Abstract: The present invention provides a method for industrial production of trihydrocarbylborane which method is excellent both in quality and in cost. The present invention is concerned with production of trihydrocarbylborane, comprising a reaction synthesizing the trihydrocarbylborane and aluminum oxide from trihydrocarbylboroxine and trihydrocarbylaluminum, characterized in that the reaction is allowed to proceed so that the trihydrocarbylaluminum is present at the end of the reaction in an amount of 0.5 moles or more per mole of the aluminum oxide produced in the reaction.

Abstract: The present invention provides a method for industrial production of trihydrocarbylborane which method is excellent both in quality and in cost. The present invention is concerned with production of trihydrocarbylborane, comprising a reaction synthesizing the trihydrocarbylborane and aluminum oxide from trihydrocarbylboroxine and trihydrocarbylaluminum, characterized in that the reaction is allowed to proceed so that the trihydrocarbylaluminum is present at the end of the reaction in an amount of 0.5 moles or more per mole of the aluminum oxide produced in the reaction.

Abstract: A method is disclosed for the concentration of an aqueous acrylamide solution prepared by hydration of acrylonitrile or an aqueous acrylamide solution substantially free of acrylonitrile. The method makes use of a concentration apparatus at least a part of whose solution-contacting section is made of a copper-containing material. The concentration is conducted while introducing an oxygen-containing gas into the apparatus. Use of this method can prevent formation, adhering, accumulation and the like of popcorn polymers inside the concentration apparatus upon concentration of the aqueous acrylamide solution, and can also produce high-quality acrylamide.

Abstract: A process for preparing acrylamide is disclosed herein which comprises subjecting acrylonitrile to a hydration reaction in the presence of a copper-based catalyst, said process comprising the step of allowing a compound having an active methylene group and an acidic group in one molecule or a salt of the compound, for example, malonic acid, cyanoacetic acid or its salt to be present in a reaction system. According to the hydration reaction, it is possible to inhibit the secondary formation of impurities which cannot be heretofore removed, without any deterioration of a catalyst activity, and acrylamide can be obtained which is useful as a material for the manufacture of a high-molecular weight flocculant having a sufficiently large molecular weight and a good water solubility.

Abstract: This invention provides a process for the preparation of acrylamide. Acrylonitrile is treated through at least two purification steps in which acrylonitrile is brought into contact with a strongly-acidic cation exchange resin and then with a resin having primary and/or secondary amino groups or with activated carbon. The resulting acrylonitrile is subjected to hydration in the presence of a copper-base catalyst. The process of this invention can provide high-quality acrylamide even when acrylonitrile of ordinary quality is used, and permits preparation of a polyacrylamide suitable for use in the production of a coagulant having good water solubility or the like.

Abstract: The present invention relates to a process for producing dipentaerythritol through the dehydration condensation of pentaerythritol in the presence of an acid catalyst. This production process comprises the step of carrying out the dehydration condensation preferably in the presence of an acid catalyst, and/or the step of lowering the temperature of the reaction mixture before the conversion of pentaerythritol becomes not less than 25%, to stop the reaction so that the concentration of tripentaerythritol formed during the reaction may not be increased, and at the same time to give a reaction mixture containing dipentaerythritol in an increased concentration.

Abstract: A catalyst useful in the practice of a process, in which (meth)acrylamide is prepared through the hydration reaction between (meth)acrylonitrile and water in a suspended liquid-phase bed of a Raney copper catalyst, has been obtained by leaching a Raney copper alloy in the presence of the Raney copper catalyst which has been deteriorated. The above useful catalyst has higher performances, compared with a catalyst obtained by conventionally leaching the Raney copper alloy alone, has satisfactory handling properties in settling and filtering, and can significantly reduced the amount of catalyst to be discarded.

Abstract: A molten Raney copper alloy containing copper and a metal selected from Al, Si and Zn as major components and, if necessary, specific metals as minor components is solidified at a cooling rate of not less than 1.times.10.sup.2 K/sec by a rotary water atomizing process, water or gas atomizing process, single roll process or similar process. The Raney copper alloy thus obtained is leached to obtain a Raney copper catalyst. The resultant catalyst exhibits activity several times higher than that of conventional Raney copper catalysts in the reaction of acrylonitrile with water to give acrylamide.

Abstract: Acrylamide crystals are prepared from an aqueous solution of acrylamide by causing the aqueous solution and a coolant to flow inside each electrolytically-polished cooling tube of a double-walled or shell-and-tube heat exchanger and outside the cooling tube, respectively, instead of relying upon vacuum crystallization.

Abstract: An aqueous solution of acrylamide obtained by catalytic hydration of acrylonitrile in the presence of a copper-based catalyst is purified by the steps, in sequence, of (a) removal of the unreacted acrylonitrile, (b) removal of copper, (c) treatment under basic conditions, (d) cation exchanging treatment and (e) weakly basic anion exchanging treatment. The acrylamide obtained by this process has good storage stability. An acrylamide polymer produced from this monomer is useful as a flocculant having a reduced content of the unreacted monomer, a high molecular weight and excellent solubility in water.