Anchored synthesis for some novel mono and disarylazo 1,2,4- benzothiadiazine-based dyestuffs as alternatives for benzidine-based dyes

Article abstract of DOI:10.1080/10426500600605863

A one mono and two disarylazo series of 1,2,4-benzothiadiazine-based dyestuffs has been synthesized with a view that these products, with their new all-round tinctorial properties, might find an application as new categories of direct dyes that satisfacto

Full text of DOI:10.1080/10426500600605863

This article was downloaded by: [University of Saskatchewan Library]
On: 21 October 2013, At: 13:26
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954
Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,
UK
Phosphorus, Sulfur, and Silicon
and the Related Elements
Publication details, including instructions for
authors and subscription information:
http://www.tandfonline.com/loi/gpss20
Anchored Synthesis for Some
Novel Mono and Disarylazo
1,2,4-Benzothiadiazine-Based
Dyestuffs as Alternatives for
Benzidine-Based Dyes
M. A. Hanna a , A. A. Al-Sarawy b , I. G. Rashed b
H. F. Elgamal b & F. K. M. Wali a
,
a Damietta Faculty of Science , Mansoura
University , Mansoura, Egypt
b Mansoura Faculty of Engineering , Mansoura
University , Mansoura, Egypt
Published online: 21 Sep 2006.
To cite this article: M. A. Hanna , A. A. Al-Sarawy , I. G. Rashed , H. F. Elgamal
& F. K. M. Wali (2006) Anchored Synthesis for Some Novel Mono and Disarylazo
1,2,4-Benzothiadiazine-Based Dyestuffs as Alternatives for Benzidine-Based Dyes,
Phosphorus, Sulfur, and Silicon and the Related Elements, 181:9, 2089-2108, DOI:
10.1080/10426500600605863
To link to this article: http://dx.doi.org/10.1080/10426500600605863
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the
information (the “Content”) contained in the publications on our platform.
However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness,
or suitability for any purpose of the Content. Any opinions and views
expressed in this publication are the opinions and views of the authors, and

are not the views of or endorsed by Taylor & Francis. The accuracy of the
Content should not be relied upon and should be independently verified with
primary sources of information. Taylor and Francis shall not be liable for any
losses, actions, claims, proceedings, demands, costs, expenses, damages,
and other liabilities whatsoever or howsoever caused arising directly or
indirectly in connection with, in relation to or arising out of the use of the
Content.
This article may be used for research, teaching, and private study purposes.
Any substantial or systematic reproduction, redistribution, reselling, loan,
sub-licensing, systematic supply, or distribution in any form to anyone is
expressly forbidden. Terms & Conditions of access and use can be found at
http://www.tandfonline.com/page/terms-and-conditions

Phosphorus, Sulfur, and Silicon, 181:2089–2108, 2006
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500600605863
Anchored Synthesis for Some Novel Mono
and Disarylazo 1,2,4-Benzothiadiazine-Based Dyestuffs
as Alternatives for Benzidine-Based Dyes
M. A. Hanna
Damietta Faculty of Science, Mansoura University, Mansoura, Egypt
A. A. Al-Sarawy
I. G. Rashed
H. F. Elgamal
Mansoura Faculty of Engineering, Mansoura University,
Mansoura, Egypt
F. K. M. Wali
Damietta Faculty of Science, Mansoura University, Mansoura, Egypt
A one mono and two disarylazo series of 1,2,4-benzothiadiazine-based dyestuffs
has been synthesized with a view that these products, with their new all-round
tinctorial properties, might find an application as new categories of direct dyes that
satisfactorily replace prohibited benzidine-based dyes.
The assigned structures for the hitherto prepared dyes were confirmed on the
basis of elemental analysis as well as spectral data and, whenever possible, by
alternative synthetic routes. Moreover, the predominant tautomeric structures for
these highly colored products were tested and discussed on the basis of their spectral
behavior.
Keywords 1,2,4-Benzothiadiazine-based dyes; benzidine-based dyes alternatives; mono
and disarylhydrazono dyes; predominant tautomeric structures
INTRODUCTION
The use of benzidine-based dyestuffs in the field of textile dyeing has
been largely discontinued in view of the toxicological hazards asso-
ciated with them. The problem of replacing benzidine dyes has not
been fully resolved, although a number of approaches have been made
based on two concepts. The first consists of the use of other classes
of dye for dyeing purposes, and the second approach involves the use
Received September 14, 2005; accepted December 20, 2005.
Address correspondence to M. A. Hanna, Damietta Faculty of Science, POB 48
Mansoura University, Mansoura 35516, Egypt. E-mail: mahanna69@hotmail.com
2089

