURAN COMPOUNDS AND ANTIOXIDANTS COMPRISING THE SAME

Abstract: There is disclosed a novel 3,3′(2H,2′H)-spirobibenzo­ furan compound. The spirobibenzofuran compound has the strong antioxidizing action and is thus useful as an antioxi­ dant for dyes, synthetic polymer products such as rubbers, plastics and the like, and for petroleum. In addition, the com­ pound is effective in preventing fading and discolouration of color photographic images obtained by a subtractive color process.

Description: This invention relates to 3,3′(2H,2′H)-spirobibenzofuran compounds useful as antioxidants and also to antioxidants comprising the same. It is well known that dyes, dyestuffs or polymer materials deteriorate by oxidation reactions with oxygen in air. A variety of deterioration inhibitors have been developted. Various types of antioxidants are known including, for example, derivatives of hydroxybenzenes such as phenol and hydroquinone and piperidine derivatives. These hydroxybenzenes are described, for example, in U.S. Patent Nos. 2,735,765, 3,700,455, 3,764,337, 3,770,431, 3,930,866, 4,138,259 and 4,388,404, and the piperidine derivatives are described, for example, in U.S. Patent Nos. 4,452,884, 4,465,757, 4,465,765 and 4,584,265 and British Patent No. 1,326,889. However, these known deterioration inhibitors have unsatisfactory properties when used as a deterioration inhibitor for a color photographic dye or dye image. Accordingly, there is a demand for antioxidants which can improve the stability of the photographic image. Also, the known deterioration inhibitors do not show any satisfactory effect when used as an antioxidant for natural or synthetic polymers and, thus, there is a demand for powerful antioxidants for this purpose. GB-A-2062888 discloses a silver halide color photographic light-sensitive material comprising an antifading agent which may be a spirocoumaran compound wherein two substituents are joined to form an alkyleneoxy group. DE-A-2165371 discloses a color photographic material comprising a dihydroxyspirochroman compound. Accordingly, it is the object of the invention to provide 3,3′(2H,2′H)-spirobibenzofuran compounds having a good antioxidizing action and which are useful as deterioration inhibitors and for improving the stability of photographic images. In accordance with the present invention, there are provided 3,3′(2H,2′H)-spirobibenzofuran compounds of the following general formula (I) in which R and R′ independently represent a hydrogen atom or a straight chain, branched chain or cyclic alkyl group having up to 20 carbon atoms, each R₁ represents a straight chain, branched chain or cyclic alkyl group having up to 14 carbon atoms, -OR or -OR′ in which R and R′ have, respectively, the same meanings as defined above, or R or R′ and R₁ may form a ring, and n is an integer of from 0 to 3, provided that when (R₁) n is positioned at the 6- or 6′- position, it does not form a ring having an alkylenedioxy by joining with R or R′. Furthermore, 3,3′(2H,2′H)-spirobibenzofuran compounds compounds of the following general formula (I) in which R and R′ independently represent a hydrogen atom or a 2-(n-hexyloxy)ethyl group, a 3,6-dioxadodecyl group, a 1-octylethoxycarbonylmethyl group or a 1-tridecylethoxycarbonylmethyl group, each R₁ represents a straight chain, branched chain or cyclic alkyl group having up to 14 carbon atoms, -OR or -OR′ in which R and R′ have, respectively, the same meanings as defined above, or R or R′ and R₁ may form a ring, and n is an integer of from 0 to 3, as well as 3,3′(2H,2′H)-spirobibenzofuran compounds of the formula or are provided. The 3,3′(2H,2′H)-spirobibenzofuran compounds of the general formula (I) exhibit good antioxidizing properties and can satisfy the above objects. Preferable straight-chain alkyl groups for R and R′ include for example a methyl group, an n-butyl group, an n-octyl group, an n-dodecyl group, an n-tetradecyl group and an n-hexadecyl group; branched alkyl groups include for example, an isobutyl group and a 2-ethylhexyl group. Substituted alkyl groups include a 2-(n-hexyloxy)ethyl group, a 