DE1445698A1 - Process for making fluorescent compounds - Google Patents

Description

Eastman Kodak Company, 3 ^ 3 State Street, Rochester, New York State, United States of America

Process for the production of fluorescent compounds "

The invention relates to a method of manufacture fluorescent compounds of the formula:

* .C-A-C = C-A-C>

0 Q

cd ⁰⁴

CO

oo

where mean:

A is an optionally substituted o-phenylene group,

2
A is an optionally substituted p-phenylene group

and

Y is a hydrogen atom or a monovalent group such as an aryl or cyano group.

The fluorescent compounds which can be prepared by the process of the invention are valuable optical brightening agents for polymeric substances, in particular Textiles made from high polymers.

Methods for preparation of the ζ !!, ip stilbenes of the invention are already in the older

Patent applications E 26 038 IVd / l2b and E 26 039 IVd / l2b of the applicant described. The processes described in the applicant's earlier applications are 4-stage processes. With this one. Process is first (a) the ^^ - stilbene dicarboxylic acid prepared by heating p-eolüolic acid with sulfur, after which (b) the acid is converted into the 4,4 ^f -stilbenedic acid chloride by heating the acid with thionyl chloride or phosphorus pentachloride. In the 3rd stage (c) the acid chloride is ^{reacted with an o-aminophenol to give 4 »4 f} -bis (2-hydrOxyphenylearbamoyl) stilbene» whereupon in the 4th stage (d) the 4,4'-bis (2- hydroxyphenylearbamoyl) stilbene is heated under reduced pressure to form the 4 »4'-bis (benzoxazol - 2-yl) stilbene compound»

It has now been found that * 4'-bis (benzoxazol-2 ~ yl) stilbenes to 4 can reach in other ways in which the use of the 4 ", 4 ^r -Stilbendicarbonsäure is avoided. A process which comprises the preparation of 4,4'-bis (benzoxäzol-2-yl) stilbenes enables _r without for preparing compounds of the 4r4 ^T must be used -Stilbendicarbonsäure is therefore advantageous "because the 4.4 ^f - Stilbene dicarboxylic acid is relatively difficult to manufacture and purify due to its high melting point and its low solubility in many solvents.

009813/1295

The process of the invention is characterized in that a 2- (p-tolyl) benzoxazole of the formula:

JL ¹ '^ G - A ² - GE ₂

wherein Y is an hydrogen atom or one other monovalent substituents, such as a jüLjqjfxLx -: ^ aryl- or cyano group, mixed with sulfur and heated the mixture.

The method of the invention can be represented, for example, by the following reaction equation:

A "! - CA ₉ -CH, + 2S At ^ CA -CH = CH-A -C ^ A ¹ + 2H ₉ S

^X 0 0

1 2

In this action equation, A and A have the given Meaning.

Thus, the 2- (p-tolyl) benzoxazole compounds useful in practicing the process of the invention include for example, the following benzoxazole compounds

1 X 2

C - A ^ - CH ₅ or A ^ / C - A ^ - CH ₂

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Y here, as "already stated, has the meaning« 4a. «« ·

for example an aryl

group, e.g. a Pheny! group », a cyano group, etc.

The o-phenylene group A has the formula:

R ¹

2.

The p-phenylene group A has the following Pormeli

R 'R «

R · R ^r

The substituents R ^{1 of} the phenylene groups can be identical to or different from one another. They represent monovalent substituents which are bound to the rings by eovalent bonds and which do not negate the fluorescent properties of the 414'-bis (benzoxazol-2-yl) stilbene compounds. .

It has proven advantageous to use 2- (p-tolyl) benzoxazoles as starting compounds, which are not substituted i.e. do not have any nitro groups that react with sulfur or hydrogen sulfide can, since the presence of such active groups the

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"" 5 ™ *

Yield of 4 _f 4'-bis (benzoxazol-2-yl) stilbene compounds can decrease. Normally, however, any reductions in yield can be accepted because of the excellent properties of the 4,4'-bis (benzoxazol-2-yl) compounds.

