CA1062702A - Disazo dyes - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Disazo dyes are prepared by the alkaline hydrolysis of a compound of the formula R1-A-R2 where R1 is , A is carbonyl or solfonyl and R2 is alkyl or aryl. The hydrolysis mass is preferably use as a liquid formulation without further treatment. A preferred dye has the formula

Description

Z7~)2 B~CKGROUND OF THE INVE~rION

Field o~ the Invention This invention relates to disazo dyes prepared by an al~aline hydrolysis process and, particularly9 to water- .
soluble disazo dyes and liquid formulations thereof useful for the dyeing of paper.

Description of the Prior Art .
United States Patent No. 933,448 discloses a dye said . to be obtained by "first producing aminoazo compounds.~rom^diazo-tized amins of the benzene series containing a negative group in the ortho-position to the amino-group with suitable amins and therea~ter diazotizing these inter~ediate products and combining the thus produced diazoazo compounds with 2-amino-5-naphthol compounds having the ~ormula:
X ,.

S3 ~ C ` ~C ~ ' IIH2 (X meaning hydrogen or S03H)" (page I, lines 16-33). The dyes : I are said to have utility in the coIoration of cotton ~rom red .~ : :
to blue shades yielding dyeings which are remarkable for their extraordi~ary fastness to light. ~ .
: Dyes of the formula OH

H 9 ~
~ are disclosed in German O~fenlegungschrift 2058816, The dyes : are prepared by indirectly diazotizing sulfanilic acid and ~ ~ ..
. .' i , ~. ;''

- 2 -. .
., . . . ...
~, , .. . ~ . ,'.'''1~ . . . ~ . ....
;: . , , .. ,, , ~ : . . . . .

coupling with m-tolnidine under alkaline conditions; treating the resulting suspension o~ aminomonoazo dye with sodium nitrite solution; dropping the mixture into dilute hydrochloric acid and cooling, and combining the obtained diazo suspension ~at a pH o~ 7-8 with a weakly alkaline aqueous solution of 6-amino-l-naphthol-3-sulfonic acid The dyes are disclosed to have utility in dyeing leather and ~urs.
..

S~MMARY OF THE INVENTION

According to the present invention, disazo dyes are prepared by the alkaline hydrolysis of disazo compounds o~ the formula Rl-A -R~ where Rl is 14 ~ 3 ~ -wherein:
R3 is hydrogen, sul~o, :lower alkyl, lower alkoxyl, chlori~e, bromine or nitro;
R is hydrogen, lower alkyl, lower alkoxyl, chlorine, bromine or nitro;
: R5 and R6 are independently hydroge~, lower alkyl, lower alkoxyl, chlorine or bromine;
R is hydr~gen, lower alkyl or lower alkyl substituted with cyano and . .
M is ionizable hydrogen or a cationic metallic ion selected ~rom .
Na+, K+, Li~, 1/2 Ca++, 1/2 Sr ~, or ammonium ions selected ~rom ~N ~ Rl~ in which R9, R10, Rll are independently R hydrogen, lower alkyl or lower hydroxy_ alkyl;
.
. - 3 _ . .

~g~6Z~7~2 and where A is c~rbonyl or sul~onyl and R is al~yl or aryl.
The res~lltant dyes, which c~rrespond to the general formula Rl-H, wherein Rl is as de~ined above, are structurally analogous to the dyes produced according to the direct coupling method of the U.S. patent and ~erman publication bu-t have superior bright-ness. The hydrolysis mass may advantageously be employed directly as a liquid dye ~ormulation without ~urther treatment.
The dyes according to the invention have been found to be particularly suitable ~or the dyeing of paper pulp a~d glass. ~ -DETAILED D~SCRIPTIO~ .

