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Organic compounds of niobium
JOURXAL
OF THE
ORGANIC I’.
LESS-COMMON
COMPOUNI)S
REACTION
XETALS
OF NIOBIUM
OF NIOBIUM
PENTAETHOXIDE
WITH
GLYCOLS
Reactions of niobium pentaethoxide with diols(ethane, 1,2- and x,3-propane, 2,3- and r,4-butane and I&pentane diols, hexylene giycol and pinacol) have been carried out in different stoichiometric ratios and the following three types of new derivatives (EtO)~~b(glycol), (EtO)Nb(glycol~~ and Nb(gl~~ol)~ have been isolated. Molecular weights of the few soluble glycollates shows that they are dimeric.
INTRODUCTION FAIRBROTHER and co-worker+ have reported a number of polynuclear complexes of niobium and tantalum with catechol and other r,z-diols. Recently, alcoholi~ter~l~ange technique has been used for the preparation of orthoesters of a number of metals, including cyclic orthoesters of aluminiunl~, barons, titanium4, zirconium”, tin”, vanadium7, antimony8 and tellurium~. Preparation of similar derivatives of niobium has now been achieved by the reaction between niobium pentaethoxide and various glycols. BRADLEY and co-workers10 were the first to synthesise the normal alkoxides of niobium by passing a current of dry ammonia through a mixture of niobium pentachloride and the appropriate alcohol in benzene solution or by an alrohol-interchange technique. The reaction between niobium pentaethoxide and glycols in equimolar ratio was carried out in benzene. Ethanol produced during the reaction was removed azeotropically, the progress of tbe reaction being ascertained by the amount of ethanol in the azeotrope. On removal of the solvent, the triethoxy niobium monoglycollate derivatives were obtained:
OH /
+
R
Nb(OEt)s
+ R
Nb(OEt)s
+ z EtOH
io”
\ OH
miscible
These mixed alkoxide glycollates are light yellow viscous liquids or semisolids, with benzene, the only insoluble derivative being that of penta-methylene
R. C.
420
MEHROTRA,
P. N. KAPOOR
glycol. These derivatives can be purified by distillation under reduced pressure, with the exception of those of ethylene and penta-methylene glycol, which undergo decomposition as follows.
.‘O\R
5(EtO)aNb
3
I<>]
-
'0'
Nb-0-R-0-Nbrd 0
+ 3 Nb(OEt)s
Lo
-Jz
12
The reaction of pinacol in I:I molar ratio at room temperature yielded the triethoxy niobium mono pinacolate derivative, The reactions of niobium pentaethoxide with the above glycots was also carried out in a I :2 molar ratio when, in all cases, monoethoxy niobium diglycollate derivatives were obtained : OH 2R
/
+
\
Nb(OEt)s
+ R
OH
/“\Nb/o\ ‘0’1
R + 4 EtOH
‘0’ (OEt)
These products were either white viscous liquids or spongy solids and showed an interesting variation in their solubiliti~s in benzene. Only the hexylene glycol derivative was found to distil under reduced pressure; all the other derivatives decompose when heated under reduced pressure. The reactions of niobium pentaethoxide with these glycols were also studied in a molar ratio of 1:3, in all these reactions triglycollate derivatives being obtained. These triglycollate drivatives decomposed when heated under reduced pressure, with the exception of butane-z,g-diol and hexylene glycol derivatives, which on heating lost a molecule of glycol interamolecularly, giving derivatives corresponding in composition to di-niobium pentaglycollates. A similar derivative of hexylene glycol was prepared by the reaction of niobium pentaethoxide and hexylene glycol in the molar ratio of 2:s. OH 3R
/ \
+
Nb(OEt)s
+
R + 5 EtOH
OH
-0
2 Nb-0-R-0-Nb
2
-
ILo’\/‘R__I2 I
The molecular weights of a few typical soluble glycollates have been determined in boiling benzene and the compounds are found to be dimeric, which may be due to J. Less-Co?wm98 Metals, 8 (1965) 419-427
REACTION OF NIOBIUM PENTAETHOXIDE
WITH GLYCOLS
the tendency of niobium to attain a coordination and molecular weights are given in Table I.
TABLE
of six. The boiling
points
I
SUMMARY
OF
BOILING
POINTS
AND
MOLECULAR
(EtO)aNb(propylene glycol) Nb(propylene glycol)3 (EtO)aNb(trimethyleneglycol)
WEIGHTS
‘7’ -‘74/0.5 162~168lo.r Kefr. index 1.531 168/1.0 Sublimes 178/r.o 181/0.3 2o3/o.7 14r/o.4 Kefr. index 1.521
(Et0)3Nb(butane-z,3-diol) (EtO)Nb(butane-2,3-diol)z Nbz(butane-z,3-diol)s (EtO)sNb(hexylene glycol) (EtO)Nb(hexylene glycol)8 Nba(hexylene glycol) 5 (EtO)~Nb(pinacol) (EtO)Kb(pinacol)?
