天堂网亚洲,天天操天天搞,91视频高清,菠萝蜜视频在线观看入口,美女视频性感美女视频,95丝袜美女视频国产,超高清美女视频图片

Welcome to chemicalbook!
Chinese English Japanese Germany Korea
400-158-6606
Try our best to find the right business for you.
Do not miss inquiry messages Please log in to view all inquiry messages.

Welcome back!

ChemicalBook CAS DataBase List Methylparaben
99-76-3

Methylparaben synthesis

14synthesis methods
Produced by the methanol esterification of p-hydroxybenzoic acid in the presence of sulfuric acid. The materials are heated for distillation in a glass-lined reactor under reflux. The acid is then neutralized with caustic soda and the product is crystallized by cooling. The crystallized product is centrifuged, washed, dried under vacuum, milled and blended, all in corrosion-resistant equipment to avoid metallic contamination.
-

Yield:99-76-3 99.3%

Reaction Conditions:

with oxygen at 80; under 3750.38 Torr; for 4 h;Sealed tube;Temperature;Reagent/catalyst;Pressure;

Steps:

1-5 Example 4

(1) In a stainless steel jacketed pressure batch reactor, adding a ratio of p-hydroxybenzaldehyde to methanol of 1:100, and adding a nano-cobalt supported CexMe1-xO2 solid solution catalyst with [Rpy]+ [PF6]- The mass ratio of the ionic liquid is 1:10. After the reaction device is sealed,First, oxygen was introduced to 0.5 MPa, the oxygen flow rate was 10 mol/min, and then the circulating water bath was heated at a temperature of 80 ° C, stirring was started, and the reaction was started. After the reaction for 4 hours, the intake and the agitation were stopped, the heating was turned off, the circulating cold water was introduced, and the temperature was lowered to vent the air.(2) The reaction solution is poured into a clean single-mouth flask, and excess methanol is distilled off by vacuum distillation, and the remaining portion is poured into a beaker, and an appropriate amount of 2 to 10% sodium carbonate solution is added Cooling and crystallization, the obtained white solid can be washed with deionized water.Drying yields pure methylparaben.The yield of methylparaben was determined to be 99.3 %.

References:

CN110105207,2019,A Location in patent:Paragraph 0016-0030

Methylparaben Related Search: