Synthesis of 3,5-diphenyl-1H-pyrazoles

Article abstract of DOI:10.1081/SCC-200054225

An efficient and convenient synthesis of 3,5-diphenyl-1N-pyrazoles from chalcones by the action of hydrazine hydrate on chalcone-epoxide followed by simultaneous dehydration is reported. Copyright Taylor & Francis, Inc.

Full text of DOI:10.1081/SCC-200054225

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Synthesis of 3,5‐Diphenyl‐1H‐Pyrazoles
B. A. Bhat a , S. C. Puri a , M. A. Qurishi b , K. L. Dhar a & G. N. Qazi a
a Division of Natural Products Chemistry, Regional Research Laboratory
(CSIR), Jammu, India
b Department of Chemistry, University of Kashmir, Srinagar, India
Version of record first published: 16 Aug 2006
To cite this article: B. A. Bhat, S. C. Puri, M. A. Qurishi, K. L. Dhar & G. N. Qazi (2005): Synthesis of
3,5‐Diphenyl‐1H‐Pyrazoles, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 35:8, 1135-1142
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Synthetic Communicationsw, 35: 1135–1142, 2005
Copyright # Taylor & Francis, Inc.
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1081/SCC-200054225
Synthesis of 3,5-Diphenyl-1H-Pyrazoles
B. A. Bhat and S. C. Puri
Division of Natural Products Chemistry, Regional Research
Laboratory (CSIR), Jammu, India
M. A. Qurishi
Department of Chemistry, University of Kashmir, Srinagar, India
K. L. Dhar and G. N. Qazi
Division of Natural Products Chemistry, Regional Research
Laboratory (CSIR), Jammu, India
Abstract: An efficient and convenient synthesis of 3,5-diphenyl-1H-pyrazoles from
chalcones by the action of hydrazine hydrate on chalcone-epoxide followed by simul-
taneous dehydration is reported.
Keywords: Chalcone-epoxide, chalcones, dehydration, hydrazine, pyrazoles
Pyrazoles, an important class of compounds in medicinal chemistry,
constitute the basic framework of drugs such as celecoxib and are well recog-
nized for their multifaceted pharmacological and medicinal applications.[1]
3,5-Diphenyl-1H-pyrazoles, have displayed a wide range of biological activi-
ties.[2] Synthesis of 3,5-diphenyl-1H-pyrazole was first reported by the action
of hydrazine on dibenzoyl- methane.[3] Later, Parham and Dooley[4] adopted a
different route involving the reaction of 2,2-dichloro-1,3-diphenyl-1-cyclo-
propyl acetate with large excess of hydrazine. Although yields were good
for 3,5-diphenyl-1H-pyrazoles, it was not found convenient to use this
route, particularly for substituted diphenyl pyrazoles. There is a very brief
Received in India on November 17, 2004
Address correspondence to K. L. Dhar, Division of Natural Products Chemistry,
Regional Research Laboratory (CSIR), Jammu 180001, India. E-mail: dharkl@
yahoo.com

1136
B. A. Bhat et al.
mention about formation of 3,5-diphenyl-4-hydroxy-4,5-dihydro-1H-
pyrazoles by the action of hydrazine on the corresponding epoxides.[5] An
interesting approach to the synthesis of pyrazoles has been made by the
Japanese workers using hydrazyl radicals initiated by 2,2-diphenyl-1-
picrylhydrazyl (DPPH) directly on a,b-unsaturated ketones without any
leaving group.[6] While writing this manuscript, a new publication appeared
for the synthesis of 1,3,5-substituted pyrazoles from acetylenic ketones and
hydrazines,[7] which in fact appears to be an extension of earlier work.[8]
As a part of our drug discovery program, we needed a convenient route to
prepare 3,5-diphenyl-1H-pyrazoles in large quantities. We initiated efforts to
prepare such compounds starting from chalcones.[9] The chalcone (1a) was
[10]
subjected to epoxidation by using hydrogen peroxide in alkaline media
at 08C and yields were 85–94%. The epoxychalcone (2a) was subjected to
the Wharton reaction[11] using hydrazine hydrate (1.5–2 mol) as nucleophilic
reagent without the addition of acetic acid. As expected, it did not form allylic
alcohol, but a heterocyclic compound, which was identified as 3,5-diphenyl-4-
hydroxy-4,5-dihydro-1H-pyrazole (3a). In case of the Wharton reaction, a
large excess of hydrazine is used (not less than 4 mol) along with catalytic
amounts of acetic acid. Whenever acetic acid was added, the same product
was obtained in poor yield along with other side products. 3a thus formed
was subjected to acid-catalyzed dehydration to give the desired 3,5-
diphenyl-1H-pyrazole, 4a (Scheme 1). However, when 2a was allowed to
reflux with hydrazine hydrate for 6 h, and removal of alcohol was followed
with the addition of CH3COOH along with catalytic amount of conc.
