NOVEL PREPARATION PROCESS FOR MANUFACTURE AND PURIFICATION OF MIXTURES OF FLUORAN COMPOUNDS AND RECORDING MATERIAL COMPRISING SAID MIXTURES OF FLUORAN COMPOUNDS

Abstract: A process for the manufacture of mixtures of fluoran compounds by the reaction of keto acids of formula (II) with a compound of formula (III) in the presence of a dehydrating condensation agent, wherein R1 and R2 independently represent hydrogen; an alkyl of 1-18 carbon, a secondary alkyl with respect to the carbon atom bonded to the nitrogen atom of 3-13 carbon atoms, a cycloalkyl of 4-8 carbon atoms or a phenyl, both of which may be substituted by at least one substituted selected from the group consisting of halogen atoms and alkyls having 1-4 carbon atoms, an aralkyl of 7-10 carbon atoms; or R1 and R2, together with the adjacent nitrogen atom from a heterocyclic ring; R3 is hydrogen, an alkyl of 1-4 carbon atoms, an alkoxy of 1-4 carbon atoms, a phenyl; a substituted phenyl or a halogen; R4 is an alkyl group of 1-18 carbon atoms, a carboxyalkyl of 1-18 carbon atoms, a carboxycycloalkyl of 4-8 carbon atoms, an alkylamino of 1-18 carbon atoms, a cycloalkylamino of 4-8 carbon atoms, a dialkylamino or dicycloalkylamino; an arylamino, a substituted arylamino; an aralkylamino of 7-10 carbon atoms; a diaralkylamino; R5 is an alkyl of 1-18 carbon atoms, a carboxy alkyl of 1-18 carbon atoms or a halogen and R6 is hydrogen or alkyl of 1-4 carbon atoms.

Description: Novel preparation process for manufacture and purification of mixtures of fluoran compounds and recording material compnsing said mixtures of fluoran compounds Technical Field The present invention relates to mixtures of fluoran compounds which are useful as colour forming compounds in recording matenals More particularly, the invention relates to a process for the preparation of said mixtures of fluoran compounds and to the use of said mixtures of fluoran compounds as colour formers in recording matenals such as heat sensitive and pressure sensitive recording matenals Descnption of the Prior Art Pressure sensitive recording, heat sensitive recording and electroheat sensitive recording have conventionally been used as systems for recording transferred information through the mediation of external energy such as pressure, heat or electπcity, by utilising a colour reaction between a colourless or pale coloured electron donative compound (colour forming compound) and an organic or inorganic electron acceptor (developer) In such recording systems, mixtures of more than one colour former have been used as the colour forming compound For example, US 4,226 912 discloses a system wherein the chromogenic mateπal is a physical mixture of two black fluoran colour formers in a heat sensitive recording system At present, such mixtures of fluorans are prepared by physical mixing of the component fluoran colour formers Where a mixture of more than one colour former is to be used then, an additional mixing step is necessary in the preparation of the final recording system It is advantageous to mix thoroughly in order to generate a homogenous system To achieve good mixing the intensity of mixing and the time of mixing can be altered However, unless separate analysis of the mixture is earned out the relative composition of the dispersed system is unknown In addition where two or more colour formers are used the relative ouπty / lmpunty of eacn component may have an impact on the final characteπstics of the recording mateπal As such, the formulators challenge is to develop a multi-colour former system in which the individual components are present at optimal puπty levels in order to deliver desirable recording properties and yet which can be manufactured both simply and efficiently It has now been found that mixtures of specified fluoran colour forming compounds can be synthesised directly by the reaction of at least two deπvatives of ammo phenols, phthahc anhydπdes keto acids and/or diphenylamines with a phenol deπvative The advantages of the present process are that a separate mixing step in the preparation of the final recording system is obviated with the relevant savings in time and energy in the process and the relative impact of mixed impuπties or impuπty levels from diffeπng colour former components is reduced Obiect of the Invention An object of the present invention is to provide an efficient process for the manufacture of mixtures of fluoran compounds that does not require separate manufacture of the individual component fluoran compounds, subsequent mixing and further treatment of the mixture Thus the present invention provides a novel process for the manufacture of mixtures of fluoran compounds from appropπate mixtures of starting matenals in a single process Detailed Descπption of the Invention The mixtures of fluorans prepared by the present invention may be amorphous mixtures mixed crystals, monophase solid solutions, multiphase solid solutions, aggregates of different compounds each in pure crystal modification and mixtures thereof In the literature, the definitions by the vaπous authors, such as, G H Van't Hoff A I Kitaigorodsky and A Whitacker for solid solutions and mixed crystals are often contradictory, (cf e g 'Analytical Chemistry of Synthetic Dyes Chapter 10/page 269 Editor K Venkataraman, J Wiley, New York, 1977) The term monophase solid solution' or multiphase solid solution' or mixed crystal' as defined herein therefore, should be taken from the following definitions which have been adapted to the current improved state of knowledge of such systems A monophase (or single-phase or guest-host) solid solution possesses a crystal lattice which is identical with the crystal lattice of one of its components One component is embedded as the 'guest' in the crystal lattice of the other component, which acts as the 'host' The X-ray diffraction pattern of such a monophase solid solution is substantially identical to that of one of the components, called the 'host' Within certain limits, different proportions of the components produce almost identical results A multiphase solid solution possesses no precise, uniform crystal lattice It differs from a physical mixture of its components in that the crystal lattice of at least one of its components is partially or competely altered In compaπson to a physical mixture of the components which gives an X-ray diffraction diagram that is additive of the diagrams seen for the individual components The signals in the X-ray diffraction diagram of a multiphase solid solution are broadened, shifted or altered in intensity In general, different proportions of the components produce different results A mixed crystal (or solid compound type) solid solution possesses a precise composition and a uniform crystal lattice, which is different from the crystal lattices of all its components If different proportions of the components lead, within certain limits, to the same result then a solid solution is present in which the mixed crystal acts as a host As hereinbefore detailed, the novel mixtures of fluorans compπse a plurality of colour forming compounds Suitable mixtures of fluoran colour forming matenals which may be prepared according to the present invention may include at least one fluoran compound such as 3-dιbutylamιno-7-dιbenzylamιnofluoran, 3-dιethylamιno-6-methylfluoran 3- dιmethylamιno-6-methyl-7-anιlιnofluoran, 3-dιethylamιno-6-methyl-7-anιiιnofluoran, 3- dιethylamιno-6-methyl-7-(2,4-dιmethylanιlιno) fluoran, 3-dιethylamιno-6-methyl-7- chlorofluoran, 3-dιethylamιno-6-methyl-7-(3-tπfluoromethylanιlιno) fluoran 3-dιethylamιno-6- methy!-7-(2-chloroanιlιno) fluoran, 3-dιethylamιno-6-methyl-7-(4-chloroanιlιno) fluoran 3- dιethyiamιno-6-methyl-7-(2-fluoroanιlιno) fluoran, 3-dιethylamιno-6-methyl-7-(4-n- octylanilino) fluoran 3-dιethylamιno-7-(4-n-octylanιlιno) fluoran, 3-dιethylamιno-7-(n- octylamino) fluoran 3-dιethylamιno-6-methyl-7-(dιbenzylamιno) fluoran 3-dιethylamιno-7- (dibenzylamino) fluoran 3-dιethylamιno-6-chloro-7-methylfluoran 3-dιethyiamιno-7-t- butylfluoran 3-dιethyiamιno-7-carboxyethylfluoran 3-dιethylamιno-6-chloro-7-anιlιnofluoran 3-dιethylamιno-6-methvl-7-C3-methylanιlιno) fluoran 3-αιethylamιno-6-methyl-7-(4- methylanilino) fluoran, 3-dιethylamιno-6-ethoxyethyl-7-anιlιnofluoran, 3-dιethylamιno-7- methylfluoran, 3-dιethylamιno-7-chlorofluoran, 3-dιethylamιno-7-(3-tπfluoromethylanιlιno) fluoran, 3-dιethylamιno-7-(2-chloroanιlιno) fluoran, 3-dιethylamιno-7-(2-fiuoroanιlιno) fluoran, 3-dιethylamιno-benzo[a] fluoran, 3-dιethylamιno-benzo[c] fluoran, 3-dιbutylamιno-6-methyl fluoran, 3-dιbutylamιno-6-methyl-7-anιlιnofluoran, 3-dιbutylamιno-6-methyl-7-(2,4- dimethylanilino) fluoran, 3-dιbutylamιno-6-methyl-7-(2-chloroanιlιno) fluoran, 3-dιbutylamιno- 6-methyl-7-(4-chloroanιlιno) fluoran, 3-dιbutylamιno-6-methyl-7-(2-fluoroanιlιno) fluoran, 3- dιbutylamιno-6-methyl-7-(3-tπfluoromethylanιiιno) fluoran, 3-dιbutylamιno-6-ethoxyethyl-7- ani nofluoran, 3-dιbutylamιno-6-chloro-anιlιnofluoran, 3-dιbutylamιno-6-methyl-7-(4- methylanilino) fluoran, 3-dιbutylamιno-7-(2-chloroanιlιno) fluoran, 3-dιbutylamιno-7-(2- fluoroanihno) fluoran, 3-dιpentylamιno-6-methyl-7-anιlιnofluoran, 3-dιpentylamιno-6-methyl- 7-(4-2-chioroanιlιno) fluoran 3-dιpentylamιno-7-(3-tπfluoromethylanιiιno) fluoran, 3- dιpentylamιno-6-chloro-7-anιlιnofluoran, 3-dιpentylamιno-7-(4-chloroanιlιno) fluoran, 3- pyrτolιdιno-6-methyl-7-anιlιnofluoran, 3-pιpeπdιno-6-methyl-7-anιlιnofluoran, 3-(N-methyl-N- propylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-methyl-N-cyclohexylamιno)-6-methyl-7- ani nofluoran, 3-(N-ethyl-N-cyclohexylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-p- toluιdιno)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-N-ιsoamylamιπo)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-N-ιsoamylamιno)-6-chloro-7-anιlιnofluoran, 3-(N-ethyl-N-tetrahydrofurfurylamιno)- 6-methyl-7-anιiιnofluoran, 3-(N-ethyl-N-ιsobutylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-butyl- N-ιsoamylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-ιsopropyl-N-3-pentylamιno)-6-methyl-7- anilinofluoran, 3-(N-ethyl-N-ethoxypropylamιno)-6-methyl-7-anιlιnofiuoran, 3- cyclohexylamιno-6-chlorofluoran, 2-methyl-6-p-(p-dιmethylamιnophenyl)amιnoanιlιnofluoraπ 2-methoxy-6-p-(p-dιmethylamιnophenyl)amιnoanιlιnofluoran, 2-chloro-3-methyl-6-p-(p- phenylamιπophenyl)amιnoanιlιnofluoran, 2-dιethylamιno-6-p-(p- dιmethylamιnophenyl)amιnoanιiιnofiuoran, 2-phenyl-6-methyl-6-p-(p- phenylamιnophenyl)amιnoanιlιnofluoran, 2-benzyl-6-p-(p- phenylamιnophenyl)amιnoanιlιnofluoran, 3-methyl-6-p-(p- dιmethylamιnophenyl)amιnoanιlιnofluoran, 3-dιethylamιno-6-p-(p- dιethyiamιnophenyl)amιnoanιltnofluoran, 3-dιethylamιno-6-p-(p- dιbutylamιnophenyl)amιnoanιlιnofluoran, 2,4-dιmethyl-6-[(4-dιmethylamιno)aπιlιno] fluoran 3-[(4-dιmethyiamιnophenyl)amιno]-5 7-dιmethylfluoran Highly preferred mixtures of fluoran colour formers according to the present invention are composed of at least two fluoran compounds of the general formula (I) Formula Wherein R1 and R2 independently represent hydrogen, an alkyl of 1-18 carbon, a secondary alkyl with respect to the carbon atom bonded to the nitrogen atom of 3-13 carbon atoms, a cyctoalkyl of 4-8 carbon atoms or a phenyl both of which may be substituted by at least one substituent selected from the group consisting of halogen atoms and alkyls having 1-4 carbon atoms, an aralkyl of 7-10 carbon atoms Alternatively, R1 and R2, together with the adjacent nitrogen atom may form a heterocyclic ππg R3 is hydrogen, an alkyl of 1-4 carbon atoms, an alkoxy of 1-4 carbon atoms, a phenyl a substituted phenyl or a halogen R4 is an alkyl group of 1-18 carbon atoms a carboxyalkyl of 1-18 carbon atoms a carboxycycloalkyl of 4-8 carbon atoms a alkylamino of 1-18 carbon atoms, a cycloalkylamino of 4-8 carbon atoms, a dialkylamino or dicycloalkylamino as previously defined, an arylamino, a substituted arylamino, an aralkylamino of 7-10 carbon atoms, a diaralkylamino as previously defined R5 is an alkyl of 1-18 carbon atoms a carboxy alkyl of 1-18 carbon atoms or a halogen The ratio of the components being in the range 0 1-99% by mole Highly preferred are the following exemplary mixtures of fluorans comprising two components A and B in the stated ratios 3-dιbutylamιno-6-methyl-7-anιiιnofluoran (95%), 3- dιbutyiamιno-7-dιbenzylamιnofluoran (5%) 3-dιbutylamιno-6-methyl-7-anιlιnofluoran (90%), 3-dιethylamιno-6-methyl-7-anιlιnofluoran (10%) 3-dιbutylamιno-6-methyl-7-anιlιnofluoran (46%), 3-dιethylamιno-6-methyl-7-anιlιnoτluoran (56%) 3-dιethylamιno-6-methyl-7- anilinofiuoran (52%) 3-dιethylamιno-6,3'(4')-dιmethyl-7-anιlιnofluoran (48%), 3- dιethylamιno-6-methyl-7-anιlιnofluoran (10%), 3-N-(1-ethylpropyl)-N-oropylamιno-6-methyt- 7-anιlιnofluoran (90%), 3-dιbutylamιno-6-methyl-7-m-tolyiamιnofluoran (10%), 3- dιbutylamιno-6-methyl-7-anιlιnofluoran (90%) The mixtures of fluoran colour formers are prepared from mixtures of the appropriate starting matenals Such a methodology is novel and can be used to produce amorphous mixtures, monophase solid solutions, multiphase solid solutions and mixed crystals The technique can be used to produce mixtures of two or more fluorans Preferably, mixtures of two fluorans are produced by replacing a single starting mateπal with two analogous matenals to the same or similar total molar concentration in the reaction In the case of fluorans, these starting matenals are deπvatives of ammo phenols, phthalic anhydrides, keto acids and diphenytamines The mixtures of starting matenals may themselves be physical mixtures, monophase solid solutions, multiphase solid solutions, mixed crystals, aggregates of the different compounds each in pure crystal form or mixtures thereof By utilising mixtures of more than one starting mateπal it is possible to produce mixtures of more than two fluorans For instance, the controlled reaction of an appropπate mixture of keto acids of formula (II) and compound(s) of formula (III) will produce a mixture of fluoran colour formers R1-R5 have the meanings given previously and R6 is a hydrogen or an alkyl of 1-4 C atoms Formula Formula A mixture of n different fluorans where n>1 may be manufactured by the reaction of x different keto acids of formula (II) and y different compounds of formula (III) where one or both of x and y are >1 For instance, a mixture consisting of two compounds of general formula (I) may be prepared by reaction of, i Two different keto acids of general formula (II) with a single compound of general formula (III) ii Two different compounds of general formula (III) with a single keto acid of formula (ID Compounds of general formula II are exemplified by, but not limited to, 2-hydroxy-4-N,N-dι- methyl ammo-2'-carboxybenzophenone, 2-hydroxy-4-N N-di-ethyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N,N-dι-n-propyt amιno-2'-carboxybeπzophenone, 2- hydroxy-4-N,N-dι-n-butyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N,N-dι-n-pentyl amιno-2'-carboxybenzophenone 2-hydroxy-4-N,N-dι-n-hexyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N,N-dιιsopropyl amιno-2'-carboxybenzophenone 2- hydroxy-4-N,N-dιsecbutyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N N-dnsobutyl amιπo-2'-carboxybenzophenone, 2-hydroxy-4-N,N-dιιsoamyl amιno-2'- carboxybenzophenoπe, 2-hydroxy-4-N-methyl-N-cyclohexyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-methyl-N-phenyl amιno-2'-carboxybenzophenone 2- hydroxy-4-N-methyl-N-(2-methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N- methyl-N-(3-methylphenyl) amιno-2'-carboxybeπzophenone 2-hydroxy-4-N-methyl-N-(4- methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-methyl-N-propyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-methyl-N-ιsopropyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-methyl-N-butyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-methyl-N- isobutyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-methyi-N-secbutyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-methyl-N-pentyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-methyl-N-1-methylbutyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N- methyl-N-isoamyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-methyl-N-1-methylpentyl amιno-2'-carboxybenzophenone 2-hydroxy-4-N-methyl-N-hexyl amιno-2'- carboxybenzopheπone, 2-hydroxy-4-N-methyl-N-tetrahydrofurylmethyi amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-methyl-N-ethoxypropyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-methyl-N-cyclohexylmethyl amιno-2'- carboxybenzoohenone, 2-nydroxy-4-N-methyl-N-phenethyl amιno-2'- carboxybenzophenoπe 2-hydroxy-4-N-ethyl-N-cyciohexyl amιno-2'-carboxybenzophenone _ g _ 2-hydroxy-4-N-ethyl-N-phenyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-(2- methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-(3-methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-(4-methylphenyl) amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-propyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-ethyl-N-ιsopropyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-butyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-ιsobutyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-secbutyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-ethyl-N-pentyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-1 - methylbutyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-ιsoamyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-1-methylpentyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-hexyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-ethyl-N-tetrahydrofurylmethyl