Abstract: A porous polysaccharide gel is cross-linked in that(a) the gel is substituted with a monofunctional reagent having at least one functional group that can be activated,(b) the functional group of the reagent is activated,(c) the activated group is reacted,(d) the resulting product is, optionally, reacted with the monofunctional reagent,(e) the steps (b) and (c) are repeated, and(f) the steps (d) and (e) are repeated at least once.

Abstract: Novel pyridine compounds having the formula R.sup.1 -S-S-A-Z are disclosed, in which formula R.sup.1 is 2-pyridyl, 5-nitro-2-pyridyl or 4-pyridyl, A is a hydrocarbon residue having 1-10 carbon atoms and Z is a group ##STR1## or acid addition salts of the last mentioned group, where n is 2 or 3, R.sup.1 has the same significance as R.sup.1 above and is equal thereto and R.sup.2 is methyl or ethyl. These compounds are particularly useful as bifunctional coupling agents and as thiolating agents.

Abstract: A novel class of reactive derivatives of polymers containing HS-groups is disclosed in which derivatives a number of the HS-groups are converted to a disulphide group of the formula -S-S-A-Z, where A is a hydrocarbon residue having 1-10 carbon atoms and Z is a group ##STR1## or acid addition salts of the last mentioned group, where n is 2 or 3, R.sup.1 is 2-pyridyl, 5-nitro-2-pyridyl or 4-pyridyl and R.sup.2 is methyl or ethyl. The novel derivatives may be used, for example, as thiolating agents or as carriers for e.g. enzymes or other proteins etc.

Abstract: Novel pyridine compounds having the formula R.sup.1 -S-S-A-Z are disclosed, in which formula R.sup.1 is 2-pyridyl, 5-nitro-2-pyridyl or 4-pyridyl, A is a hydrocarbon residue having 1-10 carbon atoms and Z is a group ##STR1## or acid addition salts of the last mentioned group, where n is 2 or 3, R.sup.1 has the same significance as R.sup.1 above and is equal thereto and R.sup.2 is methyl or ethyl. These compounds are particularly useful as bifunctional coupling agents and as thiolating agents.