Indian Journal of Fibre & Textil e Research Vol. 24, December 1999, pp. 297-302

Disperse Red 60 analogs

David a Ukponmwan , Chris A Odilora" & Mercy NaIlor

Department of Chemistry, Faculty of Science, University of Benin, Benin Cit y. Nige ri a

and

Harold S Freeman

Department of Textile Engineering, Chemistry and Science, Co llege of Textiles , North Carolina State University, Raleigh, North Carolina 27695-830 I, USA

Received 29 May 1998; revised received alld accepled 18 March 1999

The synthesis and properties of a series of Disperse Red 60 analogs containing substituents in the phello xy moi ety arc described . While the introduction of substilUents into the phenoxy ring does not result in a signifi cant shift in the ;Ihsorption maximum of the parent compound, most of the dyes synthesized afford better li ght fastness, was h fa stness. crock fasl nes.s and sublimation fas tness. The structure of each dye has been confirmed by IR , 'H NMR , 2- D NMR and mass spectromelr ic analyses. The mutagenic properties of these dyes have also been determined in the standard Ames test. usi ng S({/IIIII//I' /1({

ryphimuriul11 strains TA98 and TA I 00. The results indicate that all of the dyes arc non-mutageni c. SO llle of lhe dyes arc toxic towards strain TA I 00, with toxicity correl ating well with partition coeflicient values.

Keywords: Disperse Red 60, Mutagenic properties , Partition coefficient, Polyester IIber

1 Introduction Derivatives of l-aminoanthraquinone such as

] -amino-2-alkoxy-4-hydroxyanthraqui nones a nd

] -amino-2-aryloxy-4-hydroxyanthraquinones were the

original bright red dyes for cellulose acetate fibers and are now widely used for dyeing polyester fibers I .

Despite the apparent declining importance of

anthraquinone disperse dyes , dyes such as Disperse

Red 60 (I) and Disperse Red 91 (II) are quite popular

for the coloration of PET for automobile uphol ster/ '

Since the polyester fiber has gained commercial

importance in recent times , the search for improved disperse dyes has continued to be a commercially

important undertaking.

$OR o OH

A=CsHs; II R=(CH2)60H

It is known that the sublimation ' fas tness of

Disperse Red 60 is only moderate and that, the

introduction of substituents into the phenoxy ring leads to hi gher sublimation fastness. Thus,

a Present address: Department of Chemistry, Edo State University, Ekpoma, Nigeria

substitution of auxochromes suc h as -HO, -OM e and

-OROH (where R= 1-4 C atoms ) into the phe no xy ring

have been reported to g ive derivatives of Dispe rse

Red 60 having brig ht red shades and exce ll e nt fastness on cellulose acetate".

The present work was a imed at sy nthes iz ing a

group of anthraquinone red dispe rse d yes havin g the

general structure shown in Tabl e I. This was

achieved by the reac ti o n of l-amino-2-bro mo-

4-hydroxyanthraquinone with the appropriate

phenolic compounds in an alkaline medium at

moderately high te mperatures'. The e ffect o f ring

substituents on fastness prope rti es and reac ti o n y ie lds

was inves tigated . Whil e much has been publi s hed abo ut the

mutageni c properties of azo d yes, the o pe n lite rature contains very little informati o n o n the mutagenicity o f

anthraquinone dyes. Among the few pape rs that have been published in thi s area is o ne from S igman el (//~ dealing with se lected anthraquino ne va t d yes . 1n

addition , Brown and De ithric lY' summari zed the

mutagenicity of a large group o f mono-and di­substituted anthraquinones , mos t of whi c h are not dyes . In view of the pauc ity o f info rmati o n in thi s area as well as o ur inte rest in deve lop ing new dyes

based on toxicological conside rati o ns. mutagenic ity testing of the synthes ized anthraquin o ne di sperse dyes was also carried o ut.

