| 摘要 |
The invention relates to the chemical and pharmaceutical industry. The essence of the invention consists in that the bark is removed from Siberian or Dahurian larch wood, the wood is chopped and dried at 40 - 50°C to a residual humidity of 15 - 25 per cent. The dried wood is ground, and the soluble substances are extracted from the sawdust using a 75 per cent aqueous solution of ethyl alcohol at a temperature of 40 - 50°C with a ratio of raw material to extraction agent of 1 : (6-7). The extraction agent is then distilled off, and the aqueous portion of the extract is cooled to 38 - 42°C over a period of 20 - 30 minutes for the removal (sedimentation) of the heavy resinous impurities accompanying the DHQ. The resin-free aqueous DHQ extract is fed into a chromatographic column filled with the hydrophobic polyvinyl benzene-based sorbent LPS 500. The desired product is eluted with a 32 - 40 per cent solution of ethyl alcohol. The eluate is collected in a single portion or is divided into two or three fractions, depending upon the required purity of the product obtained (DHQ). Each fraction is evaporated until the ethyl alcohol is completely removed, and the residue is crystallized from deionized water. The desired product is obtained with a purity level of 95.5 - 99.5 per cent and a yield of 1.5 - 2.5 per cent of the mass of absolutely dry wood. The technical effect includes simplifying the method, increasing its ecological compatibility and reducing its duration, while increasing the purity of the product obtained to 99.5 per cent. |
