Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
T~e present invention provides novel fluoran compounds which are
normally colourless or only weakly coloured but which by variation of the
substituents in position 2 can give intense dark green,grey-black or red
colours when contacted with an electron accepting co-reactant. The invention
specifically relates to fluoran compounds, having in position 6 a nitrogen
heterocyclic residue attached to the fluoran system through the nitrogen atom,
and in position 2 a substituted amino group; a process for the manufacture of
such compounds and their use as colour formers in pressure-sensitive or thermo-
reactive recording materials.
The new fluoran compounds according to the invention correspond to
the formula
R3
~Co
wherein
Rl, R2 and R3 independently of the other, represent hydrogen,
alkyl with 1 to 12 carbon atoms, nitro or halogen, or
-- 2 -
R2 and R3 together complete a condensed carbocyclic ring, especially
a condensed benzene or tetrahydro benzene ring,
Xl and X2 independently of the other, represent hydrogen, alkyl with
1 to 12 carbon atoms, alkenyl with at most 12 carbon atoms,
alkoxyalkyl with 2 to 8 carbon atoms, alkoxycarbonylalkyl
with 3 to 9 carbon atoms, cycloalkyl with 5 or 6 carbon
atoms, acyl having 1 to 12 carbon atoms or
a benzyl, phenyl or naphtyl radical which is unsubstituted
or substituted by alkyl of 1 to 4 carbon atoms, aLkoxy of
1 to 4 carbon atoms, alkoxycarbonyl of 2 to 5 carbon atoms,
acyl of 1 to 4 carbon atoms, nitro, halogen or by an amino
group which is unsubstituted or substituted by alkyl of 1
to 4 carbon atoms or benzyl, and
~he nitrogen ring A represents a pyrrolidino or a piperidino ring, and
the benzene ring B may be substituted by nitro or 1 to 4 haolgen atoms.
Halogen, in each occurrence in the defini~ions of the substituents,
preferably stands for fluorine, bromine or especially chlorine.
When Rl, R2 and ~3, as well as Xl and X2 represent alkyl~ they
may be straight or branched chain alkyl groups. Examples of said alkyl
groups are methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec.butyl or
tert.butyl, octyl or dode-
- 3 -
~ 3 ~ ~
cyl. Rl, R2 and R3 are preferably hydrogen, halogen or allcyL
having 1 to 4 carbon atoms such as methyl or ethyl.
- Alkenyl in Xl and X2 stands e.g. for allyl, 2-meth-
0~ _ --- .
allyl, 2-ethylallyl, 2-butenyl or octenyl.
Alkoxyalkyl and Alko~ycarbonylalkyl in Xl and X2
may have 1 to 4 carbon atoms in each alkyl part and stand
pre~erably for ~-methoxyethyl or ~-ethoxyethyl and ~-methoxy-
carbonylethyl or ~-ethoxycarbonylethyl, respectively.
Cycloalkyl in the meaning of these X-radicals may
be cyclopentyl or preferably cyclohexyl. The optional sub-
stituents in the benzyl, phenyl or naphthyl group may be
alkyl with l to 4 carbon atoms, alkoxy with 1 to 4 carbon
atoms, alkoxycarbonyl with 2 to 5 carbon atoms, acyl having
1 to 4 carbon atoms, nitro, halogen or an amino group optionally
substituted by alkyl with 1 to 4 carbon atoms or by benzyl.