H2SO4, the corresponding 4a was obtained in a one-pot reaction in
excellent yield.
The scope of the presented invention was explored by using a variety of
substituted chalcones (Table 1).
Scheme 1.

Synthesis of 3,5-Diphenyl-1H-Pyrazoles
1137
Table 1. Preparation of substituted 3,5-diphenyl-1H-pyrazoles
Yield (%)
from epoxide
Entry
Compound
Mpa (8C)
4a
4b
R1, R2, R3, R4, R5, R6 ¼ H
200 (201)b
165 (168–169)c
79
83
R1, R2, R3, R4, R6 ¼ H; R ¼ OCH3
5
4c
R1, R2, R3, R6 ¼ H; R4, R5 ¼
192
81
4d
4e
R1, R3, R4, R6 ¼ H; R2, R5 ¼ OCH
153
83
80
76
R1, R3 ¼ H; R2, R4, R5, R6 ¼ OCH3
4f
R1, R2, R3 ¼ OCH3; R6 ¼ H; R4,
R5 ¼
104
73
4g
4h
4i
R1, R2, R3, R5 ¼ OCH3; R4, R6 ¼ H
R1, R2, R3, R4, R5, R6 ¼ OCH3
66
204
90
75
71
76
R1, R2, R3 ¼ OCH3; R4, R6 ¼ H; R5 ¼ F
aMelting points are uncorrected.
bFrom Ref.[12]
cFrom Ref.[8d]
.
.
We have isolated the intermediates, 4-hydroxy-4,5-dihydro-1H-
pyrazoles, for biological screening and in certain cases they showed higher
and specific cytotoxic activity, when compared to desired pyrazoles.
EXPERIMENTAL
NMR spectra were recorded on a Brucker DPX200 spectrometer. Chemical
shifts are given in d units relative to the tetramethylsilane (TMS) signal as
an internal reference. Coupling constants (J) are reported in Hz. IR were
recorded on a Brucker Vector 22 spectrometer as KBr pellets with absorption
given in cm21. MS spectra were obtained by using electrospray ionization
(ESI). All the compounds showed appropriate Mþ in MS. Elemental
analysis data were obtained for all compounds.

1138
B. A. Bhat et al.
General Procedure: Preparation of 4a
To a solution of 1a (2.08 g, 10 mmol) and 30% aq. H2O2 (2 mL) in ethanol
(30 mL) at 0–58C was added 5% NaOH (2 mL). After 15 h, the solid was
filtered and washed with water to give 2a (1.85 g, 83%). Compound 2a (1 g,
4.46 mmol) and hydrazine hydrate (0.35 g, 7 mmol) in ethanol (50 mL) were
heated under reflux for 6 h. Solvent was evaporated and the residue crystal-
lized from methanol to give 3a (0.94 g, 88%). Compound 3a (0.10 g,
0.42 mmol), acetic acid (4 mL), and conc. H2SO4 (1 drop) were stirred at
room temperature for 6 h and then neutralized by adding NH4OH solution.
The reaction mixture was poured over crushed ice, filtered, washed with
water, and crystallized from methanol to give 4a (84 mg, 90%).
One-Pot Reaction Procedure
2a (2.0 g, 8.92 mmol) and hydrazine hydrate (0.52 mg, 10.5 mmol) in ethanol
(80 mL) were heated under reflux for 6 h and concentrated. The residue
was taken in acetic acid (60 mL) and conc. H2SO4 (0.5 mL), heated in a
water bath for 30 min, and worked up as discussed previously to give 4a
(1.64 g, 82%).
