Preparation Process of MIBC Solvent

MIBC solvent methanol is an excellent medium boiling point solvent, used as a solvent for dyes, petroleum, rubber, resin, paraffin, nitrocellulose and ethyl cellulose; used as a raw material for brake fluid and organic synthesis; Used as a mineral flotation agent, such as extracting silicon and copper sulfate; as an inert solvent for nitrocellulose paint, which can increase the gloss and smoothness of the paint, and improve the redness; used as a solvent in the manufacture of lubricant additives.

Nature of MIBC solvent

MIBC solvent is a kind of colorless and stable liquid. Melting point -90℃, freezing point -90℃, boiling point 132℃, relative density 0.8083 (20/20℃), refractive index 1.4112, flash point 40.6℃, vapor pressure (20℃) 0.373kPa, viscosity 5.2mPa·s. It solidifies into a glass body below -90°C. Vapor and air form an explosive mixture with an explosion limit of 1%-5.5%. It is miscible with a variety of organic solvents, slightly soluble in water, and 1.9% in water at 20°C.

Preparation of MIBC solvent

First, acetone is converted into diacetone alcohol by adding compression in the presence of a basic catalyst. The catalyst used is calcium hydroxide or barium hydroxide. When the catalyst particles are small and the surface area is large, this liquid phase contact reaction is close to a homogeneous reaction. The reaction process emits heat, and the equilibrium conversion rate is large at low temperature. Therefore, the raw material acetone should be pre-cooled, and the reaction should be operated at 0-10°C. 

Then, diacetone alcohol is dehydrated to produce mesityl oxide. The diacetone alcohol obtained in the process generally has a content of 10-15%, and is concentrated to 80% by atmospheric distillation, while separating and recovering unconverted acetone. In the presence of acidic catalysts such as nitric acid, boric acid or benzenesulfonic acid, heating to 100-200°C, diacetone alcohol is dehydrated to produce mesityl oxide, and the conversion rate is 80-85%. However, diacetone alcohol can be decomposed into acetone by heat, so the dehydrated product needs to recover the acetone in the base. 

The last step is the hydrogenation of mesityl oxide to produce 4-methyl-2-pentanol. In fact, if nickel or copper is used as a catalyst and the gas phase hydrogenation is carried out under normal pressure under relatively mild conditions, more partial hydrogenation products, methyl isobutyl ketone, will be obtained. When the temperature is controlled at 170-210°C and the molar ratio of hydrogen to mesityl oxide is increased, more fully hydrogenated product methyl isobutyl ketone is obtained. In general, a mixture of the two is obtained, and a vacuum distillation system is used for rectification and separation. It can also be produced by catalytic hydrogenation of methyl-isobutyl (meth) ketone through nickel, and fractionated by a rectifying tower to obtain the finished product.

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