The Preparation And Application Research Of Natural Moisture Retention Reagent

In this thesis, the synthesis, optimization, performance identification of2,2,6,6-tetramethyl-1-piperidine-N-oxyl free radical (TEMPO) and moisture retention ofthe oxidated chitin were primarily researched.2,2,6,6-Tetramethyl-1-piperidine-N-oxyl free radical was synthesized by two steps. Inthe first step, 2,2,6,6-tetramethyl-4-piperidinone (industrial grade) was reducted to2,2,6,6-tetramethyl-piperidine with the hydrazine and strong alkali by the HuangminglongReaction, which includes the formation of the hydrazone and the decomposition of thehydrazone. The optimized reaction conditions of the formation of the hydrazone is: thereaction is kept at 120℃ for 2h with the ratio(hydrazine:2,2,6,6-tetramethyl-4-piperidinone)2.0:1(mol ratio). The optimized reaction conditions of the decomposition of the hydrazone isthat the reaction is kept at 190℃ for 2h. In the second step, 2,2,6,6-tetramethyl-piperidinewas oxidated to TEMPO by 30% hydrogen peroxide with Mg(OH)2 as the catalyst. Afterbeing recrystallizated, the product was identified by IR, UV, DSC and ESR. The betteroptimized conditions is: the reaction is kept at 65℃ for 10h with the ratio (hydrogenperoxide: 2,2,6,6-tetramethyl-piperidine) 2.5:1(mol ratio), the titration time of hydrogenperoxide 6h, methanol as the solvent and Mg(OH)2 as the catalyst. The yield of two stepsreached to 66.34% and 80.17%. No data about the synthesis of TEMPO is reported in thedomestic.Oxidated chitin was prepared by the oxidation of the chitin with the NaClO solution,TEMPO and NaBr as the catalyst. After being purified, the product was inspected that thereis C6 carboxyl in it by 13C-NMR and IR. The selection of materials and synthesistechnological conditions were researched, the proper reaction temperature and pH wereacquired, the yield is up to 40%. The control of oxidated degree is a main research directionin future. No data about the synthesis of oxidated chitin is reported in the domestic.The moisture retention of oxidated chitin was researched and compared with lots ofmoisture retention reagent (glycerol, aloe, silk p, sorbitol, hyaluronic acid, chitosan). Themoisture retention of all the moisture retention reagent were acquired with the comparisonwith the loss of moisture, which were determined on the definite conditions. On the sameconditions and at the same concentration, the moisture retention of HA is the best, that ofoxidated chitin is the second and the chitosan is the worst. From these data we also foundthat the moisture retention between oxidated chitin and HA is approximate. But the cost ofoxidated chitin is low, so it is very possible that it is applied in the cosmetics instead of HAin the future.