Peroxidation of ketones and aldehydes with iodine as a catalyst was studied. Ketones reacted with 30% aq hydrogen peroxide in the presence of 10 mol % of iodine to yield gem-dihydroperoxides in ...acetonitrile and hydroperoxyketals in methanol. The yield of hydroperoxidation of various cyclic ketones was 60−98%, including androstane-3,17-dione, while acyclic ketones were converted with a similar efficiency. Aromatic aldehydes were also converted to gem-dihydroperoxides with hydrogen peroxide and iodine as catalyst in acetonitrile and to hydroperoxyacetal in methanol, while the reactivity of aliphatic ones remained the same as in noncatalyzed reactions. tert-Butylhydroperoxide reacted in a similar manner, giving the corresponding perether derivatives. A study was also made of the relative kinetics of dihydroperoxidation from which the Hammet equation gave a reaction constant (ρ) of −2.76, indicating the strong positive charge development in the transition state and the important role of rehybridization in the conversion of hydroperoxyhemiketal to gem-dihydroperoxide. In acetonitrile, the iodine catalyst is apparently able to discriminate between the elimination of a hydroxy, methoxy, and hydroperoxy group and addition of water, methanol, and H2O2 to a carbonyl group.
Soil contaminated with cadmium presents a potential hazard for humans, animals and plants. The latter play a major role in the transfer of cadmium to the food chain. The uptake of cadmium and its ...accumulation by plants is dependent on various soil, plants and environmental factors. In order to identify soil properties with statistically significant influence on cadmium concentration in vegetables and to reduce the collection of data, time and costs, regression models can be applied. The main objective of this research was to develop regression models to predict the concentration of cadmium in 9-vegetable species: zucchini, tomato, cabbage, onion, potato, carrot, red beet, endive and chicory, based on soil properties. Soil samples were collected from 123 home gardens of the Municipality of Celje and 59 of these gardens were also included in vegetable sampling. The concentration of elements (e.g. arsenic, cadmium, copper, lead, and zinc) in the samples was determined by Inductively Coupled Plasma Mass Spectrometry. Single (for cabbage, potato, red beet and chicory) and multiple (for tomato, onion, carrot and endive) linear regression models were developed. There was no statistically significant regression model for zucchini. The most significant parameter for the influencing the cadmium concentration in vegetables was the concentration of cadmium in soil. Other important soil properties were the content of organic matter, pH-value and the concentration of manganese. It was concluded that consuming carrots, red beets, endives, onions, potatoes and chicory which are grown in gardens with Cd concentrations (mgkg−1 DW) above 2.4, 3.2, 6.3, 7.9, 8.3 and 10.9, respectively, might represent an important contribution to dietary Cd exposure.
•High Cd concentrations were determined in selected root and leafy vegetables.•Single and multiple regression models were developed to predict Cd concentrations.•Important model parameters were Cd and Mn concentrations, pH-value and organic matter.•Intake of two-thirds of contaminated selected vegetables may increase Cd exposure.
We addressed the condition of restored soil on alluvial plain in the south-eastern Slovenia after they have been given for the gravel deposit easement during construction. According to ...pre-investigation using soil probes, two soil profile pits were dug: Profile 1 on the area where excavated soils were deposited over original soils; and Profile 2 on the area where topsoil had been removed before gravel deposition and reapplied after the easement. Undisturbed and disturbed soil samples were collected and analyzed for physical and chemical properties. The results show that chemical properties were generally not the limiting factor for soil fertility. Compaction of the soil reduced hydraulic conductivity and resulted in water stagnation. The bulk density on the area where the material was deposited directly on the soil surface ranged from 1.41 to 1.77 g cm-3. The hydraulic conductivity of the saturated soil was practically impermeable at depths of 10, 20, and 30 cm, indicating compaction due to high mechanical load. At the area where topsoil was removed before deposition and restored after easement the hydraulic conductivity of the saturated soil was low to moderate. Removal of the topsoil before construction began was an appropriate action, but reclamation measures are also required.
Iodine has been shown to be an efficient catalyst for the selective dihydroperoxidation of ketones with aqueous hydrogen peroxide. Ketones were directly converted to their corresponding ...gem-dihydroperoxides using a "green" oxidant (30% aq H(2)O(2)) and a simple catalyst (iodine) under neutral conditions in acetonitrile. The yield of hydroperoxidation of various cyclic ketones was 60-98% including androstane-3,17-dione, and acyclic ketones were converted with a similar efficiency. reaction: see text
•Soil probing revealed high variability of soil development in the Dinaric Mountains.•Stem analysis of 65 dominant silver fir trees displayed differences in height growth.•Tree age and soil ...parameters were the key factors for height growth of trees.•Competition intensity and soil parameters were the key factors for radial growth.•The influence of competition on radial increment was the highest on leached soils.
Tree growth can be influenced by a wide variety of complex interacting factors. The contribution of soil to site productivity is confounded by the interactions between other site factors and silviculture. The contribution of soil properties to the growth of silver fir (Abies alba Mill.) was studied in the Dinaric Mountains, which are characterised by abundant sinkholes and limestone outcrops, resulting in diverse micro topography and different soil development at small spatial scales. Basal area increment and height growth data were estimated based on stem analysis of dominant silver fir trees (n=65) on a 50m×50m sampling grid, and competition intensity was determined. The soil development around each tree was defined using morphological properties of the genetic horizons based on soil probing (n=65×12). In the study area, the chemical and physical soil characteristics (based on 21 soil profiles) were favourable for plant growth. Soil parameters e.g. soil depth, thickness of genetic soil horizons, share of soil types around each tree and soil associations were the factors controlling tree growth. Tree age and competition intensity were also influential factors in the case of height and radial tree growth respectively. Positive effects on height and radial growth were confirmed also for available water capacity of soil and location of tree in slope position (in the sinkhole, out of the sinkhole). The decrease in specific basal area increment with increasing competition intensity was most evident for trees growing on leached soils. The coefficient of determination and the statistical significance of the relationship between height growth and soil association over the last 100years emphasised the cumulative effect of the soil condition on tree height growth.
Efficient hydrogen peroxide enhanced iodofunctionalisation of ketones, 1,3-dicarbonyl derivatives and activated aromatic molecules using elemental iodine in water is achieved, whereas alkynes were ...stereoselectively converted into (E)-1,2-diiodoalkenes.
KLJUČNE BESEDE kmetijska zemljišča, pridelovalni potencial, boniteta, nadomestna kmetijska zemljišča, komasacije ABSTRACT _ Agricultural soils are a non-renewable natural resource, and substitute ...land can only be acquired at the cost of losing other resources, such as forest ecosystems or restoring degraded land. An alternative is to improve soils of poorer quality through topsoil application and meliorative measures, thus increasing the production potential of existing agricultural land. In this paper, we present the measure of topsoil addition for maintaining production potential and the method of calculating the agricultural land equivalent (EKZ) to evaluate the impact of topsoil addition. The examples of EKZ calculation presented show that the addition of fertile topsoil can be an appropriate measure to mitigate the effects of soil sealing on the loss of production potential of agricultural land but not to the same extent for all soil types.
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