Bis benzoxazoles

In addition to the most common synthesis (the reaction of dicarboxylic acids or their chlorides with 2-aminophenols) other industrially interesting processes have been developed recently. 

Compound 38 is obtained, for example, by condensing 2-amino-4-methylphe-nol with maleic acid to yield the diamide. Ring closure and the formation of the ethylene bridge occur on heating in a mixture of diphenyl ether and diphenyl at 135-155 °C in the presence of boric acid [68], 

To obtain 2,5-bis(benzoxazol-2-yl)thiophene (39), two equivalents of 2-chloro-methylbenzoxazole are treated with sodium sulfide and the thiophene ring is formed with glyoxal hydrate [70]  

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Bis(benZoxaZol-2-yl) Derivatives. Bis(benzoxazol-2-yl) derivatives (8) (Table 3) aie prepared in most cases by treatment of dicaiboxyhc acid derivatives of the central nucleus, eg, stilbene-4,4Cdicarboxyhc acid, naphthalene-l,4-dicarboxyhc acid, thiophene-2,5-dicarboxyhc acid, etc, with 2 moles of an appropriately substituted o-aminophenol, followed by a ring-closure reaction. These compounds are suitable for the brightening of plastics and synthetic fibers. 

In the presence of air or oxygen, it has been shown15 that />-tolyl-substituted heterocycles in DMF with potassium hydroxide are oxidized to symmetrical stilbenes. Thus, for example, 2-(/ -tolyl)benzoxazole yields 4,4 -bis(benzoxazol-2-yl)stilbene (14). Similar reactions have also been carried out with p-tolyl-substituted benzotriazoles, oxazoles, 1,3,4-thiadiazoles, 1,2,4-and 1,3,5-triazines, and quinazolines. 

Table 7.6 lists the most important bis(benzoxazole) brighteners. 

In a closely related publication, carboxylic acids were employed instead of acid chlorides in a microwave-assisted direct synthesis of 2-substituted benzoxazoles [79]. The reactions with 2-aminophenol were performed in a household microwave oven and worked well with aromatic, heteroaromatic, aj/i-unsalurated and arylalkyl carboxylic acids (35-82% yields). Phthalic acid formed only mono-benzoxazoles, while the use of succinic acid led to a mixture of mono- and bis-benzoxazoles. Phthalic and succinic anhydrides could... 

Optical brighteners are usually derivatives of coumarin, stilbene, dis-tyrylbipheny, and bis(benzoxazole). Examples of chemical structures of some important optical brighteners are given ... 

Oxazoles and benzoxazoles with an aryl substituent at C2 are strongly fluorescent and can act as an optical brightener. Some washing agents include 4,4 -bis(benzoxazol-2-yl)stilbene as an additive. The additive is... 

CAS 1533-45-5 EINECS/ELINCS 216-245-3 Synonyms 4,4-Bis (benzoxazol-2-yl) stilbene 4,4-Bis (2-benzoxazolyl) stilbene... 

Lenape Zinc Stearate ZD-22, Lenape Zinc Stearate ZM-22, Lenape Zinc Stearate ZN-20, Lenape Zinc Stearate ZVF-G, Lenape Zinc Stearate ZVF-P, Lenape Zinc Stearate ZV-G, Lenape Zinc Stearate ZV-P. See Zinc stearate Lenbrite OB-1. See 2,2 -(1>2-Ethenediyldi-4,1-phenylene) bisbenzoxazole Lenbrite PB. See 2,5-Bis (benzoxazole-2) thiophene... 

THO. See 2,5-Bis (benzoxazole-2) thiophene Thomas balsam. See Balsam tolu (Myroxylon... 

Bis (benzoxazol-2-yl) naphthalene brightener, fluorescent paper 7-Diethylamino-4-methylcoumarin brightener, fluorescent plastics 7-(4-Amino-6-diethylaminotriazin-2-yl) amino-3-phenylcoumarin 7-(4-Chloro-6-diethylaminotriazin-2-yl) amino-3-phenylcoumarin Cl fluorescent brightener 236... 

Bis (benzoxazol-2-yl) naphthalene C24HisCl2N3Na209S2 Acid red 107 C24H15NO7 Resorcine bue C24H16AS2O3... 

These are primarily bis-benzoxazoles, triazines and triazoles of phenyl coumarins, and bis-styryl biphenyls (Fig. 5.12). They absorb invisible UV light, dispose of part of the en-... 

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