R ¹ can, for example, mean a hydrogen atom, a halogen atom * or alkyl, aryl, substituted aryl, hydroxy, alkoxy, aryloxy, acyl, acyloxy, amino, substituted amino, cLuaternary ammonium, Have sulfo, substituted sulfonyl, sulfamyl, substituted sulfamyl, cyano, thiocyano, thiol, carbamyl, substituted carbamyl, garbamoyloxy and nitro groups. In addition to these listed groups and atoms, R * can consist of all those atoms and groups that do not negate or impair the fluorescent properties of the 4,4 * -bis (benzoxazol-2-yl) stilbene compounds.

Suitable halogen atoms are, for example, chlorine, bromine, fluorine and iodine atoms. ^T , 7if R 'is an alkyl group, it preferably has 1 to 18 carbon atoms and is, for example, methyl, ethyl, propyl, isopropyl, η-butyl, isobutyl, n-pentyl, n-hexyl , n-decyl, n-dodecyl

- V

n-hexadecyl or an n-octadecyl group. When R * is an aryl **; represents a group or a substituted aryl group, so is

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this preferably mononuclear and consists of a phenyl, methy! phenyl, ethylphenyl, chlorophenyl, bromophenyl, methoxyphenyl, ethoxyphenyl or another substituted phenyl nucleus »R ¹ can also, for example, mean an aryl nucleus, such as an l -Uaphthyl or a 2-naphthyl nucleus or substituted derivatives thereof or a heterocyclic nucleus, such as, for example, a furyl or thienyl nucleus. If R ^{f has} the meaning of an alkoxy group, it has, for example, 1 to 18 carbon atoms and preferably consists of 1 to 4 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy ^ -, n-amoxy, isoamoxy or a hexoxy group. Particularly suitable aryloxy groups are, for example, the phenoxy and naphthoxy groups. Suitable acyl groups are, for example, the formyl, acetyl, propionyl, butyryl, isobutyryl, benzoyl and naphthoyl groups. Suitable acyloxy groups are, for example, the acetoxy, benzoxy ^ -v GB ₅ CH ₂ COO, Oli ^ effgCHg-COO * and CH ^ CHgCHgCHgÖHgCÖO groups. Suitable substituted amino groups are, for example, monoalkylaEiiiiogruppeh, dialkylamino groups, in which the alkyl groups can have different or the same character, a ^ rylamino, aralkylamino, cycloalkylamino, monohydroxyalkylamino, ^ dihydroxyalkylamino, alkoxyalkylamino and other alkoxyalkylamino ^{5 ::} _f amino Especially advantageous compounds are normalerwei8, e then before, the wenix. ^ lkyl-, hydroxyalkyl or

8 0 981 3/1 295>

Alkoxyalkyl groups of the amino groups not more than 4 carbon atoms have, although of course the number of carbon atoms can also be larger »

If R ^{f represents} a substituted sulfonyl group, this consists, for example, of an alkylsulfonyl group with up to 18 carbon atoms such as, for example, a? Methylsulphonyl, ethylsulphonyl, propylsulphonyl, butylsulphonyl, etc. Also suitable are arylsulphonyl groups, preferably mononuclear arylsulphonyl groups, such as, for example, a phenylsulphonyl, methylphenylsulphonyl, chlorophenylsulphonyl or ethoxyphenyl group. Suitable substituted sulfamyl groups are, for example, the alkyl and bialkylsulfamyl groups such as, for example, an N, N-dimethylsulfamyl, N-ethylsulfamyl, N-methylsulfamyl, H-butylsulfamyl or an N-ethyl-N-butylsulfamyl group. Suitable aryl and diaryleulfamyl groups are, for example, the F-phenylsulfamyl, ΙΓ, Ν-diphenylsulfamyl, N, S-diethylphenylsulfamyl, N-phenyl-N-ethylphenylsulfamyl, Ν, Ν-dibutylphenylsulfamyl and H-ethoxyphenylsulfamyl. Suitable N-alkyl-K-arylsulfamyl groups are, for example, the 1-ethyl-N-phenylsulfamyl, N-methyl-N- (methoxyphenyl) sulfamyl and N-butyl-N-chlorophenylsulfamyl groups.