Ex~nples of these aromatic or aralLphatic radicals are p-methyI-
benzyl, p-chlorobenzyl, p nitrobenzyl, p-tolyl, xylyl,
p-chlorphenyl, p:nitrophenyl, l-methylnaphthyl-(2) or
2-methylnaphthyl-(1)0
Among the acyl groups the alkanoyl groups contain-
ing 1 to 12 carbon atoms, such as formyl, acetyl or propionyl
are especially noteworthy, Further acyl substituents may
be alkylsulphonyl having 1 to 12 carbon atoms, such as
methylsulphonyl, as well as benzoyl or benzene-
~5 sulphonyl groups which may be substituted in benzene ring
by halogen, methyl or methoxy groups~
In the fluoran compoullds fall;ng under formula (1),
the nitrogen ring A denotes a heterocyclic radical which is
attached to the fluoran ring through the nitrogen atorn. The
heterocyclic ra~ical may have 3 to 12, preferably 5 or 6 ring
members~ wherein..l or ~ hetero atoms may be included as ring
members It is for instance a pyrrolidinyl, piperidino,
pipecolino, perhydroazepinyl, hëptamethyleneimino, octamethylen-
imino, 1,2~3,4-tetrahydroquinolinyl~ indolinyl or hexahydro-
carbazolyl group, or in case the hetero ring includes a further
hetero atom, a morpholino, thiomorpholino, piperaæino~ N-alkyl
piperazino with 1 to 4 carbon atoms in the alkyl part, or a
pyrazollnyl or 3-methylpyrazolinyl group.
As halogen, the benzene ring B may contain fluorine,
bromine or especially chlorine. Preferably, it is not further -
substituted or contains 4 chlorine atoms.
Practically important groups of the compo~mds of
formula (1) may be de~ined by the following formula
,
~2) ~ ; ~ ~
wherein
R4, R5 and R6 independently of the other, represent hydrogen,
--- halogen ? methyl or ethyl$
X3 represents alkyl with 1 to 8 carbon atoms,-
alkoxyallcyl with 2 to 8 carbon atoms; cyclo-
alkyl with 5 or 6 carbon atoms, acyl with 1
to 7 carbon atoms, phenyl or benzyl optionally
substituted in the ring by methyl or halogen,
X4 represents hydrogen, allcyl with 1 to 8 carbon
atoms, cycloalkyl with 5 or 6 carbon atoms,
acyl with 1 to 7 carbon atoms or benzyl option-
ally substituted in the ring by methyl or
halogen, and
the nitrogen ring A and the benzene ring B have the given
: 15 meanings.
Particularly useful fluoran compounds oE the
formulae(l) and ~2) may be represented by the formula
.
. - -R6
N
~CO
u - - - - ... . . -
wherein
~ 6 --
R4, R5 and R6 have the meaning given under formula (2),
X5 represents alkyl with 1 to 8 carbon atoms,
acyl with 1 to 7 carbon atoms, phenyL or
benzyl,
S X~ represents hydrogen, alkyl with 1 to 8 carbon
atoms, acyl with 1 to 7 carbon atoms or benæyl,
the nitrogen ring Al represents a morpholino, piperazino or
especially a pyrrolidinyl or piperidino ring and the benzene
ring Bl may be further substituted by 1 to 4 halogen atoms~
especially chlorine atoms.
Of special interest are fluoran cornpounds falling
under formulae (1) to (3), which are listed under A, B and C,
respectively.
A. Compounds of the formula
. . .
- .
R6 .
(4) ~ ~ 5 ~
~ ' ' -, "
.
wherein
Al 9 Bl, R4, R5 and R6 have the meaning given under formula (3),
X7 and X8 independently of the other,represent
alkyl with 1 to 8 carbon atoms or benzyl~
These ~luoran compounds are distinguislled as dark
green colour formers.
.
B. Compounds of the ~ormula
C~
¢~,CO
wherein
Al, Bl, R4, R5 and E~6 have the meaning given under formula (3)
and
Xg reprcsents alkyl -~ith 1 to 8 carbon
atoms, benzyl or phenyl.
These fluoran compounds are colour formers which
give a grey or black colour when contacted wi'~h an electron
accepting co-reactant.
C. Compounds of the formula
.. . . .
~KD~X lo
. .~. -
' ' , -
wherein
Al, Bl, R4, R5, R6 and X9 have the given meanings and
X10 represents acyl. having 1 ~o 7 carbon
atoms,for examp~le,alkanoyl with 1 to 4
S carbon atoms, such as formyl, acetyl
or propionyl, or benzoyl a methyl-
sulphonyl or p-tolylsulphonyl J
These fluoran compounds are scarlet-red colo-lr formers.
i The new fluoran compounds of the formulae (1') to (6) .
