9046-40-6

powder pH (1%) 4.2-5

forms strong resilient films and fibers

Citrus pectic acid (500g) is refluxed for 18hours with 1.5L of 70% EtOH, and the suspension is filtered hot. The residue is washed with hot 70% EtOH and finally with ether. It is dried in a current of air, ground and dried for 18hours at 80o under vacuum. [Morell & Link J Biol Chem 100 385 1933.] It can be further purified by dispersing it in water and adding just enough dilute NaOH to dissolve the pectic acid, then passing the solution through columns of cation-and anion-exchange resins [Williams & Johnson Ind Eng Chem (Anal Ed) 16 23 1944], and precipitating with two volumes of 95% EtOH containing 0.01% HCl. The precipitate is worked with 95% EtOH, then Et2O, dried and ground. [Rees & Walsh Angew Chem Int Edn 16 214 1977, Rees Adv Carbohydr Chem 24 267 1969.]