US2720528A - Fluorescent whitening agents - Google Patents

Description

United States Patent 2,720,523 LUQBESQENT WHIIENWQAGEPJ S I Ierbert August Lubs, Westmoreland, and Mario Francesco sartori, Monroe Park, Del., assignors to E. I. (In Pout de Nemours & Company, Wilmington, Del., a corporation of Delaware N9 Drsir n r tin atl nlr l ld 25,3, SBHIQINO, 35 F552?" lhisisrsn isaselates th .pras ust qn 9f aws $9 2 1sw isha sm t s l as c 9N9?! .t the shave e er l net W is by vb ea a tns ari b so el.

Add. ap a n, I at; 2 w ii ,g brigh in tszstilsfihe rid paperis of relatively recent developnient. I hasbe en found that fibrous materials which normally have a dull, yellowish cast when in the white, unbleached state, become whiter and brighter if treated; with agents which fluoresce under ultraviolet light. Presumably the action of the ultraviolet rays present in ordinary daylight is suflicient to eigcite these agents upon the fiber to emit fluorescence which overcomes the undesirable tinge of color in -the unbleached fiber Best results are obtained when the shade of fluorescence is complementary to that fof the unbleachedffiber,softhat the colors will c'ancel-out each other. Since the mpst common ofi-white shade of pnbleached ce llulpsic and most desirable shade in a fluorescent is blue.

Another very important demand developed 'by the trade is bleach fastness, inasmuch as the aforementioned fluorescent agents are generally incorporated into soap t-andrsynthetic detergents which'are packaged and marketned-for=household use,and inasmuch as in household .prac miceuilaunderedl-articlesareoften subjected to bleaching r withtvanious: agents, for instance hy-poch-lorites; it is essenitialuthat tthe fluorescent transferred frorntthe detergent to wtheifiberishall not :be removed ortdestroyedby the .action of bleach. Unfortunately, .most of \therfluorescent agents ,lnowsonsthemarket, and having t the desirable blueshade, aarer-tweaklzin respect ;to "this qualification of :bleach resistonce. r i in additiondtoithesabove two-primary qualifications, an Lagent:tforxtheipurzposes .of :this invention .should be capable of rbeingt-syn'thesized economical-1y from readily available materials, and should "have sufficient fluorescent powei' .(often Preferred l to as itinctorialstrength) to give lithe desired effect at a minimum cost. -Itishould also have affinity tfor cellulose ortnylon eflher and-should betcapable ..of Jibeing dissolved or readily dispersed in: ,water in the "concentrations that would normally betused .in the treatmenttof t the respective fibers. Now according "to our invention inewtchemical compounds are synthesized which satisfy to an excellent deg ree, -all the aforegoing qualifications. The novel com- -poundsof this invention are aromatic -triazoles which are #pbtained by oxidizing QIthO amino azo dyes obtained by coupling 2-diazobenzothiazple s to naphthylamihes which are free to couple in'position ortho to tlie amino group. They may be defined generally the formula nelsfN -NT=WQ -whereimR-is-the 2-C radical of-a benzothiazole selected ylon fibers is yellowish, the

2,720,528 atented 04 t- 1 955 "ice ' monosulf o and sulfamyl derivatives of any of thesei is a 1,2;naphthalerie radical of the grqllp-l flusist ing of naphthal ne and in w rse, di msi flsar s 'i when and alltam 'ds st st m .l ltamy' is used here in a generic sense, to include primary sullfss rl (SQ NHZ i ws m asa k ul l f la s 1W ul x ll by lowe alk l di a s w ria radisal h ms Q-atsms ea Whe e t sl CQIQPQUPQT h s s l a s Par-bear smi e the? ma l 1 th q m free acids or i 11 s r'n O sew 9 1 al 11292 mi e ab wee -s l hls sal s uc asfth e kal' met la art- 2 1 1is Salts ,As ,py is of the nsmsnp atyr 9 91 na el se ie 9 2 P 9 the .n s t at ta hgrsili 'q haii .sluhil en subse sms a a l- It m be e e b the general formula i i wherein Xdesignates hydrogen, methyl, methoxy, ethyl or ethoxy, and which may be named --2- (-6 X 2- benzothiazolyl)t-2 H-naphtho (ll;2)-triazo1es. i

The compounds having lsulfo and car-boxy groups are generally water-soluble, and may be applied to textile *fibersor paper .fromtanfaqueous bath. Those haviing only ,suliarnyl sirbstituents or no substituents at all are of interest as fluorescents for, nylon fiber,.and1 may be applied thereto .frpm aqueous dispersions. of the finely divided ptoduct or from dispersions made by pouring into @Water a solution of the fluorescent in an vorganic solvent such as the Cellosolves (lower monoalkyl ethers of diethylene glycol).

