Background
Morpholine, also known as morpholine and 1,4-oxazacyclohexane, is a colorless liquid at room temperature with hygroscopicity and special amine odor, miscible with water in any ratio, readily soluble in aromatic hydrocarbons, alcohols, ketones, ethers and organic solvents, slightly soluble in mineral oil and aliphatic hydrocarbons, and slightly toxic. Morpholine is one of the important cyclic amines for industrial use, due to the characteristics of the nitrogen oxide heterocyclic, morpholine occupies an important position in chemical production, is the manufacture of many fine chemical products intermediates, can be used in the production of rubber additives (such as sulfur accelerator, antioxidants, etc.), but also used as rust inhibitors, surfactants, brighteners, whitening agents, emulsifiers, polyurethane foam foaming agent, boiler system water treatment agent; in pesticides, pharmaceuticals. It also has a wide range of applications in pesticides and pharmaceuticals.

Morpholine

Applications[3]
Due to the characteristics of the azoxane ring, morpholine occupies an important position in chemical production and is an intermediate in the manufacture of many fine chemical products, which can be used to prepare NOBS (N-oxodiethylene-2-benzothiazole hyposulfonamide), OTOS (N-oxodiethylene-subthiocarbamoyl-N-oxodiethylene-hypothionamide) and other rubber vulcanization accelerators and rust inhibitors, anticorrosive agents, detergents, detergents, and It is widely used in the fields of rubber, medicine, pesticide, dyestuff, paint, etc.

Morpholine contains secondary amine groups and has all the typical reaction characteristics of secondary amine groups. It reacts with inorganic acids to form salts, and with organic acids to form salts or amides. Alkylation reactions can be carried out, as well as reactions with ethylene oxide, ketones, or the Wiigerodt reaction. The chemical properties of morpholine make it one of the fine petrochemicals with important commercial applications today. In addition, morpholine is an important organic solvent.

In recent years, new uses of morpholine have been developed, such as new pesticides and pharmaceuticals, solvents for the chemical fiber industry, pH regulators, gas absorbers, synthetic herbicides, environmentally friendly solvents for man-made fibers, metal corrosion inhibitors, including metal gas rust inhibitors, have been widely used in mechanical instruments, automobiles, medical devices and other fields, China is just starting in this area.

Antioxidant: a small amount of morpholine and ascorbic acid complex can be used as a synergistic antioxidant for oil and grease products. The morpholine salt of pentosuccinic acid is the antioxidant of glycerolipids and the stabilizer of vitamins and carotene.

Corrosion inhibitor and scale inhibitor: Morpholine is widely used as corrosion inhibitor and scale inhibitor for steam boilers. Bis-morpholine-based polysulfides and other substances are used as lubricant corrosion inhibitors. Petroleum sulfonates of tert-butyl morpholine and morpholine have anti-corrosion effect on petroleum distillate storage tanks, oil pipelines and other equipment. Paraffin wax and morpholine compounds can be coated on the wrapper to prevent moisture and corrosion.

Cleaners and polishers: morpholine and oleic acid reaction to produce soap has excellent properties for window and door and car cleaners and polishers.

Pharmaceuticals: Derivatives of morpholine have been used as painkillers, respiratory and vasodilating stimulants, local anesthetics, antispasmodics, body builders and antimalarials.

Textile auxiliaries: Ethylenebismorpholine quaternary derivatives can be used as softeners for natural or recycled fibers, and “morpholine-based acrylic acid can also be used as textile auxiliaries.

Aromatic extractant: morpholine has high selectivity and solubility for aromatic hydrocarbons, while the solubility of non-aromatic hydrocarbons is low. Aromatic extraction processes using formyl morpholine as a solvent have been implemented in industry.

Morpholine can be used in the manufacture of strongly basic ion exchange resins, quick-setting inks and paints. Morpholine aqueous solutions can be used for degassing. Methyl morpholine and ethyl morpholine can be used as foaming agents for polyurethane foam. Morpholine can also be used in the manufacture of surfactants, pesticides, synthetic fluorescent brighteners, catalysts, etc.

Preparation [2]
Crush φ3.2 clover-shaped Ni-MgO/Al2O3 catalyst and sieve the 20-30 mesh part as catalyst. Measure 10 ml of the above treated catalyst and 10 ml of 20-30 mesh crushed porcelain ring mixed and loaded into the reaction. And reduce with hydrogen at 380℃ for 8 hours, the flow rate of hydrogen is controlled at 50m1/min.

Then the temperature is lowered to 220℃, and N-ethylmorpholine and liquid ammonia are added to the batching tank in proportion to the raw material, and the raw material is continuously added to the mixer in the upper part of the gasifier by the advection pump and mixed with the hydrogen gas from the hydrogen cylinder and then entered into the vaporizer in the upper part of the reactor for gasification. The liquid phase is the crude product, and the gas phase is absorbed by the backpressure valve and absorption tower and then emptied. The reaction conditions were as follows: the reaction pressure was 0.4 MPa, the reaction temperature was 220°C, the air speed of N-ethylmorpholine was 0.14 h-1, the reactor height-to-diameter ratio was not less than 6:1; the molar ratio of hydrogen and N-ethylmorpholine was 100:1, and the molar ratio of liquid ammonia and N-ethylmorpholine was 10:1. The reaction results were as follows: the conversion of N-ethylmorpholine was 42.7% (mol%), the morpholine The yield was 42.6 % (mol%).

Main references
[1] Xing Peng, Wang Yong, & Chen Ligong. (2003). Synthesis of morpholine derivatives. Chemical Industry and Engineering, 20(6), 347-350.

[2] Wang, Medallion, & Tian, Zhensheng. (2005). Current status and development prospects of morpholine at home and abroad. Chemical Technology, 13(5), 63-67.

[3] Han Xiushan. (2002). Application and production of morpholine. Sichuan Chemical Industry and Corrosion Control, 5(5), 33-36.