3,6-dioxadodecyl group, a 1-octylethoxycarbonylmethyl group and a 1-tridecylethoxycarbonylmethyl group. Straight-chain alkyl groups for R₁ include for example a methyl group, an n-butyl group, an n-octyl group and an n-tetradecyl group. Branched alkyl groups include an isobutyl group, a t-butyl group and a t-octyl group. In case where R₁ is -OR or -OR′, R and R′ have respectively, the same meanings as defined above. n is an integer of from 0 to 3. R or R′ and R₁ may be joined to form a ring. When R₁ is plural in number, the respective R₁'s may be the same or different. It is preferred that n is an integer of from 0 to 2. It is further preferred in the claimed compounds that R and -OR or -OR′ are joined to form an alkylenedioxy group. Preferably R, R′ and R₁ independently represent a hydrogen atom or a methyl group or R₁ and R or R′ are joined to form a methyleneoxy group and n is 0 or 1. The 3,3′(2H,2′H)-spirobibenzofuran compounds of the general formula (I) are useful as an antioxidant and especially, as a deterioration inhibitor for polymer materials. Typical examples of the 3,3′(2H,2′H)-spirobibenzofuran compounds of the general formula (I) are exemplified below. The 3,3′(2H,2′H)-spirobibenzofuran compounds of the general formula (I) are prepared by the following process in which R, R′, R₁ and n have, respectively, the same meanings as defined before. The compound of the general formula (I) is prepared by reacting p-alkoxyphenol analogues (II) and (III) with 1,3-dichloro-2-propanone to obtain compound (IV) and subjecting compound (IV) to intramolecular cyclization to obtain 3,3′(2H,2′H)-spirobibenzofuran compound (I). In this preparation process, at least one of the ortho positions with respect to hydroxyl groups of the phenol compounds (II) and (III) should be a hydrogen atom. It will be noted that compound (IV) is unstable and is, in most cases, impossible to isolate. The term "antioxidant" used herein is intended to mean not only mixtures of 3,3′(2H,2′H)-spirobibenzofuran compounds as an effective ingredient and suitable diluents, solvents, carriers or the like at arbitrary ratios, but also the spirobibenzofuran compound itself. The antioxidant of the invention may comprise the compounds of the general formula (I) used singly or in combination. Any known antifading agents or color image stabilizers may be used in combination. Preferable known antifading agents include, for example, hydroquinones, 6-hydroxychromans, spirochromans and alkyl ethers thereof. In addition, bisphenols, methylenedioxybenzenes, spiroindanes and N-substituted anilines are also preferred. The 3,3′(2H,2′H)-spirobibenzofuran compounds of the invention have a strong antioxidizing action and are thus useful as an antioxidant for dyes, synthetic polymer products such as rubbers or, plastics, and for petroleum. In addition, these compounds are effective in preventing fading and discoloration of color photographic images obtained by a subtractive color process. The invention is more particularly described by way of examples. Examples 1 to 3 show the synthesis of 3,3′(2H,2′H)-spirobibenzofuran compounds of the general formula (I) prepared according to the process described before, and Examples 4 and 5 are applications of these 3,3′(2H,2′H)-spirobibenzofuran compounds as an antioxidant. Example 1 Preparation of 5,5′-dimethoxy-3,3′(2H,2′H)-spirobibenzofuran (exemplified compound (3)): 100 ml of methylene chloride was added to 37.2 g (0.30 moles) of p-methoxyphenol, to which 19 g (0,15 moles) of 1,3-dichloro-2-propanpne was further added for dissolution, followed by agitation at 0°C to 5°C. 9ml of concentrated sulfuric acid was dropped into the solution in 1 h and agitated for further 2 h. The reaction mixture was poured into 200 ml of iced water, to which 200 ml of methylene chloride was added for extraction. After washing twice with 200 ml of cold water, the extract was dried with calcium chloride. After filtration of the calcium chloride, the methylene chloride was distilled off under reduced pressure and the resultant oily substance was subjected to column chromatography to remove unreacted starting materials quickly. 