,Our ,noyel compounds, may i be synthesized by diazotizjug 6-X-Zfllfiumhenzothiazole (wherein 'X has the rneaning aboye indicated), or a monosulfoor. monosulfia derivative thereof, and coupling the diazo comprnrnci in ,acid medium ,to an amino naphthalene which ma 1.1 2 LQtI LbQXY, .1.llf0 or .sulfamyl radicals in the nucleus, ,whichjs adapted forcoupling inposition ortho to the amino grpup. The last condition :impliestthatlthe amino group ,is located ,in position ;2 while fthe l-position i s free; or that 21 =l-,naphthylarnine is employedwhich Mill rse als int e -PQ iQ y y tu of a ng h v41 tion blocked due ,to the presenceof a waterjsolubilizing smut i pos tiqnn o 5- Wher tthe aminowbenzothiazole tselssts s t ee tram s lfp gro p tw sulfo .or t o carboxy groups may be present in the naphthylarnine comllt i lli- Ihe resulting ,orthoarnino azo ,cornpqund is then con- .ye rt e d into ,a :triazole by oxidation in known manner, for i 5rstance by heating in an ,eguous'sqlutio n of cupric amtrnonipm sulfate or in an aqueous alkaline solution of sodium hypochlorite until ,the color of the intermediate .azo ,dyehas essentially disappeared, ,andsthen recovering ,thmprqductin a desiredphysical or chemical form, .for

instance ,in the form ,ofian alkali-metal ,or ammonium agents of this invention may be purified by crystallization from organic solvents or by hypochlorite treatment of an aqueous slurry of the product.

As suitable Z-amino-benzothiazoles for the aforegoing purpose may be mentioned Z-amino-benzothiazole, its 6-methyl, 6-ethyl, 6-methoxy and 6-ethoxy derivatives; the monosulfo derivatives of any of these, obtained for instance by sulfonation of same with 20% oleum at room temperature; the alkali-metal or ammonium salts of such sulfo derivatives; and the corresponding sulfamyl derivatives.

As coupling components for the intermediate amino azo dyestufis prepared above may be used 2-naphthylamine; 1-naphthylamine-4-sulfonic acid, 2-naphthylamine-6-sulfonic acid, and the various isomers of these; the various primary sulfamyl, monoalkyl sulfamyl and dialkyl sulfamyl derivatives of lor 2-naphthylamine; 2-amino-naphthalene-3-carboxylic acid; l-aminoand Z-amino-naphthalene-4,S-dicarboxylic acid; the various l-aminoand 2-amino-naphthalene-disulfonic acids; and the alkali-metal or ammonium salts of any of the aforegoing.

The requisite sulfamyl derivatives of lor 2-naphthylamine may be prepared by first acetylating the corresponding naphthylamine with acetic anhydride, to block the amino group; then sulfonating the compound with chlorosulfonic acid to convert it into a sulfonyl chloride. The latter is then treated with the appropriate amine (ammonia, methylamine, ethylamine, dimethylamine, etc.) to obtain the sulfonamide. Finally, hydrolysis with hot hydrochloric acid regenerates the amino group and gives the desired sulfonamide compound.

The requisite Bz-sulfamyl derivatives of 2-aminobenzothiazole may be obtained by reacting an aminobenzene sulfonamide and sodium thiocyanate in the presence of bromine and acetic acid, according to the procedure described by H. P. Kaufmann et al. in Arch. Pharm. 279, 195, 202-3 (1941).

Without limiting this invention, the following examples are given to illustrate our preferred mode of operation. Parts mentioned are by weight.

Example 1 15.0 parts (0.1 mol) of 2-aminobenzothiazole were dissolved in 20 parts of concentrated sulfuric acid and diazotized at to C., with a solution of sodium nitrite in concentrated sulfuric acid. The obtained diazo solution was added to a solution of 27 parts (0.11 mol) I of Broenners acid (2-amino-naphthalene-6-sulfonic acid) sodium salt in 400 parts of water, while keeping the temperature at 0 to 5 C. The acidity was then reduced by the aid of sodium acetate to a weakly acid test on Congo red paper and the mixture was allowed slowly to assume room temperature. The mixture was then made alkaline to brilliant yellow paper by addition of 30% sodium hydroxide solution and the amino azo dye was salted out with sodium chloride and filtered 0E.

The wet dye cake prepared above was dissolved in water and heated at 60-70 C., for 23 hours With an alkaline solution of sodium hypochlorite, into which additional alkaline sodium hypochlorite solution was fed at a rate sufficient to maintain a positive test to starchiodide paper. After clarification of the solution with charcoal, the product was recovered by salting out, filtering and drying. It was a cream-colored powder, soluble in water with bright bluish fluorescence. The absorp tion maximum of this compound in aqueous solution is located at 360 millimicrons.

