Abstract: A preparation method for semaglutide. The method comprises: producing a semaglutide resin by means of a solid-phase synthesis, producing crude semaglutide by cleavage and deprotection, producing refined semaglutide by purification and freeze-drying, comprising the solid-phase synthesis of a semaglutide 1-6 peptide fragment resin, which is cleaved and purified to serve as a first peptide fragment; and synthesizing a lysine having a sidechain group at locus 20 of semaglutide to serve as a second peptide fragment. In the method, prepared is a semaglutide loci 1-6 fully protected peptide fragment, which serves as a key starting material applied in the solid-phase synthesis of semaglutide, thus reducing the generation of D-His, D-Glu, D-Thr, D-Phe racemic impurities and +Gly impurities, reducing the difficulty of coarse product purification, increasing the purity and yield of semaglutide, reducing synthesis costs, and favoring industrialized large-scale production.

Abstract: A synthesis method for low-racemization impurity liraglutide comprises the following steps: performing synthesis to obtain a propeptide, coupling 2 to 5 peptides comprising Thr-Phe on the propeptide by using a solid-phase synthesis method; further, performing solid-phase synthesis to obtain a liraglutide resin; the liraglutide resin is cracked after modification, or the liraglutide resin is directly cracked, purified and frozen dry, so as to obtain the liraglutide.

Abstract: A synthesis method for low-racemization impurity liraglutide comprises the following steps: performing synthesis to obtain a propeptide, coupling 2 to 5 peptides comprising Thr-Phe on the propeptide by using a solid-phase synthesis method; further, performing solid-phase synthesis to obtain a liraglutide resin; the liraglutide resin is cracked after modification, or the liraglutide resin is directly cracked, purified and frozen dry, so as to obtain the liraglutide.

Abstract: Disclosed is a liquid crystal medium containing a 2,4-diflurophenyl compound and the use thereof. The liquid crystal composition comprises the compounds as represented by formula I and formula II. The liquid crystal composition has a low rotary viscosity, good chemical and thermal stability and a fast response speed, it is suitable for a liquid crystal display device and particularly suitable for the use in an active matrix display of a TN, IPS or FFS mode.

Abstract: Disclosed is a liquid crystal medium containing a 2,4-diflurophenyl compound and the use thereof. The liquid crystal composition comprises the compounds as represented by formula I and formula II. The liquid crystal composition has a low rotary viscosity, good chemical and thermal stability and a fast response speed, it is suitable for a liquid crystal display device and particularly suitable for the use in an active matrix display of a TN, IPS or FFS mode.