When R * means a substituted carboxyl group has »so these are preferably alkyloarbamyl or

809813 / T29 5

- ο -

Dialkylcarbamyl groups in which the alkyl groups in the Usually 1 Mb 4 carbon atoms. Have such as an N-methylcarbamyl, N-ethylcarbamyl, N-propylcarbamyl, N-isopropylcarbamyl-, N-butylcarbamyl-, Ν, Ν-dimethylcarbamyl-Ν, Ν-diethylcarbamyl, Ν, Ν-dibutylcarbamyl or an N-ethyl-N-methylcarbamyl group. Suitable aryl and diarylcarbamyl groups are, for example, N-phenylcarbamyl, Ν, Ν-diphenylcarbamyl, N, N-di (ethylphenyl) carbamyl or an N, N-di (methoxyphenyl) carbamyl group. - ■

However, R ^f can also have the meaning of one of the following groups:

Q J ^,

-OC-N _V ; -NHSO ₉ Q; -F;

Il \ ^ \

S Ql -., Acyl

. ^ - acyl acyl

wherein Q and Q ₁ can be: hydrogen atoms, alkyl groups with preferably 1 to 4 carbon atoms, substituted alkyl groups with preferably not more than 4 carbon atoms, aryl groups such as phenyl, methylphenyl, ethyphenyl, methoxyphenyl, ethoxyphenyl, chlorophenyl or Bromophenyl groups or cycloalkyl groups such as cyclobutyl, cyclopentene or cyclohexyl groups. . , -. . .. ... -

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acyl j -C-OQ ; -NHC-N M. H SO ₂ Q 0 0

-. 1Λ45698

The term "acyl ^11" is to be understood in the broadest sense, ie apart from the acyl groups specified here, this also includes groups such as the tJreido group, -SOpQ group and

- groups, in which Q

H
Q '

and Q-, have the meaning given

R ¹ can also have the meaning of a fluorinated alkyl group having 1 to 18 carbon atoms. For example, let hia | called difluoroalkyl groups of the formula - (GH) CKP ^ Trifluoroalky! groups of the formula - (GHg) _n O ^, where η is an integer from 1 to 17, but R ¹ can also have the meaning of a more highly fluorinated alkyl group, such as one - (GHg) _m , (Cig J ^ GF - ^^ rW m is, for example, a number from 1 to 4 and m ^{1 can be} a number such as 1 or 2. For example, R 'can have the meaning of one of the following fluorinated alkyl groups, ie R * can be a 2,2-difluoroethyl-, 3 »3-difluoro-n-propyl- _t 4,4-difluoro-n-butyl-, 5,5-difluoro-n-amyl-, 6,6-- Difluoron-hexyl-, 2,2,2-trifluoroethyl-, 3,3,3-trifluoro-n-propyl-, 4,4,4-trifluoro-n-butyl-, 5,5,5-trifluoro-n- amyl-, 6,6,6-trifluoro-n-hexyl-, -CHgCHgGF ^ '-, -GHgCHgCFgGF ^ -, -CHgCHgCHg-CFgCF, - or a -CHgCHgCFgCFgCF ^ group «

R 'can also mean an unsaturated acyclic Have hydrocarbon group such as one Allyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl,

8 0 9 813/1295

- ίο -

2-pentenyl, 3-pentenyl, isobutenyl or a 1-isopentylene group,

The ratio of the reaction components can be wide Boundaries be different. Thus, per gram-mole of 2- (p-tolyl) benzoxazoles for example about 0.1 gram atoms to about 100 gram atoms of sulfur can be used. According to one preferred embodiment of the method of the invention is used at least one stoichiometric equivalent of sulfur, i.e. at least 1 gram atom of sulfur per gram-mole 2- (p-Tolyl) benzoxazole.

