THE NATURE OF THE RESINS IN JACK PINE (PINUS BANKSIANA)

Abstract

Green and seasoned jack pine were found to have an average crude resin content of 4.58% and an ether-soluble of 3.52%. The value of "total acids" present in the resin was the same in each case, but the proportion of "fatty" acids was greater in green wood, while the unsaponifiable matter was considerably less. The seasoned wood contained a lower percentage of fats than the green wood and a correspondingly higher percentage of resin acids. The amount of unsaponifiable, polymerized terpenic substances was also higher. There was a marked decrease in the amounts of phytosterol and "resene" in the seasoned wood.The isolated resin acids obtained by distillation, or esterification, contained a high percentage of abietic acid formed by transformation of the original acids. The percentage of natural (pimaric) acids was, however, quite high in the resin acids isolated by petroleum ether and recrystallized only twice.A higher percentage of crystalline acids was found in the resin acids from green wood than from seasoned, due presumably to change into amorphous products during storage.The fatty constituents were chiefly members of the unsaturated series, present both as free acids, glycerides, or other esters. The seasoned wood contained much less linolic acid in the glycerides than green wood. Oleic acid was present in about the same proportion in both cases; linolenic was present in only very small amount. The free fatty acids had practically the same percentage composition in both green and seasoned wood.The amount of the total unsaturated fatty acids was higher in the glycerides and free acids from green wood than from seasoned wood. The latter was found to contain a high percentage (30.2%) of oxidized acidic material in the fatty glycerides, indicating that extensive polymerization, or decomposition of some kind, had taken place in the fats present in the green wood during the time of seasoning.The quantities of essential oil obtained from the resins of each kind of wood were very small, amounting to 1.5 to 4.3% of the total crude resins. The products showed no difference in properties, or variation in amount, with time of storage of the wood. Owing to the small amount available for investigation, only α-pinene could be identified, although other terpenes may possibly be present.The percentages of phytosterol and resene were extremely small, and were appreciably less in the seasoned than in the green wood. The amount of polymerized terpenic material found in the unsaponifiable matter was much higher in the case of the seasoned wood. This was probably due to extensive polymerization of the essential oil having taken place during the storage of the wood.