Allantoin Vivant exists in cystic liquid, fetal urine as well as some plants. However the expense of drawing out capsules from these substances is expensive. Currently, the methods of manufacturing Allantoin Vivant consist of: potassium permanganate oxidation urea acid technique; dichloroacetic acid as well as urea home heating to synthesize allantoin; glyoxylic acid and also urea direct condensation approach.
1. The procedure of using dichloroacetic acid and urea as resources is as follows: put salt methoxide option and also methanol right into the reaction storage tank, warm to 40-50 ° C, slowly include dichloroacetic acid dropwise, and reflux for 2 hrs after the enhancement.It was cooled to room temperature level, filtered, cleaned with methanol, and the filtrate was integrated and also washed with methanol service of salt dimethoxy. The remedy was reduced to dryness under lowered pressure, 2.8 parts of hydrochloric acid was added, heated up on a water bathroom as well as mixed right into a paste.After that heat up to 90 ° C, after that awesome to about 10 ° C, filter, add 0.25 parts of hydrochloric acid and urea to the little fluid, warm to dissolve, and also react at 80 ° C for 2 hours. Amazing and also crystallize, after that keep at 0 ° C for greater than 3 hours, centrifuge, clean with water, rotate dry, as well as completely dry to acquire a fine product. The unrefined product was recrystallized with 15 times of water to obtain allantoin. The complete return of p-dichloroacetic acid was 30.3%.
2. Operation example of straight condensation of glyoxylic acid as well as urea (glyoxylic acid is gotten by oxidation of glyoxal):.
( 1) Oxidation In a 500ml four-necked flask equipped with a mechanical mixing, a condenser, a thermometer as well as a going down channel, include 193g (1mol) of 30% glyoxal aqueous solution, and also add 135.5 g dropwise under mixing at a temperature level of 40 ± 2 ° C.( Chemicalbook 1mol) 45% nitric acid, remain to stir and also react at this temperature for 2-3h after the addition, until the reddish-brown oxidation no longer gets away, and also the reaction solution is turquoise as well as goes away. Change to a basic purification gadget, vapor about 125g of water at about 2.76 kPa as well as the exterior temperature level does not surpass 60 ℃, the focused option is maintained area temperature overnight, as well as the precipitated oxalic acid crystals (19g after drying, amounting to 0.21 mol), the focus is 39% ). Remain to stir the reaction at an internal temperature level of 40 ± 2 ° C for about 8 hrs, as well as the oxidation reaction is completed.
( 2) Condensation In a 500ml three-necked flask outfitted with a mechanical mixing, a condenser as well as a thermostat, add the above-mentioned 150g glyoxylic acid aqueous option, then include 170g (2.83 mol) urea and also 23.3 g concentrated hydrochloric acid, and also warmth to an interior temperature of 80 ° C under mixing. ° C. After around 15 minutes, the urea was dissolved, and the catalyst was a clear liquid. After about 30-45 minutes, the reactant showed up gloomy, and then the white precipitate slowly enhanced. Stir at an internal temperature of 80 ° C for 1 hr, quit heating and also cool down the reactant to space temperature. The white precipitate was gathered with a Buchner funnel and also precipitated with cold water for numerous times to acquire crude Allantoin Vivant. Recrystallize with 1000ml of distilled water. Get white great crystalline allantoin 60-63%, melting point 236 ℃ (disintegration). The return of Allantoin Vivant was 38-40% of concept based on glyoxal (103-108% by weight).
