Gas-Phase Ozone Oxidation of Monoterpenes: Gaseous and ...

GAS-PHASE OZONE OXIDATION OF MONOTERPENES 217
Table IV.
(Continued)
Name Structure Pseudo-molecular ions in CI
mass spectrum
P 9 :C 10 H 16 O 4 M+73: 612 M+1: 540
hydroxy pinonic acid M-15: 524 M-89: 450
MW = 200 M-181: 358 M-197: 342
deri. MW = 539 M-326: 213
P 10 :C 8 H 12 O 2 M+1: 530 M-181: 349
2,2-dimethyl-cyclobutane-1,3- M-197: 333 M-224: 306
dicarboxaldehyde
MW = 140
deri. MW = 530
P 11 :C 9 H 12 O 2 M+29: 571 M+1: 543
3-oxo-pina ketone M-197: 345
MW = 152
deri. MW = 542
mono-deri. MW = 347
a deri. denotes derivative.
b Identification confirmed with an authentic standard.
ure 1(a) are ascribed to the mono-derivative of 3-keto-nopinone, with a MW of 347.
For a dicarbonyl, PFBHA may derivatize only one of the two carbonyl groups and
leave the other intact if unfavorable derivatization conditions occur. Among unfavorable
conditions are steric hindrance and insufficient amount of derivatization
agent and reaction time.
Compounds P 4 ,P 5 ,P 6 ,P 7 ,P 8 ,andP 9 have both carbonyl and OH/COOH groups
(type 3 compounds), indicated by their presence in both Figures 1(a, b). Compound
P 4 is tentatively identified as a hydroxy substituted nopinone, 3-hydroxy-pina
ketone or 1-hydroxy-pina ketone. The derivatized form of P 4 has a MW of 421
(see Figure 2-P 4 for its CI mass spectrum). Compound P 5 is tentatively identified
as 2,2-dimethyl-3-formyl-cyclobutyl-methanoic acid, having a MW of 423 for its
derivatized form (Figure 2-P 5 ). Three peaks, labeled P 6 in Figure 1, are identified to
have a MW of 437, indicated by the presence of several pseudo-molecular ions in
their CI spectrum at m/z 510, 438, 348, 256, and 240, corresponding to M+73, M+1,
M-89, M-181, and M-197 (Figure 2-P 6 ). The observation of three peaks indicates
that at least two isomers with the same number and type of functional groups
are present. The following three isomers are possible candidates with structures
consistent with the EI and CI mass spectra fragment patterns: