新型的4,4′-二甲基二苯酮分子间的夺氢固相光化学反应

本文报道了新型的4,4′-二甲基二苯酮分子间夺氢的固相光化学反应。4,4′-二甲基二苯酮晶体分子间的晶格排列,适合于分子间夺氢的要求,得到与液相不同的新产物,4-(对-甲基苯甲酰)苄基-双-(对-甲基)苯基甲醇。初步探讨了4,4′-二甲基二苯酮的固相光化学反应机理。     

Siliciumorganische verbindungen : LXXI. Sila-paracyclophane

The reaction of 4,4′-dihydroxy diphenylsulfide (Ia) and 4,4′-dihydroxydiphenylsulfone (Ib) with hexamethyldisilazane leads to 4,4′-bis)trimethylsiloxy) diphenylsulfide and 4,4′-bis(trimethylsiloxy)diphenylsulfone. Ia and Ib treated with hexamethylcyclotrisilazane form sila-paracyclophanes.     

Pulse radiolysis of 4,4'-bipyridyl aqueous solutions at elevated temperatures: spectral changes and reaction kinetics up to 400 degrees C

The spectral changes as well as the reaction kinetics of the transient species of 4,4'-bipyridyl (4,4'-bpy) have been experimentally investigated by pulse radiolysis techniques up to 400 degrees C. The results show that the transient species such as OH adduct 4,4'-bpyOH*, monoprotonated electron adduct 4,4'-bpyH*, and doubly protonated electron adduct 4,4'-bpyH2+* have 15-20 nm blue shifts from room temperature to 400 degrees C. For a deaerated neutral solution of 4,4'-bpy in the presence of tert-butyl alcohol, ethanol, or NaCOOH, the doubly protonated electron adduct is the main transient species at room temperature. But at temperatures > 350 degrees C, a monoprotonated form, the N-hydro radical 4,4'-bpyH*, becomes predominant. Interestingly, at room temperature, CO2-* could not efficiently react with 4,4'-bpy, but the reaction was accelerated with increasing temperature; at 350 degrees C, this reaction completed within 2 mus. Using an alkaline solution (pH = 11.5) of 4,4'-bpy in the presence of tert-butyl alcohol, we studied the N-hydro radical 4,4'-bpyH* from room temperature to 400 degrees C at 25 MPa. An estimation of the temperature-dependent G(e(aq)-) at 25 MPa agrees with our previous result with methyl viologen as a scavenger.     

Reaction of the 4-biphenylnitrenium ion with 4-biphenyl azide to produce a 4,4'-azobisbiphenyl stable product: a time-resolved resonance Raman and density functional theory study

A time-resolved resonance Raman (TR(3)) and density functional theory (DFT) study of the reaction of the 4-biphenylnitrenium ion with 4-biphenyl azide in a mixed aqueous solution is reported. The reaction of the 4-biphenylnitrenium ion with its unphotolyzed precursor 4-biphenyl azide in a mixed aqueous solution generates a 4,4'-azobisbiphenyl stable product via an intermediate species. With the aid of DFT calculations for likely transient species, this intermediate was tentatively assigned to a 4,4'-azobisbiphenyl cation. The DFT calculations predict this reaction can take place via two pathways that compete with one another to produce the trans and cis 4,4'-azobisbiphenyl product. The observation of the 4,4'-azobisbiphenyl cation intermediate demonstrates that the reaction of the arylnitrenium ion with its aryl azide to produce a stable azo product occurs via a stepwise mechanism.     

A new oxidative alkoxylation reaction The preparation of 5-alkoxy-4,4-dialkyl-1-aryl-3-pyrazolidinones

A new oxidative alkoxylation method is described. According to this method alkoxy groups are introduced in the 5-position of 4,4-dialkyl-1-aryl-3-pyrazolidinones by oxidation with HgO or SeO₂ in alcohols. The mechanism, the scope and limitations of the reaction are discussed. The 5-alkoxy-4,4-dialkyl-1-aryl-3-pyrazolidinones may be converted to 1-aryl-4,4-dialkyl-5-(1-aryl-3-oxo-4,4-dialkyl-5-alkoxy-5-pyrazolidinyl)-3-pyrazolidinones. The structure of the reaction products was studied by IR and NMR analyses.     

新的二苯并环状溴鎓盐的合成及性质研究

以4,4'-二取代联苯(或4,4'-二取代二苯甲烷)为原料合成了几种新的3,7-二取代二苯并环状溴(鎓)盐.对几种溴(鎓)盐与KBH₄及与NaN₃的反应进行了研究.结果表明,前一反应主产物为2-溴-4,4'-二取代联苯(或2-溴-4,4'-二取代二苯甲烷),后一反应的主产物为2-叠氮基-2'-溴-4,4'-二取代联苯(20a-20d).通过20a-20d的热反应合成几种新的多取代咔唑(21a-21d).     

Highly stereocontrolled synthesis of gem-difluoromethylenated azasugars: D- and L-1,4,6-trideoxy-4,4-difluoronojirimycin

[reaction: see text]. D-1,4,6-trideoxy-4,4-difluoronojirimycin and L-1,4,6-trideoxy-4,4-difluoronojirimycin, a novel series of gem-4,4-difluoromethylenated azasugars, were synthesized from CF3CH2OH in 10 steps. A key step was the highly diastereoselective construction of the piperidine ring via reductive amination.     

