Dihydrocarbylamino metal compounds

Details Dihydrocarbylamino metal compounds Dihydrocarbylamino metal compounds

2002-07-31

2004-12-14

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C427S587000, C427S593000, C423S409000

Reexamination Certificate

active

06831188

ABSTRACT:

TECHNICAL FIELD
This invention relates to the preparation and purification of dialkylamino metal compounds.
GLOSSARY
As used herein, the terms “dihydrocarbylamino metal compound” and “dihydrocarbylamido metal compound” are synonymous. Such compounds are also referred to as metal amides. Also, as used herein, the term “halometal amide” means a metal compound that contains both halide and dihydrocarbylamino ligands.
BACKGROUND
Metal amides, particularly homoleptic dialkylamino metal compounds, are useful as precursor compounds for chemical vapor deposition. See in this connection U.S. Pat. Nos. 5,178,911; 5,417,823; and 6,080,446. Such metal amides are also useful in the synthesis of polymerization catalysts; see for example U.S. Pat. No. 6,020,444. The usual method employed for making metal amides is to react a metal halide with lithium amide, and to purify the product via vacuum distillation. See D. C. Bradley and I. M. Thomas,
Proc. Chem. Soc
., 1959 225-226, D. C. Bradley and I. M. Thomas,
J. Chem. Soc
., 1960 3857-3861; and M. T. Reetz et al.,
Synthesis
, 1983 7 540. Most often, the lithium amide is made from butyl lithium or lithium, expensive reagents, and the corresponding amine. When a lithium amide is used, the solid lithium halide by-product often consists of very small particles that are difficult to remove, especially at large scales. An alternative method employs halomagnesium amide in place of lithium amide; see D. Steinborn et al.,
Synthesis
, 1989 4 304, and DD 269387 A1. After either synthetic procedure, the metal amide is usually purified by vacuum distillation. Many metal amides decompose at the distillation temperature, causing yield losses.
Also known in the art are metal complexes having both halide and dialkylamino ligands. Such compounds can be made by ligand exchange between, for example, TiCl
4
and Ti[N(CH
3
)
2
]
4
, or by the use of less than four moles of LiN(CH
3
)
2
when the reactant is TiCl
4
, see U.S. Pat. No. 3,370,041. Another approach, described by R. T. Cowdell and G. W. A. Fowles,
J. Chem. Soc
., 1960 2522-2526, is reacting TiCl
4
with four moles of dialkylamine, which results in the replacement of only one chlorine ligand. The halide ligands on these halometal amide compounds have been replaced with organic groups; for example, TiBr[N(CH
3
)
2
]
3
is reacted with methyllithium; see H. Burger and H. J. Neese,
J. Organometallic Chem
., 1969 20 129-139.
It has been reported that reaction occurs when dialkylamino metal compounds are contacted with acetonitrile. See D. C. Bradley and M. C. Ganorkar,
Chem. Ind
., 1968 1521-1522, and D. C. Bradley and M. Ahmed,
Polyhedron
, 1983 2 87. The reaction of TiCl
4
with acetonitrile in the presence of amines has been described by N. A. Chumaevskii et al.,
Koord. Khim
., 1991 17 463-466 (
Chemical Abstracts
, 115:84101n, 1991).
It would be advantageous to find a better synthetic route to dialkylamino metal compounds. A more effective purification method for these compounds is also desirable.
SUMMARY OF THE INVENTION
This invention is deemed to enable achievement of the above advantages.
The process of this invention for making the dihydrocarbylamino metal compound has the advantage that the amount of alkali metal amide used decreases from four moles to less than about two moles, and the amount of alkali metal halide by-product produced is correspondingly reduced. Additionally, the dihydrocarbylamino metal compound does not have to be purified via distillation.
An embodiment of this invention is a process of preparing dihydrocarbylamido metal compounds. This process comprises bringing together, in a liquid reaction medium, at least one metal halide, MX
4
, where M is titanium, zirconium, or hafnium, and X is a halogen atom, with at least one dihydrocarbylamine, such that a mixture of (i) halometal amides in which the atom ratio of halogen to metal is greater than about 0.1 and less than about 2, and (ii) dihydrocarbylamine hydrohalide is produced. Then (i) and (ii) are separated from each other, and (i) is brought together with an alkali metal amide, ANR
