Laboratory Synthesis of Technical-Grade Hydroxypropyl Methylcellulose from Hemp Shive (Industrial Hemp)

Introduction. Hydroxypropyl methylcellulose (HPMC) is an important cellulose derivative widely used in various industries. The aim of the study is to develop a method for synthesizing HPMC from industrial hemp cellulose, which is a renewable and cost effective raw material. Materials and Methods. The study used samples of cellulose containing hemp shive and industrially produced chemical reagents without additional purification. The synthesis was carried out in a heterogeneous medium of toluene/isopropanol. The product was characterized using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy on nuclei ¹H and ¹³C. The viscosity of 2 % aqueous solutions was determined using a Brookfield viscometer. Results. The synthesis of HPMC from pre dried hemp shive was successfully accomplished. The degree of methylation (DS) and hydroxypropylation (MS) was determined by ¹³C NMR spectroscopy. FTIR spectroscopy data confirmed the formation of cellulose ether. The dynamic viscosity of the obtained samples for 2 % aqueous solutions ranged from 35 to 58 Pa · s. Discussion and Conclusion. The developed method demonstrates the possibility of efficiently producing HPMC from renewable hemp raw material under laboratory conditions. The process is reproducible and controllable, with the yield of the target product ranging from 76 to 81 %.