1H NMR Study of Hindered Internal Rotation of Tetramethylthiuram Disulfide in Binary Dimethyl Sulfoxide‐Chloroform Mixtures

Hindered internal rotation about the C‐N single bonds joining the thiuram disulfide was studied by ¹H NMR complete line‐shaped analysis in different dimethyl sulfoxide‐chloroform (DMSO‐CDCl₃) mixtures. From the temperature dependence of methyls proton spectra, activation parameters (E_a, ΔH^≠, ΔS^≠, and ΔG^≠) were obtained. The Arrhenius plots showed a distinct isokinetic temperature at about 35 °C at which the exchange rate is more or less independent of the solvent composition. The resulting ΔH^≠ against TΔS^≠ plot showed a firmly good linear correlation, indicating the existence of an enthalpy‐entropy composition in an exchange process.     

Joule-Thomson inversion curve prediction by using equation of state

In this paper five equations of state are tested for checking their ability to predict the Joule-Thomson inversion curve.These five equations of state are:Mohsennia-Modarres-Mansoori(MMM),Ji-Lemp(JL),modified Soave-Redlich-Kwang(SRK)equation of state by Graboski(MSRK1),modified SRK equation of state by Peneloux and Rauzy(MSRK2),and modified Peng-Robinson (PR)equation of state by Rauzy(PRmr).The investigated equations of state give good prediction of the low-temperature branch of the inversion curve,except for MMM equation of state.The high-temperature branch and the peak of the inversion curve have been observed,in general,to be sensitive to the applied equation of state.The values of the maximum inversion temperature and maximum inversion pressure are calculated for each component used in this work.     

Structural Elucidation of {[(CH3)2SnCl2·H2O]2·18-crown-6} n and its Hydrogen Bonding in Solution by HMBC Spectroscopy

Behavior of {[(CH₃)₂SnCl₂·H₂O]₂·18-crown-6}_n in solution have been investigated by HMBC NMR. The results show that coordination of water to tin containing species and its hydrogen bonding to crown ether remains intact in non-coordinating solvent in contrast to coordinating solvent. H-NMR reveals that the chemical shift of water in complex varies by solvent of crystallization.     

Quantitative reaction cascades of ninhydrin in the solid state

Crystalline ninhydrin (1) undergoes waste-free solid-state cascade reactions with dimedone, L-proline, three o-phenylenediamines, o-mercaptoaniline, two ureas, three thioureas, and methyl 3-aminocrotonate. The yields are quantitative and give pure crystalline products without workup just by milling stoichiometric mixtures of the crystalline reagents. The structures of the new and the previously obtained products with lower yields from solutions are established or confirmed by spectroscopic data and density functional calculations at the B3LYP/6-31G* level. The success of 3- and 4-cascade reactions in the crystal without melting is unusual and of unmatched atom economy. They are mechanistically investigated with atomic force microscopy techniques (AFM) on six different faces of 1 when o-phenylenediamine was the reagent (substitution, elimination, cyclization, elimination) and interpreted on the basis of known crystal structure data. Strict correlations to the crystal packings are observed. The characteristic surface features grow to microm heights in some cases at distances of 0.5 mm from the contact edge of the reacting crystals. The waste-free and easy syntheses of highly functionalized (C=O; O-H; C=N) heterocycles or of a tetraketone are also of interest for synthetic use.     

Normal subgroup based power graph of finite groups

Ricerche di Matematica - Let G be a finite group and $$N \unlhd G$$ . The normal subgroup based power graph of G, $$\Gamma _N(G)$$ , is an undirected graph with vertex set $$(G{\setminus }N) \cup...     

Optimizing pig marketing decisions under price fluctuations

In the manufacturing of fattening pigs, pig marketing refers to a sequence of culling decisions until the production unit is empty. The profit of a production unit is highly dependent on the price of pork, the cost of feeding and the cost of buying piglets. Price fluctuations in the market consequently influence the profit, and the optimal marketing decisions may change under different price conditions. Most studies have considered pig marketing under constant price conditions. However, because price fluctuations have an influence on profit and optimal marketing decisions it is relevant to consider pig marketing under price fluctuations. In this paper we formulate a hierarchical Markov decision process with two levels which model sequential marketing decisions under price fluctuations in a pig pen. The state of the system is based on information about pork, piglet and feed prices. Moreover, the information is updated using a Bayesian approach and embedded into the hierarchical Markov decision process. The optimal policy is analyzed under different patterns of price fluctuations. We also assess the value of including price information into the model.