Synthesis and refractive‐index control of fluoropolymers by the polyaddition of bis(epoxide)s and triazine di(aryl ether)s

The polyaddition of fluorine‐containing bis(epoxide)s and fluorine‐containing triazine di(aryl ether)s were examined to give the corresponding fluorine‐containing poly(cyanurate)s. It was observed that the synthesized fluoropolymers had good thermal stabilities and good film‐forming properties. The glass transition temperatures (T_g's) and refractive‐indices (n_D's) of synthesized polymers were determined by differential scanning calorimetry and ellipsometry, respectively, and it was found that the values of T_g's and n_D's were supported by their fluorine containing ratios and skeletons. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4421–4429, 2007     

Numerical analysis of finite amplitude motion of waves and a moored floating body under severe storm conditions

The motion of a moored floating body under the action of wave forces, which is influenced by fluid forces, shape of the floating body and mooring forces, should be analysed as a complex coupled motion system. Especially under severe storm conditions or resonant motion of the floating body it is necessary to consider finite amplitude motions of the waves, the floating body and the mooring lines as well as non-linear interactions of these finite amplitude motions. The problem of a floating body has been studied on the basis of linear wave theory by many researchers. However, the finite amplitude motion under a correlated motion system has rarely been taken into account. This paper presents a numerical method for calculating the finite amplitude motion when a floating body is moored by non-linear mooring lines such as chains and cables under severe storm conditions.     

Copper(II) diamino acid complexes: quantum chemical computations regarding diastereomeric effects on the energy of complexation

[reaction: see text] Quantum chemical calculations were used to rationalize the observed enantiodifferentiation in the complexation of alpha-amino acids to chiral Cu(II) complexes. Apart from Cu(II)[bond]pi interactions and steric repulsions between the anchoring cholesteryl-Glu moiety and an aromatic amino acid R group, hydrogen bonding also plays a role. In fact, in the case of tryptophan, C[double bond]O...H[bond]N hydrogen bonding between the glutamate moiety and the tryptophan N[bond]H group compensates for the loss of intramolecular hydrogen-bonding and diminished Cu(II)[bond]pi interactions.     

Pressure effects on the electron spin relaxation of several radicals in solution

The pressure effect on the decay rate of chemically induced dynamic electron spin polarization (CIDEP) was investigated on several free-radical intermediates in photolysis, and the spin-lattice relaxation times for these radicals were estimated from the decay rates of CIDEP signals at various pressures. The spin-lattice relaxation rates were retarded by increasing external pressure. From the pressure dependence of the spin-lattice relaxation rates the activation volume was estimated. The activation volumes of these radicals divide into two groups; ≈30 cm³ mol⁻¹ for negative ions and ≈10 cm³ mol⁻¹ for neutral radicals.     

Semiclassical study of collision-induced predissociation: Comparison of the Landau-Zener model with the method of analytic continuation

Semiclassical calculations are carried out by two methods for the problem of collision-induced predissociation of electronically excited I₂. The first method is that of surface-hopping with the Landau-Zener model. The second method is similar to surface-hopping, except that analytic continuation of the adiabatic potential energy surfaces replaces the Landau-Zener model. Results of the calculations by the two methods compare favorably with each other and with experiment. The possible advantages of the second method are discussed.Camille and Henry Dreyfus Teacher-Scholar, Alfred P. Sloan Research Fellow.     

A regio- and stereoselective alpha-methylation of gamma,delta-epoxy-alpha,beta-unsaturated esters with a Me2Zn-CuCN reagent

A highly regio- and stereoselective alpha-methylation reaction of gamma,delta-epoxy-alpha,beta-unsaturated esters was achieved by using a Me2Zn-CuCN reagent.     

1,3-Dipolar cycloaddition reaction of phenanthridinium N-imines and N-benzoylimine with acetylenic compounds

N-Aminophenanthridinium salt reacted with dimethyl acetylenedicarboxylate in the presence of potassium carbonate to give a 3,3a-dihydropyrazolo[1,5-f]phenanthridine but with mono-substituted acetylenes (ethyl propiolate and benzoylacetylene) it produced aromatized pyrazolo-[1,5-f]phenanthridines (XII and XIII). The reaction of the N-benzoylimine with di-substituted acetylenes (dimethyl acetylenedicarboxylate and methyl phenylpropiolate) and mono-substituted acetylenes (ethyl propiolate and benzoylacetylene) yielded 1,3a-dihydropyrazolo[1,5-f]phenanthridines and the aromatized products (XII and XIII), respectively.     

Studies of nucleosides and nucleotides—LXXIV: Purine cyclonucleosides—34 a new method for the synthesis of 2'-substituted 2'-deoxyadenosines

8,2'-O-Cycloadenosine was protected at 3' and 5'-OHs with acetyl groups and cleaved using liq. H₂S. Subsequent dethiolation and mesylation gave 2'-O-mesyl-3',5'-di-O-acetyl-arabinosyladenine (6). When 6 or its deacetylated parent compound (7) was heated with sodium azide in DMF, 3'-azido-3'-deoxyxylofuranosyladenine (9) was the only product. The cyclonucleoside was then protected with tetrahydropyranyl groups and subjected to a similar series of reactions as above to give 2'-O-mesyl-3',5'-di-O-tetrahydropyranylarabinosyladenine (14). The compound 14 was heated with sodium azide after which acidic deprotection afforded 2'-azido-2'-deoxyadenosine (16). Hydrogenation of 16 gave 2'-amino-2'-deoxyadenosine (18). 2'-Chloro-2'-deoxyadenosine (19) was also obtained by treatment of 14 with lithium chloride and subsequent deprotection. UV, IR and NMR spectral data of these compounds are described.