Xylylene Diisocyanate

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Abbreviations: XDI

Molecular formula: C10H8N2O2

Molecular weight: 188.19

o-XDI CAS number: 25854-16-4, EINECS number: 247-229-6

m-XDI CAS number: 3634-83-1, EINECS number: 222-852-4

p-XDI CAS number: 1014-98-8

Structural formula:

The industrial product of xylylene diisocyanate is mainly pure m-XDI, but there are also isomer mixtures of m-XDI (meta-xylylene diisocyanate) 70%–75% + p-XDI (para-xylylene diisocyanate) 30%–25%. Ortho-xylylene diisocyanate (o-XDI) is also available as a reagent. Pure p-XDI is not commercially available.

Physical and Chemical Properties

m-XDI is a colorless transparent liquid with a freezing point of approximately -7℃ and a boiling point (1.6 kPa) of 159–162℃; p-XDI has a freezing point of 45–46℃ and a boiling point (1.6 kPa) of 165℃.

At room temperature, XDI (isomer mixture) is a colorless transparent liquid. XDI is easily soluble in benzene, toluene, ethyl acetate, acetone, chloroform, carbon tetrachloride, and diethyl ether, but sparingly soluble in cyclohexane, n-hexane, and petroleum ether. Typical physical properties of XDI products are shown in Table 1-22.

Characteristics and Uses

XDI has a low vapor pressure and high reactivity. Because the isocyanate group in the molecular structure is not directly connected to the benzene ring but is separated by a methylene group (-CH2-), it prevents resonance between the benzene ring and the isocyanate group, making XDI and its polyurethane products light-stable and non-yellowing. It can be used in polyurethane coatings, elastomers, leather, adhesives, etc.