It has proven advantageous to carry out the method of the invention at atmospheric pressure. However, the process of the invention can also be carried out at higher or lower pressures, for example at pressures from about 0.1 atmospheres to about 10 atmospheres. It has proven to be advantageous to operate at temperatures of about 250 ⁰ C to about 300 ⁰ C, although the 4,4'-BiSCbSnZ-oxazol-2-yl) stilbenes _t even at temperatures of less than 250 ° C, for example, to 200 ⁰ C as well as at higher temperatures "eg" at about 350 ^ C arise. The course of the process can be followed by the evolution of hydrogen sulfide. The reaction can then be considered to have ended, the evolution of hydrogen sulfide has ended.

80 98 13/1295

Gfemäss a preferred embodiment of the method of the invention, a mixture heated consisting of at least one gram-atom of sulfur per mole of 2,2- (p-tolyl) benzoxazole at about atmospheric pressure at a temperature of about 25O ⁰ G ⁰ to about 3QO C.

The fluorescent 4,4'-bis (benzoxazol-2-yl) stilbenes • can be extracted from the reaction mass, for example by Soxhlet extraction extracted and purified, whereby chlorobenzene can be used as an extraction agent, for example, The reaction mass can also be washed with carbon disulfide and made from a mixture of, for example, trichloroacetic acid and 88 # formic acid are recrystallized.

The following examples are intended to further illustrate the process of the invention.

example 1

A mixture consisting of 10.5 grams (0.05 gram-moles) of 2- (p-tolyl) benzoxazole and 1.6 grams (0.05 gram atoms) of sulfur was heated to temperature for 5-5 hours with stirring under a nitrogen atmosphere heated from 275 ^{0 C.} In the process, hydrogen sulfide developed, and did so very quickly at first. After completion of the reaction, the reaction product was removed from the reaction flask and extracted with chlorobenzene in a Soxhlet extractor until the colored impurities were removed. The residue consisted of a lot

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1445688

pure 4.4 ^l -Bi8 (benzoxazol-2-yl) stilbene. The infrared spectrum of the obtained compound agreed with the infrared spectrum of the other obtained compound.

Example 2

200 g (6.25 gram atoms) of sulfur were heated ^{to 260 to 265 ° C. with stirring.} Then 52.25 grams (0.4 gram moles) of 2- (p-tolyl) benzoxazole were added over 30 minutes. The mixture was stirred for an additional hour after the 2- (p-tolyl) benzoxazole had been added and then allowed to cool. This solidified the mass.

20.4 g of the crude product obtained were then ground up and stirred with 100 ml of carbon disulfide until no more solid constituents were dissolved. The mixture was then filtered, whereupon the residue was washed with 25 ml portions of carbon disulfide and then dried. The product obtained (2.8 g) was then recrystallized from a mixture of equal parts of irichloroacetic acid and 88% formic acid. There were obtained 2.4 g of 4,4'-bis (benzoxazol-2-yl5stilben ·. Starting therefore a yield of 57 ° / ° was used 20.4 g of the obtained.

Example 3

A mixture consisting of 2.5 grams (0.1 gram-moles) of 2- (p-tolyl 5-chlorobenzoxazole (made from 2-amino-4-chlorophenol

8 0 9 8 13/129 5

1445693

and p-toluoyl chloride) and 0.3 g (0 01 * gram atoms) of sulfur was heated for 5 hours at 275 ⁰ C. Hydrogen sulfide was evolved at a constant rate. The obtained reaction product, namely, 4,4-bis ^t (5-chlorobenzoxazole) stilbene possessed by Umkristall! Sation from trichlorobenzene, vacuum sublimation and a second recrystallization from trichlorobenzene a melting point 305-310 ⁰ C.

