No abstract

Behandelt man ein Gemisch aus 4-Chlor-2-methyl-2-penten 1 und 2,3-Dimethyl-2-buten 2 mit ZinkchloridEther bei -78 °C, erhalt man das Cydobutan-Derivat 3 Pal I·) Priv.-Doz.

The main aim of the work is to assess physical parameters of forest woodchips and their impact on the prices achieved by the supplier in transactions with a power plant. During fragmentation of logging residue, high content of green matter and contaminants negatively impacts the quality parameters that serve as basis for settlements. The analysis concerns data on the main parameters -water content, fuel value, sulphur and ash content -from 252 days of deliveries of forest chips to a power plant. The deliveries were realised from forested areas on an average about 340 km from the plant. Average water content and the resultant fuel value of forest chips was within 27-47% and 8.7-12.9 GJ×Mg −1 (appropriately), respectively. They depend on the month in which they are delivered to the power plant. The threshold values for the above-mentioned parameters are set by the plant at a real level and the suppliers have no problems with meeting them. The parameter that is most frequently exceeded is ash content (11.5% of cases). The settlement system does not differentiate on the basis of the transport distance but gives possibility to lower the settlement price when the quality parameters are not met but provides no reward for deliveries with parameters better than the average ones. On the basis of results obtained, it was calculated that average annual settlement price is lower than the contract price by about 0.20 PLN×GJ −1 , which in case of the analysed company may translate into an average daily loss of about 700 PLN.

Allyl cations are versatile building blocks for the construction of carbocycles. Hoffmann has reported the syntheses of six-and seven-membered ring systems via [2+4]-and [3 + 4]-cycloadditions of allyl cations to 1,3-dienes"I.We previously found that [3 + 2]-cycloadditions of allyl cations to alkenes provide an easy access to cyclopentenesIZal, and now report [2 + 21-cycloadditions of allyl cations to afford cyclobutane derivatives.When a mixture of 4-chloro-2-methyl-2-pentene 1 and 2,3-dimethyl-2-butene 2 is treated with zinc chloride-ether at -78 "C, the cyclobutane 3l3"I is obtained in 72% yield1']. Similarly, 4-chloro-2,4-dimethyl-2-pentene 4 and 1-ethoxy-2-methyl-1-propene 5 give 80% 613b1. In both cases only one (probably the sterically favored trans) isomer is detected by N M R spectroscopy. No linear intermediates were detected. Lewis acid catalyzed rearrangements of 3 and 6 to give thermodynamically more stable five-membered rings, which would have to proceed via secondary carbenium ions, were not observed. Treatment of 3 with zinc chloride-ether at 20°C yields a complex mixture of products, which contains 2-chloro-2,3-dimethylbutane; its formation can be rationalized by [2 + 2]-cycloreversion of the cyclobutylcarbinyl cation and addition of HCl to 2. However, not all 1,l-dialkylated, 2-unsubstituted allylic systems react to form four-membered rings: under identical conditions reaction of l-chloro-3-methyl-2-butene with isobutene, 2-methyl-2-butene, and 2,3-dimethyl-2-butene yields exclusively linear addition products12b1. According to molecular mechanics calc~lations[~1, these acyclic adducts are more stable than the isomeric cyclobutane derivatives. On the other hand, the heat of formation of 3 is calc~l a t e d~~l to be 3.8 kcal/mol more negative than that of the isomeric 6-chloro-2,4,5,5,6-pentamethyl-2-heptene; gauche-interactions destabilize the linear isomer to a greater extent than the cyclic system (gem-dialkyl effecd5'). Since steric effects should be similar in the corresponding carbenium ions, the different behavior of 1 and l-chloro-3-methyl-2-butene in addition reactions with tetramethylethylene 2 can be rationalized.[ 59, 18.93, 21.23, 23.60, 25.84, 32.67, 32.91 (7q) NMR Studies of Yeasts Grown on Substrates at "Zero" Level RadioactivityBy Ricardo Basosi, Claudio Rossi, Enzo Tiezzi*, and Gianni Valensin The cultivation of different protein-rich microorganisms which utilize hydrocarbons (petrochemicals) as sources of carbon and energy has been frequently suggested'31. The nutritional and biological value as well as the level of toxic substances have still to be studied; the effect induced by a prolonged alimentation on substrates which have less than the natural level of I4C radioactivity has also still to be investigated.Since many correlations have been found between the N M R parameters of water and the physiological or pathological states of cells, as well as the conformations of cell constituents". l0-''1 . we have used water relaxation studies

Behandelt man" ein Gemisch aus dem Penten (I) und dem Buten (II) mit ZnCl2 , so erhält man das Cyclobutan‐Derivat (III).