2
, where A is an alkali metal, and R is a hydrocarbyl group, in a liquid medium, to produce a product comprised of substantially halogen-free dihydrocarbylamido metal compound.
Another embodiment of this invention is also a process of preparing dihydrocarbylamido metal compounds. This process comprises reacting at least one alkali metal dihydrocarbylamide, ANR
2
, where A is an alkali metal, and R is an hydrocarbyl group, with at least one halometal amide in which the atom ratio of halogen to metal is greater than about 0.1 and less than about 2, where the metal of the halometal amide is titanium, zirconium, or hafnium, to produce a product comprised of substantially halogen-free dihydrocarbylamido metal compound.
Still another embodiment of this invention is the discovery that dihydrocarbylamido metal compounds can be purified by contact with a nitrile. Thus, this purification step can be performed in connection with the other embodiments of this invention.
Other embodiments and features of this invention will become still further apparent from the ensuing description and appended claims.
FURTHER DETAILED DESCRIPTION
The metal halides used in invention have the formula MX
4
, where M is titanium, zirconium, or hafnium, and X is a halogen atom. The halogen atom can be a fluorine, chlorine, bromine, or iodine atom. Normally and preferably, all four halogen atoms are the same, as such reagents are readily available commercially. Thus, suitable metal halides include titanium tetrafluoride, titanium tetrachloride, titanium tetrabromide, titanium iodide, zirconium tetrafluoride, zirconium tetrachloride, zirconium tetrabromide, zirconium iodide, hafnium tetrafluoride, hafnium tetrachloride, hafnium tetrabromide, and hafnium iodide. Preferably, the metal is titanium or zirconium, more preferred as the metal is titanium. The halogen atom is preferably a chlorine, bromine, or iodine atom, more preferably, the halogen atom is a chlorine or bromine atom. Highly preferred metal halides for use in this invention thus are titanium tetrachloride, titanium tetrabromide, zirconium tetrachloride, and zirconium tetrabromide.
Dihydrocarbylamines that can be used in this invention have hydrocarbyl groups that may be the same or different, and each hydrocarbyl group has, independently, from 1 to about 12 carbon atoms. Preferably, each hydrocarbyl group has from 1 to about 5 carbon atoms, preferred dihydrocarbylamines are those in which the hydrocarbyl groups are the same. Examples of dihydrocarbylamines that can be used include, but are not limited to, dimethylamine, dimethylamine, ethylmethylamine, ethyl-n-propylamine, methyl-n-propyl-amine, di-n-propylamine, diisopropylamine, methylisopropylamine, ethylisopropylamine, n-butylethylamine, di-n-butylamine, diisobutylamine, isobutylpropylamine, dicyclobutylamine, (cyclobutyl)(methyl)amine, dipentylamine, methylpentylamine, (n-propyl)(pentyl)amine, dicyclopentylamine, (cyclopentyl)pentylamine, dihexylamine, ethylhexylamine, dicyclohexylamine, (isopropyl)(cyclohexyl)amine, diheptylamine, dicycloheptylamine, dioctylamine, n-butyloctylamine, methyloctylamine, dicyclooctylamine, dinonylamine, ethylnonylamine, isobutyldecylamine, didecylamine, (methyl)(phenyl)amine, (ethyl)(phenyl)amine, diphenylamine, bis(biphenyl)amine, ditolylamine, dixylylamine, di(ethylphenyl)amine, di(isopropylphenyl)amine, (n-propyl)(tolyl)amine, dinaphthylamine, (cyclohexyl)(naphthyl)amine, pyrrolidine, pyrrole, and piperidine. Preferred dihydrocarbyl-amines are dimethylamine, diethylamine, and di-n-propylamine, more preferred are dimethylamine and diethylamine. Mixtures of two or more dihydrocarbylamines may be used; preferably, a single dihydrocarbylamine is used.
For the bringing together of the metal halide and the dihydrocarbylamine, the liquid reaction medium can be comprised of one or more alkanes, aromatic hydrocarbons, hydrocarbylaromatic hydrocarbons, ethers, or mixtures thereof, that are liquid at the conditions a

Affiliated with

Also associated with

Rating

Dihydrocarbylamino metal compounds does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dihydrocarbylamino metal compounds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dihydrocarbylamino metal compounds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3321159