Example 4

4,4 ^f -Bis (5-chloro-6-methylbenzoxazol-2-yl) stuben was prepared according to the procedure described in Example 3 by heating equimolar amounts of sulfur and 2- (p * tolyl} 5-chloro-6-methylbenzoxazole). the stilbene had a melting point of 379 ⁰ C Maximum ultraviolet absorption was at a wavelength of 381 millimicrons.

Example 5

4,4'-bis (6-methylsulfonylbenzoxazol-2-yl) stilbene according to the method described in Example 3 by heating equimolar amounts of sulfur and 2- (p-tolyl) -6-methylsulfonylbenzoxazole manufactured. The stilbene had a maximum ultraviolet absorption at a wavelength of 381 millimicrons.

Example β

Following the procedure described in Example 3, 4.4 '* · Bis (5-methoxybenzoxazol-2-yl) 8-tilbene by heating in equal amounts Sulfur and 2- (p-tolyl) -5-methoxybenzoxazole 8098 13/1295

manufactured. The stilbene had a melting point of 34-2 ⁰ G. The compound had a maximum ultraviolet absorption at a wavelength of 381 millimicrons.

Example 7 .

According to the process described in Example 3, 4 »4'-bis (5-methylbenzoxazol-2-yl) tubes were prepared by heating equimolar amounts of sulfur and 2- (p ~! Eolyl) -5-methylbenzoxazole. The stilbene had a melting point of about 400 ⁰ C. The maximum ultraviolet absorption was at a / rush length of 380 millimicrons;

Example 8

4,4'-Bis (5 ~ tert «-amylbenzoxazol-2-yl) stilbene was prepared by heating equimolar amounts of sulfur and 2- (p-tolyl) ~ 5-tert-amylbenzoxazOl according to the process described in Example 3. The stilbene had a melting point of 298 to 299 ⁰ C and a maximum ultraviolet absorption with a hamlet length of 377 millimicrons,

Example 9 ■ ■■ - ■ - ■ · - ■ -. ■ ■ · ■■ ■ - ■ ->'- ,:

According to the procedure described in Example 3, 4 »4'-bis (5-phenylbenzoxazol-2-yl) stilbene produced by heating equimolar amounts of sulfur and 2- (p-tolyl) -5-pehenylbehzoxazole « The stilbene possessed maximum ultraviolet absorption a wavelength of 360 millimicrons.

8098 13/1295

Example 10

According to the procedure described in Example 3, 4.4 * - Bis (5-cyanobenzoxazol-2-yl) stilbene prepared by heating equimolar amounts of sulfur and 2- (p-tolyl) -5-cyanobenzoxazole. The stilbene had a melting point of more than 400 ° 0 «

Example 11

According to the method described in Example 3, 4,4 * - bis (5 »7-dichlorobenzoxazol-2-yl) was equimolar by heating Amounts of sulfur and 2- (p-tolyl) -5 »7-dichlorobenzoxazole manufactured. The stilbene had a melting point of 392 to 397 ° O and a maximum ultraviolet absorption at one 376 millimicron wavelength,

Example 12

4,4'-Bis (4,5f6-trichlorobenzoxazol-2-yl) stilbene was prepared by heating equimolar amounts of sulfur and 2- (p-tolyl) -4,5 »6-triehlorobenzoxazole according to the process described in Example 3. The stilbene had a melting point of 364-375 ⁰ C and a maximum ültraviolettabsorption at a wavelength of 393 millimicrons.

Example 13

According to the method described in Example 3, 4,4 * - bis (benzoxazol-2-yl) -2,2 * -dichloro8tirben was obtained by heating equimolar amounts of sulfur and 2- (3-ehloro "4-me thy! phenyl) -

809813/1295

"Benzoxazole produced. The stilbene had a melting point of 322 to 324 ⁰ C. ■.