amιno-2'-carboxybenzopheπone, 2-hydroxy-4-N- ethyl-N-ethoxypropyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N- cyclohexylmethyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-ethyl-N-phenethyl ammo- 2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N-cyclohexyl amιno-2'- carboxybeπzophenone, 2-hydroxy-4-N-propyl-N-phenyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-propyl-N-(2-methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N- propyl-N-(3-methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N-(4- methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N-ιsopropyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-propyl-N-butyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-propyl-N-ιsobutyi amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N- secbutyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N-pentyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-propyl-N-1 -methylbutyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-propyl-N-ιsoamyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N-1-methylpentyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N- propyl-N-hexyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N- tetrahydrofurylmethyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N- ethoxypropyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N-cyclohexylmethyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-propyl-N-phenethyl amιno-2'- carboxybenzophenone 2-hydroxy-4-N-butyl-N-cyclohexyl amιno-2'-carboxybeπzophenone, 2-hydroxy-4-N-butyl-N-phenyl amιno-2'-carboxybenzophenone 2-hydroxy-4-N-butyl-N-(2- methylphenyl) amιno-2'-carboxybenzophenone 2-hydroxy-4-N-butyl-N-(3-methylphenyl) amιno-2'-carboxybenzophenone. 2-hydroxy-4-N-butyl-N-(4-methylphenyi) amιno-2'- carboxybenzophenone 2-hyαroxy-4-N-butyl-N-propyl amιno-2'-carboxybenzophenone 2- hydroxy-4-N-butyl-N-ιsopropyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-butyl-N- isobutyt amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-butyl-N-secbutyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-butyl-N-pentyl amιno-2'-carboxybenzophenone 2- hydroxy-4-N-butyl-N-1-methylbutyi amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-butyl-N- isoamyl ammo-2'-carboxybenzophenone, 2-hydroxy-4-N-butyl-N-1-methylpentyl amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-butyl-N-hexyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-butyl-N-tetrahydrofurylmethyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N- butyl-N-ethoxypropyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-butyl-N- cyclohexylmethyl amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-butyl-N-phenethyl ammo- 2'-carboxybenzophenone 2-hydroxy-4-N-phenyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-(2-methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-(3- methylphenyl) amιno-2'-carboxybenzophenone, 2-hydroxy-4-N-(4-methylphenyl) amιno-2'- carboxybenzophenone, 2-hydroxy-4-N-cyclohexyl amιno-2'-carboxybenzophenone, 2- hydroxy-4-N-pyrrolιdιnyl -2'-carboxybenzophenone, 2-hydroxy-4-N-(2-methylpyrτolιdιnyl)-2'- carboxybenzophenone, 2-hydroxy-4-N-(3-methylpyrrotιdιnyl)-2'-carboxybenzophenone 2- hydroxy-4-N-mo holιnyl-2'-carboxybenzophenone, 2-hydroxy-4-N-pιpeπdιnyi-2'- carboxybenzophenone, 2-hydroxy-4-N-(2-methylpιpeπdιnyl)-2'-carboxybenzophenone, 2- hydroxy-4-N-(3-methylpιpeπdιnyl)-2'-carboxybenzophenone, 2-hydroxy-4-N-(4- methylpipeπdmyl) -2'-carboxybenzophenone, 2-hydroxy-4-N-(4-Dιmethylamιnophenyl)-2'- carboxybenzophenone, 2-hydroxy-3,5-dιmethyl-2'-carboxybenzophenone Compounds of formula 111 are exemplified by, but not limited to, 3-methoxy toluene, 3- methylphenol, 4-methoxy toluene, 4-methylphenol, 2,4-dιmethylanιsole, 2 4-dιmethylphenol, 4-methoxy-2-methyl diphenylamme, 4-hydroxy-2-methyl diphenylamme, 4-methoxy-2 2',4'- tπmethyt diphenylamme, 4-hydroxy-2,2',4'-tπmethyl diphenylamme, 2-chloro-5-methoxy toluene, 2-chloro-5-hydroxy toluene, 4-methoxy-2-methyl-3'-tπfluoromethyl diphenylamme, 4-hydroxy-2-methyl-3'-tπf!uoromethyl diphenylamme, 4-methoxy-2-methyl-2'-chloro diphenylamme, 4-hydroxy-2-methyl-2'-chloro diphenylamme, 4-methoxy-2-methyl-4'-chloro diphenylamme, 4-methoxy-2-methyl-2'-fluoro diphenylamme, 4-hydroxy-2-methyl-2'-fluoro diphenylamme n-octyl-p-anisidine N-n-octyl-p-ammophenol 2-dιbenzylamιno-5-methoxy- toluene 4-dιbenzyiamιno-3-methylphenol 4-methoxy-2-chloro diphenylamme, 4-hydroxy-2- chloro diphenylamme 4-methoxy-2,3'-dιmethyl diphenylamme < -hydroxy-2 3'-dιmethyl diphenylamme 4-methoxy-2 4'-dιmethyl diphenylamme 4-hydroxy-2,4'-αιmethyl dionenyiamine 3-chloroanιsole 3-chloropnenol 1-naphthol i-methoxy naphthalene 2- „ rt - 10 - naphthol, 2-methoxy naphthalene, 4-methoxy-2-ethoxyethyl diphenylamme, 4-hydroxy-2- ethoxyethyl diphenylamme, 4-t-butyl phenol, 4-t-butyl anisole, 4-hydroxybenzoιc acid, 4- methoxy benzoic acid, 4-hydroxybenzoιc acid ethyl ester, 4-methoxy benzoic acid ethyl ester, 3-(p-dιmethylamιno)anιlιnoanιsole, 3-(p-dιmethylamιno)anιlιnophenol, 4-N,N- dibenzylammophenol, 4-N,N-dιbenzylamιnoanιsιdιne Thus mixtures of fluoran compounds are prepared by reaction between keto acιd(s) of formula (II) and compound(s) of formula (III) in the presence of a dehydrating condensation agent, for example, concentrated sulphuπc acid, oleum - concentrated sulphuπc acid mixtures, polyphosphoπc acid, phosphorous pentaoxide or anhydrous aluminium chloπde and mixtures thereof, preferably concentrated sulphuπc acid or oleum-concentrated sulphuπc acid mixtures, and thereafter bππging the reaction mixture to an alkaline pH in the presence or absence of organic solvent The solvent, if used, is not specifically limited provided that it is insoluble or only slightly soluble in water Thus, the solvent may be exemplified by aromatic hydrocarbons such as benzene, toluene, xylenes or tπmethyl benzenes, halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzenes, tπchlorobenzenes or bromonaphthalenes, halogenated aliphatic hydrocarbons such as dichloroethane, tπchloroethane or tetrachloroethane aliphatic hydrocarbons such as hexane heptane, octane or n-decane and alicyclic hydrocarbons such as cyctohexaπe or methylcyclohexane In addition to the above there may also be used alcohols such as amyl alcohol, 2-ethylhexanol or octyl alcohol, ethers such as isopropyl ether, esters such as ethyl acetate or ketones such as cyclohexanone The solvent may be used singly or as a mixture The condensation reaction is generally earned out at from 0 to about 100°C preferably from about 10 to about 60°C for several to 100 hours When the reaction is earned out in concentrated sulphuπc acid or oleum-concentrated sulphuπc acid mixtures, the reaction temperature is preferably in the range from 0 to about 50°C The reaction time depends upon the selected reaction temperature and hence the reaction is conducted for a sufficient time to permit the reaction to go to completion Completion of reaction is determined using standard analytical techniques, including but not limited to, thin layer chromatography, gas chromatography and liquid chromatography After the dehydrating condensation reaction is completed the alkali treatment may be carried out by addition of the reaction mass to a stirred mixture of base, water and organic solvent Suitable bases include, for example, potassium hydroxide, lithium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate, ammonia or organic bases such as tπethylamme and mixtures thereof The preferred bases for use in the process of the present invention are sodium hydroxide and potassium hydroxide Suitable solvents include toluene, xylene halogenated aromatic solvents such as chlorobenzene, esters, ethers, ketones, alcohols such as 2-ethylhexanol and mixtures thereof Additional base may be added as required to achieve an alkalinity within the pH range of 9-12 The treatment may be conducted in a temperature of from 0°C to the boiling point of the solvent or solvent mixture in use, preferably 50 -100°C Duπng this process the mixtures of fluorans according to the present invention can be precipitated from the reaction media The precipitate may then be isolated by filtration from the reaction liquors After isolation, the mixture of fluoran compounds may be washed as desired with water and/or an organic solvent The solvent may be exemplified by aromatic hydrocarbons such as benzene toluene, xylenes or tπmethyl benzenes halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzenes tπchlorobenzenes or bromonaphthalenes halogenated aliphatic hydrocarbons such as dichloroethane, tπchloroethane or tetrachloroethane, aliphatic hydrocarbons such as hexane, heptane, octane or n-decane and alicyclic hydrocarbons such as cyctohexane or methylcyclohexane In addition to the above there may also be used alcohols such as methanol, ethanol, isopropanol butaπol, amyl alcohol 2-ethylhexanol or octyl alcohol, ethers such as isopropyl ether, or ketones such as cyclohexanone The solvent may be used singly or as a mixture Alternatively, after the dehydrating condensation, the reaction mass may be quenched into a stirred water-solvent mixture at from 0°C to the boiling point of the water-solvent mixture in use, preferably 50-100°C The solvent used is not specifically limited provided that it is insoluble or only slightly soluble in water Thus, the solvent may be exemplified by aromatic hydrocarbons such as benzene, toluene xylenes or tπmethyl benzenes halogenated aromatic hydrocarbons such as chlorobenzene dicnlorobenzenes tπchlorobenzenes or bromonaphthalenes halogenated aliphatic hydrocarbons such as dichloroethane, tπchloroethane or tetrachloroethane aliphatic hydrocarbons such as hexane, heptane octane or n-decane and alicyclic hydrocarbons such as cyclohexane or methylcyclohexane In addition to the above there may also be used alcohols such as amyl alcohol, 2- ethylhexanol or octyl alcohol, ethers such as isopropyl ether, or ketones such as cyclohexanone The solvent may be used singly or as a mixture Sufficient base, for example potassium hydroxide, lithium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate, ammonia or organic bases such as tπethylamme and mixtures thereof, is then added to provide an organic-aqueous phase separation The aqueous layer may then be separated if desired To the organic phase or biphasic mixture, containing the phthalide intermediate, is then added further base as descπbed hereinbefore, to pH>7 The reaction mass is stirred at from 0 to about 100°C, preferably 60-90°C, in order to complete cyclisation to the fluoran product The reaction mass is then adjusted to 25°C and the precipitated product may then be isolated by filtration as discussed previously The reaction product is isolated by filtration from the reaction liquors as the mixture of fluorans of the invention After isolation, the mixture of fluorans of the invention may be washed with water and/or an organic solvent as defined previously The mixture of fluorans of the invention may then be dπed by a usual method, such as at a raised temperature, below the melting point of the mixture of fluorans, under vacuum The composition of the mixture of fluorans so obtained is dependant upon the relative amounts of starting matenals used A second novel method of preparation is to prepare a mixed keto acid intermediate of general formula (II) from the reaction of aminophenols of general formula (IV) with phtha c anhydπdes of general formula (V) Wherein R1 R2 and R5 are as hereinbefore detailed Formula IV Formula V A mixture of n different keto acids, where n>1 , may be manufactured by the reaction of x different ammo phenols of formula (IV) and y different phthalic anhydπde derivatives of formula (V) where one or both of x and y are >1 For instance, a mixed keto acid intermediate consisting of two compounds of general formula (II) may be prepared by reaction of, i Two different ammo phenols of general formula (IV) with a single phthalic anhydπde deπvative of formula (V) n Two different phthalic anhydπde deπvatives of formula (V) with a single am o phenol of general formula (IV) in Recrystallisatioπ of two different keto acid derivatives from a suitable solvent Ammo phenols of formula IV are exemplified by, but not limited to N,N-dιmethyl aminophenol, N N-diethyl aminophenol, N N-di-n-propyl aminophenol, N N-di- n-butyl aminophenol, N,N-dι-n-pentyl aminophenol, N,N-dι-n-hexyl aminophenol, N,N- dnsopropyl aminophenol, N,N-dιsecbutyl aminophenol, N,N-dιιsobutyl aminophenol, N,N- dnsoamyl aminophenol, N-methyl-N-cyclohexyl aminophenol, N-methyl-N-phenyl aminophenol, N-methyl-N-(2-methylphenyl) aminophenol, N-methyl-N-(3-methylphenyl) aminophenol, N-methyl-N-(4-methylphenyl) aminophenol N-methyl-N-propyl aminophenol N-methyl-N-isopropyl aminophenol, N-methyl-N-butyl aminophenol, N-methyl-N-isobutyl aminophenol, N-methyl-N-secbutyl aminophenol, N-methyl-N-pentyl aminophenol, N-methyl- N-1 -methylbutyl aminophenol N-methyl-N-isoamyl phenol, N-methyl-N-1-methylpentyl aminophenol, N-methyl-N-hexyl aminophenol, N-methyl-N-tetrahydrofurylmethyl aminophenol, N-methyl-N-ethoxypropyl aminophenol, N-methyl-N-cyclohexylmethyl aminophenol, N-methyl-N-phenethyl aminophenol, N-ethyl-N-cyclohexyl aminophenol N- ethyl-N-phenyl aminophenol N-ethyl-N-(2-methylphenyl) aminophenol, N-ethyl-N-(3- methylphenyl) aminophenol, N-ethyl-N-(4-methylphenyl) aminophenol, N-ethyl-N-propyl aminophenol, N-ethyl-N-isopropyl aminophenol, N-ethyl-N-butyl aminophenol, N-ethyl-N- isobutyl aminophenol, N-ethyl-N-secbutyl aminophenol N-ethyl-N-pentyl aminophenol N- ethyl-N-1 -methylbutyl ammopnenol, N-ethyl-N-isoamyl phenol N-ethyl-N-1-methylpentyl aminophenol N-ethyl-N-hexyi aminophenol N-ethyl-N-tetrahydrofurylmethyl aminophenol N-ethyl-N-ethoxypropyl aminophenol, N-ethyl-N-cyclohexylmethyl aminophenol N-ethyl-N- phenethyl ammoohenol N-prooyl-N-cyciohexyl aminophenol -prooyl-N-ohenyl aminophenol, N-propyl-N-(2-methylphenyl) aminophenol, N-propyl-N-(3-methylphenyl) aminophenol, N-propyl-N-(4-methylphenyl) aminophenol, N-propyl-N-isopropyl aminophenol, N-propyl-N-butyl aminophenol, N-propyl-N-isobutyl aminophenol, N-propyl-N- secbutyl aminophenol, N-propyl-N-pentyl aminophenol, N-propyl-N-1-methylbutyl aminophenol, N-propyl-N-isoamyl phenol, N-propyl-N-1-methylpentyl aminophenol, N- propyl-N-hexyl aminophenol, N-propyl-N-tetrahydrofurylmethyl aminophenol, N-propyl-N- ethoxypropyl aminophenol, N-propyl-N-cyclohexylmethyl aminophenol, N-propyl-N- phenethyl aminophenol, N-butyl-N-cyclohexyl aminophenol, N-butyl-N-phenyl aminophenol, N-butyl-N-(2-methylphenyl) aminophenol, N-butyl-N-(3-methylphenyl) aminophenol N-butyl- N-(4-methylphenyl) aminophenol, N-butyl-N-propyl aminophenol N-butyl-N-isopropyl aminophenol, N-butyl-N-isobutyl aminophenol, N-butyl-N-secbutyl aminophenol, N-butyl-N- pentyl aminophenol, N-butyl-N-1 -methylbutyl aminophenol, N-butyl-N-isoamyl phenol, N- butyl-N-1-methylpentyl aminophenol, N-butyl-N-hexyl aminophenol, N-butyl-N- tetrahydrofurylmethyl aminophenol, N-butyl-N-ethoxypropyi aminophenol, N-butyl-N- cyclohexylmethyl aminophenol, N-butyl-N-phenethyl aminophenol, N-phenyl aminophenol, N-2-methylphenyl aminophenol, N-3-methylphenyl aminophenol N-4-methyiphenyl aminophenol, N-cyclohexyl aminophenol, 3-N-pyrrolιdιnyl phenol 3-N-(2-methylpyrrolιdιnyl) phenol, 3-N-(3-methylpyrrolιdιnyl) phenol, 3-N-morpholιnyl phenol, 3-N-pιpeπdιnyl phenol, 3- N-(2-methyipιpeπdιnyl) phenol, 3-N-(3-methylpιpeπdιnyl) phenol 3-N-(4-methyipιpeπdιnyl) phenol Compounds of formula V are exemplified by, but not limited to, phthalic anhydπde, terephtha c anhydπde, 3-methylphthalιc anhydπde 3-nιtrophthalιc anhydπde 3- hydroxyphthalic anhydπde 3-chlorophthalιc anhydπde, 3-fluorophthalιc anhydπde, 4- methylphthahc anhydπde, 4-t-butylphthalιc anhydπde, 4-chlorophthalιc anhydπde, 4- bromophthalic anhydπde, 4-fluorophthalιc anhydπde, 3 6-dιchlorophthalιc anhydπde, 3,6- dimethylphthahc anhydπde, 3,6-dιfluorophthalιc anhydπde, 4,5-dιfluorophthalιc anhydπde 4,5-dιchlorophthalιc anhydπde, 1 ,2-naphthoιc anhydπde 2,3-naphthoιc anhydπde, tetrabromophthalic anhydπde, tetrachlorophthalic anhydπde tetraiodophthalic anhydπde tetrafluorophthalic anhydπde tetraphenylphtha c anhydnde tetramethylphthalic anhydπde, 4-nιtrophthaiιc anhydπde, 3-dιalkylamιnophthalιc anhydπde 4-dιalkylammopnthalιc anhydπde For the reaction of the mixtures of m-ammophenol deπvatives, as above mentioned, with phthalic anhydπdes, the latter is usually used in an amount of 0 5-2 0 moles per total moles of the m-ammophenol deπvatives The ratio of solvent to m-aminophenol denvatives may be between 0 and 20 parts by weight The quantity of solvent chosen is dependent on the nature of the m-aminophenol deπvatives The amount of solvent used is determined so that the reaction mass remains mobile throughout the course of the reaction Preferably, the product is precipitated duπng the reaction The reaction is effected at an elevated temperature, preferably in the range of 60-120°C for a peπod of 3-40 hours The reaction time and temperature are chosen so as to achieve a suitable balance between completion of reaction and the amount of rhodamine type side products that are produced The amount of rhodamine produced increases at higher temperatures After the reaction, the reaction mixture is cooled to 0-60°C, most preferably 20-40°C Dependant on the viscosity of the reaction mixture at this stage, a secondary solvent may be added to the reaction mixture to maintain mobility There may be used as the secondary solvent, for example, an aromatic hydrocarbon of 6- 10 carbon atoms such as benzene, toluene or xylene, an aliphatic hydrocarbons of 5-12 carbons such as pentane, octane, isooctane, or decane, a halogenated aliphatic cycloaliphatic or aromatic hydrocarbon of 2-8 carbons, such as perclene, chlorobenzene or dichlorobenzene, ethers such as tetrahydrofuran, dibutyl ether or diphenylether, alcohols such as methanol, ethanol, propanols such as isopropanols or butanois such as n-butanol There may also be used a mixture of the alcohol with water or a mixture of the alcohol with a hydrocarbon solvent The crude keto acid deπvative may be recovered from the reaction mixture by filtration, or by diluting the mixture with a solvent in which the deπvative is barely soluble and recoveπng the precipitated deπvative by filtration, or by extracting the deπvative with an aqueous alkaline solution and precipitating it with acid, or by forming a metal salt of the deπvative isolating the salt and precipitating it with acid The organic solvents when used include for example an aromatic hydrocarbon of 6-10 carbon atoms such as benzene, toluene or xylene, an aliphatic hydrocarbons of 8-12 carbons such as octane isooctane or decane a halogenated hydrocarbon of 2-8 carbons aliphatic cycloalipnatic or aromatic such as perclene chiorooenzene or cichlorcoenzene ethers such as tetrahydrofuran, dibutyl ether or diphenylether, among which are especially preferred aromatic hydrocarbons or ethers The mixture of keto acids of general formula (II) thus isolated can then be reacted with a compound(s) of general formula (III), as descπbed previously, to produce a mixture of fluorans of formula (I) In this instance the composition of the mixture isolated is determined by the ratio of the ammo phenols used If desired, the mixture of fluorans , suitably isolated by any of the aforementioned methods, may be further purified by precipitation from an organic solvent or from a organic solvent - water mixture, for example, toluene benzene, xylene methanol ethanol, iso-propanol, n- butanoi, acetonitπle, dimethylformamide or mixtures of these solvents The mixture of fluorans may be dissolved by heating to a temperature range of from room temperature to the boiling point of the chosen solvent, or above it under pressure in an autoclave After complete dissolution the mixture of fluorans may be precipitated with stimng or on standing All of the methods of preparation as hereinbefore descπbed can be used to produce a monophase solid solution of two or more fluoran compounds Whether or not a monophase solid solution has been formed may be judged by powder X-ray diffraction analysis using K- Cuα rays A powder X-ray diffraction pattern of a monophase solid solution is substantially identical to that of one of the components, the 'host' In general the 'host' is the compound forming the greater part of the mixture A monophase solid solution will also demonstrate a different melting point to that of an equivalent physical mixture However, a change in melting point may also indicate a mixed crystal has been formed thus melting point should be considered in conjunction with powder X-ray diffraction when assessing whether or not a monophase solid solution has been formed All of the methods of preparation as hereinbefore descπbed can also be used to produce a multiphase solid solution Whether or not a multiphase solid solution has been formed can be determined by powder X-ray diffraction analysis using K-Cuα rays A powder X-ray diffraction pattern of a multiphase solid solution will different to a physical mixture of the components in that the signals may be broadeneα shifted or altered in intensity in general different proportions of the components produce different powder X-ray diffraction patterns All of the methods of preparation as hereinbefore described can also be used to produce a mixed crystal Whether or not a mixed crystal has been formed can be determined by powder X-ray diffraction analysis using K-Cuα rays A powder X-ray diffraction pattern of a multiphase solid solution will be different to a physical mixture of the components in that the signals may be broadened, shifted or altered in intensity However, within certain limits, different proportions of the components produce substantially identical powder X-ray diffraction patterns The mixtures of fluoran compounds of the general formula (I), as isolated by any of the processes according to the present invention, may be used as a colour forming compound for vanous recording matenals Isolated matenal, as defined herein, means both mateπal as obtained from precipitate and filtration as well as matenal which has been further puπfied, by say, recrystallisation As such it is a further object of the present invention to provide recording mateπal compπsmg the mixtures of fluorans of general formula (I) according to the present invention The recording matenals of the present invention include pressure sensitive recording mateπal and heat sensitive recording mateπal When used in heat sensitive recording matenals, the mixtures of fiuorans can be used alone or in combination with other colour forming compounds such as tπphenylmethanes, lactones, fluorans, benzoxazines, quinoxalmes, phtha des, phenoxazmes, phenothiazmes, leuco-auramines, rhodamine lactams, spiropyrans and the like in order to adjust the developed hue if desired The mixtures of fluoran compound of the invention may also be used together with further colour formers to improve the thermal sensitivity and image stability of the recording mateπal Other colour formers which may be used as above, include but are not limited to, 3-dιethylamιno-6-methylfluoran, 3-dιmethylamιno-6-methyl-7- anilinofluoran, 3-dιethylamιno-6-methyl-7-anιlιnofluoran 3-dιethylamιno-6-methyi-7-(2,4- dimethylaniimo) fluoran, 3-dιethylamιno-6-methyl-7-chlorofluoran 3-dιethyiamιno-6-methyl- 7-(3-tπfluoromethylanιlιno) fluoran, 3-dιethylamιno-6-methyi-7-{2-chloroanιlιπo) fluoran, 3- dιethylamιno-6-methyl-7-(4-chloroanιiιno) fluoran 3-dιethylamιno-6-methyl-7-(2- fluoroanilmo) fluoran 3-dιethylamιno-6-methyl-7-(4-n-octylanιiιno) fluoran, 3-dιethylamιno -7- '4-n-octylanιlιno) fluoran 3-dιethyiamιno - ~ - n-octyiamino) fluoran 3-dιethyιamιno - 7 - (dibenzylamino) fluoran, 3-dιethylamιno-6-methyl-7-(dιbenzylamιno) fluoran, 3-dιethylamιno- 6-chloro-7-methylfluoran, 3-dιethylamιno-7-t-butylfluoran, 3-dιethylamιno -7- carboxyethylfluoran, 3-dιethylamιno-6-chloro-7-anιlιnofluoran, 3-dιethylamιno-6-methyl-7-(3- methylanilmo) fluoran, 3-dιethylamιno-6-methyl-7-(4-methylanιlιno) fluoran, 3-dιethylamιno- 6-ethoxyethyl-7-anιlιnofluoran, 3-dιethylamιno-7-methylfluoran, 3-dιethylamιno-7- chlorofluoran, 3-dιethylamιno-7-(3-trιfluoromethylanιlιno) fluoran, 3-dιethylamιno-7-(2- chloroanilmo) fluoran, 3-dιethylamιno-7-(2-fluoroanιlιno) fluoran, 3-dιethylamιno-benzo[a] fluoran, 3-dιethylamιno-benzo[c] fluoran, 3-dιbutylamιno-6-methyl fluoran, 3-dιbutylamιno-6- methyl-7-anιlιnofluoran, 3-dιbutylamιno-6-methyl-7-(2,4-dιmethyianιlιno) fluoran, 3- dιbutylamιno-6-methyl-7-(2-chloroanιlιno) fluoran, 3-dιbutylamιno-6-methyl-7-(4- chioroaniiino) fluoran, 3-dιbutylamιno-6-methyl-7-(2-fluoroanιlιno) fluoran, 3-dιbutylamιno-6- methyl-7-(3-tπfluoromethylanιlιno) fluoran, 3-dιbutylamιno-6-ethoxyethyl-7-anιlιnofluoran, 3- dιbutylamιno-6-chloro-anιlιnofluoran, 3-dιbutylamιno-6-methyl-7-(4-methylanιlιno) fluoran 3- dιbutylamιno-7-(2-chloroanιlιno) fluoran, 3-dιbutylamιno-7-(2-fluoroanιlιno) fluoran, 3- dιpentylamιno-6-methyl-7-anιlιnofluoran 3-dιpentylamιno-6-methyl-7-(4-2-chloroanιlιno) fluoran 3-dιpentylamιno-7-(3-tπfluoromethylanιlιno) fluoran, 3-dιpentylamιno-6-chloro-7- anilmofluoran, 3-dιpentylamιno-7-(4-chloroanιlιno) fluoran, 3-pyrrolιdιno-6-methyl-7- anilmofluoran, 3-pιpeπdιno-6-methyl-7-anιlιnofluoran 3-(N-methyl-N-propylamιno)-6-methyl- 7-anιlιnofluoran, 3-(N-methyl-N-cyclohexylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-N- cyclohexylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-p-toiuιdιno)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-N-ιsoamylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-N-ιsoamylamιno)-6-chloro- 7-anιlιnofluoran, 3-(N-ethyl-N-tetrahydrofurfurylamιno)-6-methyl-7-anιlιnofluoran 3-(N-ethyl- N-ιsobutylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-butyl-N-ιsoamylamιno)-6-methyl-7- anihnofluoran, 3-(N-ιsopropyl-N-3-pentylamιno)-6-methyl-7-anιlιnofluoran, 3-(N-ethyl-N- ethoxypropylamιno)-6-methyl-7-anιlιnofluoran, 3-cyclohexylamιno-6-chlorofluoran, 2-methyl- 6-p-(p-dιmethylamιnophenyl)amιnoanιlιnofluoran, 2-methoxy-6-p-(p- dιmethylamιnophenyl)amιnoanιlιnofluoran 2-chloro-3-methyl-6-p-(p- phenylamιnophenyl)amιnoanιlιnofluoran, 2-dιethyiamιno-6-p-(p- dιmethylamιnophenyl)amιnoanιiιnofluoran, 2-pheny!-6-methyl~6-p-(p- phenylamιnophenyl)amιnoanιiιnofluoran 2-benzyl-6-p-(p- phenyiamιnophenyl)amιnoanιiιnofiuoran 3-methyl-6-p-(p- dιmethylamιπophenyl)amιnoanιiιnofluoran 3-dιethylamιno-6-p-(p- dιethylamιnoohenyl)amιnoanιlιnofluoran 3-dιethylamιno-6-p-(p- dιbutylamιnoohenyl)amιnoanιlιnofluoran 2 ^-dιmethyl-6-[(4-dιmethylamιno)anιlιno] fluoran 3-[(4-dιmethylamιnophenyl)amιno]-5,7-dιmethylfiuoran, 3,6,6'- tπs(dιmethylamιno)spιro[fluorene-9,3'-phthalιde], 3,6,6'-tns(dιethylamιno)spιro[fluorene-9,3'- phthalide], 3,3-bιs(p-dιmethylamιnophenyl)-6-dιmethyiamιnophthalιde, 3,3-bιs(p- dιmethylamιnophenyl)phthalιde, 3,3-bιs-[2-(p-dιmethylamιnophenyl)-2-(p- methoxyphenyl)ethenyl-4,5,6,7-tetrabromophthalιde, 3,3-bιs-[2-(p-dιmethylamιnophenyl)-2-(p-methoxyphenyl)ethenyl-4,5,6,7- tetrachlorophthahde, 3,3-bιs[1 ,1-bιs(4-pyrrolιdιnophenyl)ethylene-2-yl]-4,5,6 7- tetrabromophthalide, 3,3-bιs-[1-(4-methoxyphenyl)-1-(4-pyrπdιnophenyl)ethylene-2-yl]- 4,5,6,7-tetrachiorophthalιde, 3-(4-dιethylamιno-2-ethoxyphenyl)-3-(1-ethyl-2-methylιndole-3- yl)-4-azaphthalιde, 3-(4-dιethylamιno-2-ethoxyphenyl)-3-(1-octyl-2-methylιndole-3-yl)-4- azaphthalide, 3-(4-cyclohexylethylamιno-2-methoxyphenyl)-3-(1-ethyl-2-methylιndole-3-yl)- 4-azaphtha de, 3,3-bιs(1-ethyl-2-methylιndole-3-yl) phthahde, 3 3-bιs(1-octyl-2- methylιndole-3-yl) phthahde, mixture of 2-phenyl-4-(4-dιethylamιnophenyl)-4-(4- methoxyphenyl)-6-methyl-7-dιmethylamιno-3, 1 -benzoxazme and 2-phenyl-4-(4- dιethylamιnophenyl)-4-(4-methoxyphenyl)-8-methyl-7-dιmethylamιno-3 1 -benzoxazme 4,4'- [1-methylethylιdeπe)bιs(4,1-phenyleneoxy-4,2-quιnazolιπedιyl)]bιs[N,N-dιethylbenzenamιne], bιs(N-methyldιphenylamιne)-4-yl-(N-butylcarbazole)-3-yl-methane and mixtures thereof When prepaπng a heat sensitive recording mateπal of the invention, the mixture of fluoran compounds of the formula (I) of the present invention and a developer are pulveπsed separately in water or a suitable dispersing medium, such as aqueous polyvmyl alcohol, to form an aqueous or other dispersion Optionally, a fine dispersion of sensitiser may be included The fine particle dispersions thus obtained are combined and then mixed with conventional amounts of binder, filler and lubπcant Representative examples of the developer which are suitable for use in the heat sensitive recording mateπal include but are not limited to substituted phenols and bisphenols such as 4,4'-ιsopropyiιdene Bisphenol 4,4'-sec-butylιdene bisphenol, 4 4'-cyclohexylιdene Bisphenol 2,2-bιs-(4-hydroxyphenyl)-4-methylpentane 2,2-dιmethyl-3 3-dι(4- hydroxyphenyl)butane, 2 2'-dιhydroxydιphenyl, 1-phenyl-1 1-bιs(4-hydroxyphenyl)butane, 4- phenyl-2 2-bιs(4-hyαroxyphenyl)butane 1-phenyl-2,2-bis(4-hyaroxyphenyl butane, 2,2- bιs(4 -hydroxy-3'-methylphenyi)-4-methyipentane, 2 2-bιs(4'-hydroxy-3'-tert-butyllphenyl)-4- methylpentane 4,4'-sec-butylιαene-oιs (2-methylphenol), 4 4'-ιsopropylιdene-bιs (2-tert- butylpneπol) 2 2-bιs(4'-hydroxy-3'->scpropylpnenylH-methyipentane allyι--i 4-bιs (4'- hydroxyphenyl) pentanoate, propargyl- 4,4-bιs(4'-hydroxyphenyl) pentanoate, n-propyl-4,4- bis (4'-hydroxyphenyl) pentanoate, 2,4-bιs (phenylsulfonyl) phenol, 2-(4-methylsulfonyl)-4- (phenylsulfonyl) phenol, 2-(phenylsulfonyl)-4-(4-methylsulfonyl) phenol, 2,4-bιs (4- methylphenylsulfonyl) phenol, pentamethylene-brs(4-hydroxybenzoate), 2,2-dιmethyl-3,3- dι(4-hydroxyphenyl)pentane, 2,2-dι(4-hydroxyphenyl)hexane, sulphur containing bisphenols such as, 4,4'-dιhydroxydιphenyl thioether, 1 ,7-dι(4- hydroxyphenylthιo)-3,5-dιoxaheptane, 2,2'-bιs(4-hydroxyphenylthιo)dιethyl ether, 4,4'- dιhydroxy-3,3'-dιmethylphenyl thioether, hydroxybenzoate esters such as, benzyl-4- hydroxybenzoate, ethyl-4-hydroxybenzoate, propyl-4-hydroxybenzoate, ιsopropyl-4- hydroxybenzoate, butyl-4-hydroxybenzoate, ιsobutyl-4-hydroxybenzoate, hydroxy sulfones such as, 4,4'-dιhydroxydιphenyl sulfone, 2,4'-dιhydroxydιphenyl sulfone, 4-hydroxy-4 - methyldiphenyt sulfone, 4-hydroxy-4'-ιsopropoxydιphenyl sulfone, 4-hydroxy-4 - butoxydiphenyl sulfone, 4,4'-dιhydroxy-3 3'-dιallyldιphenyl sulfone, 3,4-dιhydroxy-4'- methyldiphenyl sulfone, 4,4'-dιhydroxy-3,3',5,5'-tetrabromodιphenyl sulfone, sulphonyl ureas such as 4,4'-bιs (p-toluenesulphonylaminocarbonylamino) diphenylmethane, diesters of 4-hydroxyphthalιc acid such as, dimethyl 4-hydroxyphthalate dicyclohexyl 4- hydroxyphthalate, diphenyl 4-hydroxyphthalate, salicylic acid deπvatives such as, 4-[2-(4- methoxyphenyloxy)ethyioxy] salicylate, 3,5-dι-tert-butylsalιcylιc acid, 3-benzyl salicylic acid, 3-(α-methylbenzyl) salicylic acid, 3-phenyl-5-(α,α-dιmethylbenzyl) salicylic acid 3,5-dι-α- methylbenzyl salicylic acid, metal salts of salicylic acid such as zinc salicylate, benzoic acid deπvatives such as, 2-benzylsulfonyibenzoιc acid 3-cyclohexyl-4-hydroxybenzoιc acid, metal salts of benzoic acid such as, zinc benzoate, zinc 4-nιtrobenzoate, resorcylic anihde deπvatives as descπbed in US 5,607,894 and included herein by reference, phthalic acid and isophthalic acid deπvatives such as 4-(4'-phenoxybutoxy)phthalιc acid, 4-(2'- phenoxyethoxy)phthalιc acid, 4-(3'-phenylpropyloxy)phthalιc acid, mono (2-hyαroxyethyl) -5- nitro-isophtha c acid, 5-benzyloxycarbonyl isophthalic acid, 5-(1'-phenylethanesulfonyl) isophthalic acid and bιs(1 ,2-dιhydro-1 ,5-dιmethyl-2-phenyl-3H-pyrrol-3-one- O)bιs(thιocyanato-N) zinc and mixtures thereof Representative binders used for the heat sensitive recording mateπal includes but are not limited to, polyv yl alconol (fully and partially hydrolysed), carboxy amide suifonic and butyral modified polyvmyl alcohols, deπvatives of cellulose such as hydroxyethyl cellulose methyl cellulose ethyl cellulose carboxymethyl cellulose and acetyl cellulose copolymer of styrene-maleic anhydπde, copolymer of styrene-butadiene, polyvmyl chloπde, polyvmyl acetate, polyacrylamide, polyamide resin and mixtures thereof Exemplary fillers which can be used include, but are not limited to, calcium carbonate, kaolin, calcined kaolin, aluminium hydroxide, talc, titanium dioxide, zinc oxide, silica, polystyrene resin, urea-formaldehyde resin, hollow plastic pigment and mixtures thereof Representative lubπcants for use in heat sensitive recording materials include, but are not limited to, dispersions or emulsions of stearamide, methylene bisstearamide, polyethylene, camauba wax, paraffin wax, zinc stearate or calcium stearate and mixtures thereof Other additives can also be employed if necessary Exemplary additives include sensitisers, stabilisers and the like Representative sensitisers for use in heat sensitive recording matenals include but are not limited to stearamide, methylol stearamide, p-benzylbiphenyl m-terphenyl, 2-benzyloxynaphthalene, dibenzyl oxalate, dι(4-methyibenzyl) oxalate, dι(4- chlorobenzyl) oxalate, dimethyl phthalate dibenzyl terephthalate, dibenzyl isophthalate, 1 ,2- diphenoxyethane, 1 2-bιs(4-methyiphenoxy) ethane, 1 2-bιs(3-methylphenoxy) ethane, 4,4'- dimethylbiphenyl, phenyl-1-hydroxy-2-naphthoate, 4-methylphenyl biphenyl ether, 1 ,2- bιs(3,4-dιmethylphenyl) ethane 2,3,5,6-4'-methyldιphenyl methane, 1 ,4- diethoxynaphthalene o-xylylene-bιs(phenyl ether), 4-(m-methylphenoxymethyl) biphenyl, p- hydroxyacetani de, p-hydroxybutyranilide p-hydroxynonananiiide, p-hydroxylauranihde p- hydroxyoctadecananilide and mixtures thereof Representative stabilisers for use in heat sensitive recording matenals include but are not limited by, 2,2'-methylene-bιs(4-methyl-6-tert-butylphenol), 2,2'-methylene-bιs(4-ethyl-6-tert- butylphenol), 4,4'-butylιdene-bιs(3-methyl-6-tert-butylphenol), 4,4'-thιo-bιs(2-tert-butyl-5- methylphenol), 1 ,1 ,3-tπs(2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1 1 ,3-tπs(2-methyl- 4-hydroxy-5-cyclohexylphenyl) butane, bis (3-tert-butyl-4-hydroxy-6-methylphenyl) sulfone bis (3 5-dιbromo-4-hydroxyphenyl) sulfone 4 4'-sulfιnyl bis (2-tert-butyl-5-methylphenoι) 2.2'-methyιene bis (4 6-dι-tert-butyiphenyl) phosphate and alkali metal, ammonium and polyvalent metal salts thereof 4-benzyloxy-4'-(2-methylgiycιdyioxy) diphenyi sulfone A 4'- digly dyioxyαiohenyi sulfone " 4-cjιgiycιdyιoxyoenzene 4-[α-(hydroxymetnyl)benzyloxy]--i- hydroxydiphenyl sulfone, metal salts of p-nitrobenzoic acid, metal salts of phthalic acid mono benzyl ester, metal salts of cmnamic acid and mixtures thereof The coating liquid obtained by the addition of additives to the particle dispersion of fluoran and developer can be applied to a suitable substrate such as paper, plastic sheet and resin coated paper, and used as the heat sensitive recording mateπal The system of the invention can be employed for other end use applications using colour forming matenals, for example, a temperature indicating material The mixtures of fluorans of the present invention may also be used in conventional pressure sensitive recording matenals as descπbed in GB 2,000,206 and GB 2,068,994 They may be used alone or in combination with other colour forming matenals such as those listed previously herein In