The dimeric structures
(0w
of these compounds
\
o(o$t) PW I triethoxy -
7’3 010
316 302
042
314
733 051
Or6
721 821 720
344 370 767 344
777
370
are given below:
(0Et) PW
I
0
‘db’
/I
\
niobium
/
‘12
I ‘\o/
I (OEt)
monoglycollate
Nb
li ‘lo/ II monoethoxy
III
member
421
diniobium
\ -2 niobium
diglycollate
pentaglycollate
The solubility of these derivatives does not appear to follow any regular pattern. The insoluble nature of the di and triglycollate derivatives may be ascribed either to chelation or to the formation of highly polymeric units. J. Less-&vnmon Metals. 8 (1965) 419-427
R. C. MEHROTRA,
422
P. N. KAPOOR
An exothermic reaction was observed on passing anhydrous ammonia in to a benzene solution of Nb(butane-2,x-diol)3 a white precipitate being formed, which was filtered and dried. The resulting white, light powder corresponded by analysis to NH4 Nb(butane-z,3-die 31;I3 : CH3
-
CH3 H
dH-0 I \
J
Nb
\O-
dH-0 1
&3
CH3-
_-
I
0-CH
/
CH3
0-CH
Hd-0
I
excess
ammonia
-> NH
/
AH
HCi-0’
dH3
_
‘N ‘O-CH
dH3
This compound was found to be insoluble in common organic solvents. ammonia it readily hydrolysed, with the formation of a white gelatinous of hydrated niobium pentaoxide.
II
dH3_ _3_
In aqueous precipitate
EXPERIMENTAL
Apparatus
and chemicals
All-glass apparatus fitted with interchangeable joints was used, special precautions being taken to exclude moisture. All fractionations were carried out in a column packed with Rasching rings and fitted to a total-condensation variable-takeoff stillhead. Molecular weights were determined ebullioscopically in boiling benzene. Benzene was stored over sodium wire for two days, refluxed (Na), and distilled. Finally, it was dehydrated azeotropically with ethanol. Niobium pentaethoxide was prepared by the method described by BRADLEY and co-worker+. The glycols were purified by distillation before use. Analytical
method
Niobium was estimated as niobium pentaoxide as previously describedii. Ethanol13 was estimated by oxidation with N K&r307 in 12.5 y0 sulphuric acid. Ethane, propane-r+ and butane-2,x-diols were estimated with sodium periodate by the MALAPRADE methodi3. Butane-x,4-diol and pinacol were estimated by oxidation with normal chromic acid solution. Nitrogen was estimated by Kjeldhal method. The same synthetic procedure was used in all the cases. Details are given for the derivative of hexylene glycol only, the rest of the reactions being summarised in Tables II, III and IV. REACTIONS
Reaction
of niobium
pentaethoxide
In I :I molar ratio Niobium pentaethoxide J.
Less-Common
Metals,
8 (1965)
and hexylene glycol
(2.42 g), and 419-427
glycol
(0.90 g), were refluxed
with
s
N’h(OEt)
8)
8)
(0.83
1.38
(0.51
g)
Pinacol
g)
at room
‘.I4
Pinacol
4.16
(I.54
0.59
methylenc (0.67 g)
Penta glycol
2.04
0.72
0.97
0.83
g)
g)
0.90
0.40
Tetramethylene glvcol (0.85 g)
(0.70
Butane-2,3-dial
glycol
glycol
glycol
TrimethYlcne
(0.77
Propylene
(0.28
Ethylene
Glycols
3.0’
2.47
3.35
3.12
I.40
(Si
II
TABLE
temperature
1.20 (2 mole)
0.59 (2 mole)
0.57 (2 mole)
0.71 (2 mole)
0.97 (2 mole)
0.91 (2 molc)
0.40 (2 mole)
(EtO)aNb(pinacol), soluble in benzene
(EtO)sNb(pinacol), soluble in benzene
Yellow
yellow
viscous
viscous
liquid
liquid
glycol), in henzcne
glycol), benzene.
