Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1994-09-15
1996-03-26
Reamer, James H.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D30512
Patent
active
055022189
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the production of ketene dimers from fatty acid halides and tertiary amines and more particularly to a process for the production of ketene dimers according to which the process is operated batchwise and the reaction is started in the presence of an initial reaction mixture containing ketene dimer and pre-prepared crystals of tertiary amine hydrogen halide and is carried out in the substantial absence of additional solvents.
Long-chain "alkyl" ketene dimers (AKD) are extensively used in the papermaking industry as sizing agents and usually in the form of aqueous dispersions comprising cationic starch or cationic synthetic polymers as dispersing agents.
Long-chain alkyl ketene dimers are produced by removal of hydrogen halide from fatty acid halides. The intermediate ketene is highly reactive and dimerizes. Conventionally the production of long-chain alkyl ketene dimers is carried out by addition of a tertiary amine to a fatty acid chloride substrate in an organic solvent, or by addition of fatty acid chloride to a tertiary amine in an organic solvent. The organic solvents which are used are inert with regard to the starting materials and the end-product. The tertiary amine removes hydrogen chloride from the fatty acid chloride and crystals of amine hydrochlorides are formed. These crystals are then removed and the solvent is evaporated.
As inert solvents alkanes, cycloalkanes or aromatic hydrocarbons can be used. Usually aromatic hydrocarbons, such as toluene or 1,2-dichloropropane, are used in commercial processes. The amount of solvent is usually fairly high and most often at least 0.8 parts solvent as to 1 part fatty acid chloride is used. The solvent acts both as a solvent for the fatty acid halide and the AKD and as a diluent to keep the formed crystals apart during the reaction and thereby to prevent growth of the crystals resulting in inclusion of the starting materials and end-products. Such crystal growth with inclusions leads to decreased yield. All work with organic solvents, such as toluene, is of course undesirable from an environmental point of view and requires stringent safety measures. Further, it is extremely difficult to remove all solvent from the produced AKD and this will thus usually contain about 0.1 to 0.6 per cent by weight of solvent, which of course is undesirable and which causes problems at the use of the AKD as a sizing agent. Thus the solvent will be present in the paper produced, effluent from the paper machine and in exhaust from dryers.
Attempts to reduce the amount of inert organic solvents in the production of ketene dimers have not been successful. This is mainly due to the crystal growth and the shape of the formed crystals, which to a certain extent is dependent on the type of solvent. It is also believed that the crystal shape can be influenced in a manner which is negative with regard to viscosity by interactions between free tertiary amine and formed amine salts. In particular, the dendritic growth of the crystals of tertiary amine hydrohalide results in needle-shaped crystals and/or crystals having dendritic side branches, leading to an undesirably high viscosity in the reaction mixture. Thus it becomes very difficult to stir the reactor contents and heat transfer problems arises. In addition, such crystal growth occuring in the presence of a minor amount of inert organic solvent usually leads to inclusions and substantially decreased purity of the ketene dimer.
The present invention aims at providing a process for the production of ketent dimers from fatty acid halides and tertiary amines whereby the problems connected with the use of inert organic solvents can be avoided. This is achieved by providing a process as defined in the claims. More specifically, the present invention relates to a process for the production of ketene dimers from fatty acid halides and tertiary amines wherein the process is operated batchwise and the reaction is started in the presence of an initial reaction mixture containing ketene dimer
REFERENCES:
patent: 5399774 (1995-03-01), McIntosh
Derwent Patent Abstract--Abstracting Japanese Patent Publication No. 63/258471, published Oct. 25, 1988.
Patent Abstracts of Japan--Abstracting Japanese Patent Publication No. 63-258471, published Oct. 25, 1988. Vol. 13, No. 63 (C-568).
Nicholass John F.
Zettinger Piotr
Eka Nobel AB
Mancini Ralph J.
Morris Louis A.
Reamer James H.
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