Example 2 16.4 parts (0.1 mol) of 2-amino-6-methyl-benzothiazole were diazotized and coupled to 27 parts of the sodium salt of Broenners acid, and the dye was isolated as in Example 1. The orthoamino azo dye thus obtained was.

' at 365 millimicrons.

4 dissolved in 2000 parts of water at C. A solution of 50 parts of CUSO4.5H2O in 100 parts of water and 300 parts of concentrated ammonia (28%) was added. The mixture was then heated to reflux for 16 hours and thereafter filtered. The cake was dissolved in boiling water, filtered hot; the filtrate was decolorized with aqueous sodium hypochlorite, and the product was salted out. It was a cream-colored solid, soluble in water with bright bluish fluorescence. The absorption maximum of this compound in aqueous solution is located at 350 millimicrons.

Similar compounds may also be prepared by coupling diazotized 2-amino-6-methyl-benzothiazole to naphthionic acid (1-amino-naphthalene-4-sulfonic acid) or to Laurents acid (1-amino-naphthalene-5-sulfonic acid), and oxidizing the amino azo dyes as above.

' were diazotized and coupled to the sodium salt of amino-R acid (2-amino-naphthalene-3,6-disulfonic acid) as in Example 1. The obtained ortho-amino azo dye was oxidized with cupric sulfate and purified as in Example 2. The final product was a light tan powder very soluble in water with bluish fluorescence. The absorption maximum of this component in aqueous solution is located The compound is believed to have the formula Naoas SO3N8 Similar compounds may be also prepared by coupling diazotized 2-amino-6-methyl-benzothiazole to amino-I acid (Z-amino-naphthalene-5,7-disulfonic acid) or to amino-G acid (2-amino-naphthalene-6,S-disulfonic acid) and oxidizing the amino azo dyes as in Example 2.

Example 4 19.5 parts 0.1 mol) of Z-amino-6-ethoxy-benzothiazole were dissolved in an acid solution consisting of 160 parts of water and parts of concentrated sulfuric acid, and diazotized, at 5-l0 C., with a solution of sodium nitrite (0.1 mol) in 50 parts of water. A solution of 27 parts (0.11 mol) of Broenners acid sodium salt in 400 parts of water was added.

The acidity was reduced by the aid of sodium acetate to a weakly acid test on Congo red paper and the mixture was allowed slowly to assume room temperature. The mixture was then made alkaline to brilliant yellow paper by addition of 30% sodium hydroxide solution, and the amino azo dye was salted out and filtered otf. The wet dye concentrate thus prepared was oxidized as in Example 2. The oxidation mixture was filtered, and the cake was suspended in water and heated for 15 min. at C. with an excess of a solution of sodium sulfide in water. After filtration, the product was recovered from the filtrate by salting with sodium chloride. It was a tan powder, soluble in water with bright fluorescence. The absorption spectrum of this compound in aqueous solution is located at 370 millicrons.

Compounds of similar properties are obtained by. following the same procedure as in this example, except for replacing the 27 parts of Broenners acid sodium salt by an equal weight of (a) the sodium salt of naphthionic acid, or (b) the sodium salt of Laurents acid.

Example 5 19.5 parts of (0.1 mol) of 2-amino-6-ethoxy-benzothiazole were diazotized and coupled to the sodium salt of amino-R acid as in Example 4. The obtained dye was 1'5 oxidized and purified as in Example end product was --a light tan product, soluble inwater fluorescence.

Similar fluorescent compounds. are obtained apply- 'ing the same procedure to the amino azo dyes obtained by coupling diazotized 2-am'ino-6:ethexygbenkothiazole to amino-J acid orto amino-G acid.

. Examples r t 19.5 parts (0.1 mol) of learning-d ethoxy bennothiazole were diazoti-zed andcoupled to *27 parts-of-Broenners amide (2-naphthylamine-6- sulfqnamide), as in Example 4. The obtained dye was oxidized as in Example 2. The reaction mass was filtered and the cake was slurried in water made acid to Congo red paper with hydrochloric acid. This slurry was heated to 80 90 C. to dissolve an copper salts and filtered hot. The cake was washed with water until acid-free and crystallized from Cellosolve (a lower monoalkyl ether of diethylene glycol). It was a yellow powder, soluble in Cellosolve with blue fluorescence. The absorption maximum of this compound in Cellosolve solution is located at 365 millimicrons. The product is believed to have the formula:

S OrNH:

Compounds of similar properties are obtained if the Z-amino-6-ethoxy-benzothiazole named in this example is replaced by an equivalent weight of (a) Z-amino-benzothiazole, or (b) Z-amino-6-methyl-benzothiazole.