soluble
(EtO)~Nb(pentamethvlcne white sohd, insoluble-in
(EtO)sNb(tetramethylene white viscous liquid,
in benzene
glycol), soluble in benzene
(EtO)sNb(butane-2,3_diol), yellow viscous liqud, soluble
(Et0)3Nb(trin~ethylene yellow viscous liquid,
in benzene
glycol), soluble in benzene
(EtO)aNb(propylene glycol), Yellow viscous liquid, soluble
(Et0)3Nb(ethYlene white pasty solid,
Pvoduct and state
27.27
27.15
28.03
29.jI
29.48
30.89
.30.(4
ethox? 42.0X
24.00
20.93
Clycoxy
32.09
“‘,)
Found( _\‘h
20.95
29.3x
29.38
30.71
32.25
-f:
d
2
; 0 01 c” P
.-
8
$
F
5
2.94
3.46
2.13
3.19
3.03
3.31
2.68
(g)
Nb(OEt)
REACTIONS
TABLE
5
II
OF
(2.19 g)
Pinacol
1.67
I.90
Pentamethylene
glYco1 (2.30 g)
I.2I
I.90
I. 75
1.81
I.70
2.0
I.23
1.85
(EtO)Nb(trimethylene white viscous liquid,
1.76
(EtO)Nb(pinacol)s, white solid, soluble in benzene
(EtO)Nb(pentamethylene glycol)a, white solid, insoluble in benzene
(EtO)Nb(tetramethylene glycol)2, white spongy solid, insoluble in benzene
(EtO)Nb(Butane-2,3-diol)z, white spongy solid, soluble in benzene (m.p. I2o’C)
glycol)z, soluble in benzene
(EtO)Nb(propylene glycol)z, white spongy solid, soluble in benzene
(EtO)Nb(ethylene glycol)z, white solid insoluble in benzene
mad state
I.92
I.55
Ig)
(9)
I.55
Calc.
Found
Product
WITH GLYCOIS IN MoI.AR RATIO I:2 IN BENZENE
Amount of alcohol in azsotrope
Tetramethylene glycol (1.21 g)
(I.81 g)
Butane-2,3-diol
(I.45 g)
glycol
glycol
glycol
PENTAETHOXIDE
Trimethylene
(I.58 g)
Propylene
(I.04 g)
Ethylene
Glycols
NIOBIUM
25.45
26.91
29.87
29.63
32.30
32.52
ethoxy I I.93
51.40
46.89
Glycoxy
Nb
36.11
(%)
Found
Analysis
25.10
27.14
29.57
29.57
32.47
32.47
36.00
Nb
Calc. (%)
14.32
51.76
46.54
Glycoxy
glycol
glycol
PENTAETHOXIDE
WITH
GLYCOLS
1.72
1.48
1.86
Pentamethylenc glycol (2.09 g)
Pinacol (2.97 g)
2.18
1.80
1.18
2.39
(g/J
Found
I .g2
I.54
I.73
2.18
1.86
1.23
2.47
Gale. (s)
Amount of alcohol in azeotrope
Tetramethylene glycol (2.01 g)
Butane-2,3-dioi (2.56 g)
Trimethylene g’ycol (I.85 g)
Propylene (I.21 g)
Glycols
NIOBIUM
1.70
OF
Ethylene (2.01 g)
IV
3.42
__.-.-.---
REACTIONS
TABLE IN
RATIO
OF
I :3 IN
BENZENE
Nb(pinacol)s, white solid, sparingly
soluble in benzene
Nb(pentamethylenc glYcol)a, white solid, insoluble in benzene
Nb(tetramethylene glycolja, white solid, insoluble m bcnzcne
Sbjbutnne-z,3-diol)a, white spongy solid, soluble in benzene
Nb(trimethylenc giycoi)a, yellow pasty solid, soluble in benzene
Nb(propylene glycol)3, white spongy solid, soluble in benzene
Nb(cthylene glycol)s, white solid, insoluble in benzene
Product and state
MOLAR
21.2s
23.26
25.63
25.99
29.2I
29.46
33.82
.Vb
80.00
74.61
69.86
65.10
Glycoxy
Found ( O/,J
Analysis
2I.00
13.21
25.98
25.98
29.38
19.38
33.88
*Vb
79.00
74.02
70.60
66.10
Glycoxy
Calc. ( Y/,)
R. C. MEHROTKA,
426
P. W. KAPOOR
benzene (50 ml), followed by slow fractionation of ethanol azeotropically. The remaining solvent was removed under reduced pressure and the product dried at 35YJo.5 mm for 2 h. A white, moisture-sensitive viscous liquid (2.61 g) remained. 