Spectroscopic Data
3,5-Diphenyl-4-hydroxy-4,5-dihydro-1 H-pyrazole (3a). White solid; mp
2058C; IR (KBr): 3390, 3288, 1595, 1450, 1345, 1036, 757, 694 cm21
;
1H NMR (CDCl3): d 4.78 (d, 1 H, J ¼ 5.1 Hz), 5.17 (d, 1 H, J ¼ 5.1 Hz),
7.36 (m, 6 H), 7.89 (d, 4 H, J ¼ 8.6 Hz). 13C NMR (DMSO): d 72.0, 81.8,
125.5, 126.4, 127.1, 127.6, 128.2, 128.4, 132.5, 141.4, 148.8; Anal. calcd.
for C15H14N2O: C, 75.61; H, 5.92; N, 11.76. Found: C, 75.48; H, 5.97;
N, 11.61.
3,5-Diphenyl-1H-pyrazole (4a). White solid; IR (KBr): 1605, 1461,
1
1316, 1181, 1075, 1000, 753, 687 cm21; H NMR (MeOD): d 6.99 (s, 1 H),
7.41 (m, 6 H), 7.8 (d, 4 H, J ¼ 8.5 HZ); 13C NMR (CDCl3): d 100.1, 125.7,
128.2, 128.8, 131.3, 148.8; Anal. calcd. for C15H12N2: C, 81.79; H, 5.49; N,
12.72. Found: C, 81.57; H, 5.72; N, 12.48.
3-Phenyl-5-(4-methoxyphenyl)-4-hydroxy-4, 5-dihydro-1H-pyrazole
(3b). White solid; mp 1778C; IR (KBr): 3424, 3246, 1606, 1510, 1459,
1
1251, 1173, 1036, 886, 828, 765 cm21; H NMR (MeOD): d 3.77 (s, 3 H),
4.61 (d, 1 H, J ¼ 6.3 Hz), 5.10 (d, 1 H, J ¼ 6.3 Hz), 6.90 (d, 2 H,
J ¼ 8.7 Hz), 7.33 (m, 5 H), 7.80 (d, 2 H). 13C NMR (DMSO): d 55.1, 71.6,
81.9, 113.9, 125.6, 127.6, 127.7, 128.4, 132.8, 133.4, 149.1, 158.6; Anal.
calcd. for C16H16N2O2: C, 71.63; H, 6.01; N, 10.44. Found: C, 71.69; H,
6.34; N, 10.19.

Synthesis of 3,5-Diphenyl-1H-Pyrazoles
1139
3-Phenyl-5-(4-methoxyphenyl)-1H-pyrazole (4b). White solid; IR
1
(KBr): 1617, 1509, 1460, 1297, 1254, 1187, 1036, 832, 765, 685 cm21; H
NMR (MeOD): d 3.84 (s, 3 H), 6.90 (s, 1 H), 7.00 (d, 2 H, J ¼ 8.7 Hz),
7.40 (m, 3 H), 7.73 (d, 2 H, J ¼ 8.7 Hz), 7.80 (d, 2 H); 13C NMR (CDCl3):
d 55.5, 99.5, 114.1, 123.6, 125.6, 126.9, 127.9, 128.7, 131.5, 148.1, 148.9,
159.8; Anal. calcd. for C16H14N2O: C, 76.78; H, 5.68; N, 11.19. Found: C,
76.65; H, 5.84; N, 11.27.
3-Phenyl-5-(3,4-methylenedioxyphenyl)-4-hydroxy-4,5-dihydro-1H-
pyrazole (3c). White solid; mp 1718C; IR (KBr): 3319, 3192, 1590, 1486,
1
1443, 1253, 1040, 926, 817, 687 cm21; H NMR (MeOD): d 4.65 (d, 1 H,
J ¼ 5.1 Hz), 5.13 (d, 1 H, J ¼ 5.1 Hz), 5.97 (s, 2 H), 6.82 (m, 3 H), 7.41
(m, 3 H), 7.84 (d, 2 H, J ¼ 7.2 Hz); 13C NMR (DMSO): d 74.2, 84.4, 103.0,
108.2, 109.9, 121.5, 128.0, 130.2, 130.4, 133.9, 136.6, 149.2, 150.1, 153.7;
Anal. calcd. for C16H14N2O3: C, 68.08; H, 5.00; N, 9.92. Found: C, 68.14;
H, 5.23; N, 9.78.
