Preparation method of diphenyl ethylene glycol_Kain Industrial Additive

Background and overview^[1-2]

Diphenylethanedione is a yellow prismatic crystal. Molecular weight 210.22. Melting point 95~96℃. Boiling point 346~348℃. Soluble in ethanol, ether, chloroform, benzene, insoluble in water. Toxicity: Rat oral LD₅₀ is 2710 mg/kg. Organic synthesis intermediates. Also used as insecticide. It is also a promising photosensitizer for UV-curable resins and is suitable for making printing inks for food packaging. Benzoin is obtained by the condensation of benzaldehyde and sodium cyanide, and is produced by oxidation with air or nitric acid in the presence of copper sulfate. The oxidation of benzoin (also known as benzoin) is the main pathway for aryl glycol compounds. In the past two decades, people have conducted extensive research on this. Reports mainly focus on the screening of oxidants. HNO3, CuSO4/Py, Bi2O3/H+, etc. can be used as oxidants in aqueous solution systems, and Fe2O3/A12O3/Py can be used in organic solvent systems. , CoPc(SO2NH2)4/MeOH, Ar3Sb/DCM, Ti(OPr-i)4/THF, FeCl3·6H2O/CH3COOH, Ph3PBr2/MeCN, DMSO/(COCl)2/CH2Cl2, MnO2 -SiO2/EDC, MnO2-Kieselguhr/DCM, (PhCH2-Et3N)+Br3-/(PhCO2)2O2/MeCN, TCC-Al2O3/C6H12, CrO3/DMSO, etc.

Among these methods, some reagents are highly toxic, some are expensive, complex reaction operations, difficult to separate and purify, and some have large emissions of environmental pollutants. Recently, it has been reported that the use of microwave radiation (Microwave, MW) can accelerate the oxidation of diaryl ethanol ketone to diaryl ethylene glycol. But it is necessary to develop a simple, convenient and easy-to-react method. At present, green organic synthetic chemistry has attracted more and more people’s attention and is becoming an important research content of modern chemistry. Among them, finding environmentally friendly reaction media is an important topic in green chemistry research. Low molecular weight polyethylene glycol (PEG, HO-(CH2CH2O)n-H) is widely used as an environmentally friendly solvent and phase transfer catalyst due to its advantages such as high thermal stability, difficult to volatilize, non-flammable, cheap, and biodegradable, and It is widely used in organic synthesis. Organic synthesis reactions using PEG-400 as the reaction medium have also recently been reported. Ceric ammonium nitrate has little environmental pollution and is known as an excellent oxidant and catalyst in organic synthesis.

Apply^[3-6]

Diphenylethylenedione (also known as benzil) compounds are important organic chemical raw materials and are widely used in the synthesis of polymer curing photosensitizers and drugs. Examples of its application are as follows:

1) Prepare a moth-proof low-density polyethylene cable material, which is made of the following raw materials by weight: low-density polyethylene 46-62, polyethylene terephthalate 24-36, celluloid 18 -32, diphenyl ethylene glycol 3-7, dimethyl fumarate 5-10, red mud 7-14, porcelain tailings 9-16, dimethylpropane carboxylate 6-12, gray calcium powder 10-15, dimethyl phthalate 10-15. The invention combines low-density polyethylene, polyethylene terephthalate and celluloid with each other, significantly improving the heat resistance and climate change resistance of the polyethylene cable material, adding diphenylethylene glycol, Dimethyl fumarate, dimethylpropane carboxylate, arborvitae essential oil, 3-chloropropylene and other raw materials can significantly improve the anti-moth properties of polyethylene cable materials and protect cables from moths, and have good application prospects. .

2) Prepare a (±)-1,2-diphenylethylenediamine. Using 1,2-diphenylethylenedioxime, one of hydrazine hydrate, formic acid, sodium formate, ammonium formate, and ammonium formate-triethylamine system is used as the hydrogen source, at 20℃-100℃, using thunder Nickel is used as a catalyst and activated carbon is used as a cocatalyst. The reaction is catalytically reduced in a polar solvent to obtain (±)-1,2-diphenylethylenediamine. The invention has the advantages of simple and wide sources of raw materials, low price, safe production process, short process flow, mild reaction conditions, low cost, environmental friendliness, etc., and is very suitable for industrial production.