100 ml of benzene was added to the remaining oily substance and agitated at 15°C - 20°C, followed by gradual addition of 2 g (0.083 moles) of sodium hydride. After further agitation for one hour, the mixture was cooled down to 0°C to 10°C and agitated, during which 20 ml of methanol was dropped in 10 min. The reaction mixture was poured into 200 ml of iced water containing 7 ml of concentrated hydrochloric acid. Extraction with 100 ml of ethyl acetate was performed, followed by washing twice with 200 ml of cold water and drying with anhydrous Glauber's salt. After removel of the Glauber's salt by filtration, the ethyl acetate was distilled off under reduced pressure and the resultant oily substance was purified with column chromatography. 40 ml of methanol was added to the thus purified product for crystallization, followed by recrystallization from further 40 ml of methanol to give 9.4 g of exemplified compound (3). Yield: 22%, m.p.: 179°C - 180°C IR(KBr,cm⁻¹); 2940,2890,2835,1602,1480,1435,1270,1200,1180 NMR(CDCℓ₃,δ); 6.8 6.6(4H,m), 6.6 6.5(2H,m) 4.6(2H,d,J8 .OHz), 3.7(6H,S) MS(m/e) ; 284 (M⁺) Elementary analysis (for C₁₇H₁₆O₄): found C: 71.78%, H: 5.64% calculated C: 71.82%, H: 5.67% Example 2 Preparation of 5,5′-dimethoxy-6,6′-dimethyl-3,3′-(2H,2′H)-spirobibenzofuran (exemplied compound (7)): 100 ml of methylene chloride was added to 27.6 g (0.20 moles) of 3-methyl-4-methoxyphenol, in which 12.7 g (0.10 mole) of 1,3-dichloro-2-propanone was then dissolved, followed by agitation at 0°C to 5°C. 6 ml of concentrated sulfuric acid was dropped into the reaction mixture in 1 h and further agitated for 2 h. The reaction mixture was poured into 200 ml of iced water, to which 100 ml of methylene chloride was added for extraction. After washing twice with 200 ml of cold water, the extract was dried with calcium chloride. After removal of the calcium chloride by filtration, the methylene chloride was distilled off under reduced pressure. The resultant oily substance was subjected to column chromatography to quickly remove unreacted starting materials. 70 ml of benzene was added to the remaining oily substance and agitated at 10°C to 15°C, to which 1.5 g (0,063 moles) of sodium hydride was gradually added. After further agitation for 1 h, the mixture was cooled down to 0°C to 10°C and agitated, during which 20 ml of methanol was dropped in 10 min. The reaction mixture was poured into 200 ml of iced water containing 5 ml of concentrated hydrochloric acid. 100 ml of ethyl acetate was added for extraction, followed by washing twice with 200 ml of cold water and drying with anhydrous Glauber's salt. Afrer removal of the Glauber's salt by filtration, the ethyl acetate was distilled off under reduced pressure and the resultant oily substance was purified with column chromatography. 20 ml of methanol was added to the thus purified product for crystallization, followed by recrystallization from 30 ml of methanol to give 5.9 g of exemplified compound (7). Yield: 19%, m.p.: 79°C - 80°C IR(KBr,cm⁻¹); 2930,2820,1604,1485,1460,1410,1300,1190,1010 NMR(CDCℓ₃,δ); 6.6(2H,S), 6.5(2H,S), 4.6(2H,d,J=9.0Hz), 4.4(2H,d,J=9.0Hz), 3.7(6H,S), 2.2(6H,S) Elementary analysis (for C₁₉H₂₀O₄) found C: 73.11%, H: 6.47% calculated C: 73.06%, H: 6.45% Example 3 Preparation of 5,6,5′,6′-dimethylenedioxy-3,3′(2H,2′H)-spirobibenzofuran (exemplified compound (10)): 100 ml of methylene chloride was added to 13.8 g (0.10 mole) of 3,4-methylenedioxyphenol, to which was further added 6.35 g (0.05 moles) of 1,3-dichloro-2-propanone for dissolution, followed by agitation at 5°C to 10°C. 3 ml of concentrated sulfuric acid was dropped into the mixture in 15 min, followed by agitation for further 4 h whereupon crystals precipitated. The thus precipitated crystals were collected by filtration and washed with 50 ml of methylene chloride. the crystals were dissolved in 100 ml of DMAc and agitated at 0°C to 5°C. 2.4 g (0,10 mole) of sodium hydride was gradually added to the reaction mixture and, after further agitation for 1 h, 20 ml of methanol was dropped into the mixture in 10 min. The reaction mixture was poured into 200 ml of ice water containing 5 ml of concentrated hydrochloric acid and extracted with 300 ml of ethyl acetate, followed by washing twice with 200 ml of cold water and drying with anhydrous Glauber's salt. After removal of the Glauber's salt by filtration, the ethyl acetate was distilled off under reduced pressure to precipitate crystals. 