2090
M. A. Hanna et al.
of other diamines, i.e., diaminostilbenedisulphonic acid1 and diamin-
odiphenylaminesulphonic acid2 in the dye synthesis. The first solution
does not usually ensure obtaining all the hues possible from disarylazo
benzidine-based dyestuffs; it is more expensive and often requires an
alternative dyeing technology. Although the second concept is of great
interest since it could yield new, harmless dyes having the same color
and application properties as the benzidine dyes, it still faces a problem
associated with the pollution of the environment. These diamine-based
dyestuffs are designed to be chemically and photolytically stable; they
exhibit a high resistance to microbial degradation and are highly per-
sistent in a natural environment. The release of these compounds into
the environment is undesirable, not only for aesthetic reasons, but also
because many of these disarylazo dyestuffs and their breakdown prod-
ucts are toxic and/or exhibit mutagenic effects.3,4
In continuation of our interest5−8 in synthesizing new symmetric
and/or asymmetric disaryl azo dyestuffs, we report herein on the syn-
thesis of a novel group of mono and disarylazo dyestuffs that are based
on the 1,2,4-benzothiadiazine 1,1-dioxide moiety. The produced dyes,
being accommodating solublizing functions, are likely to undergo oxi-
dation and/or hydrolysis to soluble metabolites, thus ensuring a lack
of carcinogenicity9 and in turn satisfying the basic requirements for a
satisfactory replacement of prohibited benzidine-based dyes.
DISCUSSION
The synthesis of the previously mentioned dyestuffs involved different
synthetic pathways. The multistep synthesis of the first series of these
dyestuffs, as illustrated in Scheme 1, required the cyclization of the pre-
viously unreported 2-(2ꢀ-Phenoxyacetylamino)-benzenesulphonic acid I
in the presence of acetic anhydride to the corresponding 3-phenoxy-
methyl-2,1,4-benzoxathiazine 1,1-dioxide II.
SCHEME 1

Alternatives for Benzidine-Based Dyes
2091
While compound I revealed intense absorption bands at 3430, 1350,
1140, and 1685 cm−1 corresponding to the sulphonic acid and pri-
mary amidic functions, compound II revealed its sulphonate ester
and azomethine functions at 1360, 1155, and 1630 cm−1, respectively.
The 1H NMR spectrum of this product exhibited a singlet signal at
4.05 ppm assignable to the methylene protons, respectively. Moreover,
its 13C NMR spectral pattern showed a characteristic sp3 triplet signal
at δ = 79 ppm (assignable to the methylene-carbon atom of the phenoxy
methyl moiety). Beside the molecular ion peak, the mass spectral pat-
tern of the same product revealed a group of characteristic signals that
might be obtained as a result of α-cleavage fragmentation patterns.
This is in accordance with the assigned structure of this product (cf.
Experimental section).
The condensation of the later product with hydrazine hydrate
in a 1:1 molar ratio afforded the 2-amino-3-phenoxymethyl-1,2,4-
benzothiadiazine 1,1-dioxide III in a good yield. The assigned structure
for this product was confirmed on the basis of its IR spectrum, which
revealed the lack of a sulphonate ester function and the presence of
stretching vibrations near 3340, 3330, 1350, and 1145 cm−1 that might
be attributed to the N-amino and cyclic sulphonamido functions, re-
1
spectively. Beside the aromatic proton signals, the H-NMR spectrum
of this compound showed a broad exchangeable hump centered at 4.90
ppm and a singlet signal at 4.05 ppm corresponding to the amino and
methylene protons, respectively.
Subjecting the latter product to coupling reactions in basic a medium
with different arene diazonium salt solutions gave rise to a novel series
of the benzothiadiazine-based arylazo dyestuffs IVa–e.
The structure of these products was established on the basis of el-
emental as well as spectral data (c.f. Experimental section). Table I
depicts the characteristic physical properties of these benzothiadiazine-
based arylazo dyes.
The latter coupling products might be represented by three possible
tautomeric forms as illustrated in Scheme 2.
These structures are referred to as the azo-CH form (IV-A), the hy-
drazo form (IV-B), and the azo-NH form (IV-C). The available data indi-
cated that the predominant tautomeric structure of (IV)a−e derivatives
is the chelated hydrazono form (IV-B).
On the basis of the information obtained from the study of IR spec-
trum of 2-amino-3-phenoxymethyl-1, 2,4-benzothiadiazine 1,1-dioxide
III, it is possible to assign absorption bands of the diazonium coupling
products IVa–g with some confidence. Each of the compounds exam-
ined exhibits a strong band in the region of 1608–1605 cm−1, which is
assigned to the skeletal C C in plane vibrations of phenyl rings.10 The
broad and strong absorptions near 1350 and 1140 cm−1 were ascribed