The dyes of the in~entlon may be represented by the general ~ormula R ~ where R is M 3 ~ ~ ~ ~ N~

whereiu R is hydrogen, sul~o, 3lower alkyl, lower alkoxyl, chlorine, bromine or nltro, .
. ~ R4 is hydrogenJ lower alkyl, lo~er alko~yl, chlorine, . . . bromine or nitro, ` ~ I
R5 and ~i are independently hydrog~n, lower alkyl, . lower alko~yl, chlorine or bromine, . -R is hydrogen, lower alkyl or lower alkyl subst ituted .
with cya~o such as, ~or example, ethyl, methyl, propyl, or cyanoethyl, and as . ~ is ionizable hydrogen or a cationic metallic ion selected from -Na~, K+, Li~, 1/2 Ca~+, 1/2 Sr , or ammonium .
ions selected ~rom +N \R10 in whlch R9, R10 ~nd Rll are :
independendently hydrogen, lower alkyl . or lower hydroæyalkyl _ ~ _ , ( ~ !
96;~7~

In the foregoing definition lower alkyl as defined for R9, R10 and Rll is intended to include methyl, ethyl and the like, and lower hydroxyalkyl is intended to include 2-hydroxyethyl, or

3-hydroxypropyl and the like.
The disazo dy~s are prepared by hydrolyzing with an alkali a compound of the ~ormula Rl-A _R2 wherein Rl is de~ined as abo~e, A is carbonyl or sul~onyl and R2 may be alkyl includ-ing methyl, ethyl, propyl, chloromethyl or cyanoethyl or may be aryl including phenyl, p-nitrophenyl or p-chlorQphenyl, or may be the same as Rl in the case where A is carbonyl.
The method for producing the compound Rl-A _R2 is itsel~ Xnown. Representatlve materials may be made by coupling . representative diazotized (aminophenylazo)benzenesulfonic acids . into, respectively, 6-benzamido-1-naphthol-3-sulfonic acid;
6-(p-nitrobenzamido)-1-naphthol-3-sul~onic acid; 6-acetamido-l-naphthol-3-sul~onic acid, ~-prvpionamido-1-naphthol-3-sulfonic acid; 6-(a-chloroacetamido) 1-na]?hthol-3-sul~onic acid; 6-ureido-l-naphthol-3-sulfonic acid; 6,6'-~ureylenebis-1-naphthol-3-. sul~onic acid (-"J Acid Urea"); 6-benzenesul~onamido-l~naphthol- . .
3-sulfonic acid; 6-(p-toluenesulfonamido-1-naphthol-3-sul-fonic : ~ acid.
: . The diazotized (aminophenylazo)ben2enesulioDic-acids ~ --may be prepared by well-established methods known ~or ami~o- ~
azobenzenes generally. A general way to make aminoazobenzenes is to couple a diazotized aromatic amine into the same or a diY~erent primary aromatic amine with an available coupling position In certain cases, it is desirable to promote the coupling and to protect the primary amine by a group which can be removed by hydrolysis a~ter the coupling. The technique . ~-.. .... ...

o~ten used is the ~ormation o~ the anilinome-thane sul~onic acid.
The aminoazobenzene intermediate is dia7o~ized in the usual way by heating it in a concentrated aqueous solution of a strong mineral acid, such as hydrochloric acid, cooling ¦
the resulting solution to a temperature o~ 0-10C. and adding thereto a quantity o~ sodium nitrite slightly in excess o~ the stoichiometric requirement. An alternate method o~ diazotiæation involves dissolving sodium nitrite in concentrated sul~uric acid, heating to a temperature o~
about 60-70C., cooli~g the resulting solution to ~-10C.
and addi~g thereto the aminoazobenzene.
~he hydrolysis reaction itsel~ may be carried out at temperatures -irom 80 to 150C. However, the lower range and below requires inconveniently long reaction times, and temperatures above 100C ~equire autoclaves or other pressure equipment. There~ore, temperaturles o~ 90-100C are pre~erred, with the top o~ -the range being especially suitable. At these latter temperatures, the hydrolysis is generally complete a~ter about three hours.
The amount o~ starting product (R -A -R ~ in the - hydrolysls mass may vary Prom about 60% or more to extremely `
dilu~e, as 1%. However, percents below 3% are somewhat im-practical. Pre~erred concentrations are ~% t~ 55%, with the upper range especially use~ul in the desirable case i~ which the hydrolysis mass is to be iurnished to the ultimate user as a liquid ~ormulation. Such liquid ~ormulations are well accepted in the textile and paper trades since the handling o~
possibly dl ty dyes ls avoided. ~lso, a liquid ~ormulation is . . , ' ' ~ ~ ., . . ' . , .