pressure sensitive recording matenals, a solution of colour formers is allowed to come into contact with an acidic developer to produce the image Typical solvents used include but are not limited to, dnsopropyl naphthalene, butylated biphenyls isopropylated biphenyls, phenyl xylyl ethane, butylated diphenylethane, xylenyl xylene, esters of tπmethylol propane, biodegradable solvents of natural or synthetic oπgin such as rapeseed oil, sunflower oil, coconut oil, palm oil, dialkyl esters of carboxylic acids such as adipic acid, sebaαc acid and azaleic acid The solvent may be diluted with diluents exemplified by, but not limited to, kerosenes, normal paraffins and naphthenic oils Typical developers include but are not limited to, activated bentonite, activated montmoπllonite, synthetic aluminosi cates, phenolic resins especially Zinc modified phenolic resins, attapulgite clay, Silton clay and zinc salicylates Preferably, the colour former solution is encapsulated in microcapsules thus preventing contact with the developer and premature image development Typical microcapsule wall matenals include but are not limited to; gelatine, melamιne-formaldehyde(MF), urea- formaldehyde^ F) MF-UF, polyurea, poiyuret ane and polyamide Typically the microcapsules containing the colour former may be coated on to a sheet of paper (coated back or CB) and the developer may be coated onto a separate sheet of paper (coated front or CF) The imaging set may then be formed by bππgmg together the two coated papers with the coated surfaces in contact with each other Pressure may then oe applied to the reverse of the CB to rupture the microcapsules and allow the colour former solution to come into contact with the developer on the CF ana form the desired image If more than one copy is reαuired one or more intermediate sheets usually known as CFB (coated front and back) sheets are provided, each of which is coated on it's lower surface with microcapsules and on it s upper surface with colour developer composition The microcapsules and colour developing material may also be coated onto the same surface of a sheet usually known as a self-contained system The following non-limiting examples illustrate the processes of the present invention, Example 1 Preparation of monophase solid solution from reaction of 2'-carboxy-4-dιethylamιno-2- hydroxybenzophenone (10mol%) and 2'-carboxy-4-dιbutylamιno-2-hydroxybenzophenone (90mol%) with 4-methoxy-2-methyldιphenylamιne To 249 5g of 98% sulphuπc acid and 61 2g oleum was added 78 97g of 2'-carboxy-4- dιbutylamιno-2-hydroxybenzophenone and 7 44g of 2'-carboxy-4-dιethylamιno-2- hydroxybenzophenone over about 2hr with the temperature being maintained below about 25°C by use of an ice-bath Once in solution, 50 7g of 4-methoxy-2-methyldιphenylamιne was added and the mixture was stirred for about 3hr at 30°C The reaction mass was then added, over about 30 minutes with stirπng, to a mixture of 135g toluene-45g water at 85°C To this was then added, over 30 minutes, 135 7g water Agitation was ceased and the separated aqueous phase was removed To the remaining organic phase was added 244g sodium hydroxide 100°TW, 199g toluene and 387g water and the reaction was stirred for 2h at 85°C The reaction was cooled to 25°C and the precipitated product was isolated by filtration The product was washed with hot water (about 60°C) then methanol and dπed to yield 106 2g of a monophase solid solution of the invention (melting point 179 9-181 4°C) The composition of the monophase solid solution was confirmed by dissolving the crystalline compound in toluene to release the component fluorans Standard analytical techniques such as thin layer chromatography, high pressure liquid chromatography and gas chromatography can be used to confirm the ratio of the two components in the monophase solid solution Example 2 Preparation of a mixture of fluoran compounds from reaction of 2'-carboxy-4-dιethylamιno- 2-hydroxybenzophenone (54mol%) and 2'-carboxy-4-dιbutylamιno-2-hydroxybenzophenone (46mol%) with 4-methoxy-2-methyldιphenylamιne To 232 3g of 98% sulphuric acid and 83 6g oleum was added, 44g of 2'-carboxy-4- dιbutylamιno-2-hydroxybenzophenone and 44g of 2'-carboxy-4-dιethylamιno-2- hydroxybenzophenone over about 2hr with the temperature being maintained below about 25°C by use of an ice-bath Once in solution, 59 7g of 4-methoxy-2-methyldιphenylamιne was added and the mixture was stirred for about 2hr at 30°C The reaction mass was then added, over about 30 minutes with stirπng, to a mixture of 137g toluene-36g water at 85°C To this was then added, over 30 minutes 202 6g water and 91 4g sodium hydroxide 100°TW Agitation was ceased and the separated aqueous phase was removed To the remaining organic phase was added methanol 12 4g, 245 6g sodium hydroxide 100°TW, 205 8g toluene and 362 4g water and the reaction was stirred for 2h at 85°C The reaction was cooled to 25°C and the aqueous layer was removed Solvent was then removed by steam distillation and the precipitated product was isolated by filtration The composition of the mixture of fluorans was confirmed by chromatography Example 3 Preparation of a mixture of fluorans from phthalic anhydπde(52mol%) and 3-methyiphthalιc anhydπde(48mol%) An amount of 72g (0 44moi) of N,N-dιethylamιnophenol, 35 4g (0 24mol) phthalic anhydπde, 35 4g(0 22mol) 3-methylphthalιc anhydπde and 98 3g of toluene were placed in a reactor, and stirred whilst the reaction mass was heated to 90°C over 2 hours and then heated to 107°C and stirred at this temperature for 6 hours Toluene 167g was added and the reaction mass cooled to 20°C overnight The product was isolated by filtration The crude product was washed with methanol to yield 73 2g of the mixed keto acid The mixed keto acid was then converted to the mixed fluoran using the method descπbed in example 1 Example 4 Preparation of a mixture of fluorans from 3-N-(1-ethylpropyl)-N-propylamιnophenol (90mol%) and 3-N,N-dιethylamιnophenol (10mol%) An amount of 3 3g (0 02mol) of N,N-dιethylamιnophenol, 39 8g (0 18mol) 3-N-(1- ethylpropy -N-propylaminophenol, 32 6g(0 22mol) phthalic anhydπde and 46g of toluene were placed in a reactor, and stirred whilst the reaction mass was heated to 90°C over 2 hours and then heated to 85°C and stirred at this temperature for 12 hours Toluene 40g was added and the reaction mass cooled to 20°C The product was isolated by filtration The crude product was washed with methanol to yield 41 6g of the mixed keto acid The mixed keto acid was then converted to the mixed fluoran as descπbed in example 1 Example 5 Preparation of a mixture of fluoran compounds from reaction of 2'-carboxy-4-dιbutylamιno- 2-hydroxybenzophenone with 4-methoxy-2-methyldιphenylamιne (90mol%) and 4-methoxy- 2,3'-dιmethyldιphenylamιne (10mol%) The mixture of fluorans was prepared as in example 1 but with 2'-carboxy-4-dιbutylamιno-2- hydroxybenzophenone (100mol%) being used in place of the mixture of 2'-carboxy-4- dιbutylamιno-2-hydroxybenzophenone (90mol%) and 2'-carboxy-4-dιethylamιno-2- hydroxybenzophenone (10mol%) and a mixture of 4-methoxy-2-methyldιphenyiamιne (90mol%) and 4-methoxy-2,3'-dιmethyldιphenylamιne (10mol%) being used in place of of 4- methoxy-2-methyldιphenyiamιne (100mol%) The resulting product was a white solid with melting point (179 3-180 7°C) Example 6 Preparation of a mixture of fluoran compounds from reaction of 2'-carboxy-4-dιbutylamιno- 2-hydroxybenzophenone with 4-methoxy-2-methyldιohenylamιne (90mol%) and Dibenzyl-p- anisidme (10mol%) The mixture of fluorans was prepared as in example 1 but with 2'-carboxy-4-dιbutylamιno-2- hydroxybenzophenone (100mol%) being used in place of the mixture of 2'-carboxy-4- dιbutylamιno-2-hydroxybenzophenone (90mol%) and 2'-carboxy-4-dιethylamιno-2- hydroxybenzophenone (10mol%) and 4-methoxy-2-methyldιphenylamιne (90mol%) and dibenzyl-p-anisidme (10mol%) being used in place of of 4-methoxy-2-methyldιphenylamιne (100mol%) The resulting product was a white solid with melting point (181-183°C) A heat sensitive recording mateπal including a monophase solid solution prepared according to the present invention was prepared as follows -Example 7 Preparation of heat sensitive coating formulations comprising the monophase solid solution prepared according to the invention Dispersions A-C were prepared by gπnding the compositions shown below in an attπtor until an average particle size of 1 μ was attained Dispersion A (Colour Former) Monophase solid solution of -Example 1 3 01 parts Polyvmyl alcohol (10% aq soln ) 10 50 parts Water 6 49 parts Dispersion B (Colour Developer) Bis Phenol A 7 5 parts Polyvmyl alcohol (10% aq soln ) 7 5 parts Water 22 5 parts Dispersion C (Sensitiser) p-Benzyibiphenyl 10 0 parts Polyvmyl alcohol (10% aq soln ) 10 0 parts Water 20 0 parts A thermal coating