3) Prepare a photosensitive conductive silver paste, which is composed of the following raw materials by weight: highly dispersed conductive silver powder 100-106, triterpene saponin 0.6-1, methacrylic resin 12-14, 2 , 2,4-trimethyl-1,3-pentanediol monoisobutyrate 20-30, toluene 20-30, titanium nitride 0.1-0.2, diphenylethylene glycol 1-2, polyethylene glycol 1-2. Phthalates 2-3, polyvinyl alcohol 0.2-0.4, glass powder 10-15, ceramic powder 2-3. The highly dispersed conductive silver powder of the present invention is uniformly and densely coated with nano-silver powder. On the surface of polymer microspheres, it can not only reduce the amount of precious metal silver powder and reduce production costs, but also greatly improve the dispersion and stability of nano silver powder.

4) Prepare a type of 2,3-diphenyl-6-amidoquinoxaline compound. The preparation method includes the following steps: 1) causing benzoin condensation reaction of benzaldehyde to generate benzoin; 2) oxidizing the generated benzoin to generate 1,2-diphenylethylenedione; 3) 1,2-diphenylethylenedione Then cyclization reaction occurs with 4-nitro-o-phenylenediamine to generate 2,3-diphenyl-6-nitroquinoxaline; 4) 2,3-diphenyl-6-nitroquinoxaline is reduced Generate 2,3-diphenyl-6-aminoquinoxaline; 5) 2,3-diphenyl-6-aminoquinoxaline reacts with various acid chlorides to generate 2,3-diphenyl-6-amide group Quinoxaline compounds.

Preparation^[7-8]

Method 1: Preparation of diphenyl ethylene glycol by oxidation of ketone acetate:

Add different amounts of benzoin, 10mL glacial acetic acid, powdered ammonium nitrate and 2% copper acetate solution into a 100mL three-neck round bottom flask in sequence, add a few grains of zeolite, install a reflux condenser, and slowly heat reflux on the asbestos mesh. Thin layer chromatography and��React until the reaction is complete (dichloromethane is used as the developing agent). The reaction mixture was cooled to 50-60°C, poured into 10 mL of cold water with stirring, and benzophenone crystals precipitated. Filter with suction, wash thoroughly with cold water, and press dry as much as possible to obtain the crude product. Recrystallize with 75% ethanol 1 to 2 times to obtain yellow needle crystals, which is pure diphenylethylenedione. After the sample was dried, it was confirmed by melting point and spectral data: (m.p.94～95℃) (literature value 93～94℃) [3]; 1HNMR (500MHz, CDCl3) δ: 7.11～7.87 (m, Ar-H); IR (KBr)v: 1661, 1592, 1578, 1452, 793, 718, 692, 682cm-1.

Method 2: Synthesis method of drug intermediate diphenylethylenedione, including the following steps:

A: Add 2mol 2-bromo-2′-hydroxy-diphenyl-2-methylethanone into the reaction vessel, raise the temperature to 50°C, and then add 900ml of 9% potassium chloride solution with a mass fraction of , react for 2 hours, gradually increase the temperature, and increase the temperature to 70°C within 60 minutes;

B: Control the stirring speed to 150rpm, add 4 mol of isoamyl butyrate solution with a mass fraction of 30%, add dimethyl titanium dimethyl in 5 times within 60 minutes, continue the reaction for 2 hours, and then add 1.2L mass fraction 10% sodium sulfate solution, stir for 90 minutes, add 15% mass fraction of potassium carbonate solution to adjust the pH to 10, lower the temperature to 10°C, add 800ml of 20% mass fraction of sodium chloride solution, precipitate the solid, and filter. Wash 4 times with a 40% mass fraction of didecylamine solution, 2 times with a 60% mass fraction of p-cresol solution, recrystallize in a 80% mass fraction of 3-dimethylaminopropionitrile solution, anhydrous Calcium sulfate dehydrating agent was dehydrated to obtain 413.7g of the finished product diphenylethylenedione, with a yield of 98.5%.