10 are obtained by a method known in the art, The process o ~ -~
manufacturing the fluoran compounds of formuLa,(l) comprises
reacting a benæophenone compound o the formula
~ N ~ ~ / OZ~
(~) C.=O
l~ ,
.. . .
with a compound o~ the formula - , -
. - R3
(8) Z~O ~ ~ R2 X
' Rl 2
wherein A, B, Rl, R2, R3, Xl and X2 have the given Ineani~g~
and Zl and Z2 represent hydrogen or alkyl having 1 to 4
carbon atoms, such as methyl,ethyl or butyl. Preferably, of
Zl and Z2 one is hydrogen, methyl or ethyl and the other
is hydrogen. Most preferably, Zl is hydrogen and ~2 i~
hydrogen or methyl.
The reaction is advantageously carried out at 10 to
lOO~C by allo~ring the reactants o~ formuLae (7) and (8) to
react together in the presence of an aciclic condensing agent.
Examples o~ suitable condensing agents are acetic
anhydride, sulphuric acid, zinc chloride or phosphorous oxy-
chloride. This reaction is preferably completed by the addition
of a base. The bases may be organic or inorganic and can ln-
c~ude, for example, alkali metal hydroxides, such as sodium
hydroxide or potassium hydroxide, as well as aliphatic amines,
such as triethylalnine or trihydroxyethylamine.
~he starting compounds of formula (7) are new and are generally
prepared by reacting 3 phthalic anhydride of the ~ormuLa
(9) ~ : '
with a compound of the formula
f~ 0~- , . .
(10) ~ ~3~ . .
.
wher~in Zl represents hydrogen or alkyl having 1 to 4
carbon atoms and A and B have the meaning described above.
-- 10 -
~c~
This reaction is suitably carried out in an organic solvent,
such as acetone, benzene, toluene, xylene, or a chloroben-
zene, preferably at temperatures at or below the boiling
~,,, _._.
point of such solvents.
The compounds of formula (10) may be produced by
condensing the heterocyclic base ~ NH, in which the c~cle A
has the meaning described above, with resorcinol or a mono-
alkyl ether derivative thereof at temperatures between 50
and 250C and cptionaL~ ullder pressure. This reaction may or
may not be assisted by the use of a condensing agen~,
examples of which are zinc chloride, aluminium chloride or
sulphanilic acid. Alternatively, the compounds of formula
(10) may be prepared from the reaction of meta hydroxy- or
alkoxy-aniline with a ,~-dihalogenoalkanes in which the
halogen is, for example, bromine or chlorine but more
usually bromine.
- Compounds of formula (1), wherein Xl or X2 or both re-
present acyl may be manufactured by reacting a compound of
formula (1), wherein at least one of Xl and X2 represents hydro_
gen, with acylatil~g agents having at most 12 carbon atoms, e.g.
reactive functional derivatives of aliphatic carboxylic or
sulphonic acids, particulaxly fatty acid halides and anhydrides
such as acetyl chloride, acetyl bromide or acetic anhydride
or of aromatic carboxylic or sulphonic acids such as benzoic
acid halides or benzene sulphonic acid halides.
~ 11 -
3~13L
The acylation is generally carried out by known methods,
e.g. in the presence oE acid binding agents such as alkali me~al
carbonates or tertiary nitrogen bases such as pyridine and
optiona~ly ln the presence of inert orgallic solvents such as
acetone, isopropanol, chlorobenzene or ni~robenzene.