298 INDIAN J. FIBRE TEXT. RES .. DECEMBER 1999

2 Materials and Methods All the chemicals and reagents used were obtained

from Aldrich Chemical Company (Milwaukee, WI, USA) and Fisher Chemical Company (Pittsburgh, PA, USA) . Melting points were determined on a MEL­TEMP capillary melting point apparatus and are uncorrected.

Infrared spectra were recorded in a KBr disc on a Nicolet 5lOP FT-IR spectrophotometer. Visible spectra were recorded on a Varian CARY 3E UV­visible spectrophotometer in 2-methoxyethanol at a concentration of 4 x 10.5 M, using a 1.0 cm cell. Thin layer chromatography (TLC) was performed using What man 250 Ilm silica gel 60 AMK6F plates . Dry column chromatograph/ was conducted using silica gel (Merck grade 60, 230-400 mm mesh type 60A) .

I H NMR spectra were recorded on a Geo-Omega 500 MHz NMR instrument and CI and EI mass spectrometric analyses were recorded on a Hewlett­Packard 5985B quadrupole mass spectrometer with the aid of an RTE-VI data system.

Dyeings were obtained on 100% polyester fabric (Dacron 54) at I % depth using an Ahiba Polymat (type PN) pressure dyeing machine at 130 DC for I.5 h from a dyebath containing 0.1 % (owf) dispersing agent (lrgasol DA(

The light fastness of the 1% (owf) dyeings was determined using an Atlas ES 25 Weather-Ometer (Xenon arc) according to AA TCC Test Method 16E-19938

. The test conditions were:

Black panel temp. Relative humidity Chamber temp. Irradiance Counter setting

60 DC 30±5% 50 DC 0 .75W/m2

54 kJ/m2

The samples were rated with the aid of ACS Spectro-Sensor n instrument. Sublimation fastness testing was conducted with the aid of an Atlas Scorch Tester at 177±2DC for 30s and 60s according to AATCC Test Method i 77- I 9848

. The change in color of the dyed fabric and color staining and transfer on the multifiber warp were evaluated using the Grey scale.

Fastness to washing was assessed by washing the samples of dyed fabrics with 0.2% soap solution in an Atlas Launder-O-meter at 49DC for 45 min according to AATCC Test Method 61- I 9938

. Evaluation was also conducted with the aid of the Grey sca le.

Crock fastness was determined using a:n AATCC 8 crockmeter (AATCC Test Method- I 989 ). The fabric

was then evaluated uSlIlg the Grey scale for co lor transfer.

Mutagenicity testing was conducted usin g the method of Ames and Maron') and th e meth od of Claxton et ai. 10 was used to characteri ze the dyes as mutagenic , non-mutageni c or equi voca l. Partiti on coefficients were measured at 300nl11 usin !2; the method of Conway and Ito ll. ~

2.1 Preparation of l-amino-4-hydroxy-2-phcnoxyanthra­quinone (Dye I)

A mixture of phenol (5.33g. 0.057 mol). KOH (0.52g, 0.009 mol) and I -amino-2-broIll0-4-hydroxyanthraquinone (2.0g, 0.006 mol) was st irred at 155-160 °C for 6h. the mi xture was cooled to 100 DC, diluted with 8 ml of 2-methoxyethanol ove r 15 min and stirred for I h at 100 °C. The mi xture was then cooled to room temperature, stirred for 30 min and filtered . The collected solid was washed with methanol and then with warm water C'iO-60DC) to give a dark red powder. The crude product was purified by dry column chromatograph y using sili ca gc l (230-400 mm mesh) and toluene: hexane (4: I ) to yield 1.64 g (82.6%) pure Dye L m.p.= 180-1 82DC. R,(4: I :: toluene: hexane)=0 .3 1.

