Hydrophobic materials containing oils, fats or waxes such as candles, floor polishes, floor stains or other wood stains and furniture polishers are protected against the action of ultraviolet light by incorporating therein a compound of the formula <FORM:0893236/III/1> in which R1 represents a residue of the benzene series which contains a hydroxyl group ortho to the ketonic group and R2 represents a cyclic residue (see Group IV(b)) The radical R2 may contain a heterocyclic ring, e.g. a pyridine, thiophene or furane ring or a benzene ring or two benzene rings linked through a bridge member. Additional substituents which may be present in R1 include sulphonic acid or sulphonic acid amide or tertiary amino methyl groups or hydroxyl groups which may be etherified.ALSO:Compositions comprising resinous condensation or polymerization products or cellulose derivatives are protected against the action of ultra violet light by incorporating therein a compound of the general formula <FORM:0893236/IV (a)/1> in which R1 represents a residue of the benzene series which contains a hydroxyl group in ortho-position to the -CO- group and R2 represents a cyclic residue (see Group IV(b)). The radical R2 may contain a heterocyclic ring, e.g. a pyridine, thiophene or furane ring, or a benzene ring or two benzene rings linked through a bridge member.  The diketones are either dissolved or suspended in the substances protected and may be used to protect spun goods or foils of cellulose derivatives such as viscose spinning compositions, acetyl-cellulose spinning compositions (including cellulose triacetate), polymers or copolymers of vinyl chloride, vinylidene chloride, methacrylic esters, or styrene or in compositions for making fibres such as polyamide melts or polyacrylonitrile spinning compositions, lacquers and films of acetyl-cellulose, polyvinyl acetate, alkyd resins, nitrocellulose regenerated cellulose, acetyl cellulose and polyethylene, epoxy resins, urea- or melamineformaldehyde resins, emulsions of synthetic resins, e.g. oil-in-water or water-in-oil emulsions.  In examples: a film is produced from an acetone solution of acetyl cellulose containing 1,4-bis(21,41-dihydroxybenzoyl)benzene (11), filaments are produced from a polyamide melt prepared from hexamethylene diamine adipate, titanium dioxide and a disulphonic acid derivative of 1,4-bis(21,41-dihydroxybenzoyl benzene (12); tin foil is coated with a stoving lacquer containing coconut oil fatty acid modified non-drying alkyd resin, toluene, a butanol solution of a melamine-formaldehyde condensation product partially etherified with butanol, a copper phthalocyanine-tetramethoxypropyl sulphonamide and the diketone employed in (11) (15); and with a lacquer containing stabilized polyvinyl chloride, dioctyl phthalate, methyl ethyl ketone and the pigment and diketone employed in (15), (16).ALSO:The invention comprises compounds of the formula <FORM:0893236/IV (b)/1> in which R1 represents a residue of the benzene series which contains a hydroxyl group in ortho-position to the -CO- group and R2 represents a cyclic residue and a process for the preparation thereof wherein (a) a dihalide of a cyclic dicarboxylic acid is reacted in the presence of a Friedel Crafts catalyst with a compound of the benzene series which contains as a nuclear substituent at least one hydroxy group which may be etherified or (b) the dihalide of a cyclic dicarboxylic acid is reacted with a compound of the benzene series which contains at least one hydroxyl group as nuclear substituent and the resulting diester is rearranged to form the corresponding oxydiketon by treatment with a Friedel Crafts catalyst.  Acid dichlorides specified for use in the process include those obtainable from pyrdine dicarboxylic acids, thiophene- and furane dicarboxylic acids, diphenyl-4,41 dicarboxylic acids and benzene dicarboxylic acids, e.g. benzene 1 : 2- or 1 : 3- or 1 : 4-dicarboxylic acids. The compounds from which the radicals R1 are derived may be the bicyclic, e.g. diphenyl hydroxy compounds and they may contain, e.g. from 1 to 3 hydroxy groups which may be etherified, e.g. as alkoxy groups or hydroxyalkyloxy groups containing up to 3 carbon atoms. Specific aromatic hydroxy compounds include phenol, 1-hydroxy-2,3 or 4 methyl benzene, p  1,3- or 1,4-dihydroxy, 1-hydroxy-3 methoxy or -3-ethoxy-benzenes, 1,3-dimethoxy-and diethoxy benzenes 1-hydroxy-2 : 4- or 3 : 5-dimethylbenzene or 2 : 4-dihydroxybenzoic acid or an alkyl ester thereof.  Friedel Crafts catalysts specified include boron-fluorine compounds, zinc chloride, stannic chloride, phosphoric acid, phosphorus pentoxide, aluminium bromide or chloride or ferric chloride.  