Synthesis and polymerization of 8,9-benzo-2-methylene-1,4,6-trioxaspiro[4,4]nonane (BMTN)

8,9-Benzo-2-methylene-1,4,6-trioxaspiro[4,4]nonane (BMTN) was prepared by the reaction of phthalide with epichlorohydrin, followed by dehydrochlorination. BMTN was polymerized with di-t-butyl peroxide (DTBP) to give a solyble polymer with a high molecular weight and good thermal stability. The infrared (IR) and nuclear magnetic resonance (NMR) spectra indicated that the polymer structure contained aromatic ester and ketone in the backbone. T_g and T_m of homopolymer of BMTN were, respectively, 98 and 282°C. BMTN was also readily copolymerized with such vinyl monomers as methyl methacrylate (MMA), acrylonitrile (AN), and maleic anhydride (MA), but not with styrene, in the presence of radical initiators. AN and MA, in particular, were spontaneously copolymerized with BMTN in the absence of radical initiators at 40°C. From the results of ultra violet (UV) spectra it is suggested that spontaneous copolymerization proceeds via a charge-transfer complex between BMTN as an electron donor and AN or MA as an acceptor.     

Synthesis and polymerization of 2-butyl-7-methylene-1,4,6-trioxaspiro(4,4)nonane

2-Butyl-7-methylene-1,4,6-trioxaspiro(4,4)nonane ( 7 ) was prepared by the reaction of 2-(bromomethyl)-5-oxo-tetrahydrofuran with 1,2-epoxyhexane, followed by dehydrobromination. Compound 7 could be polymerized by free radical initiators to give a viscous polymer. The IR and NMR spectra of the polymers indicated that the polymer structure contained ester and ketone units in the backbone, and a cyclic acetal side chain. Compound 7 readily copolymerized with acrylonitrile in the presence and absence of radical initiators, but did not copolymerize well with styrene. Ultraviolet spectra suggest that the spontaneous polymerization proceeds via a chargetransfer complex between 7 as an electron donor and AN as an electron acceptor.     

Cationic photopolymerization of cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,4]nonane

The spiro‐orthoester, cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,4]nonane (cis‐TTN) ( I ), underwent rapid cationic photopolymerization when exposed to UV light using diphenyliodonium salts as a photoinitiator. The polymer, poly[(trans‐OCB)_x′‐(cis‐OCB)_x″‐(CHO)_y] thus formed consisted of poly(trans‐2‐oxycyclohexyl butanoate) (trans‐OCB)_x′ ( II ), poly(cis‐2‐oxycyclohexyl butanoate) (cis‐OCB)_x″ ( III ), and poly‐ (1,2‐cyclohexene oxide) (CHO)_y segments, and no expected pure poly(ether‐ester), that is, poly(2‐oxycyclohexyl butanoate), was isolated. The structure of the polymer was identified, and the mechanism of the reaction was deduced. The polymer thus formed exhibited expansion in volume during cationic photopolymerization when compared to that obtained by conventional cationic polymerization using a Lewis acid (e.g., BF₃OEt₂, CH₃OSO₂CF₃, or SnCl₄) as an initiator, which demonstrated volume shrinkage during polymerization. The volume expansion of the polymer during polymerization was due to (1) the lower content of the higher density (CHO)_y segment in the polymer chain and, more importantly, (2) the higher and optimal mole ratio of (trans‐OCB)_x′ and (cis‐OCB)_x″ segments that led the polymer in a more disordered, less dense, and higher volumetric state. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3680–3690, 2009     

用动力学方法研究8,9-苯并-2-亚甲基-1,4,6-三氧螺[4,4]壬烷的聚合反应机理

根据在自由基引发剂存在下,8,9-苯并-2-亚甲基-1,4,6-三氧螺(4,4)壬烷(Ⅰ)可能存在的竞争反应,推导了动力学方程式。用红外光谱法测定了单体的消失速率和苯酞的生成速率。实验结果与推导动力学方程式相符。进一步证明了单体(Ⅰ)的增长反应由加成聚合和开环—异构化—加成这两个反应组成。这两个反应对总速率的相对贡献与单体浓度有关。得到了共聚物的结构。     