3-Phenyl-5-(3,4-methylenedioxyphenyl)-1H-pyrazole (4c). White solid;
IR (KBr): 1605, 1466, 1247, 1045, 797, 759 cm21; 1H NMR (MeOD): d 6.01
(s, 2 H), 6.75 (s, 1 H), 6.88 (d, 1 H, J ¼ 8.4 Hz), 7.24 (s, 1 H), 7.27(d, 1 H,
J ¼ 8.4 Hz), 7.42 (m, 3 H), 7.71 (d, 2 H); 13C NMR (CDCl3): d 98.9, 101.2,
106.0, 108.5, 116.8, 119.2, 125.4, 126.2, 127.8, 128.8, 131.8, 147.3, 148.0;
Anal. calcd. for C16H12N2O2: C, 72.72; H, 4.58; N, 10.60. Found: C, 72.36;
H, 4.83; N, 10.92.
3-(4-Methoxyphenyl)-5-(4-methoxyphenyl)-4-hydroxy-4,5-dihydro-
1H-pyrazole (3d). White solid; mp 1528C; IR (KBr): 3318, 3210, 1608,
1583, 1511, 1245, 1178, 1119, 1023, 828, 807, 774 cm21 1H NMR
;
(CDCl3): d 3.78 (s, 3 H), 3.82 (s, 3 H), 4.65 (d, 1 H, J ¼ 4.1 Hz), 5.09
(d, 1 H, J ¼ 4.2 Hz), 6.88 (m, 4 H), 7.20 (d, 2 H, J ¼ 8.6 Hz), 7.75(d, 2 H,
J ¼ 8.6 Hz); 13C (DMSO): d 55.5, 55.6, 71.9, 82.7, 114.3, 114.3, 125.8,
127.4, 127.6, 128.1, 133.9, 149.9, 159.0, 159.6; Anal. calcd. for
C17H18N2O3: C, 68.44; H, 6.08; N, 9.39. Found: C, 68.21; H, 6.32; N, 9.32.
3-(4-Methoxyphenyl)-5-(4-methoxyphenyl)-1H-pyrazole (4d). White
1
solid; IR (KBr): 1611, 1504, 1446, 1251, 1176, 1025, 837, 794 cm21; H
NMR (CDCl3): d 3.84 (s, 6 H), 6.69 (s, 1 H), 6.92 (d, 4 H, J ¼ 8.3 Hz), 7.64
(d, 4 H, J ¼ 8.3 Hz); 13C NMR (CDCl3): d 55.5, 99.1,114.4, 124.4,
127.3,148.7, 159.8; Anal. calcd. for C17H16N2O2: C, 72.84; H, 5.75; N,
9.99. Found: C, 72.91; H, 5.98; N, 10.37.
3-(4-Methoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-4hydroxy-4,5-dihydro-
1H-pyrazole (3e). White solid; mp 1868C; IR (KBr): 3331, 3160, 1607, 1589,
1
1518, 1458, 1233, 1127, 993, 832, 665 cm21; H NMR (CDCl3): d 3.84
(s, 12 H), 4.66 (d, 1 H, J ¼ 5.2 Hz), 5.14 (d, 1 H, J ¼ 5.2 Hz), 6.57 (s, 2 H),
6.92 (d, 2 H, J ¼ 8.8 Hz), 7.77 (d, 2 H, J ¼ 8.7 Hz); 13C NMR (DMSO):
d 55.2, 55.9, 60.0, 72.2, 82.4, 103.6, 113.8, 125.3, 127.2, 136.6, 137.3,
149.6, 152.9, 159.1. Anal. calcd. for C19H22N2O5: C, 63.68; H, 6.19;
N, 7.82. Found. C, 63.62; H, 6.43; N, 7.58.

1140
B. A. Bhat et al.
3-(4-Methoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-1H-pyrazole (4e).