~627~ -already in a suitable ~orm ~or metering into a dyebath or pulp mass wi-th or without ~urther dilution. Another advantage is that a colorant which is already completely in solution is unlikely to deposit specks during a coloration procedure, as occasionally happens when a solid material is imper~ectly dissolved. Obviously, it is economically advantageous to have the liquid formulation as concentrated as possible without compromising storage stability, since weaker solutions would cost more in shipping, handling and storage charges.
The medillm in which the hydrolysis is carried out may have other organic mate~ials present in addition to the dye base Rl-A _R2 or the product Rl-H These materials are especially use~ul in those cases in which the hydrolysis mass is to be used as a liquid ~ormulation without ~urther treatment and serve to stabilize the comparati~ely high concentration o~
R -H made during the hydrolysis, by delaying or preventing gelling, crystallization or development o~ inconveniently viscous materials.
Th~ organic materials capable o~ stabilizing the hydro1ysis mass which may contain amounts o~ R -~ o~ up to about 55% are sometimes re~erred to as co-solvents and include, - ~ :- . :. - . . i - - - ~ ...
I ~or example: (a3 water-soluble aliphatic mono-, di--, and tri-hydric alcohols (and their alkyl ethers), optionally sub-stituted with lower alkoxy or amino, or bearing oxy,-thio or imino links; (b) lower aliphatic amides, optionally substituted on the nitrogen atoms with lower alkyls; (c) certain other water-soluble liquids. Ex~mplary are (a) ethanol, 2-propanol, l-propanol, l-butanol, 2-butanol, 2-methoxyethanol, 2--ethoxy-ethanol, ethylene glycol, tetrahydro~ur~uryl alcohol, glyceral, .
. ' diethylene glycol, 2,2'-iminodiethanol, 2-aminoethanol, . 2,2',2"-nitrilotriethanol~ 2,2'-thiodiethanol, 2-(2'-methoxy-ethoxy)ethanol, 2~2-ethoxyethoxy)ethanol, 2,2'-dimethoxydiethyl ether, 2,2'-diethoxydiethyl ethar and polyethylene glycol~ of the ~ormula H(OCH2C~2)nOH (n = 3 to 30); (b) formamide, aceta-mide, N,N-dimethylformamide, N,N-dimethylacetamide; (c) di-methylsulfoxide, tetrahydrothiophene-l,l-dioxide, dioxane, 4-methyl-3-pentene-2-one . .
Useful ranges for the proportions o~ liquid materials in the hydrolytic system which is to be used as a liquid ~ormula$ion may be about 95% to 20% water, and 5% to 80% co- .
solvent. The amount o~ starting disazo (R -A-R ) may vary with the liquid portion from about the ratio 90% liquid, and 10% Rl-A -R2 to about 45% liquid to 55% Rl-A -R2. Alkali can range from about slightly more (on a molar basis) than the amount o~ A _R2 charged to about ~ive moles alkali per mole Rl-A -R~
The pre~erred ranges o~ charges are about as ~ollows:
liquid; 80% to 40% ~made up oi about 30% to 70% water, 70% to 30% co-solvent~; dye base Rl-A -R2; 18% to 54%; al~ali 2% to : ~ 6%, with th~ alkali amou~t chosen to be at least slightly more ~than the theoretical amount required for-their~action R --k-R~
Rl_H ' .
- The hydrolysis mass, or reaction mixture, resulting irom hydrolysis oi the ~oregoing mixtures is a stable liquid dye formulation particularly use~ul ~or the dyelng of paper or ~iberglass and provides dyeings of outstanding brightness The liquid dye ~ormulations o~ the invention comprise~ there-~ore, th- e Rl-R and liquid, including water and the organic ' : , ' ' ~ ' . . - ' , '. '.' . . ' `'`'.
. ,.
~ 8 -: . , : , . . . . - .... . . . : . , l materials, or co-solvents, capable of providing stable ! solutions, in relative amounts corresponding to the molar amounts of the liquid and R -A -R in the starting hydrolysis mass. The liquid formulations also contain a salt R2- A - 0 M+, where M~ represents the metal ions present in the hydrolysis mass, in a molar amount corresponding to molar amount of Rl- A _ R2 hydrolyzed, and may contain amounts o~ alkali not consumed in the hydrolysis It is, of course, possible to practice the invention without the presence during the hydrolysis o~ organic co-solvents. Typically, the starting disazo material R -A -R
can be dissolved or slurried in water in ratios o~ ~rom 3% to 40% Rl-A _R2 to water. Alkali, typically 1% to 10% o~ the weight of the solution, is added and the solution is heated until the hydrolysis is essentia].ly complete. The aPo~u~lon can be isolated by crystalli~ation, sometimes without, but usually with the addition o~ an inorganic salt o~ the alkali used The pre~ipitate can be ~iltered, washed with a salt solution and dried ~or later hanclling and use as a concentrated powder. The powder may be diluted with inert soluble substances - to bring to ~ta~dard strength, i~-desired. Typically, a salt ~ . -~ .:
of the base used ~or the hydrolysis can be used~ or a soluble carbohydrate, urea or the like. ~
The amount o~ alkali used for the hydrolysis may vary ~rom slightly more than the theoretical amount based on the moles o~ Rl-A - R2 charged to about a ten-~old e~cess. The preferred range is ~rom about 1.5 to 4.0 moles^alkali per mole R - A - R , since this is a reasonable compromise between the . . :"
' ' . ' :
. . ' ' Z7~2 ineP~iciency o-~ slow hydrolysis i~ the alkalinity is very low, to the dangers o~ salting out by common ion ef~ect i~
a very large amount o-F alkali is charged. As the alkali, lithium hydroxide, sodium hydroxide or potassium hydroxide may be employed with lithium hydroxide being particularly pre~erred The disazo dyes according to the invention have been found to possess superior brightness as compared to .
the compounds Rl- A ~ R2, ~rom which they are derived and as compared to corresponding dyes prepared according to a direct coupling method such as that described in U S. Patent 933,448.
The improved brightness o~ the dyes of the invention is easily noticeable to the eye and can be measured qualitat-ively and quantitatively by established spectrophotometric measurements. One ~uantitative measurement o~ the krightness of dyes is the Hal~ Height Brightness Factor (HHBF~ The iactor is de~ined as:

