Dammar table

Table 5.1 Components of fresh dammar resin, as reported in the literature [34] with corresponding m/z values of the sodium adducts (see Figure 5.6a)...

Several studies have dealt with the problem of discriminating between mastic and dammar, and three marker compounds of mastic have been identified moronic, masticadienonic and acetyl masticadienolic acids [42], The chemical structure of (iso)masticadienonic acid and 3-0-acetyl-3-epi(iso)masticadienonic acid is characterized by a side chain, as for dammarane molecules, but with a carboxylic acid end group (Table 12.1). Under pyrolysis conditions this side chain is susceptible to cleavage as demonstrated by the presence, among the pyrolysis products of mastic, of 2-methyl-pent-2,4-dienoic acid, that perfectly matches with the chemical structure of the side chain end. In addition 3-(9-acetyl-3-epi-(iso)masticadienolic acid also loses the acetyl group and, in contrast to masticadienonic acid, is not detected at all. 

The natural resins used for picture varnishes are made up of mixtures of larger molecules, many of which have now been separated and identified. The molecular formula of the major component of dammar, oleanonic acid (Boon and van der Doelen, 1999), is C30H45O3, MW 454. There are many terms that are used for this concept (Table 2.2), but this book will use molecular weight for simplicity. 

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