0.70 g of ethanol was formed (complete reaction requires 0.70 g). Found: Nb, 27.43 y,. (EtO)aNb(h ex yl ene glycol) requires: Nb, 26.98 ‘$$. This compound (1.42 g) was distilled under reduced pressure at 178”C/1.0 mm as a colourless viscous liquid (1.18 g). Found: Nb, 27.32%. In r 12 molar ratio Hexylene glycol (z.zz g), niobium pentaethoxide (2.98 g), were refluxed with benzene (40 ml) for 3 h. The benzene-ethanol azeotrope was then distilled off, the remaining solvent removed under reduced pressure, and the product dried under reduced pressure. A white semisolid (3.47 g), remained. The azeotrope contained 1.73 g of ethanol (reaction requires I.73 g). Found: Nb, 25.87 %. Calc. for (EtO)Nb(hexylene glycol)g: Nb, 25.10 %. This compound (2.91 g) was distilled at 181”C/o.3 mm as white viscous liquid which solidified on keeping (2.42 g). Found: Nb, 25.46 %. In I :3 molar ratio Niobium pentaethoxide (2.23 g) was allowed to react with hexylene glycol (2.48 g) in benzene (50 ml). The binary azeotrope of ethanol-benzene was collected slowly after refluxing the reaction mixture under a fractionating column. The total refluxing was carried out for about 3 h. Excess of the solvent was distilled out under vacuum. A colourless viscous liquid (3.10 g) was obtained. The azeotrope cont~ned 1.56 g of ethanol (reaction requires 1.62 g). Found: Nb, 2r.23 %. Calc. for Nb (hexylene glycol)s: Nb, 21.00%. This compound (1.50 g) when heated under reduced pressure (8o”C/x.o mm) gave a few drops of a colourless liquid which was assumed to be hexylene glycol. The temperature of the bath was then increased and at 203”C/o.7 mm a pasty solid (0.90 g) was obtained which became a glassy solid on standing. Found: Nb, 25.05 %. Calc. for Nba(hexylene glycol) : Nb, 24.23 %. In 2 :5 molar ratio A mixture of niobium pentaethoxide (2.72 g), hexylene glycol (2.50 g) and. benzene (50 ml) gave a clear solution which was refluxed, this being followed by a drop-wise fractionation of the ethanol-benzene azeotrope at 68°C. After removal of the excess of the benzene under reduced pressure, a white spongy solid (3.35 g) was obtained. The amount of ethanol in azetrope was found to be 1.89 g; talc. 1.96 g. Found: Nb, 24.34%. Calc. for Nbs(hexylene glycolja: Nb, 24.23%. The compound (3.0 g) distilled at 208”C/1.0 mm to give a colourless viscous liquid which on standing became a glassy solid (2.61 g). Found: Nb, 24.68 %. Reaction of Nb(butane-2,3-diol)z (IV) with anhydrous ammonia in benzene An exothermic reaction was observed on passing anhydrous ammonia into a benzene (50 ml) solution of (IV) (2.73 g), and a white gelatinous precipitate was formed. This was filtered off (filtrate contained no niobium) and the precipitate was dried under reduced pressure. A fine white powder (2.69 g) was obtained. Found: Nb, 25.07 y0 ; N, 3.45 y0 ; glycol, 70.00 y0 ; talc. for NH4[Nb(butane-z,3 diol)d : Nb, 24.76% ; N, 3.73% ; glycol, 70.450/b. f.
&XT-COWW?XWt
it!ftTtak,8
(1965)
419-427
REACTION
OF NIOBIUM PE~TAETHOXI~E
WITH GLYCOLS
427
One of us (P.N.K.) is grateful to the Council of Scientific Research, New Delhi, for the award of a Junior Research Fellowship.
and
Industrial
REFERENCES
I F. FAIKBROTHER,N.AHAMAD, K. EDGER AND A.THOMPSON,J. Less-Common Metals, 4 (1962) 466. 2 K. K. MEHROTRAAND
3 4 5 6 7 8
9 10 II I2
13
R.C.MEHROTRA, J.Ind.Chem.Soc..3g (1962)635. Ii.C. MEHROTRA AND G. SRIVASTAVA,~. Chem. Sac., (1961) 4045;ibid., (1962)1032. R. C. MEHROTRA AND D.M. PuRI,J.Ilzd. Chem.Soc., in press. R. C. ~~~~~~~~,privatecommunication. V. D. G~PTA, Ph.D. Tisesis, RajasthanUniversity, 1965. R. KMITTAL, Ph. D. Thesis, RajasthanUniversity, x963. R.C. MEHROTRAANDD.D.BHATNAGAR,J.I&. Chem..%c.,(r965) inpress. I(.CMEHROTRA AND S.N.MATHuR,J. Ind.Chem.Soc., (1965) in press. ~.C.BRADLEY,B.N.CHAKARVARTI,ANDW.WARDLAW.J.C~~~.S~C.,(I~~~)~~SI. R. C. MEHROTRA AND P. N. KAPOOR. J. Less-Common Metals, 7 (1964) 98, 176. D.C. BRADLEYANDW.WARDLAW, J. Chem..Soc.,(1950)3450. L. MALAPRADE, Bull. Sot. Chim. France, 43 (1928) 683. J.
LeSS-COWnO??
