Abstract: The present invention relates to a process for the preparation of high purity crystalline peptides Arg Lys Asp hydrate acetate and Arg Lys Asp Val from crude, amorphous peptides Arg Lys Asp and Arg Lys Asp Val hydrate acetate.The process is characterized in thatthe crude, amorphous peptide Arg Lys Asp or Arg Lys Asp Val is let stand at room temperature in 5 to 20 unit volume of ethanol containing 0.5 to 4.0% by volume of acetic acid and 5 to 25% by volume of water, wherein the volume unit is calculated for the mass unit of the material and mass unit relates to volume unit as g relates to ml,then the crystallized peptide is separated from the crystalline suspension, preferably after cooling.

Abstract: A process for the preparation of L-aspartyl-(O-sulfato-L-tyrosyl)-L-methionyl-glycyl-L-tryptophyl-L-methion yl-L-aspartyl-L-phenylalanine amide, which comprises treating the protected octapeptide amide of the general formula (II) ##STR1## wherein X is BOC, Cbz or Ddz,Y is O.sup.t Bu, OBzl or OH andW is O.sup.t Bu, OBzl or OH,in the presence of an ether with an excess of the complex compound of sulfur trioxide and a tertiary amine containing at least one alkyl group, converting the obtained sulfate ester of the protected octapeptide amide into an alkali metal salt and simultaneously removing the formyl group from the tryptophan unit by reacting the sulfate ester with an alkali metal hydroxide, and then splitting off the remaining protective groups by acidolysis.