2092
M. A. Hanna et al.
SCHEME 2 Tautotomeric structures of compounds IVa–g.

2093

2094
M. A. Hanna et al.
to the asymmetric and symmetric stretching vibrations of the cyclic
sulphonamide function.
The parent amino thiadiazine derivative III was found to exhibit a
moderate absorption near 1625 cm−1 corresponding to the endocyclic
C N stretching vibration. As to the coupling products IVa–g, each dye
revealed two absorption bands of moderate intensity near 1625 and
1615 cm−1 that were assigned to the two C N stretching vibrations.
Besides the asymmetric and symmetric stretching vibrations of the
amino function, which were displayed in the range 3360–3340 cm−1 in
IR spectra of these products, each spectrum revealed the presence of a
very weak and broad band in the region between 3320 and 3310 cm−1
.
This might be ascribed to the NH stretching vibration of the hydrazone
moieties. The large shift and broadening of this band, as compared with
those reported by Ramirz and Kerby11 for simple hydrazones, can re-
sult only from strong intramolecular hydrogen bonding as in structure
(B). The fact that compounds IVa–g show evidence for intramolecular
hydrogen bonding at all is in favor of the hydrazone structure.
The lack of any stretching vibrations assignable to the N N azo
function in IR spectra of these products adds a further confirmation
for the exclusion of A and C structures from the actual presentation of
these coupling products.
1H-NMR spectra of IVg, as a typical example for this series of com-
pounds, indicated its presence in the aryl hydrazono form rather than
in the azo form. Thus, if the azo form (IV-A), which contains a CH
group, was to represent the actual structure of these coupling products,
the spectrum should exhibit a peak position at about 4.00 ppm that is
similar to that of the methylene proton of the corresponding parent ben-
zothiadiazine III. Such a peak is actually absent. Moreover, besides the
triplet and quartet proton signals for the methylene and methyl protons
of the ester function at δ = 3.92 and 1.65 ppm respectively, the spectrum
revealed a multiplet centered at 7.95–6.82 ppm and two other small,
broad, and exchangeable humps near δ = 4.96 and 12.95 ppm. These
data are consistent with the amino hydrazone structure (IV-B). The
multiplet absorption in the region 7.95–6.82 ppm is undoubtedly due to
the aromatic protons. The peak at δ = 12.95 ppm indicates the presence
of a highly deshielded proton, which could be assigned to an intramolec-
ularly hydrogen-bonded acidic proton. Since the shifts of the hydrogen-
bonded NH proton usually occur near 13.0 ppm,12 the peak can be rea-
sonably assigned to the NH proton of the hydrazone moiety. On the
basis of these visualizations, the broad signal at 4.96 ppm undoubt-
edly represents the two-proton signal of the amino function. The lack of
any sp3 doublet signal in the off-resonance 13C NMR spectral pattern of
this product adds further support for the exclusion of structure (IV-A)

Alternatives for Benzidine-Based Dyes
2095
from the actual presentation of these coupling products. The presence
of a characteristic signal for the p-carbethoxy anilinium cation in mass
spectrum of this product (cf. Experimental section) highly confirms the
exclusion of the azo-NH form (IV-C) and substantiates the presence of
these products in the aryl hydrazono form (IV-B). These visualizations
are in accordance with the assigned structure for these products.
The presence of a latent amino function in the structure of these
arylhydrazono dyes prompted us to utilize these products as a precursor
for synthesizing a new group of disarylazo dyestuffs, as illustrated in
Scheme 5. Thus, the treatment of a base-catalyzed ethanolic solution
of the hitherto synthesized dye IVg, as an example for the series of the
parent compounds IV, with benzaldehyde furnished the corresponding
benzylidine derivative V in a moderate yield (Scheme 3).
SCHEME 3

2096
M. A. Hanna et al.
1H NMR spectra of the latter product revealed the absence of the
N-amino proton signal and the presence of a new singlet signal at
8.40 ppm assignable to the azo-methine proton.
The produced benzylidine derivative V reacted smoothly with mer-
capto acetic acid in the presence of a few drops of piperidine to af-
ford the corresponding thiazolidinone derivative VI. The IR spectrum
of the latter product exhibited characteristic absorptions that are in
accordance with the assigned structure. Beside the ester and aromatic
proton signals, the 1H NMR spectrum of this product revealed two sin-
glet signals at 5.65 and 3.10 ppm and a broad exchangeable hump at
12.90 ppm corresponding to the methine, methylene (of thiazolone moi-
ety), and hydrazono NH protons, respectively. The relatively low chem-
ical shift value for the C-5 mrthylene protons might be attributed to
the anisotropic effect of the juxtaposed carbonyl function.
A coupling of an ethanolic buffered solution of the hitherto prepared
thiazolone derivatives VI with different sulphoaryl diazonium salt so-
lutions yielded the target disaryl azo dyestuffs (VII)a−g in an average
good yield (Scheme 3).
In a similar behavior to compounds (IV)a−g, the produced coupling
products (VII)a−g might be represented by three tautomeric forms as
illustrated in Scheme 4.
IR spectra of these products revealed characteristic absorption bands
at 3420 cm−1 (OH), 3320 cm−1 (NH), 1730 cm−1 (ester function),
1675 cm−1 (tertiary amidic carbonyl), and 1630 and 1625 cm−1(exo and
1
endo C N functions). The H-NMR spectrum of compound VIId, as a
representative example for these products, revealed a singlet signal at
5.66 ppm (C-2 proton of the imino-thiazolone moiety) and two broad
exchangeable humps near 13.55 and 12.90 ppm assignable to the NH
protons of the two hydrazone moieties.
The lack of any characteristic absorption corresponding to the
N N azo linkage, as required by structures (B) & (C), in IR spec-
tra of these products highly substantiates the exclusion of the latter
two forms, and in turn, confirms the presence of these products in the
disaryl hydrazono form (A). Further proof for the exclusion of structure
(B) was drawn from 1H-NMR of these coupling products that revealed
the absence of any singlet signal corresponding to the C-5 proton, as
required by this azo-CH tautomeric structure (B).
Judging from these spectral data, it is not unreasonable to assign the
disaryl hydrazono form (A) for the actual structure of these coupling
products. Physical properties of these coupling products are given in
Table II.
An investigation was also extended in this study to explore the
synthetic potentiality of the latent active functions in the parent