Metals, 8 (1965) 419-427
OF THE
ORGANIC I’.
LESS-COMMON
COMPOUNI)S
REACTION
XETALS
OF NIOBIUM
OF NIOBIUM
PENTAETHOXIDE
WITH
GLYCOLS
Reactions of niobium pentaethoxide with diols(ethane, 1,2- and x,3-propane, 2,3- and r,4-butane and I&pentane diols, hexylene giycol and pinacol) have been carried out in different stoichiometric ratios and the following three types of new derivatives (EtO)~~b(glycol), (EtO)Nb(glycol~~ and Nb(gl~~ol)~ have been isolated. Molecular weights of the few soluble glycollates shows that they are dimeric.
INTRODUCTION FAIRBROTHER and co-worker+ have reported a number of polynuclear complexes of niobium and tantalum with catechol and other r,z-diols. Recently, alcoholi~ter~l~ange technique has been used for the preparation of orthoesters of a number of metals, including cyclic orthoesters of aluminiunl~, barons, titanium4, zirconium”, tin”, vanadium7, antimony8 and tellurium~. Preparation of similar derivatives of niobium has now been achieved by the reaction between niobium pentaethoxide and various glycols. BRADLEY and co-workers10 were the first to synthesise the normal alkoxides of niobium by passing a current of dry ammonia through a mixture of niobium pentachloride and the appropriate alcohol in benzene solution or by an alrohol-interchange technique. The reaction between niobium pentaethoxide and glycols in equimolar ratio was carried out in benzene. Ethanol produced during the reaction was removed azeotropically, the progress of tbe reaction being ascertained by the amount of ethanol in the azeotrope. On removal of the solvent, the triethoxy niobium monoglycollate derivatives were obtained:
OH /
+
R
Nb(OEt)s
+ R
Nb(OEt)s
+ z EtOH
io”
\ OH
miscible
These mixed alkoxide glycollates are light yellow viscous liquids or semisolids, with benzene, the only insoluble derivative being that of penta-methylene
R. C.
420
MEHROTRA,
P. N. KAPOOR
glycol. These derivatives can be purified by distillation under reduced pressure, with the exception of those of ethylene and penta-methylene glycol, which undergo decomposition as follows.
.‘O\R
5(EtO)aNb
3
I<>]
-
'0'
Nb-0-R-0-Nbrd 0
+ 3 Nb(OEt)s
Lo
-Jz
12
The reaction of pinacol in I:I molar ratio at room temperature yielded the triethoxy niobium mono pinacolate derivative, The reactions of niobium pentaethoxide with the above glycots was also carried out in a I :2 molar ratio when, in all cases, monoethoxy niobium diglycollate derivatives were obtained : OH 2R
/
+
\
Nb(OEt)s
+ R
OH
/“\Nb/o\ ‘0’1
R + 4 EtOH
‘0’ (OEt)
These products were either white viscous liquids or spongy solids and showed an interesting variation in their solubiliti~s in benzene. Only the hexylene glycol derivative was found to distil under reduced pressure; all the other derivatives decompose when heated under reduced pressure. The reactions of niobium pentaethoxide with these glycols were also studied in a molar ratio of 1:3, in all these reactions triglycollate derivatives being obtained. These triglycollate drivatives decomposed when heated under reduced pressure, with the exception of butane-z,g-diol and hexylene glycol derivatives, which on heating lost a molecule of glycol interamolecularly, giving derivatives corresponding in composition to di-niobium pentaglycollates. A similar derivative of hexylene glycol was prepared by the reaction of niobium pentaethoxide and hexylene glycol in the molar ratio of 2:s. OH 3R
/ \
+
Nb(OEt)s
+
R + 5 EtOH
OH
-0
2 Nb-0-R-0-Nb
2
-
ILo’\/‘R__I2 I
The molecular weights of a few typical soluble glycollates have been determined in boiling benzene and the compounds are found to be dimeric, which may be due to J. Less-Co?wm98 Metals, 8 (1965) 419-427
REACTION OF NIOBIUM PENTAETHOXIDE
WITH GLYCOLS
the tendency of niobium to attain a coordination and molecular weights are given in Table I.
TABLE
of six. The boiling
points
I
SUMMARY
OF
BOILING
POINTS
AND
MOLECULAR
(EtO)aNb(propylene glycol) Nb(propylene glycol)3 (EtO)aNb(trimethyleneglycol)
WEIGHTS
‘7’ -‘74/0.5 162~168lo.r Kefr. index 1.531 168/1.0 Sublimes 178/r.o 181/0.3 2o3/o.7 14r/o.4 Kefr. index 1.521
(Et0)3Nb(butane-z,3-diol) (EtO)Nb(butane-2,3-diol)z Nbz(butane-z,3-diol)s (EtO)sNb(hexylene glycol) (EtO)Nb(hexylene glycol)8 Nba(hexylene glycol) 5 (EtO)~Nb(pinacol) (EtO)Kb(pinacol)?
