Chemistry Reference
In-Depth Information
which yielded zirconium tetraacetate containing a small proportion of chloride as
impurity [ZrCl
0
.
2
OAc
3
.
8
].
Contrary to the facile straightforward reactions of ethoxides and isopropoxides of
different metals according to Eq. (2.268), an entirely different course of reaction,
resulting in the final formation of metal acetate, can be further illustrated by the reac-
tion of aluminium tertiary butoxide with acetyl chloride. In this case, the first stage of
the reaction is fast, but the aluminium monochloride di-
tert
-butoxide formed initially
reacts
926
with tertiary butylacetate also formed during the reaction, to produce the
corresponding mixed alkoxide-acetate:
Al
OBu
t
3
C
x
CH
3
COCl ! Al
OBu
t
3
x
Cl
x
C
x
CH
3
COOBu
t
2
.
273
AlCl
x
OBu
t
3
x
C
y
CH
3
COOBu
t
! Al
OBu
t
3
x
OCOCH
3
y
Cl
x
y
C
y
Bu
t
Cl
2
.
274
where
x
D 1 - 3;
y
D 0or
<
x
.
This assumption was confirmed by treating aluminium trichloride with tertiary butyl-
acetate, whereby aluminium triacetate was finally obtained:
AlCl
3
C 3CH
3
COOBu
t
! Al
OCOCH
3
3
C 3Bu
t
Cl
2
.
275
4.11.4
Reactions with Metal Halides
The reactions between titanium tetra-alkoxides and titanium tetrachloride (excess) at
low temperatures lead to the deposition of less soluble titanium trichloride mono-
alkoxides:
909
,
927
Ti
OR
4
C 3TiCl
4
(excess)
! 4TiCl
3
OR
2
.
276
In the case of zirconium, crystalline chloride-isopropoxide complexes
913
have been
obtained according to the reactions illustrated by Eqs (2.277) and (2.278):
Zr
OPr
i
4
.
Pr
i
OH C ZrCl
4
.
2MeCO
2
Pr
i
! ZrCl
2
OPr
i
2
.
Pr
i
OH C ZrCl
2
OPr
i
2
.
MeCO
2
Pr
i
C MeCO
2
Pr
i
2
.
277
Zr
OPr
i
4
Pr
i
OH C ZrCl
2
OPr
i
2
.
Pr
i
OH ! 2ZrCl
OPr
i
3
.
Pr
i
OH
2
.
278
These reactions are not confined to metal chloride/metal alkoxide systems, but are
also applicable to organometal chloride/organometal alkoxide combinations as demon-
strated by Eqs (2.279) - (2.282):
CH
2
Cl
2
!
x
C
y
MeTiCl
x
OR
y
928
x
MeTiCl
3
C
y
MeTi
OR
3
2
.
279
where R D Et, Pr
i
;
x
D 2,
y
D 1or
x
D 1,
y
D 2; the dichloro derivatives are less
stable.
2RSnCl
3
C RSn
OPr
i
3
! 3RSnCl
2
OPr
i
210
2
.
280
RSnCl
3
C 2RSn
OPr
i
3
! 3RSnCl
OPr
i
2
210
2
.
281
R
2
SnCl
2
C R
2
Sn
OMe
3
! 2R
2
Sn
OMe
Cl
210
2
.
282