mixture was then prepared by combining together the following components parts by weight Dispersion A 6 6 Dispersion B 10 0 Dispersion C 6 0 Calcium Carbonate (25% aq dispersion) 12 0 Zinc stearate (33% aq dispersion) 0 9 Polyvmyl alcohol (10% aq soln ) 4 5 Tmopal® ABP-X (fluorescent whitening agent) 0 12 Water 2 48 This coating mixture was applied on one side of a base paper weighing 50 g/m2 in a coating weight of about 5 0 g / m2 and then dπed The resulting sheet was calendered by means of a laboratory calender to produce a recording sheet with excellent background whiteness The heat sensitive recording paper obtained by a process of the invention demonstrates excellent background whiteness (bnghtness) of paper after application of the coating liquid and in storage stability, i e resistance to light, heat and moisture, of uncoloured portion of the coated paper and good resistance of the image to water and plasticiser Additionally, the recording paper obtained shows a high dynamic sensitivity Evaluation of water resistance was conducted by immersing a facsimile image in de-ionised water for 24 hours at room temperature and then observing the remaining image density Evaluation of plasticiser resistance was made by contacting a facsimile image with a sheet of PVC under 100gcm "2 pressure for 5 hours at 50°C and observing the remaining image density Evaluation of sensitivity was done using an Infotec fax machine 3301 at pulse widths of 0 30 0 50 0 68 and 1 00 milliseconds Evaluation post application was conducted by observing the bnghtness of the paper Evaluation of light resistance was conducted by inspecting the degree of yellowing of the uncoloured portion of the paper after exposure to 120 hours of artificial daylight Evaluation of heat and moisture resistance was conducted by examining the soiling of the uncoloured portion of paper after storage at 60°C and 50% relative humidity for one hour Example 8 Evaluation of the use of mixtures of fluorans of the invention in pressure sensitive recording mateπal 2% solutions of the mixtures of fluorans of the present invention were prepared in dnsopropylnaphthalene/kerosene (70 30 w/w) These solutions were then gravure pπnted on to commercially available clay, phenolic resin and zinc salicylate CF papers After one hour, the [_ * , a * and b * values were measured using a Gretag SPM 50 spectrophotometer Example CF L* a" Monophase solid solution Clay 58 6 6 05 -5 03 of example 1 Monophase solid solution Zinc 63 56 6 22 3 82 of example 1 salicylate Monophase solid solution Phenolic 62 30 5 99 1 06 of example 1 Resin Mixture of fluorans of Clay 59 77 7 20 -4 71 example 2 Mixture of fluorans of Zinc 63 89 6 60 3 58 example 2 Salicylate Mixture of fluorans of Phenolic 61 91 6 07 0 59 example 2 Resin Mixture of fluorans of Clay 59 95 5 47 -4 98 example 5 Mixture of fluorans of Zinc 64 17 5 34 3 61 example 5 Salicylate Mixture of fluorans of Phenolic 62 77 5 56 1 10 example 5 Resin Mixture of fluorans of Clay 58 -2.31 -3.51 example 6 Mixture of fluorans of Zinc 64 -1.22 3 43 example 6 Salicylate Mixture of fluorans of Phenolic 64 -1.83 1.80 example 6 Resin The L * ,a * ,b * values obtained demonstrate the ability of the mixtures of fluoran compounds of the invention to be used in pressure sensitive copying systems.

Claims: Claims 1. A process for the manufacture of mixtures of fluoran compounds by the reaction of keto acids of formula (II) with a compound of formula (III) in the presence of a dehydrating condensation agent- Formula Formula wherein, R1 and R2 independently represent hydrogen, an alkyl of 1-18 carbon, a secondary alkyl with respect to the carbon atom bonded to the nitrogen atom of 3-13 carbon atoms, a cycloalkyl of 4-8 carbon atoms or a phenyl. both of which may be substituted by at least one substituent selected from the group consisting of halogen atoms and alkyls having 1-4 carbon atoms, an aralkyl of 7-10 carbon atoms; or R1 and R2, together with the adjacent nitrogen atom form a heterocyclic πng; R3 is hydrogen, an alkyl of 1-4 carbon atoms, an alkoxy of 1-4 carbon atoms, a phenyl; a substituted phenyl or a halogen; R4 is an alkyl group of 1-18 carbon atoms, a carboxyalkyl of 1-18 carbon atoms, a carboxycycloalkyl of 4-8 carbon atoms, an alkylamino of 1-18 carbon atoms, a cycloalkylammo of 4-8 carbon atoms, a αialkylamino or dicycloalkylammo: an arylamino, a substituted arylamino; an aralkylammo of 7-10 carbon atoms; a diaralkylamino; R5 is an alkyl of 1-18 carbon atoms, a carboxy alkyl of 1-18 carbon atoms or a halogen and R6 is hydrogen or alkyl of 1-4 carbon atoms. 2. A process according to Claim 1 wherein the dehydrating condensation agent is selected from concentrated sulphuric acid, oleum - concentrated sulphuπc acid mixtures. polyphosphoric acid, phosphorous pentaoxide or anhydrous aluminium chloride, and mixtures thereof, and is preferably concentrated sulphuric acid or oleum-concentrated sulphuric acid mixtures. 3. A process according to Claim 1 or 2 wherein the condensation reaction is carried out at from 0 to about 100°C, preferably from about 10°C to about 60°C. 4. A process according to any of Claims 1 to 3 wherein the reaction mixture comprising keto acids of formula (II) and compound of formula (III) is brought to an alkaline pH after the addition of the dehydrating condensation agent. 5. A process according to any of Claims 1 to 3 wherein the reaction mixture comprising keto acids of formula (II) and compound of formula (III) is quenched into a stirred water- solvent mixture after the addition of the dehydrating condensation agent. 6. A mixture of fluoran compounds obtainable by the reaction of mixed keto-acids of formula (II), derived from the reaction of compounds of formula (IV) with compounds of formula (V), together with the compounds of formula (111): Formula IV Formula V wherein R1 and R2 independently represent hydrogen; an alkyl of 1-18 carbon, a secondary alkyl with respect to the carbon atom bonded to the nitrogen atom of 3-13 carbon atoms; a cycloalkyl of 4-8 carbon atoms or a phenyl, both of which may be substituted by at least one substituent selected from the group consisting of halogen atoms and alkyls having 1-4 carbon atoms, an aralkyl of 7-10 carbon atoms; or R1 and R2. together with the adjacent nitrogen atom form a heterocyclic ring; R3 is hydrogen; an alkyl of 1-4 carbon atoms; an alkoxy of 1-4 carbon atoms; a phenyl; a substituted phenyl or a halogen; R4 is an alkyl group of 1-18 carbon atoms; a carboxyalkyl of 1-18 carbon atoms; a carboxycycloaikyl of 4-8 carbon atoms; an alkylamino of 1-18 carbon atoms; a cycloalkylamino of 4-8 carbon atoms; a dialkylamino or dicycloalkylamino, an arylamino; a substituted arylamino; an aralkytamino of 7-10 carbon atoms; a diaralkylamino; R5 is an alkyl of 1-18 carbon atoms; a carboxy alkyl of 1-18 carbon atoms or a halogen. 7. A process according to any of Claims 1 to 6 for the manufacture of mixtures of fluoran compounds comprising two fluoran components A and B. 8. A process according to any of Claims 1 to 7 for the manufacture of mixtures of fluoran compounds comprising two components A and B wherein the ratio of the components A to B is in the range of from 0.1 - 99%. 9. A process according to any of Claims 1 to 8 wherein the fluoran mixture comprises two components A and B in the stated ratios: 3-dibutylamino-6-methyl-7-anilinof!uoran (95%), 3- dibutylamino-7-dibenzylaminofluoran (5%); 3-dibutylamino-6-methyl-7-anilinofluoran (90%), 3-diethylamino-6-methyl-7-anilinofluoran (10%); 3-dibutylamino-6-methyl-7-anilinofluoran (46%), 3-diethylamino-6-methyl-7-anilinofluoran (56%); 3-diethylamino-6-methyl-7- anilinofluoran (52%), 3-diethylamino-6,3'(4')-dimethyl-7-anilinofluoran (48%); 3- diethylamino-6-methyl-7-aniiinofluoran (10%), 3-N-(1-ethylpropyl)-N-propylamino-6-methyl- 7-anilinofluoran (90%); 3-dibutylamino-6-methyl-7-m-tolylaminofluoran (10%), 3- dibutylamino-6-methyl-7-anilinofluoran (90%). 10. A heat sensitive recording material comprising a mixture of fluorans according to any of Claims 1 to 9 in combination with a developer, a dispersing medium and optionally another colour foπning material, a binder, a sensitiser, a filler, a lubricant or a stabiliser and mixtures thereof. 11. A pressure sensitive recording material comprising a mixture of fluorans according to claims 1 to 9 in combination with other known colour forming materials, a solvent, a developer and optionally a diluent and a capsule wail material.

Inventors: HENEGHAN MICHAEL, TAYLOR JAMES PHILIP, HENEGHAN, MICHAEL, TAYLOR, JAMES, PHILIP
Applicants: CIBA SC HOLDING AG, HENEGHAN MICHAEL, TAYLOR JAMES PHILIP, CIBA SPECIALTY CHEMICALS HOLDING INC., HENEGHAN, MICHAEL, TAYLOR, JAMES, PHILIP
Application year: 1999
Main classification: C07D493
IPC codes: B41M5, C07B61, C07D493