The new 1uorans, according to the invention, are more
or less colourless compounds which are particularly useful when
they are brought into contact with an acidic co-reactant sub-
stance, that is an-electron-accepting substance. Typical co-
reactants are, for example, attapulgus clay, silton clay, silica,bentonite, halloysite, aluminium o~ide, aluminium phosphate,
kaolin or any acidic clay, or an acid reacting polymeric material
such as a phenolic polymer, an alkylphenpl acetylene pol~ner,
a maleic acid-rosin resin or a partially or wholly hydrolysed
polymer o maleic anhydride with styrene, ethylene, vinyl
methylether or carboxy polymethylenes.
The prefereed co-reactants are attapulgus clay, silton
clay or a phenol-formaldehyde resin, these electron acceptors,
preferably, are coated on the front side of the receiving sheet.
As indicated above, the fluoran compounds of
formula (4~ behave as dark green colour formers, while com-
pounds of formula ~5) behave as grey or black colour formers.
On the other side, the fluoran compounds o the ormula (6)
behave as red or scarle~-red colour ormers~
- 12 -
~, By varying the structure of this new range of fl~torans
certain properties may be "built-in", for example, the colour
as described in the previous paragraph, fade stability for com-
patibility with other colour formers in mixtures, and any
solubility charac~eristics which wouLd allow greater flexibility
in the choice of solvents used in microencapsulation and other
modes of application.
As already mentioned, these colour formers above all
are suitable for tne use in so-called pressure-sensitive recording
ma~eriaL.Such a material e.g. includes a~ l~ast one pair of
sheets, which comprises at least a colour former of ~ormula (1)
dissolved in an organic solvent, preferably contained in
pressure ruptura~le microcapsules and an electron accepting
substance.
' The colour ormer, upon coming into contact with the
electron accepting substance being able to produce a coloured
marking at the points where the pressure is applied.
These colour formers which are comprised in the
pressure-sensitive copying material are prevented from becom-
ing active by being separated from the electron accepting sub-
stance. As a rule this is done by incorporating these colour
formers into a foam-, sponge- or honeycomb~like structure,
Preferably however these colour formers are microencapsulated.
When these colo-trless eolour formers o~ ormula (1)
are dissolved in an organic solvent, they may be su~jected to
a microencapsulation process and subsequently used for making
pressu~-~sensitive papers. When the capsules are ruptured by
pressure from e.g. a pencil and the colour former solution is
.. . .
- thus transferred into an adjacent sheet coated with a substrate
capable of acting as an electron acceptor, a coloured image
is produced. This new colour results rom the thus produced
dyestuff which ab~orbs in the visible region of the electrow
magnetic spectrum.
The general art o maki-ng Inicrocapsules oE some
character has long been Icnown. I~ell known methods e.g. are
disclosed in US Patent Specification 2,183,053~ 2,800,457,
2,800~458, 3,265~630, 2,964,331, 3,~18,656, 3,418,25~,
3,016,308, 3,42~,827, 3,4~7,250, 3,405,071, 3,171,878,
and 2,7979201. Further methods are disclosed in British Patent
Specifications 989,264 and above all 1,156,725. Any of these
and other methods are suitable for encapsulating the present
colour formers.
Preferably the present colour ormers are encapsulated
dissolved in organic solvents. Suitable solvents are preferably
non-volatile e.g. polyhalogenated diphenyl such as trichloro-
diphenyl and its mixture with liquid paraffin, tricl~esyl phos-
phate 9 di-n-butyl phtlalate, dioctyl phthalate, trichlorobenzene ,
- 25 nitrobenzene, trichloroethyl-phosphate, petroleumether, hydro-
carbon oils, such as paraffinJ condensated derivatives of di-
phenyl or triphenyl J chlorinated or hydrogena~:ed condensed
aroma~ic hydrocarbons. The capsule walls preferably have been
obtained by coacervation forces evenly around the droplets oE
the colour former solution, the encapsulating material consisting
of gelatine, as e.g. described in United States Patent Specifica-
tion 2,800,457.
Alternatively, the capsules preerably may be made
of aminoplast or modified aminoplasts by polycondensation as
described in British Patent Specification 989,264 or 1,156,725.