The dimeric structures
(0w
of these compounds
\
o(o$t) PW I triethoxy -
7’3 010
316 302
042
314
733 051
Or6
721 821 720
344 370 767 344
777
370
are given below:
(0Et) PW
I
0
‘db’
/I
\
niobium
/
‘12
I ‘\o/
I (OEt)
monoglycollate
Nb
li ‘lo/ II monoethoxy
III
member
421
diniobium
\ -2 niobium
diglycollate
pentaglycollate
The solubility of these derivatives does not appear to follow any regular pattern. The insoluble nature of the di and triglycollate derivatives may be ascribed either to chelation or to the formation of highly polymeric units. J. Less-&vnmon Metals. 8 (1965) 419-427
R. C. MEHROTRA,
422
P. N. KAPOOR
An exothermic reaction was observed on passing anhydrous ammonia in to a benzene solution of Nb(butane-2,x-diol)3 a white precipitate being formed, which was filtered and dried. The resulting white, light powder corresponded by analysis to NH4 Nb(butane-z,3-die 31;I3 : CH3
-
CH3 H
dH-0 I \
J
Nb
\O-
dH-0 1
&3
CH3-
_-
I
0-CH
/
CH3
0-CH
Hd-0
I
excess
ammonia
-> NH
/
AH
HCi-0’
dH3
_
‘N ‘O-CH
dH3
This compound was found to be insoluble in common organic solvents. ammonia it readily hydrolysed, with the formation of a white gelatinous of hydrated niobium pentaoxide.
II
dH3_ _3_
In aqueous precipitate
EXPERIMENTAL
Apparatus
and chemicals
All-glass apparatus fitted with interchangeable joints was used, special precautions being taken to exclude moisture. All fractionations were carried out in a column packed with Rasching rings and fitted to a total-condensation variable-takeoff stillhead. Molecular weights were determined ebullioscopically in boiling benzene. Benzene was stored over sodium wire for two days, refluxed (Na), and distilled. Finally, it was dehydrated azeotropically with ethanol. Niobium pentaethoxide was prepared by the method described by BRADLEY and co-worker+. The glycols were purified by distillation before use. Analytical
method
Niobium was estimated as niobium pentaoxide as previously describedii. Ethanol13 was estimated by oxidation with N K&r307 in 12.5 y0 sulphuric acid. Ethane, propane-r+ and butane-2,x-diols were estimated with sodium periodate by the MALAPRADE methodi3. Butane-x,4-diol and pinacol were estimated by oxidation with normal chromic acid solution. Nitrogen was estimated by Kjeldhal method. The same synthetic procedure was used in all the cases. Details are given for the derivative of hexylene glycol only, the rest of the reactions being summarised in Tables II, III and IV. REACTIONS
Reaction
of niobium
pentaethoxide
In I :I molar ratio Niobium pentaethoxide J.
Less-Common
Metals,
8 (1965)
and hexylene glycol
(2.42 g), and 419-427
glycol
(0.90 g), were refluxed
with
s
N’h(OEt)
8)
8)
(0.83
1.38
(0.51
g)
Pinacol
g)
at room
‘.I4
Pinacol
4.16
(I.54
0.59
methylenc (0.67 g)
Penta glycol
2.04
0.72
0.97
0.83
g)
g)
0.90
0.40
Tetramethylene glvcol (0.85 g)
(0.70
Butane-2,3-dial
glycol
glycol
glycol
TrimethYlcne
(0.77
Propylene
(0.28
Ethylene
Glycols
3.0’
2.47
3.35
3.12
I.40
(Si
II
TABLE
temperature
1.20 (2 mole)
0.59 (2 mole)
0.57 (2 mole)
0.71 (2 mole)
0.97 (2 mole)
0.91 (2 molc)
0.40 (2 mole)
(EtO)aNb(pinacol), soluble in benzene
(EtO)sNb(pinacol), soluble in benzene
Yellow
yellow
viscous
viscous
liquid
liquid
glycol), in henzcne
glycol), benzene.