White solid; IR (KBr): 1588, 1505, 1466, 1249, 1126, 1004, 837 cm21
;
1H NMR (CDCl3): d 3.81 & 3.89 (2s, 4 ꢀ OCH3), 6.66 (s, 1 H), 6.87
(d, 2 H, J ¼ 8.3 Hz), 6.94 (s, 2 H), 7.59 (d, 2 H, J ¼ 8.3 Hz). 13C NMR
(CDCl3): d 55.2, 55.9, 61.0, 99.0, 102.8, 114.2, 123.3, 126.9, 127.7, 137.9,
147.4, 149.7, 153.4, 159.6; Anal. calcd. for C19H20N2O4: C, 67.04; H, 5.92;
N, 8.23. Found: C, 67.14; H, 6.24; N, 8.31.
3-(3,4,5-Trimethoxyphenyl)-5-(3,4-methylenedioxyphenyl)-4-hydroxy-
4,5-dihydro-1H-pyrazole (3f). White solid; mp 1268C; IR (KBr): 3340,
3167, 1592, 1577, 1503, 1412, 1359, 1237, 1126, 1035, 999, 933, 832, 804,
1
731 cm21; H NMR (CDCl3): d 3.86 (s, 9 H), 4.6 (d, 1 H, J ¼ 4.2 Hz), 5.10
(d, 1 H, J ¼ 4.2 Hz), 5.95 (s, 2 H), 6.77 (s, 3 H), 7.10 (s, 2 H); 13C NMR
(DMSO): d 56.3, 60.6, 72.3, 82.3, 101.4, 103.5, 107.1, 108.6, 120.1, 128.7,
135.9, 138.0, 146.9, 147.9, 149.6, 153.3; Anal. calcd. for C19H20N2O6: C,
61.29; H, 5.41; N, 7.52. Found: C, 61.18; H, 5.58; N, 7.43.
3-(3,4,5-Trimethoxyphenyl)-5-(3,4-methylenedioxyphenyl)-1H-pyrazole
(4f). White solid; IR (KBr): 1592, 1506, 1476, 1242, 1131, 1037, 823,
773 cm21
;
1H NMR (CDCl3): d 3.88 and 3.90 (2s, 3 ꢀ OCH3), 6.01
(s, 2 H), 6.68 (s, 1 H), 6.85 (d, 1 H, J ¼ 8.3 Hz), 6.95 (s, 2 H), 7.17 (s, 1 H),
7.18 (d, 1 H, J ¼ 8.3 Hz); 13C NMR (CDCl3): d 55.7, 60.6, 98.8, 101.3,
102.4, 105.9, 108.9, 119.2, 124.4, 127.2, 137.5, 147.3, 147.9, 149.3, 153.3;
Anal. calcd. for C19H18N2O5: C, 64.40; H, 5.12; N, 7.90. Found: C, 64.08;
H, 5.34; N, 8.19.
3-(3,4,5-Trimethoxyphenyl)-5-(4-methoxyphenyl)-4-hydroxy-4,5-dihydro-
1H-pyrazole (3g). White solid; mp 1058C. IR (KBr): 34811, 3339, 1613,
1595, 1564, 1512, 1468, 1415, 1244, 1132, 825, 711 cm21 1H NMR
;
(CDCl3): d 3.80 (s, 3 H), 3.87 (s, 9 H), 4.70 (d, 1 H, J ¼ 4.2 Hz), 5.10
(d, 1 H, J ¼ 4.2 Hz), 6.87 (d, 2 H, J ¼ 8.6 Hz), 7.1 (s, 2 H), 7.2 (d, 2 H,
J ¼ 8.6 Hz); 13C NMR (CDCl3): d 55.3, 56.0, 60.8, 72.1, 82.5, 103.6, 114.3,
127.0, 127.1, 132.1, 138.7, 152.0, 153.2, 159.2; Anal. calcd. for
C19H22N2O5: C, 63.68; H, 6.19; N, 7.82. Found: C, 63.57; H, 6.28; N, 7.53.
3-(3,4,5-Trimethoxyphenyl)-5-(4-methoxyphenyl)-1H-pyrazole (4g).
White solid; IR (KBr): 1613, 1587, 1506, 1467, 1249, 1177, 1126, 1002,
1
835, 731 cm21; H NMR (CDCl3): d 3.84 and 3.89 (2s, 4 ꢀ OCH3), 6.70
(s, 1 H), 6.89 (d, 2 H, J ¼ 8.7 Hz), 6.92 (s, 2 H), 7.61 (d, 2 H, J ¼ 8.7 Hz);
13C NMR (CDCl3): d 55.1, 55.7, 60.8, 99.5, 102.5, 114.0, 122.9, 126.7,
127.6, 137.9, 146.5, 150.0, 153.3, 159.5; Anal. calcd. for C19H20N2O4: C,
67.04; H, 5.92; N, 8.23. Found: C, 67.38; H, 6.42; N, 8.31.
