Comparative Properties of Ethyl, n -Butyl, and n -Octyl Cyanoacrylate Bioadhesives Intended for Wound Closure - Biologically Responsive Biomaterials for Tissue Engineering - page 96

Table 5.3 Assignment of the main characteristic signals in the
1 H NMR spectrum of the n -butyl cyanoacrylate monomer
H d (ppm) Multiplicity Integral

H 1 7.06 Single 1.00

H 2 6.62 Single 1.00

H 3 4.29 Triple 2.01

H 4 1.70 Multiple 2.20

H 5 1.38 Multiple 2.06

H 6 0.96 Triple 3.00

Fig. 5.7 13 C NMR spectra of the cyanoacrylate monomers

the cyanoacrylate monomer decreases by increasing the length of the alkyl chain.
The protons of the CH 2 groups appear at 4.3 ppm and the signal is less marked by
increasing the length of the alkyl chain in the cyanoacrylate monomer; however, the
signals of the protons at the end of the alkyl chain (below 1 ppm) are more intense
in the OCN. The signals at 2.18 and 1.25 ppm in the 1 H NMR spectrum of the BCN
monomer should correspond to aliphatic protons but they cannot be assigned to its
chemical structure; these signals can be ascribed to additives in the commercial
product. Similarly, the signals of the CH 2 of the OCN do not appear in its 1 H NMR
spectrum but several overlapped signals are shown at 0.95 and 1.42 ppm that cor-
respond to protons of this compound and to additives in the commercial product.
The 13 C NMR spectra of the cyanoacrylate monomers (Fig. 5.7 ) show the typical
signals of the different carbons in their structure. Table 5.4 shows as typical example