50 ml of methanol was added to the crystals and filtered, followed by recrystallization from 100 ml of ethyl acetate to give 9.8 g of exemplified compound (10). Yield: 63%, m.p.: 211°C - 213°C IR(KBr,cm⁻¹); 3025,2900,1615,1500,1475,1295,1160,1100 NMR(CDCℓ₃,/DMSO-d₆,δ); 6.5(2H,S), 6.4(2H,S), 5.9(4H,S), 4.6(2H,d,J=10.0Hz), 4.4(2H,d,J=10.0Hz), MS(m/e) ; 312 (M⁺) Elementary analysis (for C₁₇H₁₂O₆): found C: 65.42%, H: 3.88% calculated C: 65.39%, H: 3.87% Example 4 10 g of a yellow coupler of α-benzoyl-α-(2,4-dioxo-5,5-dimethyl-3-oxazolidinyl)-2-chloro-5-[alpha-(2,4-di-tert-amylphenoxy)butylamido]acetoanilide was dissolved in 10 ml of tricresyl phosphate and 20 ml of ethyl acetate. The solution was emulsified and dispersed in 80 g of a gelatine solution containing 8 ml of a 1% sodium dodecylbenzenesulfonate aqueous solution. Thereafter, the emulsified dispersion was mixed with 145 g (containing 7 g of Ag) of a blue-sensitive silver chlorobromide emulsion (80 mole% of Br), to which sodium dodecylbenzenesulfonate was added as a coating aid, followed by coating onto a paper support laminated with polyethylene on both sides thereof. The coated amount of the coupler was set at 400 mg/m². A gelatine protective layer (1 g/m² of gelatine) was coated onto the coupler layer to obtain sample A. In a similar manner, samples were made in which when the emulsified dispersion was prepared, compounds of the invention and compounds for comparison indicated in Table 1 were added, as an antioxidant, in an amount of 50 mole% of the coupler. These samples were exposed to light at 1000 luxes for 1 s and treated with the following solutions. In this manner, a color image was formed on the respective samples. In order to determine the light fastness of the image-bearing samples, each sample was exposed to light from a xenone tester (illumination intensity of 100,000 luxes) through a UV absorption filter, made by Fuji Film Co., Ltd., in order to cut light having wavelengths below 400 nm. The residual dye after the exposure at an initial intensity of 1.5 was indicated by percent. In order to determine the heat resistance, a residual dye at an initial intensity of 1.5 upon storage at 100°C for 500 h in the dark was indicated by percent. From the results of Example 4, it will be seen that the compounds of the invention exhibit a remarkable antioxidizing action. Example 5 A composition of the following formulation using IIR (Tradename, made by Polyser Co., Ltd., butyl #100 with a degree of unsaturation of 0.7%) as a resin base was prepared. Polyuser Butyl #100 100 parts by weight Hard clay 120 parts by weight Zinc oxide 5 parts by weight Stearic acid 2 parts by weight Sulfur 1 part by weight Tetramethylthiuram disulfide 2 parts by weight SRF carbon 10 parts by weight Mercaptobenzothiazole 0.5 parts by weight This composition was kneaded with rolls, followed by press vulcanization at 160°C for 45 min to obtain a 2 mm thick sheet. The sheet was punched by means of a dumbell die JIS (Japanese Industrial Standards) No. 3 to give a sample piece (a). Similarly, samples (b) - (f) were made using 1.5 parts by weight of antioxidants indicated in Table 2. The sample pieces were each placed for deterioration test in a gear oven at 120°C for 100 h and subjected to measurements of a tensile strength kg/mm²) and an elongation (%). The aging resistance was evaluated according to the ratios (retention, %) to values prior to the aging test. The results are shown in Table 2. Comparative compound: (Compound described in United States Patent No. 3,764,337.) These results reveal that when used as an antioxidant, the compounds of the invention have a better antioxidizing property than the known compound.

