Application of 2-Hydroxy-5-methyl isophthalol_Industrial Additives

Background and overview^[1][2]

2-Hydroxy-5-methyl isophthalol is an organic synthesis intermediate and pharmaceutical intermediate that can be used in laboratory research and development processes and chemical and pharmaceutical synthesis processes.

Preparation^[1]

Add aqueous formaldehyde solution (21.5g, 37%) to a solution of p-cresol (10.8g, 0.1mol) and NaOH (5.0g) in H₂O (20mL). After stirring at room temperature for 24 hours, it was filtered and washed with saturated aqueous NaCl solution (100 mL). The resulting salt was dissolved in water (mL) and neutralized with acetic acid to obtain light pink crystals, which were filtered and washed with H₂O. The product was dissolved in hot ethyl acetate (40 mL), dried over Na₂SO₄, hot filtered, concentrated to 27 mL, and recrystallized overnight. The product crystals formed were filtered and washed with cold ethyl acetate and air dried. (12.11 g, 72%).

Apply^[2]

Used to prepare a polyester resin for high-gloss powder coating:

CN201811046105.5 provides a polyester resin for high-gloss powder coatings, and further discloses its preparation method; including the following steps:

(1) Mix the selected amounts of neopentyl glycol, glyceryl isostearate, 2-hydroxy-5-methylisophthalein, and 1,6-hexanediol dimethacrylate , and control the temperature below 125°C for heating and melting;

(2) Add a selected amount of the octadecanedioic acid, isophthalic acid and 4-trifluoromethylsalicylic acid to the above mixture, and add a selected amount of the catalyst, under nitrogen protection Gradually increase the temperature of the reaction until no obvious distillate is evaporated, and the acid value of the reactant is less than 30 mgKOH/g, and the reaction temperature is controlled not to exceed 245°C;

(3) Add a selected amount of the antioxidant, maintain a vacuum of 40-60mmHg for 2-7h to promote the formation of polyester resin, and stop vacuuming when the acid value drops below 14mgKOH/g;

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(4) When the material is cooled to 210-220°C, add a selected amount of 2,3-quinolinedicarboxylic acid, and slowly raise the temperature to 240°C to react with the polyester resin for 2-8 hours. Stop the reaction when the acid value is 68-74mgKOH/g, discharge the material while it is hot, and then cool, crush and granulate to obtain it.

The polyester resin for high-gloss powder coatings of the present invention is composed of octadecanedioic acid, isophthalic acid, 4-trifluoromethylsalicylic acid, and 2-hydroxy-5-methylisophthalic acid. It is obtained by polymerizing methanol, neopentyl glycol, glyceryl isostearate, 1,6-hexanediol dimethacrylate, and 2,3-quinolinedicarboxylic acid as raw materials.

Among them, the introduction of octadecanedioic acid results in the final polyester resin having good structural flexibility, low melt viscosity at 200°C, and good fluidity; at the same time, the use of large sterically hindered compounds with quinoline rings 2,3 – Quinolinedicarboxylic acid performs carboxyl end-capping. The carboxyl groups retained in the end-capped polyester resin have great steric hindrance, which makes the reactivity of the polyester resin low, resulting in a greatly prolonged gelling time and a leveling time of up to In about 200s, better leveling properties are obtained.

At the same time, since the final mixed powder coating requires the use of 50/50 polyester resin and E-12 epoxy resin for mutual curing, the synthetic formula of the polyester resin specifically uses a resin with low surface tension and easy to form a film when cured. The surface-migrating fluorine-containing raw material 4-trifluoromethyl salicylic acid and ester compounds that can assist lubrication and improve compatibility with E-12 epoxy resin such as glyceryl isostearate and 1,6-hexanedi Alcohol dimethacrylate, the final polyester resin product not only ensures mechanical properties, but also has a high surface gloss after curing into a film. It can be used in 50/50 mixed powder coatings to obtain high-gloss coating boards. noodle.

Main reference materials

[1] Organic Letters, 17(2), 214-217; 2015

[2] CN201811046105.5 Polyester resin for high-gloss powder coating and its preparation method and application