Alternatives for Benzidine-Based Dyes
2097
SCHEME 4 Tautotomeric structures of compounds IVa–g.
compounds (IV)a−g. Thus, the treatment of an ethanolic solution of the
hitherto synthesized dye IVc with phenyl isothiocyanate afforded the
corresponding thiourea derivative VIII in a good yield. Aside from
the correct elemental analysis, spectral patterns of the latter product
came in accordance with the assigned structure (cf. Experimental
section).
Cyclization of the latter product with chloroacetic acid furnished the
corresponding imino thiazolidinone derivative IX.
The formation of the imino-thiazolone derivative IX from the corre-
sponding thiourea derivative VIII was established by elemental and
spectral data where IR spectral data of the latter product IX revealed
the presence of a new strong absorption band at 1680 cm−1 assignable
to the tertiary amidic carbonyl function. Further confirmation for the
structure of this product was obtained from its straightforward 1H-
NMR spectrum, which displayed a characteristic singlet signal at
3.16 ppm for the methylene protons of the thiazolone moiety.

2098

Alternatives for Benzidine-Based Dyes
2099
The latter product was used, through coupling with a group of sulfur-
containing arene diazonium salts, as a precursor for a second series of
the disaryl azo dyestuffs (X). These coupling products were prepared by
following the general procedure that was described for the preparation
of sulphoaryl hydrazone derivatives (IV)a−g
.
The crude products that were recrystallized from acetic acid yielded
highly colored crystals of the pure dyestuffs (VII)a−e in an average yield
of 68–73%. The prepared dyestuffs together with their physical data are
given in Table II.
Thus, the treatment of the parent imino-thiazolone derivative IX
with sulphoaryl diazonium salt in alkaline medium afforded the corre-
sponding 5-sulphoarylazo derivatives (X)a−e (Scheme 5).
SCHEME 5
As in the case of aryl hydrazono derivatives (VII)a−g, the produced
coupling products (X)a−g might be represented by three tautomeric
forms, as illustrated in Scheme 6. These tautomeric structures are

2100
M. A. Hanna et al.
SCHEME 6 Tautotomeric structures of compounds Xa–g.
referred to as the keto-hydrazo form (A), the azo-keto form (B), and
the hydroxyl-azo form (C).
In the present study, the predominant tautomeric structure of these
compounds has been found to be the hydrazo form (A). The spectral
evidence, upon which such a conclusion is based, is discussed in view
of their spectral behavior.
In IR spectrum of each of the prepared dyestuffs (X)a−e, a sharp and
well-defined peak was found near 1670 5 cm−1 assignable to the tert.
amidic-carbonyl stretching vibrations. If the hydroxy-azo form was to
represent the actual structure of these coupling products, one would ex-
pect the lack of such a strong absorption band. The presence of strong
absorption in the range 1675–1665 cm1, in their IR spectra, thus ex-
cludes the possibility of the hydroxy-azo structure of type (C).
Moreover, in the spectrum of each of the hitherto examined imino-
thiazolone dyestuffs, two other absorption bands were noted near 1630
and 1620 cm−1. As these bands were observed in spectra of both of
the N-phenyl Nꢀ-benzothiadiazinyl thiourea derivative (VIII) and the
corresponding cyclized product (IX), it was plausible not to assign any
of these two bands to an N N azo stretching vibration but to the exo
and endo azo-methine stretching vibrations, which are common in all
the three series of compounds.