HHBF Peak Neight (in Absorbance Unlts) x 1000 .
Peak Width at Half Height ( in nanometers) As may be seen ~rom the ~ormula, HHBF varies directIy with the . ~ . ~ . - , .
brightness o~ a dye.
The dyes according to the invention have values of HHBF which are greater than those o~ the compounds Rl--A - R2 ~rom which they are derived and as compared to corresponding dyes prepared according to a direct coupling method. Thus, for example, the dye o~ the invention represented by the formula:

~ OH

~. . " ' . .
. - 10- ` , ' ' , .

I ~62~2 has a H~IBF o~` about 5.1 (-the dye was dissolved in water and its spectral absorbnnce determined on a ~E Hardy Recording . .
Spectrophotometer~. CI Direct Red 81 on the other hand has I a HHBF of about 4 7 and a dye made by coupling directly dia~-tized p-(p-aminophenylazo)benzenesulfonic acid into 6-amino~
l-naphthol-3-sul~onic acid has a HHBF of about 4,1, It is theorized that the relative dullness of the dye composition prepared according to the direct coupling method (as compared to the dyes prepared according to the process o~ the invention) is attributable to the production o~ a diazoami~o byproduct, or possibly triazole materials, durisg the reaction o~ the diazonium salts with the amino . .
materials at a~ alkaline pH, By products of this type are not possible according to the method o~ the inven~ion, The b~-products produced in the alkaline ~ydrolysis o~ the inve~tion, i such as, for example, metal be~oates (whe~ A is carbonyl a~d R is phenyl) are not colored and do not a~ect the quality o~ the resultant dye. This ~act is o~ particular significance whe~ the hydrol~sis mass is employed directly as a liquid dye for~ulation. ~
.: The invention m~y be better understood by referrin~ .:.
to the following examples: .`:
. ` , . ' E~ample 1 : .
. , _, . .' . Preparation o~ dye .

OH

H035 - ~ ~ N=~ ~ N = N ~ ~l2 ~rom the compound, CI Direct Red 81, CI 28160, . ,, :
. ~ ~ ~-~ .
. , . .