The information used here SuIf amyl and Garbamylgruppen are synonymous with the terms sulfamoyl and carbamoyl groups according to the information / '' The Naming and Indexing of Chemical Compounds from Chemical Abstracts ¹¹ , Introduction to the Subject, Index of Chemical Abstracts, Vol. 56 ( January to June 1962),

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Claims (8)

1. Process for the preparation of fluorescent compounds of the formula: A ¹ . C - A ^ - C «C - A ^ - CA 0 · O ^ where mean: A is an optionally substituted o-phenylene group, 2
A is an optionally substituted p-phenylene group and Y is a hydrogen atom or a monovalent group such as an aryl or cyano group, characterized in that a 2- (p-tolyl) benzoxazole the formula: '12 wherein A, A and Y have the meaning given, with Sulfur mixed and the mixture heated. 2. The method according to claim 1, characterized in that the 2- (p-ToIyI) benzoxazole is heated with at least a stoichiometric amount of sulfur at a pressure of about 0.1 to about 10 atmospheres to a temperature of about 200 to 350 ° C . 809813/1295 ~ 18 - 3. The method according to claims 1 and 2, characterized in that that you get the mixture of 2 ~ (p-tolyl) benzoxazole and sulfur at a pressure of about 1 atmosphere to a temperature heated from 250 to 300 ° 0. 4. Process according to Claims 1 to 3, characterized in that that to prepare a compound of the formula: R ' E «R ' R 'R ¹ R ^f e - R » R 'R » where R ^f represent: Hydrogen or halogen atoms or alkyl, aryl, alkoxy, Aeyloxy, alkylsulfamyl, arylsulfemyl, cyano, aryloxy, Amino, carbamyl, carbamoyloxy or heterocyclic group "" in 2- (p-tolyi) benzoxazole of the formula Ψ R »R» R » where R * has the meaning given at a temperature of 200 biB. 35O ⁰ C and a pressure of 0.1 to 10 atmospheres with at least the stoichiometric amount of sulfur implemented * «. - 80 98 1 3/129 5 5. The method according to claims 1 to 3, characterized in that nan for the production of 4 »4 ^f -bis (benzoxazol-2-yl) stilbene at a pressure of 1 atmosphere, a mixture of sulfur and 2- (p-tolyl) benzoxazol clay to a temperature 250 - 300 ⁰ C heated. 6. The method according to claims 1 to 3 »characterized in that aan for the production of 4,4 ^f -BiB (6-methyleulfonylbenzoxazol ~ 2 ~ yl) tubes at a pressure of 1 atmosphere a mixture of sulfur and 2- (p» tolyl) -6-methylsulfonylbenzoxazol to a temperature of 250 - 300 ⁰ C heated. 7. The method according to claims 1 to 3 »characterized in that for the production of $ on 4» 4 ^t -bis (5-methoxybenzoxazol-2-yl) atilbene at a pressure of 1 atmosphere, a mixture of sulfur and 2- (p- Tolyl) ~ 5-methoxybenzoxazole heated ^{to a temperature of 250-30O 0 C.} 8. The method according to claims 1 to 3, characterized in that for the preparation of 4,4'-bis (6-chlorobenzoxazol-2-yl) stilbene at a pressure of, 1 atmosphere, a mixture of sulfur and 2- (p- tolyl) -6-chlorobenzoxazole to a temperature of 250 - 300 ⁰ C heated. 9 «Process according to claims 1 to 3», characterized in that for the production of 4 * 4 * -BiB (5-eyanobenzoxazole- 8098 13/1295 2-yl) stilbene at a pressure of 1 atmosphere, a mixture of sulfur and 2- (p-tolyl) -5-cyanobenzoxazol to a temperature of 250 - 300 ⁰ C heated. . 8098 13/1295