2.2 Preparation of 1-amillo-4-hydroxy-2 -( .f -1-hul.vlphl'l1ox~· )

anthraquinone (Dye III )

4-t-Butylphenol (5.33g, 0.035 11101). KOH (O.52g. 0.009 11101) and l-amino-2-bromo-4-hydroxyalllhra­quinone (2.00g, 0.006 mol ) were combined, stirred for 15 min at room temperature and then at 155-160°C for 6h. The reacti on mi xture was coo led to 100DC, 8 ml of 2-methoxyethanol was added and thc mixture was stirred at this temperature for 30 min . Thereafter, the reaction mi xture was allowed to coo l to room temperatu \'e over a peri od of :2 h and stirred for 20 min . The crude produ ct was co llected by filtration, washed first with methanol and then with warm water, and dried in vacuo at 40-45DC. Purification of crude was achieved hy dry co lumn chromatography using silica gel (70-nOlllm mesh) and toluene: hexane (4 : I) to give 0.48g (22 .5 %) shiny dark red crystals of Dye Ill , m.p.=2()()-20 I DC. RI (4: I :: toluene: hexane)=0.36 .

2.3 Preparation of l-alllino-4-hydroxy-2- (2' -naphthoxy) anthraquinone (Dye IV)

2-Naphthol (5.33g, 0.037 mol), KOH (O.5 2g. O()09 mol) were mixed with vi go rous st irr ing. 1-<Ill1in o-~­

bromo-4-hydroxy-anthraquinonc (2 .00g. 0.006 111 <.1

was added and the resu ltant mi xture ,,',IS st irred kr

1

f

UKPONMWAN e/ al.: DISPERSE RED 60 ANALOGS 299

IS min. This mixture was then stirred under reflux at ISS-160 °e for 6h. The reaction mi xture was cooled to 100oe , whereupon 8ml of 2-methoxyethanol was added all at once, and stirred at thi s temperature for 30 min . Following cooling to 2S-28 °e over a 2h period, the mixture was stirred for 20 min. The crude product was collected by filtration, washed with methanol and warm water to give a dark purple so lid . Purificat ion of the impure product by dry column chromatography using sili ca gel (230-400mm mesh) and toluene: hexane (4 : I) affo rded pure Dye IV (0.394g, 18.7%) , m.p.=2 12°e, Rr (4:1 :: toluene: hexane)=0.28.

2.4 Preparation of l-amino-4-hydroxy-2-(4'-methylphen­oxy) anthraquinone (Dye V)

By the procedure described for the preparati on of dye I, p-cresol (S.33g, 0.049 mol), KOH (0.S2g, 0.009 mol) and l-amino-2-bromo-4-hydroxyanthraquinone (2.0g, 0 .006 mol) afforded 1.35g (70.9%) of pure Dye V, m.p.=1 82- 183°e , Rr(4: 1 :: toluene: hexane)=0.32.

2.5 Preparation of l-amino-4-hydroxy-2-(2'-chlorophenoxy) anthraquinone (Dye VI)

A mixture of 2-chlorophenol (S.33g, 0.042 mol) and KOH (0.S2g, 0.009 mol) was stirred vigorously for IS min and l-amino-2-bromo-4-hydroxyanthra­quinone (2.0g, 0.006 mol ) was added. The mixture was kept at ambient temperature for 10 min and then stirred at ISS-160oe for 6h. Iso lation of the product was accomplished as described for dye III. The product was recrystalli zed from 2-methoxyethanoll methanol to give a dark purple-red powder ( 1.97g). Purification as described for dye I yie lded pure Dye VI (0.676g, 33.4%), m.p.= 190oe , Rr (4: I :: toluene: hexane)=0.3S.

2.6 Preparation of l-amino-4-hydroxy-2-(4' -chloro-3-methyl-phenoxy)anthraq uinone (Dye VII)

Usi ng the procedure described fo r the synthes is of dye III, a mixture of 4-chl oro-m-creso l (S.33g, 0.037 mol), KOH (0.S2g, 0.009 mol) and l-amino-2-bromo-4-hydroxyanthraquinone (2.0g, 0.006 mol) afforded Dye VII ( 1.49g, 71.2%), m.p.=210-211 °e , Rr(4: 1 .. toluene: hexane)=O.4 I.

