Polymerization behavior of 2,5‐bis(dicyanomethylene)‐ 2,5‐dihydrofuran

2,5‐Bis(dicyanomethylene)‐2,5‐dihydrofuran (TCNF) is not homopolymerizable with any initiators, but copolymerizable with styrene (St) in an alternating fashion. Reactivity of TCNF was compared with that of 2,5‐bis(dicyanomethylene)‐2,5‐dihydrothiophene (TCNT) on the basis of the terpolymerization of the TCNT‐TCNF‐St system and the rates of addition reactions of AIBN with TCNT and with TCNF. TCNF was found to be lower in reactivity than TCNT. The relative reactivity was explained with the energy difference between quinonoid structure and benzenoid one. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1285–1292, 1999     

Bis(2,5‐dimethoxy‐4‐methylphenyl)methane and bis(2,5‐dimethoxy‐3,4,6‐trimethylphenyl)methane

Bis(2,5‐di­methoxy‐4‐methyl­phenyl)­methane, C₁₉H₂₄O₄, (IIa), was obtained and characterized as a minor product from the reaction of tolu­hydro­quinone di­methyl ether (1,4‐dimethoxy‐2‐methylbenzene) with N‐(hydroxy­methyl)­tri­fluoro­acet­amide. Similarly, bis(2,5‐di­methoxy‐3,4,6‐tri­methyl­phenyl)­methane, C₂₃H₃₂O₄, (IIb), was prepared from the corresponding reaction of tri­methyl­hydro­quinone di­methyl ether (2,5‐dimethoxy‐1,3,4‐trimethylbenzene). The mol­ecules of (IIa) and (IIb) each lie on a twofold axis passing through the methyl­ene group. The dihedral angle between the planar phenyl rings is 73.4 (1)° in (IIa) and 77.9 (1)° in (IIb). The external bond angles around the bridging methyl­ene group are 116.6 (2) and 117.3 (2)° for (IIa) and (IIb), respectively. In (IIa), the methoxy substituents lie in the plane of the ring and are conjugated with the aromatic system, whereas in (IIb), they are almost perpendicular to the phenyl ring and are positioned on opposite sides.     

1,3,5,7‐Tetraselena‐2,4,6,8(2,5)‐tetrathiophenaoctaphane

The novel title tetraselenacalix[4]arene, C₁₆H₈S₄Se₄ or [(C₄H₂S)Se]₄, has a centrosymmetric cyclic molecular structure with approximate C_2h molecular symmetry. The four thienyl rings are joined together by Se bridges and exhibit a syn–syn–anti–anti arrangement around the mol­ecule. The lattice consists of skewed stacks of mol­ecules, with chalcogen–chalcogen close contacts binding the stacks together, forming a two‐dimensional network of mol­ecules.     

Magnesium and nickel(II) furan‐2,5‐dicarboxylate

The salts hexaaquamagnesium furan‐2,5‐dicarboxylate, [Mg(H₂O)₆](C₆H₂O₅), (I), and hexaaquanickel furan‐2,5‐dicarboxylate, [Ni(H₂O)₆](C₆H₂O₅), (II), provide the first crystallographic characterization of the furan‐2,5‐dicarboxylate dianion. Both structures exhibit extensive three‐dimensional hydrogen‐bonding networks between the octahedral coordinated hexaaquametal(II) ions and the dicarboxylate anions. Although the two structures are not isomorphous, they contain essentially identical two‐dimensional slabs. The distinction between the structures is that these slabs are related by translation in (II), whereas adjacent slabs in (I) are reflected relative to each other by the action of a glide plane. The reflection occurs so that the local contacts between slabs are not changed, and thus the hydrogen‐bond networks are identical except for the orientation of the water molecules at the interface between slabs.     

Synthesis of 2,5-bis-(Ethynyl) furan Derivatives from 2,5-Furandicarboxaldehyde

A synthesis of the title compounds has been accomplished by conversion of 2,5-furandicarboxaldehyde to the dilithium salt of 2,5-bis-(ethynyl) furan followed by reaction with electrophiles.     

The two diastereomers of [3] (2,5) (7,7,8,8-tetracyanoquinodimethano) - [3] (2,5-dimethoxyparacyclophane)

As the first set of stereomeric donor-acceptor cyclophanes with TCNQ as an acceptor, $\text{1}$ and $\text{2}$ were synthesized; their charge-transfer absorptions differ strongly as a consequence of the different donor-acceptor orientation.     

2,5-Diphenyloxazole chromium(III) complexes

Summary Complexes of chromium(III) with 2,5-diphenyloxazole (PPO) of general formula Cr(PPO)_nX₃·m H₂O, where X=Cl^–, Br^–, I^– or NO ₃ ^su– ; n=1–3 and m=0–6, have been prepared and studied by spectroscopic and magnetic methods and by molar conductivity measurements. All the complexes seem to be hexacoordinated, generally with monodentate N-bonded ligand.     