Cationic polymerization of 6,8-dioxabicyclo-[3.2.1]octane and 3,6,8-trioxabicyclo[3.2.1]octane

6,8-Dioxabicyclooctane (DBO) and 3,6,8-trioxabicyclooctane (TBO) underwent ring-opening polymerization when treated with PF₅ in dichloromethane at ?78°C. These conditions were outstandingly effective for the polymerization of these bicyclic monomers, as shown by systematic variation of catalyst, solvent, and temperature. Best results were 68–84% yields of poly-DBO, η_inh 0.26–0.33 dl/g, and ～100% yield of poly-TBO, η_inh 0.56–0.80 dl/g. The relationship of these results to those of previous investigators of DBO discussed.     

Concise synthesis of 3,7-dioxa-9-aza-bicyclo[3,3,1]-nonane

[reaction: see text] The basicity of an amine has a great impact on physicochemical properties and pharmacokinetics. To attenuate the basicity of morpholine, a bicyclic amine was designed and synthesized with the introduction of an additional beta-oxygen. A transannular cyclization and reduction of a bridgehead alpha-chloro amine functionality produces the topographically unusual amine (pKa = 6.7) in good yield.     

Cationic polymerization of 1-phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane

Cationic polymerization of bicyclo ortho ester, 1-phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane, was carried out with Lewis acids and cation sources to obtain the polyether containing ester group in the side chain. It was found that boron trifluoride etherate was the most active initiator in the Lewis acids. Magnesium perchlorate and triphenylcarbenium tetrafluoroborate, which have lower nucleophilic counter ions, initiated effectively the polymerization of bicyclo ortho ester.     

Thermal rearrangements of spiro[2.4]hepta-1,4,6-trienes

Thermolysis of spiro[2.4]hepta-1,4,6-triene (1a) at 50 degrees C yielded bicyclo[3.2.0]hepta-1,3,6-triene (5), which dimerized in two different fashions to form cyclobutanes. The 1,2-dimethyl and 1-propyl derivatives of 1a also rearranged at 50 degrees C, but at a faster rate, each yielding a pair of cyclobutane dimers. The structures of these symmetrical dimers were investigated by 1D and 2D NMR and NOE difference spectroscopy. Ab initio calculations indicated that the two strained olefins 1a and 5 had comparable energies about 50 kcal/mol lower than norborna-1(7),2,5-triene, which was thus excluded as a reaction intermediate.     

Structural studies on some 1,3,5,7-tetraazabicyclo-[3.3.1]-nonane derivatives

From a study of the ¹H NMR spectra of a number of 3,7-disubstituted derivatives of 1,3,5,7-tetraazabicycio - [3.3.1] - nonane it is concluded that these molecules exist in either chair-chair or flattened chair-chair conformations. The derivatives containing COCH₃ and NO substitutents have room temperature spectra consistent with restricted rotation about their NC and NN bonds respectively. High temperature spectra reveal an activation energy, for the rotational barrier of the NC bond in the diacetyl derivative, of 23±2K.Cal/mol.     

An Efficient Synthesis of 2,8-Diazabicyclo[4.3.0]-nonane Derivatives via Intramolecular Cyclization Reaction

Novel 5-functionalized-2,8-diazabicyclo[4.3.0]nonane derivatives 5 were synthesized from epoxide 1 through 4 steps in 46.7～52.6% yield.     

Stereospecific synthesis of exo- and endo-1,3-dimethyl-2,9-dioxabicyclo-[3.3.1]-nonane

The title compounds may be synthesised in an enantioselective and diastereospecific manner from (±)-4-hydroxynona-2,8-diene using the Sharpless asymmetric epoxidation as the key step in the reaction sequence.     

Cationic polymerization of glycidol

Polymerization of glycidyl alcohol induced by boron trifluoride tetrahydrofuran complex (BF₃ ? THF) in ethylene glycol dimethyl ether (DME) and in the presence of BF₃–water or BF₃–glycerol catalyst system was studied. Under any of the conditions employed, the reaction gave water-soluble oligoether with polydispersity of ~1.1. It was shown by mass spectrometry that during polymerization in DME, DME is incorporated into the polymer and glycidol polymerization gives the alkyl-ether. According to calculations for glycidol polymerization in the presence of hydroxy compounds, the calculated number-average degrees of polymerization were higher than the experimental values both in the presence of water and with glycerol; this may be attributable to initiation of new molecules on the hydroxy group of the unreacted monomer.     

