Functionalization of a liquid natural rubber by iron‐mediated radical chloro‐nitration and its thermal decomposition

This study presents the functionalization of liquid natural rubber (LNR) by iron‐mediated radical chloro‐nitration over the LNR backbone, resulting in a chloro‐nitro compound of liquid natural rubber (Cl‐N‐LNR). The chloro‐nitration was prepared by a reaction of LNR with iron(III) nitrate nonahydrate and iron(III) chloride in an organic solvent. The structure of the obtained product was confirmed by using Fourier‐transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), and carbon‐13 nuclear magnetic resonance (13C NMR), which showed the existence of chloro‐nitro groups in the Cl‐N‐LNR chain. The degree of functionalization with a nitro group is 13.4% mol units of Cl‐N‐LNR. The thermal degradation was determined by the thermogravimetric analysis (TGA) method. As a result, the kinetic parameters for the degradation of Cl‐N‐LNR were calculated in the range from 40 to 330 °C. The half‐life of Cl‐N‐LNR was found to be about 33.0 years. LNR (5 grams) was put into a round‐bottomed flask and dissolved in ethyl acetate (50 mL). A solution of 1.575 grams of iron(III) nitrate nonahydrate and 1.490 grams of iron(III) chloride in 50 mL of ethyl acetate was slowly added to the above LNR solution. The reaction mixture was stirred and heated at a temperature of 78 to 80 °C for 1 hour. The obtained mixture was cooled to room temperature, agglomerated, washed with 5 times methanol, and dried under a vacuum for 24 hours. After drying, the product has a clear, dark yellow viscous liquid.