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Table 1 Relative reactivity of isocyanates with nucleophiles (Herrington & Hock 1998)

From: The fire toxicity of polyurethane foams

Nucleophile with active hydrogen Structure Relative reaction rate (uncatalysed, 25 °C)
Primary aliphatic amine R-NH2 100,000
Secondary aliphatic amine R-NH-R’ 20,000–50,000
Primary aromatic amine Ar-NH2 200–300
Primary hydroxyl R-CH2-OH 100
Water H2O 100
Carboxylic acid R-COOH 40
Secondary hydroxyl R-CH(OH)-R’ 30
Di-urea R-NH-CO-NH-R’ 15
Tertiary hydroxyl (R)3-C-OH 0.5
Urethane R-NH-COOR 0.3
Amide R-CONH2 0.1