Further substituents may be introduced into the hydroxy diketones, e.g. by sulphonating with sulphonating agents, e.g. oleum and the sulphonic groups may be converted to the corresponding sulphonic acid halides in the usual manner and the latter may be converted to sulphonic amide groups by reaction with ammonia or a primary or secondary amine.  In addition the hydroxy diketones may be reacted with an aldehyde or an agent yielding an aldehyde and a secondary amine, e.g. dimethyl- or diethylamine or morpholine or with aldehyde-amine addition products, thus diethylamino-methyl groups may be introduced.  Furthermore the hydroxy diketones may be nitrated, the nitro groups reduced to amino groups and the latter alkylated or acylated.  Examples relate to the preparation of compounds of the general formula given above by reacting in the presence of aluminium chloride 1 : 3-dihydroxy benzene with terephthalic acid dichloride (1); 1 :3-dihydroxy benzene with furane dicarboxylic acid dichloride (2); 1-hydroxy-4-chloro-benzene with terephthalic acid dichloride (4); 1-hydroxy-4-chlorobenzene with furane 2 : 5-dicarboxylicacid dichloride (5); 1-hydroxy-4-methylbenzene with terephthalic acid dichloride (6); 1 : 3-dihydroxy-benzene with diphenyl 4,41-dicarboxylic acid dichloride (7); 1 : 3-dihydroxybenzene with pyridine 2 : 5 dicarboxylic acid dichloride (8); 1 : 3-dimethoxy benzene with terephthalic acid dichloride (9); by reacting terephthalic acid dichloride with resorcinol in the presence of pyridine to obtain di-(m-hydroxy phenyl) terephthalate and heating the latter with aluminium chloride (2); and by sulphonating the product of (1) to introduce a sulphonic group into each of the hydroxy phenyl nuclei.  The products are employed to protect materials against ultraviolet radiation (see Groups III, IV(a), IV(c), VI, VII, VIII and XX).ALSO:Textile materials are protected against the action of ultra violet light by incorporating therein a compound of the general formula <FORM:0893236/IV (c)/1> in which R1 represents a residue of the benzene series which contains a hydroxyl group in ortho position to the -CO- group and R2 represents a cyclic residue (see Group IV(b)).  The radical R2 may contain a heterocyclic ring, e.g. a pyridine, thiophene or furane ring, or a benzene ring or two benzene rings linked through a bridge member.  Additional substituents which may be present in the group R1 include sulphonic acid or sulphonic acid amide or tertiary amino methyl groups or hydroxyl groups which may be etherified.  The diketones of the invention may be applied by methods used for applying dispersion dyestuffs. Textile materials specified include fibre, filament, yarn, woven or knitted goods or felt and manufactured goods made therefrom and may consist of natural materials of animal origin such as wool or silk, or of vegetable origin such as cotton, hemp, flax, linen, jute or ramie, semisynthetic materials such as regenerated cellulose, viscose, staple fibres of regenerated cellulose, or synthetic materials obtained by polymerization or copolymerization, e.g. polyacrylonitrile or by polycondensation, e.g. polyesters such as "Terylene" (Registered Trade Mark) or polyamides, e.g. nylon. Coating or dressing compositions for textiles, e.g. based on starches or casein or on artificial resins, e.g. based on vinyl acetate or acrylic acid derivatives may also contain the diketones of the invention.ALSO:Cosmetic preparations, especially anti-sunlight oils and creams contain a compound of the general formula <FORM:0893236/VI/1> in which R1 represents a residue of the benzene series which contains a hydroxyl group in ortho position to the -CO- group and R2 represents a cyclic residue (see Group IV (b)).  The radical R2 may contain a heterocyclic ring, e.g. a pyridine, thiophene or furane ring, or a benzene ring or two benzene rings linked through a bridge member.  Additional substituents which may be present in R1 include sulphonic acid or sulphonic acid amide or tertiary amino methyl groups or hydroxyl groups which may be etherified.  Compositions are described in examples containing in addition to 1,4-bis-(21,41-dihydroxybenzoyl) benzene, adipic acid isopropyl tetrahydrofurfuryl ester, glycerine mono-stearate and ethyl alcohol (17): adipic acid isopropyl tetrahydrofurfuryl ester, benzoic acid diethylamide, phthalic acid dimethyl ester, ground nut and paraffin oils (19); glycerine monostearate, cetyl alcohol, sodium cetyl stearate, stearic acid and glycerine emulsified in water (20); adipic acid isopropyl tetrahydrofurfuryl ester, toluylic acid diethylamide, cetyl alcohol petroleum jelly, beeswax, lanolin, cocoa butter water and sodium benzoate (21); and ethyl alcohol, perfume oil, trichloro-mono-fluoro methane and dichloro-difluoromethane (18), the latter being an aerosol spray composition.  Compositions (17), (19) and (2) have inset repellent properties in addition to protecting the skin against the action of sunlight.