Cationic polymerization of norbornadiene

The polymerization of norbornadiene (NBD) initiated by the 2‐chloro‐2,4,4‐trimethylpentane/titanium tetrachloride system was investigated. Efforts were made to develop conditions for the living polymerization of NBD by the use of proton trap and electron donor in the ?35 to ?60 °C range however this objective was only partially attained. The molecular weights increased linearly with conversion, and the rate was first‐order in confirmed monomer concentration up to approximately 25%; however, chain transfer became operational beyond this range. The microstructure of polynorbornadiene (PNBD) was investigated by high‐resolution ¹H and ¹³C NMR spectroscopy. According to these techniques, the chain consisted of about equal amounts of exo/exo and exo/endo connected tricyclic repeat units. The head and tail groups were identified and quantitated, and this led to absolute molecular weight determination by integration. Molecular weights obtained by this method and by gel permeation chromatography (relative to polyisobutylene standards) were in good agreement. NMR spectroscopy indicated the presence of small but still identifiable amounts of branching units and their structures. The plot of the glass‐transition temperature against the reciprocal of the number‐average molecular weight was linear and yielded a glass‐transition temperature of 323 °C for the infinite molecular weight polymer. According to thermogravimetric analysis, PNBD was stable up to approximately 250 °C and showed a 5% weight loss at approximately 335 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 732–739, 2003     

Cationic polymerization of cyclocarbonates

Trimethylenecarbonate (TMC) and neopentane diol carbonate (NPC) were polymerized with two groups of initiators, proton and carbenium ion donors or Lewis acids. Initiation with methyltriflate, triflic acid or triethyloxonium tetrafluoroborate in solution gave satisfactory yields (up to 90%) but only low molecular weights (M_n < 5000), due to rapid back-biting degradation. IR- and NMR-spectroscopy demonstrate that the propagation steps involve alkylation of the carbonyl oxygen and cleavage of the alkyl-0 bond by analogy with lactones. Whereas borontribromide and trichloride form solid complexes with NPC or TMC, but do not initiate a polymerization, boron trifluoride is a good initiator. High yields (up to 99,5%) and high molecular weights (M_w > 10⁵) were obtained. However, in analogy to triflic acid initiated polymerizations all polycarbonates contain ether groups. The molar fraction of the ether groups increases with the reaction temperature. High molecular-weight polycarbonates containing ether groups were also obtained with other strong Lewis acids such as SnCl₄, SnBr₄ and TiCl₄. In contrast, weak Lewis acids such as Bu₂SnBr₂ Bu₃SnOMe and Sn(II)2-ethylhexanoate yield polycarbonates free of ether groups. This finding and the NMR-spectroscopically identified endgroups suggest that these weak Lewis acids initiate an insertion mechanism.     

Catalytic transformations of 1,6-dioxaspiro[4,4]nonanes

Summary In the vapor phase over platinized charcoal at 300–320°, 2-and 3-alkyi-1,6-dioxaspiro[4.4]nonanes undergo the following transformations: isomerization of one of the tetrahydrofuran rings with formation of tetrahydrofuran oxo compounds, decarbonylation of tetrahydrofuran aldehydes, and isomerization of tetrahydrofuran homologs and tetrahydrofuran ketones to give aliphatic ketones and -diketones, respectively.     

Synthesis of 4,4′-bipentacyclo[5.4.0.02,6.03,10.05,9]undecane

A new bi-cage hydrocarbon, 4,4′-bipentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane (12) was designed based on a strategy to construct two cages simultaneously from one key molecule scaffold. Thus 12 was conveniently synthesized from 5,5′-bi(cyclopentadiene) (9) through a three steps synthetic route in 23% overall yield. The new bi-cage hydrocarbon has high density (1.2322 g/cm³) and high volumetric heat of combustion (51.670 MJ/L).