2.7 Preparation of I-amino-4-hyd roxy-2-(4'- bromophenoxy) anthraquinone (Dye VIII)

By the procedure described for the preparati on of dye Ill, 4-bromophenol (S.33g, 0.03 1 mol), KOH (0.S2g, 0.009 mol ) and l-amino-2-bromo-4-hydroxyanthraquinone (2.0g, 0.006 mol) afforded

0.43g ( 19.0%) pure Dye VIII, m.p.=209 .8°C, Rr(4: I :: toluene: hexane)=0.40.

2.8 Preparation of I-amino-4-hydroxy-2-(2' -methylphen­oxy)anthraquinone (Dye IX)

A mi xture of a-cresol (S.33g, 0.049 mol), KOH (0.S2g, 0.009 mol ) and l-amino-2-broIll0-4-hydroxyanthraquinone (2.0g, 0.006 mol) was heated at ISS-160 °e with stirring for 6h. The crude product was iso lated and purifi ed using the procedure described for Dye III to give a redd ish pink powder as pure Dye IX (0.44g, 23 .0%), m.p.=174°C, NrH: I toluene: hexane)=0.32.

3 Results and Discussion Replacement of the 2-bromo subst ituent in 1-

amino-2-bromo-4-hydrox yanthraq uin one (Fig. I) with different phenolic compou nds in the prese nce or potassium hydroxide gave l-amino-2-aryloxy--+­hydroxyanthraqu inones in low yie ld s. with the exception of dyes I, V and Vil. Although the reason for the low yie lds of dyes HI , IV, VI, VIII and IX is not entirel y understood, the steri c hindrance caused by the bulky naphtho group in the "2. 3-pos iti on" is believed to account for the low yie ld obtained for dye IV . The chemica l reacti vity of 2-methyl and 4-methylphenol s is ex pected to be quite simila r cl ue to the comparable electronic effec ts of a methyl group in ortho and para positions, but a low yield was obtained for dye IX in contrast to the re lati ve ly good yield ror dye V. It would appear th at a methyl group in the ortho position is large enough to exert a steri c effec t in the reaction between 2-metth ylphenol and I-ami no-2-bromo-4-hydrox yanthraqu i none.

In the synthesis of dye VII, the ring deacti vating effects of a chlorine atom in the para pos ition must have been offset by the + I effects or a methyl group in the meta position , thereby making 4-c hl oro-3-methyl phenol of similar chemi ca l reacti vity to phenolJ2

. Thus, the yield ohtained I' OJ dye VII , is good. Moving the chl oro group to the ortho pos iti on causes a signifi cant reducti on in yie ld (dye VI. ). Also. a large group in the para pos iti on has a negati ve impact on yield (dyes III and VIII).

OH

QrZ ~Br ~ ~ ~I 0 ;~1 /O'R\ x ~ KOH " '- -

o OH 15 5 - 160·C . o OH Z V

Fig. I-React ion sc heme ror the preparatioll or dyes I :tlld /If-IX (X . Y, Zas perTlh k I )

300 INDIA J. FIBRE TEXT. RES., DECEMBER 1999

The electronic spectral data fo r dyes I and III-IX are shown in Tab le I. All of the dyes showed a multiplet of absorption bands corresponding to bands in the region of 250-260,480 (v. weak), 518-519 and 553-554nm. The introduction of substituents into the phenoxy ring does not result in a signi ficant shift in the position of these bands. Th is is in agreement with the previou findings" As expected, the molar absorptivities of these dyes are relatively low compared to those of azo dyes l4

. The I-butyl substituted dye (III) gave the highest molar absorptivity value and possesses the strongest ring activation in the phenolic res idue. IR spectral data collected on dyes I and III-IX (Table I) show absorption frequencies for C=O, CoN, O-H and N-H that are in agreement with literature va lues.

