Study On The Phase Equilibrium And Crystallization Separation Of Synthetic Nitro-musks

Synthetic nitro-musks are used in the most wide area recently and industrial crystallization is the most important process to separate solid mixtures such as perfumes. In order to develop new crystallization process to separate synthetic nitro- musks, the phase equilibrium of musk ketone, musk xylene and 1,3-dimethyl-2, 4- dinitro-5-tert- butyl benzene were studied.The musk ketone + musk xylene system was proved to be simple eutectics by NRTL model from a molecular-interaction point of view. The solid-liquid phase equilibrium of musk ketone + musk xylene, musk ketone + 1,3-dimethyl-2,4-dinitro- 5-tert-butyl benzene, musk xylene + 1,3-dimethyl-2,4-dinitro-5-tert-butyl benzene were measured by DSC, the experimental results showed that these binary systems were simple eutectics. A interaction energy model was put forward, it was combined with Wilson model and was used to calculate the solid-liquid phase equilibrium of musk ketone + musk xylene. The predictive results agreed well with experimental results. The solubilities of musk ketone, musk xylene and 1,3-dimethyl-2,4-dinitro-5- tert-butyl benzene in solvents such as heptane were experimentally determined. Interactive parameters of UNIFAC model were regressed with experiment data, so the modified UNIFAC model obtained could correlate the solubilities of binary systems and had predictive function. The phase equilibrium of musk ketone + musk xylene + acetone + water and musk ketone + musk xylene + dimethyl sulfoxide (or acetonitrile) + cyclohexane(or heptane) quaternary systems were studied, in addition, the whole phase equilibrium and every part of the phase equilibrium of quaternary systems were shown by three-dimensional phase diagrams, the phase equilibrium of ternary and quaternary systems were expressed clearly. On the basis of above achievements, the methods to separate musks by crystallization were studied. A new process was proposed to get musk ketone and musk xylene from the eutectics by adding acetonitrile and heptane, which was verified by experiments. The experimental results showed that this process is feasible. A new process called "two liquid phases extractive crystallization" was put forward to separate the eutectics of musk ketone + musk xylene. The feasibility of the crystallization method to separate musk ketone + musk xylene + 1,3-dimethy-2, 4-dinitro-5-tert-butyl benzene completely at 15℃ and 40℃ by adding single solvent was studied. The laws of the phase diagrams were obtained. A method was put forward to get 1,3-dimethyl-2,4-dinitro-5-tert-butyl benzene crystals from saturated solution of musk ketone and 1,3-dimethyl-2,4-dinitro-5-tert-butyl benzene in ethanol utilizing the difference between the crystal growth speed of musk ketone and 1,3- dimethyl-2,4-dinitro-5-tert-butylbenzene.This method was verified by experiments and the 1,3-dimethyl-2,4-dinitro-5-tert-butyl benzene crystal with a purity of 98.2% was gotten.