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The equilibrium of nitration of cellulose was studied at 13.1 and 20 ~ in aqueous solutions of HNO 3 (77.3--80.5 wt.%) forming quasi-homogeneous solutions with cellulose. At 20 ~ under quasi-homogeneous conditions, the rates of cellulose nitration are comparable to those of homogeneous nitration of alcohols. The effective nitration constants differ substantially for heterogeneous and homogeneous reactions. Using IR spectra, the partial conversions in the nitration to the 2, 3 and 6 positions of the glucopyranose cycle and the effective equilibrium constants of formation of different isomeric nitrates were estimated.Key words: cellulose, nitration, equilibrium, constants.The equilibrium of the reaction of cellulose (1) nitration by aqueous solutions of HNO 3 has been studied in detail, t-3 but the equilibrium constants of reactions of formation of different isomeric nitrates have been determined only in 1980--1990 J,4 using J3C NMR spectroscopy. At concentrations of HNO 3 below ~75 wt.% and above -82 wt.%, the nitration of cellulose is heterogeneous, j which can be due to a specific influence of the solid phase. Therefore, it was of interest to study the regularities of nitration of cellulose by nitric acid under homogeneous or close to homogeneity (gellike) conditions. The purpose of this work is to estimate the duration of nitration of a part of cellulose soluble in HNO 3, to analyze the effect of heterogeneity of the system on the equilibrium constants, and to study them in the region of formation of a quasi-homogeneous solution, using more accessible and widely abundant IR spectroscopy for the estimation of equilibrium constants of the cellulose nitration. ExperimentalSolutions of nitric acid with different concentrations were prepared by dilution of a stock 88.48% solution of HNO 3, and their concentrations were calculated from the weight of the stock solution and distilled water added. The stock solution was prepared by dilution of the concentrated acid distilled from fuming HNO 3 at a reduced pressure. Cotton cellulose with an ash content of 0.07% containing 98.4% a-cellulose was used.To study the equilibrium of nitration at 13.1 ~ samples of nitrocellulose (2) were prepared in several stages: first, at room temperature cellulose was mixed with a solution of HNO3 in a weight ratio of 1:(40_+0.01). The mixture was thoroughly homogenized and filtered through an acid-resisting filter. The gel-like transparent mass obtained was placed in a vessel, which was thermostatted at 13.1 ~ and had on the bottom several thick-walled capillaries with an inner diameter of ~1 mm closed with a ground plate. A vessel with a solution of nitrocellulose was hermetically mounted above another vessel thermostat'ted at the same temperature, provided with a magnetic stirrer, and containing a ~30-fold (relative to a solution of nitrocellulose) amount of 10% acetic acid. After thermostatting for 30 rain, the vessel with aqueous acetic acid was evacuated, and a solution of nitrocellulose was added through capillaries with stirring to a...

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