The relative thermodynamic stabilities of 2,5-dihydrofuran (1) and 2,3-dihydrofuran (2), and of 3,4-dihydro-6H-pyran (3) and 3,4-dihydro-2H-pyran (4), were determined at several temperatures by base-catalyzed equilibration in DMSO solution.The second-law reaction enthalpy agrees with literature data based on calorimetric enthalpies of hydrogenation of the isomeric forms in hexane. For 3 → 4, G • m = -19.3 ± 0.2 kJ mol −1 , H • m = -18.9 ± 1.1 kJ mol −1 and S • m = 1.1 ± 3.0 J K −1 mol −1 at 298.15 K: the experimental reaction enthalpy is in marked disagreement with literature data based on estimation. On the other hand, both of the experimental reaction enthalpies of the present study are in good agreement with DFT calculations using the B3LYP functional and 6-311 + G(2d,p) basis set.

Garden history can be investigated through archaeobotanical research. This paper discusses the plant remains which were obtained from the soil of the historical garden of the manor of Kumpula in Helsinki, Finland. This study was an experiment to enable macrofossil analysis without archaeological excavations. The aim was to develop an alternative method for sampling for macrofossils also including radiocarbon dates, and to evaluate the usability, cost and functionality of this method. The character of the garden was also considered. The soil samples for macrofossil analysis were collected from the garden from three to eight different levels using an end-filling open-ended sampler. A total of 38 one litre soil samples from eight different pits yielded 2,036 identified macrofossils, mostly seeds. These comprised 63 different taxa, of which 26 were identified to species level with certainty. Taxa with more than 25 seeds found were Chelidonium majus, Chenopodium spp., Juncus spp., Rubus idaeus, Sambucus racemosa and Urtica dioica. Important species were Secale cereale and Hordeum vulgare. Nine AMS radiocarbon dates were obtained from macrofossil material from four different pits, giving results ranging from 1120-920 cal BC to cal AD 1680-1930 for charred wood, and from cal AD 1450-1640 to 1640-1930 for charred grains of Secale cereale and seeds of Chenopodium album. The sampling method proved to work reasonably well, considering the limitations of the sample size.