103S _ ~ N-N ~ --- N = N

M03S N~C0R2 (M=Na+ ~ R2 = phenyl) (A) CI Direct Red 81, CI 28160, is made by diazotizing sulfanilic¦
acid and coupling it into anilinomethanesulfonic acid which, after hydrolysis, becomes p-(p-aminophenylazo)benzenesul~oni~
acid This latter material is rediazotized and coupled in~o 6-benzamido-1-naphthol-3-sulfonic acid ("N-benzoyl J Acid"), and the coupling product is isolated by saltin~ the reaction mass and filtering.
- 10 (B) Hydrolysis:
To a 2 liter beaker equipped with a heater, stirrer. .
and thermo~eter, there was charged, 19~.0 g. water, . - 150.0 g. 2(2-methoxyethoxg)ethanol, 200 0 g. polyethylene glycol, H(OCH~CH2)nOH , n = 8 to 10 . .
40.0 g. lithlum hydroxide. .
: ~ The mass was warmed to 50C while stirring. Over a i period~of one hour, 420.0 g. in portio~s ~of CI Direct Rèd:81~ :
20: : was added as presscake (300.0 g. dr~ mater~ial, 120 0 g. waterj.
~ The stirrin~ mixture was heated to 95C over one hour iand .- :
: ~ ~: stirred:at 95C - 99C for three hours. Water was replaced as ~:
needed to maintain volume and total weight of mass A~ter . removing t~e vessel from the heat the contents were ~iltered a~d the Piltrate preserved as a solution. ~ ~
. .,.

:
' ' ' , :

- 12 - ~ ~
.~
".'' ~ ~, ' , ':

`~

70~

To produce paper dyecl with the above material, take a pulp stock o~ 2 27% consistency made up o~ 50% bleached so~twood sul~ite, 360-340 Canadian Standard Freeness (a measure o~ ~iber length and consequently drain rate~ and 50%
bleached hardwood Kraft, 420-400 C~S.F, To 440 ml. stock (ie., containing 10 gO cellulose) add 0O05 g. dye solution from above. Stir one ho~r at room temperature Dilute the mass to 2000 ml., and cast the sheet on a standard wire ~rame 7-1/2 inches square. Pull dry and ~inish drying in ovenO
Dyeings on paper are a considerably yellower shade o~ red and very much brighter than similarly produced dyeings ~rom Direct Red 81. When compared in strength against a liquid formulation o~ Direct Red 81 made up as in the example, but not subjected to the heating or residence time with the alkali, the strength o~ the material o~ the invention is 10%
greater.

Example II
To a 500 ml. ~lask equipped with a heater, stirrer, thermometer and condenser arrang~ed Xor re~lux there was charged~
2Q 150. g. water. To it at 50C while stirring, there was added15 g.~C.I. Direct Red 81, (dried from presscake) and 3 g. -~;
lithium hydroxide The mass was stirred under re~lux for 4 hours, and then trans~erred to a 500 ml. beaker. To the stirring mass at 80C there was added, in portions, 21.0 g. lithium chloride.
The mixture was allowed to cool to room tempera~ure while `
stirring and the mass ~iltered~ T~e cake was washed with two 25 g. portions o~ lithium chloride solution, 10% by weight, `
and the cake dried Dyeings on paper produced by dissolvin~ the dye in water and dyeing by essentially the method o~ Example I show the same clear bright red shade.
.' . ','' _ 13 -Example I I I 106270Z
The procedure o~ E~cample II is :Eollowed, e}:cept 4 g .
sodium hyclroxide is used ins tead o:~ the lithium hydro:~ide .
The mixture is boiled :Eor 6 hours, a:Eter which ti~1~ tne prod ct is isolated by salting with soàium chloride.
Dyeings are less bright than those o:~ Eæa~ples I ar ~
II, l~ut much yellower shade o:E red and much brighter tharl .
dyeings obtained from Direct Red 81.

