Emissions from wood dryers have been of some concern for a number of years, and recent policy changes by the Environmental Protection Agency have placed emphasis upon the gaseous emissions that lead to the formation of particulate matter as small as 2.5 μm diameter. In this qualitative study, camphene, Δ3-carene, limonene, and α-terpinene were thermally degraded in the presence of air to determine the number and kind of oxidative degradation products that might be expected under drying conditions used in processing wood products. Various chromatographic methods were used to isolate the products for proof of structure by NMR and/or GC−MS. The degradation products resulted from dehydrogenations, epoxidations, double bond cleavages, allylic oxidations, and rearrangements. A number of compounds not previously associated with the thermal degradation of these terpenes were identified.

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Studies of flavan‐3‐ols in their biologically significant phenolic form show that both H‐6 and C‐6 resonances are downfield from H‐8 and C‐8. Therefore, assignments for the H atoms of the A‐ring are inverse to those commonly reported. By contrast, in the methyl ether and methyl ether acetate derivatives, both H‐8 and C‐8 are downfield from H‐6 and C‐6 and assignments commonly reported for C‐6 and C‐8 are incorrect. The assignments commonly reported for the peracetate derivatives are correct. In contrast to results observed for dimeric flavans, solvent effects on chemical shifts and coupling constants are small in monomeric flavan derivatives. The small heterocyclic ring J2,3 coupling constants of 2,3‐cis‐flavans can be defined by lineshape analysis of H‐3. These results provide the first evidence for the conformations of the common 2,3‐cis‐flavans in solution. With the exception of compounds carrying a bulky acetate at C‐3, a GMMX global search protocol provides reasonable predictions of heterocyclic ring coupling constants.