A preferred arrangement is wherein the encapsulated
colour former is coated on the back side of a transfer sheet
and the electron accepting substance is coated on the ront
side of a receiving sheet.
In another preferred material one or more of the
new fluorans are co-encapsulated with one or more other known
colour formers, such as crystal violet lactone, benzoyl leuco
methylene blue, or a bis-indolyl phthalide such as 3,3-bis(l'-
n-octyl-2'-methylindol-3'-yl)-phthalide.
The microcapsules containlng the colour formers of
formula ~1) are used for making pressure-sensitive copying
material of the various types known in the art, such as so
called "Chemical Transfer" and "Chemical Self-contained"
papers. The various systems mainly are distinguished by
the arrangement of the capsules 9 the colour reactants and
- 15 -
~ 5
the support material.
The mlcrocapsules may be in an undercoating of the
upper sheet and the colour reactznts, that is the electron
acceptor and coupler, may be in the overcoating o~ the lower
sheets. However, Lhe components may also be used in the paper
pulp. Such systems are called "Chemical '~ransfer" system,
~nother arrangement we have in the self-contained
papers. There the microcapsules containing the colour former and
and the colour reactants are in or on the same sheet as one or
more individual coatings or in the paper p-llp.
Such pressure-sensitive copying materials are de
scribed e.g. in US Patent Specifications 3,516,846, 2,730,457,
2,932,582, 3,427,180, 3,418~250 and 3~418,656. Further systems
are disclosed in British Patent Specifications 1,042,597>
1,042,598, 1,042,596, 1,042,599, 1,053,935 and 1,517,650.
- Microca~sules containing the colour formers of formula (~)
- are suitable for any of these and other sy3:tems.
The capsules are preferably fixed to the carrier
by means of a suitable adhesive. Since paper is the preferred
carried material, these adhesives are predominantly paper
coating agents, such as e.g. gum arabic, polyvinyl alcohol,
hydroxymethylcellulose, casein, metllylcell~lose or dextrin.
In the present application, the definition "paper"
not on]y includes normal papers from cellulose fibres, but
- 16 -
also papers in which the cellulose fibres are replaced
(partially or completely) by synthetic fibres o~ polymers.
The new fluoran compounds may also be used as
colour ormer in thermoreactive recording material compris~
ing at least a support, a binder, a colour former and an
electron acceptin~ substance. Thermoreactive recording
systems comprise heat-sensitive recording and copying
materials and papers. These systems are used e.g. ~or the
recording of information, for example, in electronic com-
puters, in teleprinters or telewriters, in measuring instru-
ments. The mark-forming also can be made manually with a
heated pen~ A further means for inducing heat-in:itiated
marks are laser beams. The thermoreactive recording material
may be arranged in such a manner that the colour former is
LS dissolved or dispersed in a layer of the binder, and in a
second layer the developer and the electron-accepting sub-
stance are disso'.ve~ or dîspersed in the binder. Another
possibility consists in dispersing both the colour former
ancl the developer in one layer. By means of heat the binder
is so~tened at specific areas imagewise and the dyestuff
is formed at these points, since only at the points where
heat is applled does the colour former come into contact
with the electron accepting substance.
The developers are the same e]ectron-accepting
substances as are used in pressure sensitive papers. For
practical reasons the developer should be solid at room
- 17 -
temperature ancl melt or evaporate above 50 C. Examples
of such products are the already mentioned clays, phenolic
resins, ph~nolic compounds such as 4-tert.-butylphenol,
4-phenylphenol, 4-hydroxydipllenyloxide; a-naphthol, 4-hydro-
xybenzoic acid methyl ester, ~-naphthoL, 4-hydroxyacetophe-
none,2,2'-dihydroxydiphenyl, 4,4'-isopropylidene diphenol,
4,4'-isopropyliden-bis-(2-methylphenol~, 4,4'-bis-(hydroxy-
phenyl) valeric acid, hydroquinone, pyrogallol, phloroglu-
cinol, p-, m-, o-hydroxybenzoic acid, gallic acld, l-hydro-
xy-2-naphthoic acid, boric acid, and the aliphatic dicarbo-
xylic acids e.g. tartaric acid, oxalic acid, maleic acid,
citraconic acid or succinic acid.
