Patent ID: 7812151

Claim:
A process for the preparation of a depolymerized-LMW-epiK5-N,O-sulfate containing 40%-60% iduronic units, containing at least 40% 3-O-sulfate groups in glucosamine units, having a sulfation degree of from 2.3 to 2.9 and characterized by the structure (a′) in which R represents hydrogen or SO 3 − at the reducing end of the majority of its chains, which comprises (a) treating a tertiary or quaternary organic base salt of a depolymerized-LMW-epiK5-N-sulfate containing 40%-60% iduronic units with a sulfation agent under O-oversulfation conditions to obtain a depolymerized-LMW-epiK5-amine-O-oversulfate, (b) submitting the depolymerized-LMW-epiK5-amine-O-oversulfate thus obtained to a selective O-desulfation to obtain a depolymerized-LMW-epiK5-amine-O-sulfate, (c) treating a tertiary or quaternary organic base salt of the depolymerized-LMW-epiK5-amine-O-sulfate thus obtained with a O-sulfation agent to obtain a depolymerized-LMW-epiK5-amine-O-sulfate containing at least 80% 6-O-sulfate, and (d) submitting the depolymerized-LMW-epiK5-amine-O-sulfate containing at least 80% 6-O-sulfate thus obtained to a N-sulfation reaction and isolating the depolymerized-LMW-epiK5-N,O-sulfate thus obtained; wherein (a) comprises (a1) treating a depolymerized-LMW-epiK5-N-sulfate, in acidic form, with a tertiary or quaternary organic base for 30-60 minutes, maintaining the pH at about 7 by addition of the tertiary or quaternary organic base, and isolating an organic base salt of the depolymerized-LMW-epiK5-N-sulfate and (a2) treating the organic base salt of the depolymerized-LMW-epiK5-N-sulfate with an O-sulfation agent under O-oversulfation conditions and isolating the depolymerized-LMW-epiK5-amine-O-oversulfate.