xam~le I~
- 10 The procedure o~ Example III is ~ollowed using 5 g.
potassium hydroxide i~stead o~ sodium hydroxide and isolati~ .:
by salti~g ~ith potassium chloride. Dyeings are very like . .
those o~ Eæ~mple III, being som~what less bright tha~ those c ~:
Eæample II, but much brighter and. yellower thall those o:~ the startillg Direct Red $1. - . .
...... .,' ........... ' .......... , .
. . . Example V
A dye is prepared in the manner o~ Example II, but starting with a disazo materia:l di~feri~g from Direct Red ~1 .
in that A~R o~ the structure .indicated iD E~ample I is acetyl The quality and nature of the dyeings o~ paper made n~the ~anner o~ Exa~ple II were ~ully equivalent to thos~e~ ~ ......
~produced according to that E~ample, ~ ~ ~
Examples VI ~o gI~ - . .
:~: To a suitable vessel is charged in ~he man~er des-: : 25~ cribed in Example I ~ . : .
: : 300.0 g. contained solids ~rom Direct Red 81 prepared as i~dlcated in Example I, ~ .
. 350.0 g. liquid A, as in Table 1 ~ ~ :
.~ ~ 40.0 g~ lithium hydroxide and enough water, including that : 30 charged with the presscake to bring -the total weight to .
: . `1000.0 g. Heating is carried on ~or 3 to 5 hours and the product preser~ed and dyetested as described. Dyeings hava the brightness o~ E~ample I.~
. . . ' : : ' . - . - 14- . : .
.: ., .. , . .............................. '' . , . , ~ . . ;.. . -. .

_ _____ _ _ ___ ~ O . O O O u, O O a O O O O O
_ _ __ . . . . . _ a l l l l :~ o l l ~ ~, ~ ~ :~
c_ . ~ ,~ o ~ _~ ~ ~
O N ~ c ) . R N aD c~ ~ -_ __ . . - ._ : _, .
., ~ . . . ~
~:\ O O O O O O O O O O O O O O .
E~ 1~ O Il~ O O Il~ O ~ O O 11~ U) ' ¢ ~1 ~1 ~ _1~1 ~1 ~1 C~ ~ ~

¦ ~ N ~ ~
~ ~ ~1 ~ ~ a) ~ ~ a)~ ~ . o .
~ ~1 ~ ~ ~ ~ ~ ~ 1_~ ~c P. ~ a~ ~
~ ~01 O ~; ,s: C) ~ ~.~ ~l~ O ~ E~ ~ ~
o l a) J~ o l a~ ~ .-~ ~ t~ O ~ a~ ~a ~s o ~ . C~- _ ~ ~ ~ h El ~ ~ O h ~ - v ~ ID ~ $~ c~ ~ o ~ ~ - o :~ ~ ~x l :` _ _ . , _ __ . _ . , " ~ , ~'o o~; o' o ~ o' o o o : o :"' o''''` o .
.. ~ U~ o U~ o o o o U~ o o o ~ U~ o ¢ t~ ~ N ~ C~ N . C~ C~l _ N C~ Cl ~ c~
_ _ _. _ _ _ _ _ _ . _ :, . l l ~ . :~ l I .......... I ' : ,'.. ~: -. ~ P. O ~ O O P. ~ ~: _l , ~0 O &: ~ ~: ~S O O ~:: .s:: ~ ~ ~0 ~ O , .~ ~, ;~, ~ ~ ~ ~ ~ o~ ~ s~ P, ~a~ ba .
~ ~ ~o o s ~ a~ ~ ~o5 ~ ~e ~ bO O ~:; ~:

~ : e) ~ ~ o li o~ X o I o c) o s t:: ~ x : .
o ~1 ,1 a ~ N ~ ! 5,~ ~ ! - s:N t~ ~ ~1 ~ S ..
3~ ,. ~ C`3 ~:: ~.~::N 5~ 0 a~ ca ~~ ~; O ~ ~ ~1 O ~ ~ ~_~ I ~ .~ l ~ _ i ~ I ~ l l ~ ~ _ ~
_ C) r~ ~ ~ :1 c~3 N N ~ C~ ~r ~ Q~ ~ ~1 ~ _ : . .

C~ . :, E~ . ~ 1-~ ~' ~_1 ~ . ~ ~ 1~ ~C
~ 1~ I--i ~ ~' ~1 ~C H ~C _ ~iP . 'q. _ ~ ..
. , .

, . , , . ! ~ ,, . , ,,, ' 1 . ', ! ~

ai6~27432 Example XX
A liquid formulation is made in the way described in Example I, but starting with a disazo material in which A-R2 is acetyl ins-tead o~ benzoyl, as described in Example V
The resulting formulation yields dyeings on paper which show the same shade and brightness as those from Example I~
The strength is somewhat greater than that o~ Example I.