Preerably ~usible, film-forming binders are ~isedO
These binders should be water-solub7e, since the nitrophthal-
ides and the developer are water-insoluble. The binder should
be able to disperse and fix the colour former and the
developer at room temperature. In this way the two reactive
components are present in the material in a non-associated~
form. After applying heat, the binder softens or melts,
which enables the colour former to come into contact with
the developer and to form a dyestufE.
I~ater-soluble or at least water swellable bind-
ers are e.g. hydrophilic polymers such as polyvinyl alcohol,
polyacrylic acid, hydroxyethylcellulose, methylcellulose,
carboxymethylcellulose, polyacrylamide, polyvinylpyrrolidone
gelatine or starch.
~ 18 -
In so ar as the colour ~ormer and the developer
are coated in two separate layers, binclers which are water-
insoluble may be usecl, i.e. binders soluble in non-polai or
only we~L~ olar solvents, e.g. natuL-al rubber, sylltlletic
rubber, chlo~inated rubber, alkyd resins, polystyrene,
styrene~butadienecopolymers, polymethylmethacrylates, ethyl-
cellulose, nitrocellulose or polyvinylcarbazole.
The pre~erred arrangement, l~owever, is colo~tr former
and developer in a water-soluble binder in one layer.
The coatings of the thermoreactive material may
contain further additives. To improve the degree of whiteness,
to ease the printing of the papers and to prevent the stick-
ing o~ the heated pen, tllese materials may contain etg. talc,
TiO2, ZnO or CaC03. In order to produce the dyestuf~ only
within a limited temperature range there may be added sub~
stances such as urea, thiourea, acetanilide; phthalic acid
anhydride or other corresponding m.eltable products which in-
duce the simultaneous melting o colour former and developer.
Typical thermoreactive recording materials wherein
the present colour formers may be used e.g. are described
~n German Patent Application 2,228,581, French Patent
1,524,826, Swiss Patent 407,185, German Patent Application
2,110,854, S~iss Patents 164,976, 444,196 and 444,197.
- The ~ollowing non-limitative examples illustrate
the present invention. Percentages are expressed by welght,
unless otherwise stated.
19 -
~L~5;~
2-(~T,N-dibenzylamino)~6~ pyrroliclin~lfluoran
__A mixture of 77.75 g 2'-carboxy-2-hydroxy~4-
-N-pyrrolid;nylbenzophenoLle, 75.6 g N,N-clibenzyl~p-anisidine
and 250 ml 98% sulplluric acid is stirred at 60 C for 5 hours
and then quenched into 2750 ml ice water to precipitate a
solid. The solid is filtered off, washed with water and
added to a mixture of ,00 ml water, 250 ml methanol and
26.8 g sodium hydroxide a~ 70 C. The mixl-ure is boiled for
2 hours and then cooled to 85 C. The solid product is:~ltered
off, l~ashed ~lith hot water then recrystallized from methan-
ol~acetone and dried to yield 86 g white plates m.p. 180 C.
max. in 95 % acetic acid 435, 462 and 607 nm.
A solution of the 2-(N,N-dibenzylamino)-6-N-
pyrrolidinyl-fluoran in a hydrogenated terphenyl solvent gives
a dark green print when applied to silton clay coated paper.
Absorption maxima are observed ~t ~ 444 and 602 nm.