The structures of the synthesized dyes were further estab lished with the aid of e lectron impact (EI) and chemical ion izati on (CI) mass spectrometry. Most of the spectra contai ned the molecular ion (M+) or pseudo molecular ion [M+Ht as the base peak (Table 2) . The exceptions are the spectrum of dye III which contained the M-CH, ion (mlz=372) as the base peak and that of dye VI which contained the M-CI ion (mlz=330) as the base peak. Table 2 shows that all the dyes proved to be quite stab le to 70ev energy of EI mass spectrometry. No dye affo rded a spectrum in which the molecul ar ion gave a relat ive intensity less than 59%.

The fastness tes ting data of the dyes are given in Tables I and 3. It may be concluded from Table I that all the dyes have good li ght fas tness. In add ition, dyes III , VI and VII gave a slightly improved light fastness rating in comparison to the parent dye (I). The results obtained from crock fastness tes ting (Table I) are acceptable, except in the case of dye IV which gave a relatively poor result. ]n add ition to being the only dye havi ng a naphthoxy moiety, dye IV was also the onl y dye that was di fficult to disperse well in water.

The wash fastness of the dyeings are given in Table 3. The ratings obtained for the change in co lor for all the dyes are very good. Staining/color transfer on the multifiber varied littl e with the type of fiber in the seven bands . Thus , the results from was h fastness testing reflect an excell ent 'a ll round ' performance for each dye .

Sublimation fastness results show an improvement over the parent dye on PET, in accordance with an increase in molecul ar weight. Dyes IV and VIII are clearly superior in thi s regard . The increas ing order of

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Table 2--Election impact and chemical ionization molecular ion information for dyes I and III-IX

Dye No. Phenoxy group Electron impact (EI) Chemical ionization (CI)

M+ ReI. Int. [M+Jt Rel.lnt M+ ReI. lnt. [M+Ht ReI. lnt

I H 331 100 332 22.2 331 28.4 332 100

III 4-t-Bu 387 60.6 388 16.6 387 33 .7 388 100

IV 3 ,4-(benzo) 38 1 100 382 21i.4 38 1 30.6 3112 100

V 4-Me 345 100 346 22.6 345 30.5 346 100 c

VI 2-CI 365 59.6 366 13.7 365 29.8 366 100 ;:>:: -0 0

VII 4-C1,3-Me 379 100 380 23.3 379 34.5 380 100 z 3:::

VIll 4-Br 409 99 4 10 24.4 409 33.7 410 94.0 :E » z

411 100 412 21.8 411 53.7 412 100 ~

~ IX 2-Me 345 100 346 22.7 345 31.4 346 100 S2

C/l -0

Table 3--Wash fastness and sublimation fastness data for dyes I and III-IX tTl ;>:l C/l tTl

Dye No. Wash fastness a (Color staining/Color transfer) Sublimation fastne~a (Exl2ressed as results for 30s/60s~ ;>:l tTl

Color Acetate Cotton Nylon PET PAN Wool Acetate Cotton Nylon PET PAN Wool Color 0 0-

change change 0

» 5 4/4 515 4/4 4-5/5 515 515 3/2-3 4/4 211-2 111 4-5/4-5 4/3-4 4-5/3-4 z

» r

III 5 4-5/4-5 515 4-5/4 515 515 515 4-5/4 4/3-4 3-4/3 3/2-3 4-5/4 4/3-4 5/4-5 0 Cl C/l

IV 5 515 5/5 4-5/4-5 515 515 515 4-5/4 4-5/4 4/3 3/2-3 4-5/4 5/4-5 5/5

V 5 4-5/5 5/5 4-5/4 5/5 5/5 5/5 3/2-3 4/3-4 2/1-2 III 4-5/4 4-5/4 5/4

VI 5 4-5/4 5/5 4/4 4-5/4-5 5/5 515 3-4/3 4/3-4 2-3/2 1/ 1 4/3-4 4/3 5/4-5

VII 5 4-5/4-5 5/5 4-5/4 5/5 515 515 4/3-4 4/3-4 2-3/2 III 4-5/4 4-5/4 5/4-5

VIII 5 4-5/4-5 5/5 4-5/4 5/5 5/5 5/5 4-5/4 4/3-4 3-4/3 2-3/2 4/3-4 4/4 5/5

IX 5 4-5/4-5 5/5 4-5/4 4-5/5 5/5 SIS 3-4/3 4/3-4 2-3/1 1-211 4/3 -4 4/3-4 5/4-5

' All samples were rated on a scale of 1-5. 'J~

c

302 INDIAN J. FIBRE TEXT. RES., DECEMBER 1999

Dose/plate 50-

~ LJ O.OOmg

00 r-~~r- ~

0.05mg

~~ O.tOmg ISO ~~ t-~ i>' 0.30mg

100· r-~

r- ~ t;- 0.50mg

l.00mg

50· 1300mg

f>-5.00mg

0 Dye I DyeVII Dye IX

Fig.2-TA 100 co lonies vs dose leve l

Table 4--Panition coefficients and tox icity designalions for dyes I and III-IX

Dye Partiti on coefficienl T A IOO tox icity

0.660 Yes

III 0.056 No

IV 0.122 No

V 0.393 No

VI 0. 11 7 No

VII 0.460 Yes

VIII 0.2 15 No

IX 0.496 Yes

molecul ar weight of the compounds synthes ized is: VIII> III> IV> VII> VI> IX, V> I, and the order

of sublimation fas tness for these dyes is IV> VIII> III> VII> IX, VI> V> I. However, the data indicated that significant sta ining of some fibers (espec ially spun po lyester and spun polyamide) had occurred in the multi-biber strip. This may be attributed to the lack of strong ly po lar substituents in the phenoxy moiety. Dyes devoid of strongly polar groups sublime more readily and are absorbed by adjacent fibers having high affinity for the dyes I'.

When dyes I and III-IX were eva luated for mutagenicity in the standard Salmone lla/mammalian microsomal assay, common I y known as the Ames tes t, all of the dyes proved to be non-mutagenic in both strains e mployed (T A98 and TA I 00) . Interestingly, some of the dyes ex hibited toxicity towards bacteria strain TAl 00 at dose leve ls of 1-3mg/pl ate. The data in Fig.2 show the changes in bacteria colonies as a function of dye dose for the three dyes observed to be tox ic towards TA 100 in the absence of S9 metabo lic activati on. It is c lear from Fig.2 that little change in the number of bac te ria colonies occurs over a dose range of O-Img/plate. Dye IX started to kill the bacteria at a dose le vel above 1.0mg/plate and the dyes I and VII began to kill the bacteria at a dose leve l above ::I mg/plate. It

was also found that these three dyes had the hi ghes t butanol water partition coeffi c ie nts (Tab le 4).

4 Conclusion Despite the repo rted dec lining importance or

anthraquinone dyes, Dispe rse Red 60 and re lated structures remain one of the most w ide ly used group of dyes in the world l 6

. The se ven analogs o f Disperse Red 60 prepared in this study are bri ght red dyes which ex hibit excell ent dye ing prope rties on polyester. From fastness evaluations, these anal ogs generally possess be tte r properti es than th e parent compound . Specifically , the most o f the analogs ha ve been rated higher than the parent dye in the li ght fastness, wash fastness and sublimati on tes ts. From a commercial perspecti ve, the bes t of these dyes will not be useful unless a process can be deve loped to s ignificantly enhance their reac ti on yie ll. whi ch is a perennial problem in anthraquinone dye chemi stry. Similarly, it is unlike ly that the observed ability o f some of these dyes to kill Sa lmone lla (TA 100) is potent enough to make the m use ful an tihac te ri a l agents.

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dyes, Ph 0 lhesis. Nonh Carolina S I ~llC lill l \'cr, i l y. I<' ~ \ lci ~ h.

1988.

15 Schroeder H E & Boyd S N. 1"1'.1'1 NI'.I .I. n(-I ) ( I lJ5 7) . 275.

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