Alternatives for Benzidine-Based Dyes
2101
The great intensity of such two peaks might result from the azo-
methine being superimposed in a peak due to vibration. It is reason-
able to conclude, therefore, that the hitherto prepared 4-sulphoaryl azo
imino-thiazolidinone dyestuffs (Xa–e) predominantly exist in the keto-
hydrazo form (A).
In view of the strong evidence against the presence of an absorption
for the azo function (IR spectra) and C-5 proton signal of the imino-
thiazolone moiety (1H-NMR spectra), it would not be unreasonable
to confirm the exclusion of structures (B) and (C) from presenting
the actual structure of such coupling products. This elimination is
compatible with the presence of absorption for the cyclic tert. amidic
carbonyl function. In consequence, the tautomeric structure (A) of
the hitherto prepared 5-sulphoaryl azo derivatives (X)a−g, under in-
vestigation, is the only one that accommodates these IR spectral
observations.
1H-NMR spectra of compound Xa, as a representative example for
these dyestuffs (in CDCl3), showed the usual phenyl and methyl pat-
terns at 8.05–6.85 and 2.41 ppm; three other broad peaks at 10.35,
12.90, and 13.50 ppm assignable to the acidic protons of the sulphonic
acid; and the two intramolecularly hydrogen bonded NH protons, re-
spectively. Judging from these results, it could be concluded that the di-
azonium coupling products (Xa–e) exist predominantly in keto-hydrazo
form (A.) Table III depicts the physical data for these disaryl hydrazono
dyestuffs.
Unlike other dyes that accommodate additional o-, sulphonic or car-
boxylic groups and suffer lower substantivity behavior, as a result of
deformation of the dye molecules due to the vicinity of the previous
group to an azo function,9 the hitherto synthesized highly colored prod-
ucts, being substituted with additional p-sulphonic acid groups, exhib-
ited high substantivity, preliminary good light, and washing fastness
and thus might fully satisfy all requirements for a satisfactory replace-
ment of harmful benzidine-based dyes. A detailed study for the dyeing
performance, all-round fastness properties, and evaluation of applying
Fenton oxidation process (as an advanced oxidation technology) for de-
composition and removal of the residual of these dyes from dyeing baths
are, for the time being, under investigation and will be the subject of
the forthcoming communication.
EXPERIMENTAL
All melting points are uncorrected and are measured on a Griffin &
George MBF 010T apparatus. Recorded yields correspond to the pure

2102

Alternatives for Benzidine-Based Dyes
2103
products. IR (KBr) spectra were recorded on a Perkin Elmer model 1750
FTIR. 1H NMR and 13C-NMR spectra were measured on a Varian 270
MHz spectrometer and a Bruker AM360, respectively, using CDCl3 as a
solvent and tetramethylsilane (TMS) as an internal standard (chemical
shifts are given as δ in ppm). Mass spectra (70 eV) were recorded on
a Varian VG 7035 mass spectrometer. Microanalysis was carried out
in the Microanalytical Data Units at Cairo University and National
Research Center (NRC), Cairo, Egypt. Nomenclature of the hitherto
prepared compounds are in line with the IUPAC rules for nomenclature
of organic compounds.
Synthesis of 2-(2ꢀ-Phenoxyacetylamino)-
benzenesulphonic Acid (I)
A mixture of phenoxychloroacetic acid (0.01 mol, 1.7 g) and phospho-
rous pentachloride (0.01 mol, 2.1 g) was triturated with orthanilic acid
(0.01 mol, 3.1 g), and the whole mixture was allowed to be set aside
at r.t. for 3 h; water was added to the reaction mixture, and con-
centrated sodium chloride solution (20 mL) was added to that mix-
ture. The solution was allowed to cool spontaneously for 1 h in air
and then was cooled in an ice bath until complete precipitation of the
product. The produced solid was collected by filtration, washed with
a little saturated sodium chloride solution, and dried at 80◦C. Acidi-
fication of an aqueous solution of the produced salt afforded the free
acid, which was filtered off, washed well with water, and recrystal-
lized from ethanol to give the pure product of m.p. 218◦C in a 65%
yield.
For C14H13NO5S (307.32) calcd.: C, 54.71; H, 4.26; N, 4.56; S,
10.43%. Found: C, 54.22; H, 4.43; N, 4.85; S,10.74%. IR (ν/cm−1):
3430 (OH), 3325 (NH), 1685 (CO), 1350 and 1140 (asym. and
sym. stretching vibration of sulphonic acid moiety), and 1065 (ether
linkage).
Synthesis of 3-Phenoxymethyl-2,1,4-benzoxathiazine
1,1-Dioxide (II)
A mixture of I (0.01 mol, 3.1 g) and acetic anhydride (0.05 mol, 5.1 mL)
was refluxed under anhydrous conditions for 8 h. The excess acetic
anhydride was distilled off under reduced pressure, and the whole
mixture was cooled to r.t. Trituration of the residual material with
water afforded a solid product that was filtered off and recrystal-
lized from ethanol to give the pure product of m. p. 231◦C in a 59%
yield.