The benzophenone compound used in this example
as starting material may be produced as follows:
A mixture of 74 g phthalic anhydride, 81.5 g 1-(3'-hydroxy-
phenyl)pyrrolidine and 335 ml xylene is heated at 125 C
for 6 hours, then cooled to 25 C. The precipitate is
filtered off, washed with methanol and dried to yield
110~5 g yellow solid having m.p. 194 C after crystallis-
ation from ethanol~
- 20 -
~i9~3~
Example 2
2-Ethylamino-6-N-pyrrolid~y~
A mixture of 9033 g 2'-carboxy-2-hydroxy-4-
-N-pyrrolidinylb~nzophenone, 4.54 g N-ethyl-p-anisidine
5 and 30 ml 98 vlO sulphuric acid is s~irred at 60 C
or 5 hours and then quenched into 330 ml ice-water -to pre-
cipitate a solid. The solid is filtered of, washed with
water and aclded to 75 ml methanol and 16.5 ml trieth~71amine.
The mixture i~5 boiled with stirring for 12 hours, then cool-
ed to 0 C. The precipitate is ~iltered off, washed with
methanol and dried to yield 8,32 g of 2-ethylamino-6-N-
pyrrolidinylfluoran as a white solid.
max. in 95 % acetic acid 434, 457 and 602 nm.
A solution of this compound in benzene is
colourless and gi~es a black colour on contact with silica9
greenish black on attapulgus or silton clay and green on
phenolic resin.
~ 21
Example 3
2-N-~ce~ l-N-e~h lamino-6-N-~ rroL ~ fluoran
-Y . Y _ .. Y _ ~ .
A mixture o:E 4,0 g 2-ethylamino-6-N~-pyrrolidinyl
fluoran, 12 ml acetic anhydride and 0,~ ml pyridinels stirred
S at 120 C for 4 hours. The solution is then evaporated to
dryness, the residue taken up in 20 ml 10% sodium carbonate
solution and extracted with e-ther, Ater drying and evaporating
of the ether, 3,2 g of 2-N-acetyl-N~ethylamino-6-N-pyrrolidinyl
1uoran are obtained.
~ max. in 95 ~/0 acetic acid 374~496 and 528 nm.
This compouncl Eorms a red coLour when brought in
contact with electron acceptin~ substances such as silica.
- 22 -
3~
~ )-6-N- rrolidln lfluoran
~ _ _ Y_ . ~
A mixture of 15,5 g 2'-carboxy-2 ~ ethoxy-4-N-
pyrrolidinylbenzophenone and 14,45 g p-dibenzylam no-phenol
is stirred in 50 ml 98% sulphuric acid at 60C for 5 hours,
cooled to 25C and ~ wned into a mixture of 100 ml water
and 450 g ice. The pH of the quenched mass is adjust2d to
8.5 with 120 ml 35% to ammonia solution. The precipitate
is filtered off, washed with water and dried at 70C in
vacuo to yield 19,7 g of 2-dibenzylamino-6-N-pyrrolidinyl-
fluoran. The product is recrystallized from a mixture of
methanol and acetone to yield colourless plates having a
melting point of 180C. This product is identical with the
colour former obtained according to Example 1.
The 2'-carboxy-2-ethoxy-4~N-pyrrolidiny'-benzo-
phenone compound used in this example as starting material
may be produced as follows:
To a mixture o 31.1 g 2'-carboxy-4-N-pyrroli~inyl-2-hydroxy-
benzophenone, 39.6 ml diethyl sulphate and 240 ml acetone at
35C, is added a solution of 16.8 g potassium hydroxide in
50 ml water, drop-wise over 4 hours. The reaction mixture
is then stirred for a further 20 hours at 35-40C. A solu-
tion o~ 11.2 g potassium hydroxide in 50 ml water is then
added and the reaction mixture is heated to boiling and re-
- 23 -
fluxed for 2 hours. The solvent is distilled of:E until the
temperature of the residual solution is 96C. The residue
is held at 96C for 30 minutes then cooled down to 0C
by the addition of ice. Approximately 25 ml 28~/o HCl is
added to bring the pH between 3 - 4 when the product pre-
cipitates as a white suspension. After filtering off and
washing with water 32.0 g 2'-carboxy-4 ~-pyrrolidinyl-2-
ethoxybenzophenone, melting point 184 - 5C, is obtained.
- 24 ~
.
