Moxidectin → (1R,4S,4'E,5'S,6R,6'S,8R,10E,13R,14E,16E,20R,21R,24S)-21,24-dihydroxy-4'-methoxyimino-5',11,13,22-tetramethyl-6'-[(E)-4-methylpent-2-en-2-yl]spiro[3,7,19-trioxatetracyclo[15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene-6,2'-oxane]-2-one;propan-2-ol

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Reaction Steps

To 1 ml isopropanol solution, amorphous moxidectin (lot#S090601) was added gradually to saturation at 50-60° C. The resulting solution was cooled and held at room temperature resulting in rapid formation of large prismatic crystals. The crystal image was taken and depicted in FIG. 24. Moxidectin IPA crystals were isolated and air-dried for 2 h. Powder X-ray diffraction shows that these crystals are highly crystalline (FIG. 25). When moxidectin (lot#070201, which does not contain BHT) was used for crystallization, the crystals were also formed as shown in FIG. 26. The thermal analysis of air-dried Moxidectin IPA crystals displayed a single weight loss of 14.87% from 25-200° C. (FIG. 27). This weight loss approximately corresponds to two moles of IPA per moxidectin. The theoretical calculation based on moxidectin:IPA=1:2 gives 15.78% IPA weight content which is in reasonably good agreement with the experimental data. The compound decomposes above 250° C.

Provenance & Evidence