2104
M. A. Hanna et al.
For C14H11NO4S (289.31) calcd.: C, 58.12; H, 3.83; N, 4.84; S, 11.08%;
Found: C, 58.39; H, 3.96; N, 4.50; S, 11.32%. IR (ν/cm−1) 1360 and
1155 (asym. and sym. stretching vibration of sulphonate ester func-
1
tion), 1630 (C N), and 1065 (ether linkage). H-NMR spectrum (δ in
ppm): 8.10–6.80 (m, 9H, Ar-H) and 4.05 (s, 2H, CH2-O); 13C-NMR spec-
trum (δ in ppm): 163.1 (C-3 of benzothiadiazine moiety), 159.2 (ipso-
carbon of phenoxy function), 136.4 (C-8a of benzothiadiazine moiety),
121.9 (C-4a of benzothiadiazine moiety), and 79 (methylene-carbon of
phenoxymethyl function), m/e (%): 289 (M+, 78), 212 (33), 93 (80), and
77 (85).
Synthesis of 2-Amino-3-phenoxymethyl-1,2,4-
benzothiadiazine 1,1-Dioxide (III)
A mixture of II (0.01 mol, 2.9 g), hydrazine hydrate (0.01 mol, 0.5 mL),
and piperidine (0.3 mL) in absolute ethanol (10 mL) was refluxed for
4 h and left to cool to r.t. The resulting solid that formed after cooling
was filtered off and recrystallized from ethanol to give the pure product
of m. p. 189◦C in a 43% yield.
For C14H13N3O3S (303.34) calcd.: C, 55.43; H, 4.32; N, 13.85; S,
10.57%. Found: C,55.60; H, 4.21; N, 14.07; S, 10.18%. IR (ν/cm−1): 3340,
3330 (NH2), 1625 (C N), 1350, 1145 (cyclic sulphonamide function),
and 1065 (ether linkage). 1H-NMR spectrum (δ in ppm): 8.10–6.80 (m,
9H, Ar-H), 4.90 (br., 2H, Amino function), and 4.05 (s, 2H, oxymethyl
moiety).
Synthesis of 2-Amino-3-[(α-arylhydrazono)phenoxymethyl]-
1,2,4-benzothiadiazine 1,1-Dioxide (IV)a-g
General Procedure
The aromatic amine (0.005 mol) was dissolved in 3 mL of 6 M hy-
drochloric acid, and the whole solution was cooled below 5◦C. To the
resulting cold solution, 10 mL of 0.6 M sodium nitrite solution was
added while keeping the temperature of the reaction mixture below
5◦C. After the addition was complete, the solution was stirred for an
additional 10 min. In a separate 250-mL beaker, the solution of the
coupling component was prepared by stirring compound III (0.005 mol,
1.5 g) with 50 mL of 0.3 N aqueous sodium hydroxide solution, to which
2 g of sodium acetate trihydrate was added. A few drops of ethanol were
added to ensure complete dissolution of the entire coupling component.
The resulting solution was cooled in an ice-salt bath and mechanically
stirred. To the cold solution of (III), the diazonium salt solution was

Alternatives for Benzidine-Based Dyes
2105
added dropwise while stirring and keeping the temperature below 5◦C
during the addition, which took about 15 min. The reaction mixture
was left overnight in a refrigerator, and the precipitated colored product
was filtered off, washed three times with water, and recrystallized from
glacial acetic acid. Physical data of the synthesized arylazo dyestuffs
are listed in Table I.
IR (ν/cm−1) for (IVg): 3355 and 3340 (NH2), 3320 (NH of hydrazone
moiety), 1735 (ester function), 1605 (C C), 1625 and 1615 (C N), 1350
and 1140 (cyclic sulphonamide function), and 1065 (ether linkage). 1H-
NMR spectrum (δ in ppm): 12.95 (br., 1H, hydrazone moiety), 7.95–6.82
(m, 13H, Ar-H), 4.96 (br, 2H, amino protons), 3.92 (q, 2H, O-CH2-CH3),
and 1.65 (t, 3H, O-CH2-CH3); 13C-NMR spectrum (δ in ppm): 168.3
(carbonyl-carbon of ester function), 161.8 (C-3 of benzothiadiazine moi-
ety), 154.2 (ipso carbon of phenoxy function), 152.8 (oxymethyl-carbon),
137.3 (C-8a of benzothiadiazine moiety), 124.9 (C-4a of benzothiadiazine
moiety), 61.4 (methylene-carbon in ester function), and 16.7 (methyl-
carbon in ester function). M/e (%): 479 (M+, 86), 402 (46), 164 (93), 93
(79), and 77 (42).
Synthesis of 2-Benzylidinamino-3-[α-
(p-carbethoxyphenylhydrazono)-phenoxymethyl]-1,2,4-
benzothiadiazine 1,1-Dioxide (V)
A mixture of IVg (0.01 mol, 4.8 g), benzaldehyde (0.01 mol, 1 mL), and
piperidine (0.3 mL) in absolute ethanol (10 mL) was refluxed under
anhydrous conditions for 4 h and left to cool to r.t. The resulting solid
that formed after cooling was filtered off and recrystallized from ethanol
to give the pure product of m. p. 173◦C in a 70% yield.
For C30H25N5O5S (567.62) calcd.: C, 63.48; H, 4.44; N, 12.34; S,
5.65%. Found: C, 63.79; H, 4.84; N, 12.78; S, 5.98%. IR (ν/cm−1): 3310
(NH), 1735 (ester function), 1630–1625 (C N functions), 1350 and 1160
(cyclic sulphonamide function), and 1060 (ether linkage). 1H-NMR spec-
trum (δ in ppm): 12.90 (br., 1H, hydrazone moiety), 8.40 CH N ),
7.92–6.80 (18H, Ar-H) and 3.92 (q, 2H, O-CH2-CH3), and 1.65 (t, 3H,
O-CH2-CH3).
Synthesis of 2-(4ꢀ-Oxo-2ꢀ-phenyl-1ꢀ, 3ꢀ-thiazol-3ꢀ-yl)-3-[α-
(p-carbethoxy-phenylhydrazono)-phenoxymethyl]-1,2,4-
benzothiadiazine 1,1-Dioxide (VI)
A mixture of V (0.01 mol, 5.7 g), mercaptoacetic acid (0.01 mol, 0.9 mL),
and piperidine (0.3 mL) in absolute ethanol (10 mL) was refluxed under

