Titanium chelates and processes therefor

Details Titanium chelates and processes therefor Titanium chelates and processes therefor

2002-07-03

2003-05-13

Nazario-Gonzalez, Porfirio (Department: 1621)

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

Organic compounds

Heavy metal containing

C556S054000

Reexamination Certificate

active

06562990

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a composition and processes therefor in which the composition comprises chelates of titanium alkoxides having low freezing points.
BACKGROUND OF THE INVENTION
Titanium chelates have a number of industrial uses. They are valuable in a variety of applications such as catalysis, corrosion inhibition, crosslinking and other applications. Their formula can be depicted as (RO)
2
TiX
2
where X is derived from a chelating agent such as, for example, 2,4-pentanedione and R is a straight or branched alkyl group. They can be made by reacting a titanium orthoester of the formula Ti(OR)
4
such as, for example, tetraisopropyl titanate (also known as tetraisopropoxy titanium) with approximately two equivalents of chelating agent such as, for example, 2,4-pentanedione (also known as acetyl acetone) accompanied by the release of two equivalents of the alcohol of the formula ROH.
In such titanium chelates made from a single alcohol, the compounds may have high freezing points and be difficult to handle. Some may initially be a liquid, even remaining as a liquid even after having been supercooled to some considerable extent, but then freeze spontaneously, especially in the presence of a nucleating agent such as dust or part of the reaction product in crystal form. To prevent this, these titanium chelates may be left in the reaction solution in which they were formed, that is, still containing the byproduct alcohol rather than removing it. However this is a disadvantage when the solutions are used in industry because of the resulting low flash point of the solution and the creation of solvent pollution/disposal problems. Preferably, the titanium chelate product is essentially alcohol-free.
Mixed alcohol chelates generally have lower freezing points than chelates of a single alcohol, and are thus liquid at temperatures of typical use even with all byproduct alcohol removed. Mixed chelates can be produced from a mixture of titanium orthoesters with a chelating agent. However, when such alcohols are removed from their mixtures, it is often difficult to control the ratio of alkoxides in the resulting product. This is due to distinct alcohols having different boiling points and being retained to differing and variable extents during their removal from the reaction mass, resulting in often unpredictable and variable product compositions.
U.S. Pat. No. 4,551,544 discloses a reaction product of a titanate (OR
1
)
4
Ti, 2,4-pentanedione, and either another titanate (OR
2
)
4
Ti or an alcohol R
3
OH. U.S. Pat. No. 5,349,073 discloses admixing diisopropoxy titanium bis(acetylacetonate) with a dialkoxy titanium bis(acetylacetonate) to produce isopropoxyalkoxy bis(acetylacetonate) titanium.
However, the alcohol content in the known products is higher than desired. Additionally, the known process requires multiple steps. Also, many of the component chelates can freeze at typical ambient temperatures making the storage more time consuming and can require exposing the material to extended heating in order to thaw it for recharging. Such extended heating can lead to excessive color development in the products.
Therefore, a new product and a process therefor are needed in which the product comprises mixed titanium chelates, is essentially or substantially alcohol-free, and has constant and predictable composition.
SUMMARY OF THE INVENTION
According to a first embodiment of the invention, a substantially alcohol-free composition is provided, which comprises (A) TiX
m
(OR)
4−m
, (B) TiX
m
(OR)
(4−m)/2
(OR
1
)
(4−m)/2
, and (C) TiX
m
(OR
1
)
4−m
wherein X is a radical derived from a chelating agent comprising an organic 1,3-dicarbonyl compound; m is a number from about 1.5 to about 2.5; each R and R
1
is independently a hydrocarbyl radical containing from 1 to about 10 carbon atoms per radical; and R
1
differs from R.
According to a second embodiment of the invention, a process comprises (1) contacting a tetraalkyl titanate with a chelating agent to produce a product mixture comprising a titanium chelate and an alcohol; (2) optionally substantially removing the alcohol whereby an alcohol-reduced titanium chelate is produced; (3) contacting the product mixture or alcohol-reduced titanium chelate with a second alcohol to produce another alcohol-reduced titanium chelate; and optionally (4) reducing the alcohol content of the another alcohol-reduced titanium chelate to produce a substantially alcohol-free titanium chelate wherein the second alcohol is less volatile than the alcohol derived from the tetraalkyl titanate.
Also according to a third embodiment of the d invention, a process comprises (1) contacting a mixture comprising a tetraalkyl titanate and a second tetraalkyl titanate with a chelating agent to produce a product mixture comprising a titanium chelate and a mixture of alcohols derived from the tetraalkyl titanate and second tetraalkyl titanate; (2) substantially removing the mixture of alcohols to produce an alcohol-reduced titanium chelate; and optionally (3) reducing the alcohol content of the alcohol-free reduced titanium chelate to produce a substantially alcohol-free titanium chelate.
According to a fourth embodiment of the invention, a process comprises (1) contacting a single-alcohol titanium chelate with an alcohol, a second single-alcohol titanium chelate, or both to form a desired statistical mixture of (A), (B) and (C) disclosed above in the first embodiment of the invention; (2) substantially removing the mixture of alcohols to produce an alcohol-reduced titanium chelate; and optionally (3) reducing the alcohol content of the alcohol-reduced titanium chelate to produce a substantially alcohol-free titanium chelate.
DETAILED DESCRIPTION OF THE INVENTION
The term “less volatile” refers to the boiling point of an alcohol being at least about 20° C. higher than that of another alcohol, and the term “similar boiling points” refers to boiling points of alcohols that are within about 5° C.
According to the first embodiment, X is a radical derived from a chelating agent. A preferred chelating agent is an organic 1,3-dicarbonyl compound such as a diketone, a diester, a ketoester, and combinations of two or more thereof. A radical derived from any 1,3-diketone can be used. The preferred diketones include, but are not limited to, 2,4-pentanedione, 1,4-hexanedione, 1,3-pentanedione, 2,4-hexanedione, dipivaloyl methane, or combinations of two or more thereof.
Also, a radical derived from any 1,3-diester can be used. The preferred diesters include, but are not limited to, dimethyl malonate, diethyl malonate, or combinations thereof.
Similarly, a radical derived from any 1,3-ketoester can be used. The preferred ketoester include, but are not limited to, methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, butyl acetoacetate, and combinations of two or more thereof.
The most preferred chelating agent is 2,4-pentanedione, ethyl acetoacetate, or combinations thereof.
The preferred m is a number in the range from about 1.5 to about 2.5, preferably from 1.65 to about 2.2, more preferably from 1.8 to about 2.1, and most preferably about 1.9 to about 2. Those skilled in the art can recognize that in cases where m is not 2.0, structures A, B, and C will not have integral numbers of groups and actually are abbreviated shorthand representations of the actual components. In these cases, A, B, and C represent the average compositions of individual components having integral numbers of groups totaling 4 in number for all individual components.
The preferred R or R
1
is hydrocarbyl radical having 1 to about 10 carbon atoms per radical including, but not limited to alkyl radical, cycloalkyl radical, alkylenyl radical, aryl radical, alkaryl radical, aralkyl radical, or combinations of two or more thereof. Examples of suitable radicals include, but are not limited to methyl, ethyl, propopyl, isopropyl, butyl, isobutyl, pentyl, sec-butyl, tert-butyl, and combinations of two or more thereof. However, R
1
is different from R in the same ti

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