Cycloaddition. -Significant amounts (20-45% NMR) of undesired regioisomers are also generated in some cases. -(MORI, A.; ARAKI, T.; MIYAUCHI, Y.; NOGUCHI, K.; TANAKA*, K.; Eur.

Complementary theoretical and experimental studies of the consecutive steps of superacid catalyzed polyhydroxyalkylation reactions have been carried out. Calculations for the superacid catalyzed polyhydroxyalkylation of trifluoroacetone and trifluoroacetophenone with aromatic hydrocarbons explained a number of experimental facts within a single theoretical framework of monoprotonation. The principal factors affecting kinetics of superacid mediated hydroxyalkylation were shown to be as follows: (i) the acidity of the superacid affecting protonation energy of carbonyl components; (ii) the electrophilicity of carbonyl components; and (iii) the nucleophilicity of aromatic components. The modification of those factors allows for tuning of the reactivity of carbonyl and aromatic components; thereby, reaction kinetics are controlled. The conclusions were confirmed by the experiments. Theoretically predicted stoichiometrically imbalanced polymerizations of trifluoroacetone, trifluoroacetophenone, octafluoroacetophenone, and isatin with nonactivated, aromatic hydrocarbons gave high-molecular-weight polymers with a very small excess of the carbonyl compound. The main reasons contributing to the polymerization accelerations were found to be an increase of the first, rate-determining step reaction, and a high efficiency of the superacid catalyzed polyhydroxyalkylations. The present work has thus opened a new route to preparations of polymers of linear, hyperbranched, or hybrid (e.g., linear−hyperbranched) architecture by operating on structural parameters and reaction conditions.

No abstract

A novel series of linear, high-molecular-weight polymers and copolymers was synthesized by one-pot, metal-free superacid-catalyzed reaction of trifluoromethylalkyl (1a−1c) and trifluoromethylaryl (1d−1h) ketones with the linear, nonactivated, multiring aromatic hydrocarbons biphenyl (A), p-terphenyl (B), and p-quaterphenyl (C). The polymerizations were performed at room temperature in the Brønsted superacid trifluoromethanesulfonic acid (CF 3 SO 3 H, TFSA) and in a mixture of TFSA with methylene chloride. Polymerizations of trifluoromethyl ketones (1c, 1f−1h) bearing functional groups gave polymers with reactive lateral groups such as bromomethyl, 4-(N,N-dimethylamino)phenyl-, 3-sulfophenyl-, and 2,3,4,5,6-pentafluorophenyl. The polymers obtained were soluble in most common organic solvents and flexible transparent films could be cast from the solutions. 1 H and 13 C NMR analyses of the polymers synthesized revealed their linear structure with para-substitution in the phenylene fragments of the main chain. The molecular weights (M w ) of the polymers based on trifluoromethylalkyl ketones and aromatic are very high and reach 1 000 000, while the molecular weights of the polymers based on trifluoromethylaryl ketones and aromatic ranged from 30 000 to 300 000 g/mol. The polydispersity of the polymers is generally less than 2. The polymers also possess high thermostability. Mechanistic aspects of polymerization mechanism have been discussed, and a new approach for monomer design has been proposed.

The formation of "Russian doll" complexes consisting of [n]cycloparaphenylenes was predicted using quantum chemistry tools. The electronic structures of multiple inclusion complexes containing up to four macrocycles were explored at the M06-2X/6-31G* level of theory. The binding energy between the macrocycles increases from the center to the periphery of the complex and can be >60 kcal mol(-1) for macrocycles containing 14 and 19 repeating units. It has been demonstrated that additional electrostatic interactions originating from the asymmetric electron density distribution observed when comparing the concave and convex macrocycle sides are responsible for the high binding energies in these Russian doll complexes. Oxidation or reduction of the Russian doll complexes creates polarons that are delocalized across the complexes. In the case of polaron cations, most of the polarons are localized at the macrocycle with the smallest ionization potential; for polaron anions, the negative charge is localized across the outer rings of the complex. Because anion polarons are more delocalized than cation polarons, the relaxation energies of the polaron anions were found to be smaller than those of the polaron cations.

Three possible reaction pathways have been studied for the Cl 2 (PMe 3 ) 2 RudCH 2 and Cl 2 (PCy 3 ) 2 RudCH 2 (Cy ) cyclohexyl) mediated metathesis reaction of propylene by quantummechanical DFT calculations. It was found that in all cases the metathesis reaction proceeds via dissociative substitution of a phosphine ligand with propylene, giving a monophosphine complex. This tendency increases with ligand volume, and in the case of smaller PMe 3 groups it is the entropy contribution to the reaction energetics that causes the monophosphine complex to participate in the metathesis reaction, according to the modeling data.

A novel series of linear, high-molecular-weight polymers was synthesized by one-pot, metalfree superacid-catalyzed reaction of isatins (1a-d) with linear, nonactivated, multiring aromatic hydrocarbons: biphenyl (A), p-terphenyl (B), p-quaterphenyl (C), 2-(4-biphenylyl)-6-phenylbenzoxazole (D), 9Hfluorene (E), 9,9-dimethyl-9H-fluorene (F), 2,2 0 -[2,5-bis(trifluoromethyl)-1,4-phenylene]bis(9,9-dimethyl-9H-fluorene) (G), oligo-9,9-bis(2,6-ethylhexyl)-9H-fluorene (H), biphenol (I), and bi-2-napththol (J). The reactions were performed at room temperature in the Brønsted superacid trifluoromethanesulfonic acid (CF 3 SO 3 H, TFSA) and in a mixture of TFSA with methylene chloride or TFA tolerant of hydroxyl, carboxy, and cyano groups. The polymers obtained were soluble in most common organic solvents, and flexible transparent films could be cast from the solutions. 1 H and 13 C NMR analyses of the polymers synthesized revealed their linear structure with para-substitution in the phenylene fragments of the main chain. The molecular weights M w and M n of the polymers ranged from 54200 to 742000 and from 40140 to 438500 g/mol, respectively. Most of the polymers also possess narrow polydispersity (1.15-1.50). The oxindole groups of the polymers react smoothly with alkyl bromides under basic conditions in N-methylpyrrolidinone (NMP). The amount of "click"able allyl-and propargyl-functionalities is readily controlled by adjusting the reaction ratio of polymer to alkyl bromides. The demonstrated efficiency and orthogonality of isatin-based polymer chemistry shows it to be an essential addition to the family of polymer "click" reactions.

Reaction of carbonyl compounds bearing electron-withdrawing substituents with non-activated aromatic hydrocarbons proceeds selectively in trifluoromethanesulfonic acid (TFSA) at room temperature to give linear, high-molecular-weight polymers.