soluble
(EtO)~Nb(pentamethvlcne white sohd, insoluble-in
(EtO)sNb(tetramethylene white viscous liquid,
in benzene
glycol), soluble in benzene
(EtO)sNb(butane-2,3_diol), yellow viscous liqud, soluble
(Et0)3Nb(trin~ethylene yellow viscous liquid,
in benzene
glycol), soluble in benzene
(EtO)aNb(propylene glycol), Yellow viscous liquid, soluble
(Et0)3Nb(ethYlene white pasty solid,
Pvoduct and state
27.27
27.15
28.03
29.jI
29.48
30.89
.30.(4
ethox? 42.0X
24.00
20.93
Clycoxy
32.09
“‘,)
Found( _\‘h
20.95
29.3x
29.38
30.71
32.25
-f:
d
2
; 0 01 c” P
.-
8
$
F
5
2.94
3.46
2.13
3.19
3.03
3.31
2.68
(g)
Nb(OEt)
REACTIONS
TABLE
5
II
OF
(2.19 g)
Pinacol
1.67
I.90
Pentamethylene
glYco1 (2.30 g)
I.2I
I.90
I. 75
1.81
I.70
2.0
I.23
1.85
(EtO)Nb(trimethylene white viscous liquid,
1.76
(EtO)Nb(pinacol)s, white solid, soluble in benzene
(EtO)Nb(pentamethylene glycol)a, white solid, insoluble in benzene
(EtO)Nb(tetramethylene glycol)2, white spongy solid, insoluble in benzene
(EtO)Nb(Butane-2,3-diol)z, white spongy solid, soluble in benzene (m.p. I2o’C)
glycol)z, soluble in benzene
(EtO)Nb(propylene glycol)z, white spongy solid, soluble in benzene
(EtO)Nb(ethylene glycol)z, white solid insoluble in benzene
mad state
I.92
I.55
Ig)
(9)
I.55
Calc.
Found
Product
WITH GLYCOIS IN MoI.AR RATIO I:2 IN BENZENE
Amount of alcohol in azsotrope
Tetramethylene glycol (1.21 g)
(I.81 g)
Butane-2,3-diol
(I.45 g)
glycol
glycol
glycol
PENTAETHOXIDE
Trimethylene
(I.58 g)
Propylene
(I.04 g)
Ethylene
Glycols
NIOBIUM
25.45
26.91
29.87
29.63
32.30
32.52
ethoxy I I.93
51.40
46.89
Glycoxy
Nb
36.11
(%)
Found
Analysis
25.10
27.14
29.57
29.57
32.47
32.47
36.00
Nb
Calc. (%)
14.32
51.76
46.54
Glycoxy
glycol
glycol
PENTAETHOXIDE
WITH
GLYCOLS
1.72
1.48
1.86
Pentamethylenc glycol (2.09 g)
Pinacol (2.97 g)
2.18
1.80
1.18
2.39
(g/J
Found
I .g2
I.54
I.73
2.18
1.86
1.23
2.47
Gale. (s)
Amount of alcohol in azeotrope
Tetramethylene glycol (2.01 g)
Butane-2,3-dioi (2.56 g)
Trimethylene g’ycol (I.85 g)
Propylene (I.21 g)
Glycols
NIOBIUM
1.70
OF
Ethylene (2.01 g)
IV
3.42
__.-.-.---
REACTIONS
TABLE IN
RATIO
OF
I :3 IN
BENZENE
Nb(pinacol)s, white solid, sparingly
soluble in benzene
Nb(pentamethylenc glYcol)a, white solid, insoluble in benzene
Nb(tetramethylene glycolja, white solid, insoluble m bcnzcne
Sbjbutnne-z,3-diol)a, white spongy solid, soluble in benzene
Nb(trimethylenc giycoi)a, yellow pasty solid, soluble in benzene
Nb(propylene glycol)3, white spongy solid, soluble in benzene
Nb(cthylene glycol)s, white solid, insoluble in benzene
Product and state
MOLAR
21.2s
23.26
25.63
25.99
29.2I
29.46
33.82
.Vb
80.00
74.61
69.86
65.10
Glycoxy
Found ( O/,J
Analysis
2I.00
13.21
25.98
25.98
29.38
19.38
33.88
*Vb
79.00
74.02
70.60
66.10
Glycoxy
Calc. ( Y/,)
R. C. MEHROTKA,
426
P. W. KAPOOR
benzene (50 ml), followed by slow fractionation of ethanol azeotropically. The remaining solvent was removed under reduced pressure and the product dried at 35YJo.5 mm for 2 h. A white, moisture-sensitive viscous liquid (2.61 g) remained. 