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Isocyanates and Isothiocyanates

2.2.3.1—
Isocyanates

Phenyl isocyanate (PIC) reacts with primary and secondary amines to form N,N'-disubstituted ureas
(Fig. 2.5). [22]

1-Naphthyl isocyanate (NIC) can be used for an HPLC pre-column derivatization reagent of amino
acids [23]. Derivatization is carried out by adding the isocyanate dissolved in dry acetone to a buffered
amino acid solution followed by extraction of the excess reagent with cyclohexane. The resulting
naphthylcarbamoyl amino acids are stable and highly fluorescent (excitation maxima at 385 and 305
nm, and an emission maximum at 385 nm). UV detection near 222 nm, the absorption maximum, can
also be employed. UV detection is considerably less sensitive than fluorometry. However, for cystine
and tryptophane

Fig. 2.5.
The reaction of PIC with primary amines.

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