Study On The New Synthetic Process Of 1, 5-Naphthalene Diisocyanate And The Related Process

1,5-Naphthalene diisocyanate (NDI) is used as raw material of polyurethane elastomer with high performance. At present, the industrial production of NDI takes phosgene as raw material, which is dangerous and contaminable seriously. The synthesis of NDI from 1,5-naphthalene diamine (NDA) and bis(trichloromethyl) carbonate (BTC) as the phosgene substitute material has distinct advantages, such as moderate conditions, safe and simple and convenient operation, high yield and good quality, which is easy to be industrialized. The reaction and related process were studied in the thesis.It was identified by IR, MS, and infrared-tracking that the objective product of the reaction was NDI, and the main by-products of the reaction were hydrogen chloride, 1,5-naphthalene diamine hydrochlorate and urea. And a set of suitable and effective quantiative analysis of NDI was set up by detecting 1,5-naphthalene dicarbamate derived from NDI and methanol quantificationally using ultraviolet-visiblespectrophotometer, as follws: room temperature, methanol as solvent, λmax=290nm, light path 10mm. The quantiative analysis was carried out by external stander method. The result was reliable after verification.Based on the principle of chemometrics, the key reactions of the reaction system was analyzed and defined. The result of thermodynamics analysis of the system showed that the secondary-reaction bringing urea competed with the main-reaction, and it was beneficial to the main-reaction increasing temperature. Trichloromethyl carbamate and aminoacyl chloride were identified as intermediate compound. And reaction mechanism was deduced.It was found that solvent effect influenced the reaction greatly, and dimethyl carbonate was the best solvent among those employed in the thesis. The effects of reaction conditions on the yield of NDI were discussed. The result showed that reaction temperature and time were the main influencing factors. The yield of NDI could reach 87.4% for 5h at 90 ℃, NDA 22.5g.L-1, n(NDA):n(BTC)=3:2.5. HCl produced during the reacting process could protect amidogen, and improve the reaction selectivity objectively, because it could react with NDA to form fast reaction product - NDA hydrochlorate, which restrained NDA from reactingwith NDI to form urea. Under the experimental conditions, NDI could be synthesized from NDA hydrochlorate with BTC. The yield of NDI could reach 84.9% for 5h at 90℃, NDA hydrochlorate 50.0g.L-1, n(NDA hydrochlorate):n(BTC)=3:2.5.The kinetic equation was performed. The rate of this process may be described byr = ea(CA+b)0.5a=38.80435-0.291T + 4.23982×10-4T2b = 0.29982-0.00331T+ 6.78166 ×10-6T2The statistical test proved that the kinetic equation was significant. Based on the equation, a set of curve between reaction rate and reaction temperature at different CA, which resultshowed that the kinetic equation behaved all actions in the reaction system.Theoretically, the new synthetic process of NDI was put forward using NDA and methanol as raw material merely, BTC and DMC as semifinished product. The process hasremarkable advantages, such as high utility of atoms, clean production, low cost, safe and simple and convenient operation. So it is of great potential, and easy to be industrialized. The result of investigation proved that the synthetic method was efficient and feasible.