2106
M. A. Hanna et al.
anhydrous conditions for 4 h and left to cool to r.t. The resulting solid
that formed after cooling was filtered off and recrystallized from ethanol
to give the pure product of m. p. 166◦C in a 61% yield.
For C32H27N5O6S2 (641.72) calcd.: C, 59.89; H, 4.24; N, 10.91; S,
9.99%. Found: C, 59.80; H, 4.03; N, 10.70; S, 9.89%. IR (ν/cm−1
)
for (IV): 3315 (NH), 1735 (ester function), 1630 and 1625 (C N
functions), 1350 and 1160 (cyclic sulphonamide function), and 1060
(ether linkage). 1H-NMR spectrum (δ in ppm): 12.90 (br., 1H,
hydrazone moiety), 7.95–6.75 (m, 18H, Ar-H), 5.65 (s, 1H, C-2
proton of thiazolone moiety), 3.92 (q, 2H, O-CH2-CH3), 1.70 (t,
3H, O-CH2-CH3))and 3.10 (s, 2H, methylene protons of thiazolone
moiety).
Synthesis of 2-(4ꢀ-Oxo-2ꢀ-phenyl-5ꢀ-sulphoarylhydrazono-
1ꢀ,3ꢀ-thiazol-3ꢀ-yl)-3-[α-(p-carbethoxyphenylhydrazono)-
phenoxymethyl]-1,2,4-benzo-thiadiazine 1,1-Dioxide (VII)a–e
General Procedure
In a 250-mL conical flask, 0.005 mol of the sulphoaryl amine was
mixed with anhydrous sodium carbonate (2.6 g) and water (100 mL),
and the whole mixture was warmed until a clear solution was obtained
then cooled to about 15◦C, a solution of sodium nitrite (0.052 mol, 3.6 g)
in water (10 mL) was added. The resulting solution was slowly added
with stirring to a 600-mL beaker containing hydrochloric acid (12 mL,
30%) and crushed ice (100 g). The solution was tested for the presence of
slight excess nitrous acid and stirred for 15 min, where the fine crystals
of a diazo component were soon separated. The suspension was kept in
an ice bath for a further 10 min and poured with stirring to a solution of
VI (0.005 mol, 3.2 g) in a cold 10% sodium hydroxide solution (50 mL),
and the whole mixture was cooled to 0–3◦C. Coupling readily took place,
and the dyestuff separated as a paste. The whole mixture was stirred
well for 10 min and warmed until the paste dissolved completely; con-
centrated sodium chloride solution (20 mL) was added to the mixture.
The solution was allowed to cool spontaneously for 1 h in air and then
cooled in an ice bath until complete precipitation of the product. The
produced salt was collected by filtration, washed with a little saturated
sodium chloride solution, and dried at 80◦C. Acidification of aqueous so-
lution of the produced salt, with diluted acetic acid, afforded the crude
product, which was recrystallized from acetic acid to give highly colored
crystals of the pure derivatives (VII)a−e in an average yield of 68–73%.
The prepared dyestuffs together with their physical data are depicted
in Table II.

