1.2  Application of Acetonitrile

1.2.1 Application of conventional Acetonitrile

As a wide range of uses of organic chemical raw materials, Acetonitrile has high demands on its purity, wherein the conventional Acetonitrile required to achieve 99% purity in order to be widely used.

1.2.1.1 Used as the hydrocarbon solvent for extraction separation

Acetonitrile is a widely used solvent, mainly as a solvent of extractive distillation, isolation of butadiene from the C4 hydrocarbons. Butadiene extraction processes of Shell Oil, Universal Oil Products (UOP) Corporation, Atlantic Richfield companies are using Acetonitrile as the extraction solvent. Acetonitrile was used as the extraction agent extraction of C4 hydrocarbons butadiene, the annual consumption is about 1300t, accounting for the total consumption (4000t) of 30%.
Acetonitrile is also used to separate other hydrocarbons, such as separating propylene, isoprene, and methyl acetylene from a hydrocarbon fraction.

1.2.1.2 As intermediates for synthetic pharmaceuticals, pesticide

Acetonitrile can be used for the synthesis of a variety of pharmaceutical intermediates and pesticides. In medicine, for the synthesis of vitamin B1, metronidazole azole glycolate, ethambutol, triamterene, adenine and clofedanol series of important pharmaceutical intermediates; on pesticides, used for synthetic pyrethroids and pesticide intermediates.

1.2.1.3 Acetonitrile as starting material to prepare downstream products

(1) Preparation of hydrocyanic acid

Hydrogen cyanide (HCN) is a synthetic raw material of many important chemical products. BP company describes a method of preparing hydrocyanic acid using synthetic crude Acetonitrile by product of Acrylonitrile as a raw material oxidation directly in the patent. Production process: raw materials is crude Acetonitrile. It was added to the crude acetic acid and other carboxylic acid in Acetonitrile as a polymerization inhibitor, and then generates vapor Acetonitrile by evaporation/ superheat process.

(2) Preparation of amine

Ethylamine (Ethylamine, called MEA) is an important organic chemical raw materials. Production routes of selecting catalytic hydrogenation of Acetonitrile to prepare amine, with high yield, good product quality advantages. Production processes: reaction raw materials are Acetonitrile and hydrogen. After mixing the hydrogen gas with the liquid entering the reactor, the reaction product is condensed by a condenser, then gas-liquid separation, vapor go though absorption column with water and lathered flowmeter discharged and analyzed by gas chromatograph GC-2308; after a certain period recovery liquid, and after mixing with the absorption liquid absorber, analyzed by GC-9800 gas chromatograph.

(3) Preparation of Malononitrile

Malononitrile is a fine chemicals, is an important raw material of synthetic dyes, pesticides and drugs. In the past Malononitrile prepared from the reaction of Cyanoacetamide and phosphorus pentoxide, now prepared using reaction of Acetonitrile, Chlorine, Hydrogen cyanide (or reaction of Acetonitrile and cyanogen chloride). Production processes: raw materials are Acetonitrile, chlorine and hydrogen cyanide. Reaction finished in one step, the product including malononitrile, unreacted acetonitrile, hydrochloric acid and a small amount of maleic acid, succinic acid and fumaric acid.

Further, Acetonitrile can also be used to prepare trichloro acetonitrile, acetic acid, trimethyl acetic acid, imidazole, triazine, thioacetamide and other organic.

1.2.1.4 Others

In addition to up stated uses, but conventional Acetonitrile also used for organic synthesis, catalysts or transition metal complex catalyst component. Also applied in fabric dyeing and coating formulations. Acetonitrile are also effective stabilizers of chlorinated solvents.

1.2.2 Application of high-purity Acetonitrile

1.2.2.1 High-purity Acetonitrile reagent

Production of high purity Acetonitrile, must ensure purity ≥99.9%, water ≤100ppm, metal ion content ≤10ppb, the number of dust particle size greater than 0.2μm of less than 400/ml. Acetonitrile for different uses have different requirements of impurities content, can be divided: MOS (Metal-Oxide-Semiconductor) grade, VLSI (very large scale integration) grade, HPLC (High Performance Liquid Chromatography) grade and analytical, spectral pure.

(1)  MOS grade Acetonitrile

Currently used in semiconductor cleaning of high-purity Acetonitrile is MOS grade, only meet needs of 5μm lithography line width IC production, and our production of VLSI most is 1~2μm. There is a considerable gap of domestic high purity reagent with foreign and require of domestic microelectronics technology development, mainly rely on imports.

Based on requirements on detergent and related cleaning agents of the semiconductor industry, make the mainly products specifications of MOS grade Acetonitrile, in the following table.

Table 1-3 mainly specs. of MOS grade Acetonitrile

(2)  VLSI grade Acetonitrile

With the rapid development of VLSI, integrated circuits growing area, more integrated, more and more stringent quality requirements for VLSI grade Acetonitrile used for VLSI semiconductor devices: dust grains diameter in the reagents is small,  a small number of particles, and less content of metal impurities.

The purity and cleanliness of Acetonitrile solvent has an important influence on the yield and reliability of the electrical properties of VLSI:

1)    Particles will not only block the light and will affect the quality of the lithographic cause chemical contamination.

2)    Alkali and alkaline earth metals are particularly sensitive to VLSI, will result in lower device leakage or breakdown.

3)    Transition metals Cu, Fe, Ni, etc. is fast diffusion of impurities in silicon, can affect the device reliability, and can lead to low breakdown and defects.

4)    Non-metallic impurities F-, Cl-, etc. can cause a chemical vapor deposition process.

(3)  HPLC grade Acetonitrile

Remove of the impurities in Acetonitrile, mainly in increase in purity, reduce the water content, lower acidity, remove of trace organics mainly in decreases UV absorbanceat 190~300nm. As a reversed-phase high performance liquid chromatography HPLC grade Acetonitrile solvent, not only requires Acetonitrile has low absorbance in the ultraviolet wavelength region (200nm ~ 400nm), but also has more stringent requirements for impurities in the solvent. Product specifications of HPLC grade Acetonitrile as shown in Table 1-4.

Table 1-4 mainly specs. of HPLC grade Acetonitrile

1.2.2.2 used for chemical analysis and instrumental analysis

Recently Acetonitrile as an organic modifier and solvent used in thin layer chromatography, paper chromatography, spectrum and polarographic analysis. Since pure Acetonitrile does not absorb ultraviolet light at 200nm~400nm, therefore, it is to open up the use of as a solvent in high performance liquid chromatography. With the popularity of this testing technology, HPLC grade Acetonitrile demand growth year after year.

1.2.2.3 used as the semiconductor cleaning agent in the microelectronics industry

Conventional semiconductor cleaning agent has been using hydrochloric acid, sulfuric acid, nitric acid, hydrogen peroxide, toluene, etc., these agents have strong corrosive effect, low cleaning efficiency, poor results. Because Acetonitrile is a polar organic solvents, has good solubility to oils, salts and a polymer compound, can wash away grease, wax, fingerprints, corrosive and flux residues on the silicon wafer and the like. So we began using high-purity Acetonitrile as semiconductor cleaning agent.