Selective chemical reactions and polymers of controlled architecture produced thereby

A process for the preparation of a substituted amide, characterised in that a compound comprising an aliphatic carboxylic acid group and at least one substituent selected from alcohol and thiol groups is reacted with carbonyl diimidazole to convert the carboxylic acid group to a group of the formula:

• ##STR91## and the resulting compound (A') is reacted with a compound or polymer (B') comprising at least one primary amine group to produce the substituted amide.

A dendritic polymer comprising at least two limbs radiating from a core radical, each of said limbs comprising at least two branches, wherein the branches comprise a linkage selected from carbonate, urethane, urea, amide and ester linkages and that each link has a linkage selected from carbonate and urea linkages between the branches and the core.

A dendritic polymer comprising at least three limbs radiating from a central core, each of said limbs comprising at least two branches, wherein each limb has a linkage selected from carbonate and urea between the branches and the core.

A dendritic polymer comprising at least two limbs radiating from a core radical, each of said limbs comprising at least two branches, wherein the branches contain a linkage selected from carbonate, urethane, urea, amide and ester linkages and that each limb has a linkage selected from carbonate, urethane, urea, amide and ester linkages, at least one of the said linkages being a carbonate linkage.

A dendritic polymer comprising at least two links radiating from a core radical, each of said limbs comprising at least two branches, characterised in that the branches contain a first linkage selected from carbonate, urethane, urea, amide and ester linkages and that each limb has a second linkage selected from carbonate, urethane, urea, amide and ester linkages, wherein at least one of said first and second linkages being a carbonate linkage.

A thiol-tipped polymer of the formula:

• ##STR99## in which each group Ak represents an alkylene group having 1 to 4 carbon atoms and J represents a polymer chain of molecular weight 200 to 10,000.

A compound of the formula:

• ##STR100## wherein R.sup.1, R.sup.3 and R.sup.4 are each an alkyl or aryl group which can be substituted, R.sup.2 and R.sup.5 are selected from hydrogen or an alkyl group which can be substituted, A and A.sup.1 each represent a divalent organic linkage, n is an integer of at least 2 and Z is a core radical of valency n+1.

A compound of the formula:

• ##STR101## wherein R.sup.3 and R.sup.4 are each an alkyl or aryl group which can be substituted, R.sup.5 is selected from hydrogen or an alkyl group which can be substituted, and A and A.sup.1 each represent a divalent organic linkage.

A compound of the formula:

• ##STR102## wherein R.sup.3 and R.sup.4 are each an alkyl or aryl group which can be substituted, R.sup.5 is selected from hydrogen or an alkyl group which can be substituted, and A and A.sup.1 each represent a divalent organic linkage.

A compound of the formula:

• ##STR104## wherein R.sup.1 and R.sup.4 are each an alkyl or aryl group which can be substituted, R.sup.5 is selected from hydrogen or an alkyl group which can be substituted, A and A.sup.1 each represent a divalent organic linkage, n is an integer of at least 2, Z is a core radical of valency n+1, and Y is a core radical of valency m which is at least 2.

A compound of the formula:

• ##STR105## in which Y.sup.1 is a core radical of valency y which is at least 3, Xa is --O-- or --NH-- and wherein R.sup.3 and R.sup.4 are each an alkyl or aryl group which can be substituted, and R.sup.5 is selected from hydrogen or an alkyl group which can be substituted.