Alternatives for Benzidine-Based Dyes
2107
IR (ν/cm−1) for VIId: 3420 (OH), 3320(NH), 1730 (ester function),
1675(tert. amidic CO), 1630–1625 (C N functions), 1370, 1360, 1160
and 1140 (sulphonic acid and cyclic sulphonamide moieties), and 1065
(ether linkage). 1H-NMR spectrum (δ in ppm): 13.55 and 12.90 (br., 2H,
hydrazone moieties), 10.45 (br., 1H, OH), 8.00–6.80 (m, 24H, Ar-H), 5.66
(s, 1H, C-2 proton of thiazolone moiety), 3.96 (q, 2H, O-CH2-CH3), and
1.70 (t, 3H, O-CH2-CH3).
Synthesis of N-Phenyl-[1ꢀ, 1ꢀ-dioxo-3ꢀ-[α-
(p-tolylhydrazono)phenoxy-methyl]-1ꢀ,2ꢀ,4ꢀ-benzothiadiazin-
2ꢀ-yl] Thiourea (VIII)
A mixture of IVc (0.01 mol, 4.2 g), phenylisothiocyanate (0.01 mol,
1.4 mL), and piperidine (0.3 mL) in absolute ethanol (10 mL) was re-
fluxed under anhydrous conditions for 4 h and left to cool to r.t. The
resulting solid that formed after cooling was filtered off and recrystal-
lized from ethanol to give the pure product of m. p. 196◦C in a 48%
yield.
For C28H24N6O3S2 (556.66) calcd.: C, 60.41; H, 4.35; N, 15.10; S,
11.52%. Found: C, 60.43; H, 4.70; N, 14.95; S, 11.38%. IR (ν/cm−1) for
(VIII): 3315–3305 (NH), 1630–1620 (C N functions), 1360 and 1160
(cyclic sulphonamide function), and 1060 (ether linkage). M/e (%): 556
(M+, 63), 151 (66), 106 (89), 93 (59), and 77 (94).
Synthesis of 2-(4ꢀ-Oxo-3ꢀ-phenyl-1ꢀ,3ꢀ -thiazol-2ꢀ-
ylimino)-3-[α-(p-tolyl-hydrazono)-phenoxymethyl]-
1,2,4-benzothiadiazine 1,1-Dioxide (IX)
A mixture of VIII (0.01 mol), 5.6 g chloroacetic acid (0.01 mol, 0.95 g),
and piperidine (0.3 mL) in absolute ethanol (10 mL) was refluxed
under anhydrous conditions for 4 h and left to cool to r.t. The re-
sulting solid that formed after cooling was filtered off and recrystal-
lized from ethanol to give the pure product of m. p. 213◦C in a 53%
yield.
For C30H24N6O4S2 (596.68) calcd.: C, 60.39; H, 4.05; N, 14.08; S,
10.75. Found: C, 60.13; H, 4.12; N, 13.89; S, 10.41%. IR (ν/cm−1) for (IX):
3315 (NH), 1680 (amidic CO), 1630 and 1615 (C N functions), 1360 and
1165 (cyclic sulphonamide function), and 1060 (ether linkage). 1H-NMR
spectrum (δ in ppm): 1295 (br., 1H, NH), 8.05–6.70 (m, 18H, Ar-H), 3.16
(s, 2H, methylene protons of thiazolone moiety), and 2.38 (s, 3H, methyl
protons).

2108
M. A. Hanna et al.
Synthesis of 2-(4ꢀ-Oxo-3ꢀ-phenyl-5ꢀ-arylhydrazono-1ꢀ,3ꢀ-
thiazol-2ꢀ-yl-imino)-3-[α-(p-tolyl-hydrazono)-phenoxymethyl]-
1,2,4-benzothia-diazine 1,1-Dioxide Derivatives (X)a–e
These coupling products were prepared by following the general proce-
dure that was described for preparation of sulphoaryl hydrazone deriva-
tives (VII)a−e
.
The crude products were recrystallized from acetic acid to give highly
colored crystals of the pure dyestuffs (X)a−e in an average yield of 61–
79%. The prepared dyestuffs together with their physical data are given
in Table III.
IR (ν/cm−1) for (Xa): 3425(OH), 3315(NH), 1670 (amidic CO), 1630
and 1620 (C N functions), 1360, 1345, 1165 and 1150 (sulphonic acid
and cyclic sulphonamide functions), and 1065 (ether linkage). 1H-NMR
spectrum (δ in ppm): 13.50 and 12.90 (br., 2H, NH of hydrazone moiety),
10.35 (br., 1H, OH), 8.05–6.85 (m, 22H, Ar-H), and 2.41 (s, 3H, methyl
protons).
REFERENCES
[1] K. Venkataraman, In The Chemistry of Synthetic Dyes, Vol. 1. p. 508–520 (Academic
Press, New York, 1952).
[2] M. A. Saeed, F. M. Badruddin, M. Younas, and F. Shafi, J. Chem. Soc. Pak., 10, 345
(1988).
[3] I. Ashby, D. Paton, P. A. Lefevre, J. A. Styles, and F. L. Rose, Carcinogenesis, 3, 1377
(1982).
[4] P. Gregory, Dyes and Pigments., 7, 45 (1986).
[5] M. A. Hanna and M. M. Girges, J. Chem. Tech. Biotechnol., 62, 392 (1995).
[6] M. A. Hanna, J. Pigments and Resin Tech., 20, 4 (1991).
[7] M. M. Girges, M. A. Hanna, and S. N. Ayyad, J. Pigments and Resin Tech., 24, 9
(1995).
[8] M. A. Hanna, A. El-Sarawy, I. G. Rashed, and F. K. Wali, Phosphorus, Sulfur, and
Silicon, 179, 1209 (2004).
[9] J. Szadowski and Z. Niewiadomski, Dyes and Pigments, 19, 41 (1992) and references
therein.
[10] L. G. Bellamy, Infrared Spectra of Complex Molecules (Methuen, London, 1954).
[11] F. Ramirz and A. F. Kerby, J. Amer. Chem. Soc., 76, 1037 (1954).
[12] F. A. Snavely and C. H. Yoder, J. Org. Chem., 33, 513 (1968).