Example_XXI to XXXIV
Formulations of the same liquid compositions as those of Example VI to XIX are made, but starting with the hydrolyzable disazo body as in Example XX All shades are satisfactory, being o~ the quality o~ Example I. .

.' ~._ , X
Disazo dyes use~ul in the coloration of paper are made by hydrolysis of products as indicated in Table II with definitions as given previously. The hydrolysis products may .
be furnished as liquid formulations in the manner of Examples I
and VI to XXXIV inclusive, or as powders in the manner of Examples II, III and IV~
. - ' ' . ~ :
, ,.,~ - , . - ~ ' : ~ ~

: :

. .
.
., ., ' .
,., . - 16 -. , .
-.
.- . .

LQ6Z7~2 a _ -~ _ + _ 8~ _ . _ _ al ~ I l 1+~ ' 1~ I+P4 1, 1+~
~: ___ _ .. __ _ _ .. _~ _ 0 O 0~ 0~ 1O O 1O O O a O O 0 O_ -I
~ : ~ ~ ~ l C ~
.. ~ l c~ P: :r: S: P~ ~ ~ P~ 5: ~ _ :~ :}: ~ :

~"~ ~ 3 ~ t~-~1 ~ ~ - I ~ 55

4 ~ ~-t ~ ~ ~

... -........ .... ( --- - -Il- (~ . ' ' ll \ ( l l 6;~lDZ
While the inven-tion has been described in conjunction with certain speci~ic embodiments thereo~, alternatives, modi-fications and variations will be apparent to those skilled in the art in light of the ~oregoing description. Accordingly, it is intended to embrace all such alternatives, ~odifications and variations as come within the scope and spirit o~ the append~d claims. -. I ~

' , ' . ;' .

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing a disazo dye, R1-H, comprising hydro-lyzing at a temperature of 80 to 150°C, with an alkali selected from the group consisting of lithium hydroxide, sodium hydroxide and potassium hydroxide, from 1 to about 60% by weight of the hydrolysis mass of a disazo of the formula R1-A -R2 where R1 is wherein:
R3 is hydrogen, sulfo, lower alkyl, lower alkoxyl, chlorine, bromine or nitro, R4 is hydrogen, lower alkyl, lower alkoxyl, chlorine, bromine or nitro, R5 and R6 are independently hydrogen, lower alkyl, lower alkoxyl, chlorine or bromine, R7 is hydrogen, lower alkyl or lower alkyl substituted with cyano, and M is ionizable hydrogen or a cationic metallic ion selected from Na+, K+, Li+, 1/2 Ca++, 1/2 Sr++, or ammonium ions selected from in which R9, R10, R11 are independently hydrogen, lower alkyl or lower hydroxy-alkyl;

A is carbonyl or sulfonyl; and R2 is lower alkyl which may be substituted with halogen or cyano; or is phenyl, phenyl substituted with nitro or chloro in a position para to A; or, with the proviso that A is carbonyl, is NH2 or R1.

2. The process of claim 1 wherein the hydrolyzing temperature is from 90 to 100°C and the percent by weight of the disazo used in the reaction is from 5 to 55%.

3. The process of claim 1 wherein R1 is

4. The process of any one of claims 1, 2 or 3 wherein an inorganic salt of the alkali is added to the reaction mass, which is then cooled to cause crystallization of the dye which is then separated therefrom.

5. The process of any one of claims 1, 2 or 3 wherein the disazo is hydrolyzed in the presence of an organic material capable of stabilizing the resultant liquid formulation.

6. The process of either one of claims 1 or 3 wherein the alkali is employed in an amount of from a slight excess of the molar amount of the disazo to about 5 times the molar amount and the disazo is employed in an amount of from about 3% to 40% by weight based on the weight of the disazo and water employed in the hydrolysis.

7. The process of any one of claims 1, 2 or 3 wherein the disazo is hydrolyzed in the presence of an organic material capable of stabilizing the resultant liquid formulation and the organic material is employed in an amount of from 5 to 80% by weight based on the weight of the organic material and water employed in the hydrolysis, and the disazo R1-A - R2 is employed in an amount of, by weight, 10% R1-A - R2/90% water and organic material to 55% R1-A - R2/45% water and organic material.