Ether Fission of 2,5-bis(Dialkylamino)hydroquinone Dimethylethers and O-Alkylation of 2,5-bis(Dialkylamino)hydroquinones

In connection with work underway in these laboratories on the total synthesis of Pentacyciic. triterpenes; guitable methods were sought for the introduction of angular methyl groups into preiormed polynuclear systems. A method of some generality was recognized in the work ofNagata³ on the organoaluminum catalyzed conjugate addition of cyanide to α,β-unsaturated ketones and subsequent conversion of the resulting cyano group to the desired angular methyl substttuent. The total synthesis of dl-alnusenone reported^4a earlier from these laboratories has this synthon as its central feature. Another approach that appeared attractive entailed the 1,6-addition ⁵ of cyanide to the dienone 1, available from intermediates already in hand.^4b     

Synthesis and some properties of poly-(2,5-trimethylene benzimidazole) and poly-(2,5-trimethylene benzimidazole hydrochloride)

A polymer, poly(2,5-trimethylene benzimidazole), the first of a new family of nonsymmetrical polymers, was synthesized via an eight-step synthetic route. The polymer, obtained by melt polymerization, is amorphous and in its neutral form behaves as a moderate insulator. It forms 1 : 1 HCl adducts. When cast from formic acid solution, it forms 1 : 1 formic acid adducts. The acid adducts are semiconductors with resistivities in the 10⁶–10⁸ ohm-cm range. Space-charge effects are generated in the adducts as carrier mobility rises.     

Thiophene‐2,5‐dicarboxylic acid bis‐aryl(alkyl) amides

A base‐catalyzed condensation of diacetamido sulfides [(RNHCOCH₂)₂S)] with glyoxal affording thiophene‐2,5‐dicarboxylic acid bis‐aryl(alkyl)amides has been accomplished under mild conditions. Excellent results were readily obtained when R was a substituted 3‐nitrophenyl, 4‐nitrophenyl, 4‐chlorophenyl group, but the yield was poor when R was cyclohexyl. Unknown compounds were characterized by elemental analyses, IR, ¹H, and ¹³C NMR techniques. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:503–506, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20153     

Polyimides based on 2,5‐bis(4‐aminophenoxy)biphenyl

A diamine monomer II , 2,5‐bis(4‐aminophenoxy)biphenyl, was prepared through a nucleophilic substitution reaction of phenylhydroquinone and p‐chloronitrobenzene in the presence of potassium carbonate in N,N‐dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. A series of all‐aromatic, organosoluble polyimides bearing pendent phenyl groups were synthesized from the diamine with six kinds of commercial dianhydrides via a conventional two‐stage process. For improving solubility of polypyromellitimide, copolypyromellitimides with arbitrary solubilities were prepared from II and a pair of dianhydrides, which were mixed at certain molar ratios. These polymers showed good solubilities in N‐methyl‐2‐pyrrolidone and m‐cresol. The softening temperatures of these polyimides were recorded between 206 and 269 °C. Polymers had glass‐transition temperatures at 230–286 °C and 10% weight‐loss temperatures above 521 °C in air or nitrogen atmospheres. Their films had high tensile moduli and strengths. Excellent properties of these polyimides are attributed to the incorporation of the pendent phenyl group in diamine II . © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 429–438, 2002; DOI 10.1002/pola.10116     

P,P′-(2,5-Dimethoxy-3,6-dimethyl-2,5-dioxo-2λ5,5λ5-[1,4,2,5]dioxadiphosphinan-2,5-diyl)-bis-phosphonsäuretetramethylester

P,P′-(2,5-Dimethoxy-3,6-dimethyl-2,5-dioxo-2λ⁵,5λ⁵-[1,4,2,5]dioxadiphosphinane-2,5-diyl)-bis-phosphonic acid tetramethylester The title compound 1 is formed by reaction of the corresponding phosphonic acid 2 and orthoformicacidmethylester as a mixture of four stereoisomeres. The RRSS isomer was separated. It crystallizes in the triclinic space group P ?1 with a = 649.2 pm, b = 976.1 pm, c = 1 571.7 pm, α = 80.9°, β = 88.1°, γ = 78.6° and Z = 2. The ³¹P and ¹³C NMR spectra (4 and 5 spin systems) are discussed.     

P,P′-(2,5-Dihydroxy-3,6-dimethyl-2,5-dioxo-2λ5,5λ5-[1,4,2,5]-dioxadiphosphinan-2,5-diyl)-bis-phosphonsäure

P,P′-(2,5-Dihydroxy-3,6-dimethyl-2,5-dioxo-2λ⁵,5λ⁵-[1,4,2,5]dioxadiphosphinane-2,5-diyl)-bis-phosphonic Acid The tetrahydrate 1 of the title compound crystallizes in the monoclinic space group P2₁/c with a = 845.8, b = 1 098, c = 981.7 pm, β = 113.02° and Z = 2. The anions of the oxonium compound (H₃O⁺ · H₂O)₂(C₄H₁₀O₁₂P₄^2?) are layered by hydrogen bridges. The ¹H, ¹³C and ³¹P NMR spectra (4 and 5 spin systems) are discussed.