Claims: 1. 3,3′(2H,2′H)-spirobibenzofuran compounds of the following general formula (I) in which R and R′ independently represent a hydrogen atom or a straight chain, branched chain or cyclic alkyl group having up to 20 carbon atoms, each R₁ represents a straight chain, branched chain or cyclic alkyl group having up to 14 carbon atoms, -OR or -OR′ in which R and R′ have, respectively, the same meanings as defined above, or R or R′ and R₁ may form a ring, and n is an integer of from 0 to 3, provided that when (R₁) n is positioned at the 6- or 6′-position it does not form a ring having an alkylenedioxy by joining with R or R′. 2. The compounds of claim 1, wherein R and R′ independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, an n-butyl group, an n-octyl group, an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group, an isobutyl group or a 2-ethylhexyl group and R₁ independently represents a hydrogen atom, a methyl group, an n-butyl group, an n-octyl group, an n-tetradecyl group, an isobutyl group, a t-butyl group, or a t-octyl group. 3. 3,3′(2H,2′H)-spirobibenzofuran compounds of the following general formula (I) in which R and R′ independently represent a hydrogen atom or a 2-(n-hexyloxy)ethyl group, a 3,6-dioxadodecyl group, a 1-octylethoxycarbonylmethyl group or a 1-tridecylethoxycarbonylmethyl group, each R₁ represents a straight chain, branched chain or cyclic alkyl group having up to 14 carbon atoms, -OR or -OR′ in which R and R′ have, respectively, the same meanings as defined above, or R or R′ and R₁ may form a ring, and n is an integer of from 0 to 3. 4. The compounds of claim 3 wherein R₁ independently represents a hydrogen atom, a methyl group, an n-butyl group, an n-octyl group, an n-tetradecyl group, an isobutyl group, a t-butyl group or a t-octyl group. 5. 3,3′(2H, 2′H) -spirobibenzofuran compounds of the formula or 6. The compounds of any of claims 1 to 4 wherein n is an integer of from 0 to 2. 7. The compounds of any of claims 1 to 4 wherein R₁ and -OR or -OR′ are joined to form an alkylenedioxy group. 8. The compounds of claim 1 wherein R, R′ and R₁ independently represent a hydrogen atom or a methyl group or R₁ and R or R′ are joined to form a methyleneoxy group and n is 0 or 1. 9. An antioxidant comprising a 3,3′(2H,2′H)-spirobibenzofuran compound according to any of claims 1 to 8. 10. The antioxidant of claim 9 which is a deterioration inhibitor for natural or synthetic polymer materials. 11. A process for the preparation of the compounds of any of claims 1 to 8 which comprises reacting p-alkoxyphenol analogues (II) and (III) to obtain compound (IV) wherein R, R′, R₁ and n are as defined in claims 1 and 3, and subjecting compound IV to an intramolecular cyclization to obtain a compound of the general formula (I).

Inventors: MORIGAKI, MASAKAZU, SETO, NOBUO
Applicants: FUJI PHOTO FILM CO., LTD.
Application year: 1987
Main classification: C07D493
IPC codes: G03C7, C08K5, C07D493, C10M129, C08L101, C09K15, C10N30