~3~ ~3
Example 5
2-Anilino-3-methyl-6-N-~rrol dinyl :Eluoran
15 g 2'-carboxy-2-hydroxy-4-N-~pyrrolidinyl-
benzophenone and 9,9 g 4-anilino-m-cresol are dissolved
S in 50 ml o~ 96C sulphuric acid and stirred
for 2 hours at 60C. The product is washed up in a manner
analogous to Example 2 ancl recrystallised from ethyl
aceta~hexane7 m.p. > 260C. ~max.in 95 % acetic acid
380,450 and 585 nm. When applied to paper coated with silton
clay as described in Example 1 a grey print is obtained which
gives absorption maxima a~ ~ 453 and 575 nm,
By using procedures similar to those described
in Examples 1 to 5 the fluoran compounds of the fonmula (11)
listed in the following Table have been manufactured.
(11) ~ ~ X12
~CO
- 2~ -
3~
_ ~
~ . 1,
~ ~ l o ~ o
O u~ O
,~ ~o o o o
U~ `;t ~ ~ I ~ ;I' ~ `;t I ~
. _ . .
o o o U~ ~ o
.,, ~ o o o o ~ ~ ~ ~ o o
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- 27 -
5~
APPL~CATION EXAMP _
xample 25
Preparation of Pressure-sensitive Copying Paper
A solution contain;ng 3 g of 2-dibenzylamino-6-N-pyrrolidinylfluoran
in 100 g of hydrogenated terphenyl is emulsified at 50C in 100 g of 12% pig-
skin gelatin solution 100 g of 12% gum arabic solution is added followed by
200 ml of water at 50C. The emulsion is poured into 600 g ice-water and
stirred for three hours to complete the Goacervation. The resulting capsule
slurry is coated onto paper and dried. When the coated side is placed in
lQ contact with a second sheet coated with silton clay, attapulgite clay or
phenolic resin a dark green image is obtained after application of pressure by
writing. Similar effect can be obtained by using any other colour former of
the Examples 2 to 2~.
Exam~ 6
Pr aration of Pressure-sensitive Co ying Pa er
ep P P
A solution containing 1.6 g of 2-dibenzylamino-6-N-pyrrolidinyl-
fluoran,`0.6 g of 3,3-bis(l'-n-octyl-2'-methylindol-3'-yl)phthalide, 0.1 g of
Crystal violet lactone and 0.6 g of benzoyl leuco methylene blue in 100 g of
hydrogenated terphenyl is emulsified at 50C in 100 g of 12% pigskin gelatin
solution. 100 g of 12% gum arabic solution is added followed by 200 ml of
water at 50C. The emulsion is poured into 600 g ice-water and stirred for
three hours to complete the coacervation. The resul~ing capsule slurry is
coated into paper and dried. When the coated side is placed in contact with
a second sheet coated with silton clay or attapulgite clay a grey-black image
is obtained after application of pressure by writing.
~x le 27
amp
Pre aration of Thermoreactive Pa er
P p
6 g of an aqueous dispersion containing 1.6% of 2-dibenzylamino-6-
N-pyrrolidinylfluoran, 0.8% of 3,3-bis(l'-n-octyl-2'-methylindol-3'-yl)phthal-
ide, 0.1% of Crystal violet lactone and 6.7% polyvinyl alcohol are mixed
with 134 g of an aqueous dispersion containing 14% 4,4'-isopropylidenediphenol
and 6% polyvinylalcohol, the mixture is then coated on paper and dried. When
- 28 -
1~5;~3~ ~
contacted with a heated stylus a gr0y-black mark is obtained which has ex-
cellent light fastness.
Example 28
Preparation of Thermoreactive Pa~er
When the colour formers in Example 27 are replaced by 2-dibenzyl-
amino-6-N-pyrrolidinylfluoran and 3,3-bis(l'-n-octyl-2'-methylindol-3'-yl)
phthalide in the ratio 6:4 the resulting system gives an intense black image.
- 2~ -