0.70 g of ethanol was formed (complete reaction requires 0.70 g). Found: Nb, 27.43 y,. (EtO)aNb(h ex yl ene glycol) requires: Nb, 26.98 ‘$$. This compound (1.42 g) was distilled under reduced pressure at 178”C/1.0 mm as a colourless viscous liquid (1.18 g). Found: Nb, 27.32%. In r 12 molar ratio Hexylene glycol (z.zz g), niobium pentaethoxide (2.98 g), were refluxed with benzene (40 ml) for 3 h. The benzene-ethanol azeotrope was then distilled off, the remaining solvent removed under reduced pressure, and the product dried under reduced pressure. A white semisolid (3.47 g), remained. The azeotrope contained 1.73 g of ethanol (reaction requires I.73 g). Found: Nb, 25.87 %. Calc. for (EtO)Nb(hexylene glycol)g: Nb, 25.10 %. This compound (2.91 g) was distilled at 181”C/o.3 mm as white viscous liquid which solidified on keeping (2.42 g). Found: Nb, 25.46 %. In I :3 molar ratio Niobium pentaethoxide (2.23 g) was allowed to react with hexylene glycol (2.48 g) in benzene (50 ml). The binary azeotrope of ethanol-benzene was collected slowly after refluxing the reaction mixture under a fractionating column. The total refluxing was carried out for about 3 h. Excess of the solvent was distilled out under vacuum. A colourless viscous liquid (3.10 g) was obtained. The azeotrope cont~ned 1.56 g of ethanol (reaction requires 1.62 g). Found: Nb, 2r.23 %. Calc. for Nb (hexylene glycol)s: Nb, 21.00%. This compound (1.50 g) when heated under reduced pressure (8o”C/x.o mm) gave a few drops of a colourless liquid which was assumed to be hexylene glycol. The temperature of the bath was then increased and at 203”C/o.7 mm a pasty solid (0.90 g) was obtained which became a glassy solid on standing. Found: Nb, 25.05 %. Calc. for Nba(hexylene glycol) : Nb, 24.23 %. In 2 :5 molar ratio A mixture of niobium pentaethoxide (2.72 g), hexylene glycol (2.50 g) and. benzene (50 ml) gave a clear solution which was refluxed, this being followed by a drop-wise fractionation of the ethanol-benzene azeotrope at 68°C. After removal of the excess of the benzene under reduced pressure, a white spongy solid (3.35 g) was obtained. The amount of ethanol in azetrope was found to be 1.89 g; talc. 1.96 g. Found: Nb, 24.34%. Calc. for Nbs(hexylene glycolja: Nb, 24.23%. The compound (3.0 g) distilled at 208”C/1.0 mm to give a colourless viscous liquid which on standing became a glassy solid (2.61 g). Found: Nb, 24.68 %. Reaction of Nb(butane-2,3-diol)z (IV) with anhydrous ammonia in benzene An exothermic reaction was observed on passing anhydrous ammonia into a benzene (50 ml) solution of (IV) (2.73 g), and a white gelatinous precipitate was formed. This was filtered off (filtrate contained no niobium) and the precipitate was dried under reduced pressure. A fine white powder (2.69 g) was obtained. Found: Nb, 25.07 y0 ; N, 3.45 y0 ; glycol, 70.00 y0 ; talc. for NH4[Nb(butane-z,3 diol)d : Nb, 24.76% ; N, 3.73% ; glycol, 70.450/b. f.
&XT-COWW?XWt
it!ftTtak,8
(1965)
419-427
REACTION
OF NIOBIUM PE~TAETHOXI~E
WITH GLYCOLS
427
One of us (P.N.K.) is grateful to the Council of Scientific Research, New Delhi, for the award of a Junior Research Fellowship.
and
Industrial
REFERENCES
I F. FAIKBROTHER,N.AHAMAD, K. EDGER AND A.THOMPSON,J. Less-Common Metals, 4 (1962) 466. 2 K. K. MEHROTRAAND
3 4 5 6 7 8
9 10 II I2
13
R.C.MEHROTRA, J.Ind.Chem.Soc..3g (1962)635. Ii.C. MEHROTRA AND G. SRIVASTAVA,~. Chem. Sac., (1961) 4045;ibid., (1962)1032. R. C. MEHROTRA AND D.M. PuRI,J.Ilzd. Chem.Soc., in press. R. C. ~~~~~~~~,privatecommunication. V. D. G~PTA, Ph.D. Tisesis, RajasthanUniversity, 1965. R. KMITTAL, Ph. D. Thesis, RajasthanUniversity, x963. R.C. MEHROTRAANDD.D.BHATNAGAR,J.I&. Chem..%c.,(r965) inpress. I(.CMEHROTRA AND S.N.MATHuR,J. Ind.Chem.Soc., (1965) in press. ~.C.BRADLEY,B.N.CHAKARVARTI,ANDW.WARDLAW.J.C~~~.S~C.,(I~~~)~~SI. R. C. MEHROTRA AND P. N. KAPOOR. J. Less-Common Metals, 7 (1964) 98, 176. D.C. BRADLEYANDW.WARDLAW, J. Chem..Soc.,(1950)3450. L. MALAPRADE, Bull. Sot. Chim. France, 43 (1928) 683. J.
LeSS-COWnO??
Metals, 8 (1965) 419-427