When the Broenners amide in the above example is replaced by 14.3 parts (0.1 mol) of Z-amino-naphthalene, one obtains a blue fluorescent agent which may be applied to cotton or nylon from a dispersion thereof in aqueous organic solvent or in a hot aqueous bath containing a dispersing agent.

Compounds of similar nature may also be prepared according to the above procedure by diazotizing (c) 2- aminobenzothiazole-6-sulfonamide, (d) 2-amino-6'methyl-benzothiazole-S-sulfonamide, or (e) 2-amino-6-ethoxy- S-sulfonamide (obtained respectively from p-anilino-sulfonamide, 4-methyl-3-sulfamyl-aniline and 4-ethoxy-3- sulfamyl-aniline, according to the Kaufimann et al. procedure above mentioned), coupling to Z-amino-naphthalene or to 2-naphthylamine-6-sulfonamide, and then oxidizing as in Example 2.

Example 7 NaO;S N

HsC

soma

If the Broenner's acid. salt in the above example is replaced by 14.3 parts (0.1 mol) of Z-naphthylamine, a product of similar properties is obtained.

isolatedas'the sodium salts of the sulfonic-acids. 3 By using potassium hydroxide and potassium salts in lieu of sodium hydroxide and sodium salts, throughout, the products may be obtained as potassium sulfonates. Isolation as the free sulfonic acids can be effected by acidification of the condensation mass, and the products thus obtained may be reacted with ammonium hydroxide or any suitable organic or inorganic base, to yield the corresponding salt.

In addition to producing a whitening eifect upon textile material or paper, our novel compounds may also be used for various other purposes where fluorescence or absorption of ultra-violet light is desirable, for instance to achieve fluorescent effects in costumes or stage settings, to achieve novel effects on photographic paper, as ultraviolet filters when impregnated on cellulosic films which are used for wrapping materials, etc.

We claim as our invention:

1. A compound of the general formula.

f? N=Q wherein R is the 2--C radical of a benzothiazole selected from the group consisting of benzothiazole itself, its 6-methyl, G-methoxy, G-ethyl and 6-ethoxy derivatives, and the monosulfo and sulfamyl derivatives of any of these, while Q represents the 1,2-radical of a naphthalene compound of the group consisting of naphthalene, its monosulfo, disulfo, monocarboxy, dicarboxy and monosulfamyl derivatives.

2. An aromatic triazole compound of the formula =Q wherein R is the 2-C radical of 6-ethoxy-benzothiazole, while Q is the 1,2-radical of naphthalene-6-sulfonic acid.

3. An aromatic triazole compound of the formula W N=Q wherein R is the 2-C radical of G-methyl-benzothiazole, While Q is the 1,2-radical of naphthalene-fi-sulfonic acid.

4. An aromatic triazole compound of the formula i i N=Q wherein R is the 2-C radical of 6-ethoxy-benzothiazole, while Q is the 1,2-radical of naphthalene-4-sulfonic acid.

5. An aromatic triazole compound of the formula I ll =Q wherein R is the 2-C radical of fi-ethoxy-benzothiazole, while Q is the 1,2-radical of naphthalene-fi-sulfonamide.

6. An aromatic triazole compound of the formula W N= wherein R is the 2-C radical of benzothiazole, while Q is the 1,2-radical of naphthalene-6-sulfonamide.

7. The process of producing a fluorescence agent for textile fiber, which comprises diazotizing a Z-amino-benzothiazole compound of the group consisting of Z-aminobenzothiazole itself, its 6-methyl, methoxy, ethyl and ethoxy substitution derivatives, and the monosulfo and sulfamyl derivatives of any of these, coupling the diazo compound thus formed to an amino-naphthalene which is adapted to couple ortho to the amino group and which is a member of the group consisting of unsubstituted amino-naphthalenes and amino-naphthalenes bearing substituents of the group consisting of sulfo, carboxy and s ulfamyl, and then oxidizing the coupled compound to the corresponding triazole.

8. The process of producing a fluorescence agent for textile fiber, which comprises diazotizing a Z-aminobenzothiazole compound of the group consisting of 2- amino-benzothiazole itself, its 6-methy1, methoxy, ethyl and ethoxy substitution derivatives, and the monosulfo and sulfamyl derivatives of any of these, couplingthe diazo compound thus formed to an amino-naphthalene which is adapted to couple ortho to the amino group and which is a member of the group consisting of unsubstituted amino-naphthalenes and amino-naphthalenes bearing substituents of the group consisting of sulfo, carboxy and sulfamyl, and then oxidizing the coupled compound to the corresponding triazole, the oxidation being effected by heating the compound in an aqueous solution of ammoniacal cupric sulfate.

No references cited.

Claims (1)

1. A COMPOUND OF THE GENERAL FORMULA