3-(3,4,5-Trimethoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-4-hydroxy-
4,5-dihydro-1H-pyrazole (3h). White solid; mp 1538C; IR (KBr): 3310,
1594, 1561, 1509, 1465, 1418, 1241, 1126, 999, 829, 818, 721, 676 cm21
;
1H NMR (CDCl3): d 3.82 and 3.86 (2s, 6 ꢀ OCH3), 4.66 (d, 1 H,
J ¼ 5.5 Hz), 5.12 (d, 1 H, J ¼ 5.5 Hz), 6.54 (s, 2 H), 7.01 (s, 2 H); 13C NMR
(CDCl3): d 56.3, 60.5, 60.6, 72.7, 75.3, 103.6, 103.9, 128.7, 137.1, 137.7,

Synthesis of 3,5-Diphenyl-1H-Pyrazoles
1141
138.0, 159.7, 153.3, 153.4; Anal. calcd. for C21H26N2O7: C, 60.27; H, 6.26; N,
6.69. Found: C, 60.08; H, 6.41; N, 6.64.
3-(3,4,5-Trimethoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-1H-pyrazole
(4h). White solid; IR (KBr): 1591, 1503, 1472, 1430, 1387, 1241, 1128, 1004,
1
864, 836, 770 cm21; H NMR (CDCl3): d 3.87 (s, 18 H), 6.69 (s, 1 H), 6.93
(s, 4 H); 13C NMR (CDCl3): d 56.3, 61.1, 99.9, 103.2, 127.1, 138.4, 149.0,
153.8; Anal. calcd. for C21H24N2O6: C, 62.99; H, 6.04; N, 6.96. Found: C,
62.59; H, 6.46; N, 7.05.
3-(3,4,5-Trimethoxyphenyl)-5-(4-flourophenyl)-4-hydroxy-4,5-dihydro-
1H-pyrazole (3i). White solid; mp 1078C; IR (KBr): 3491, 3352, 1594, 1562,
1509, 1416, 1245, 1220, 1130, 1033, 834, 721, 708 cm21; 1H NMR (CDCl3): d
3.87 and 3.89 (2s, 3 ꢀ OCH3), 4.73 (d, 1 H, J ¼ 4.6 Hz), 5.09 (d, 1 H,
J ¼ 4.6 Hz), 7.01 (m, 4 H), 7.29 (m, 2 H); 13C NMR (CDCl3): d 55.8, 56.0,
59.8, 60.1, 71.3, 81.9, 102.7, 103.1, 115.0, 115.4, 128.2, 128.3, 128.3,
128.4, 137.6, 137.7 (2-C), 149.1, 152.8, 153.3; Anal. calcd. for
C18H19N2O4F: C, 62.42; H, 5.54; N, 8.09. Found: C, 62.11; H, 5.73; N, 8.31.
3-(3,4,5-Trimethoxyphenyl)-5-(4-flourophenyl)-1H-pyrazole (4i). White
solid; IR (KBr): 1592, 1507, 1468, 1239, 1130, 1004, 963, 842, 770 cm21
;
1H NMR (CDCl3): d 3.81 and 3.87 (2s, 3 ꢀ OCH3), 6.71 (s, 1 H), 6.91
(s, 2 H), 7.04 (m, 2 H), 7.66 (m, 2 H); 13C NMR (CDCl3): d 50.6, 56.1,
61.1, 99.8, 103.0, 115.9, 126.8, 127.5, 138.3, 148.0, 149.0, 153.7, 161.8,
163.8; Anal. calcd. for C18H17N2O3F: C, 65.84; H, 5.23; N, 8.53. Found:
C, 66.04; H, 5.83; N, 8.34.
ACKNOWLEDGMENT
We offer thanks to the instrumentation division of Regional Research Labora-
tory Jammu for spectral data and elemental analysis and to the Council of
Scientific & Industrial Research, New Delhi, India, for the fellowship to
B. A. Bhat.
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