An Efficient Synthesis of 3,3′,4,4′‐Tetrahydro‐4,4′‐bibenzo[e][1,3]oxazine‐2,2′‐dione Derivatives with the Aid of Low‐valent Titanium

Synthesis of 3,3′,4,4′‐tetrahydro‐4,4′‐bibenzo[e][1,3]oxazine‐2,2′‐diones via reaction of salicylidendphenylhydrazone and triphosgene with the aid of low‐valent titanium reagent is described. This method has the advantages of accessible starting materials, good yields and short reaction time.     

Synthesis of 4,4'-bisaryl-2,2'-bisbenzimidazoles as building blocks for supramolecular structures

A series of 4,4'-bisaryl-2,2'-bisbenzimidazoles has been synthesized from the corresponding 4,4'-dibromo-2,2'-bisbenzimidazoles by Negishi coupling reactions. This procedure affords highly substituted bisbenzimidazoles. [reaction: see text]     

Synthesis of polyimide and poly(imide-benzoxazole) in polyphosphoric acid

A polyimide made from 4,4′-diaminodiphenyl ether (ODA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was synthesized in polyphosphoric acid. Although the polymerization proceeded heterogeneously, a polyimide with an inherent viscosity of 0.90 was obtained, and a tough and flexible film was made from this polyimide. This polymerization was a one-step reaction including polycondensation and imidization; this was also confirmed by a model reaction between aniline and phthalic anhydride. Utilizing this polymerization method, 3,3′-dihydroxy-4,4′-diaminobiphenyl and 2 mol of 4-aminobenzoic acid were reacted in PPA, then BPDA was reacted to obtain an alternate copolymer containing imide and oxazole rings. This reaction gave a homogeneous solution of the poly(imide-benzoxazole). © 1993 John Wiley & Sons, Inc.     

Mecanisme de formation et de transformation des spirophosphoranes—IX: Reactions des spirophosphoranes a liaison PH avec les ethers vinyliques et les enamines

The reaction of 1,4,6,9-tetraoxa-5-phospha(V)spiro[4,4]nonane 1 with ethyl vinyl ether gives a spirophosphorane containing a PC bond, 5-(β-ethosyethyl)-1,4,6,9-tetra-oxa-5-phospha(V) spiro[4,4]nonane 2 (radical reaction), and a tricoordinated phosphorus compound, 2-(3,5-di-oxa-4-methylheptanoxyl)-1,3,2-dioxaphospholane 3 (ionic reaction). 2,2,3,3,7,7,9-Heptamethyl-1,4,6-trioxa-9-aza-5-phospha(V) spiro[4,4]nonane 6 gives exclusively a spirophosphorane containing a PC bond, 5(β-ethoxyethyl)-2,2,3,3,7,7,9-heptamethyl-1,4,6-trioxa-9-aza-5-phospha(V)spiro[4,4]nonane 7. The reaction of 1 with alcohol or ethyleneglycol and enamine yields a pentaoxyspirophosphorane and an amine by an oxidation-reduction condensation. Suggested mechanisms of these reactions are presented.     

Preparation and photophysics of polyimide/silica organic/inorganic hybrid composites

In this work, polyimide/silica hybrid composites were prepared by the sol-gel reaction of tetraethoxysilane(TEOS) and the thermal imidization of poly(amic acid) from 3,3′,4,4′-biphenyltetracarboxylic dianhydride(BPDA) and 4,4′-oxydianiline(ODA), and their photophysical properties were investigated using a fluorescence spectroscopy. It was found that the intrinsic fluorescence of poly(4,4′-oxydiphenylene-3,3′4,4′-biphenyltetracarboximide)(BPDA-ODA) such as emission intensity and emission wavelength depends strongly on the changes in the molecular conformations during the sol-gel reaction and the thermal imidization. In conclusion, we found that the fluorescence spectroscopy can provide an insight into how the intermolecular or intramolecular interaction of polyimide in the hybrid composite system is affected by the silica contents, depending on the sample states.     

主链含有非共轭结构的聚芴类蓝光聚合物的合成与性能研究

通过Suzuki偶合反应合成出了主链中含有非共轭烷氧基组分(-O-CH2-CH2-CH2-CH2-O-)的聚芴类衍生物聚- 2,7-(9,9-二辛基芴)-co-4,4’-丁氧基二苯(PFP)和聚-2,7-(9,9-二辛基芴)-co-4,4’-丁氧基二苯-co-N-苯基-4,4’-二苯胺(PFTP11)并通过相同的条件合成出主链由芴和三苯胺交替相连的聚合物聚-2,7-(9,9-二辛基芴)-co-N-苯基-4,4’-二苯胺(PFTPA)作为参比材料. 通过1H NMR和FT-IR分析对这些聚合物的化学结构进行了表征. 这三种聚合物在常用的有机溶剂中具有很好的溶解性, 可通过溶液加工的方式制备聚合物薄膜. 这些聚合物均具有较高的热分解温度(＞400 ℃), 聚合物PFP具有较高的玻璃化转变温度(～130 ℃)而PFTP11和PFTPA则未出现明显的玻璃化转变过程. 通过对聚合物的吸收特性进行测试得知它们具有较大的光学带宽(2.89～3.29 eV). 所有聚合物在固体薄膜状态下均发射出蓝色荧光, PFP, PFTP11和PFTPA的最大PL发射分别位于425, 437和440 nm. 通过对其电化学性能进行测试可知由于三苯胺基团的引入聚合物的HOMO能级明显提高, 这意味着聚合物的空穴传输能力得到了有效的改善.     

An electron spin resonance study of azaallyl radicals

The ESR spectrum of the 2-aza-allyl radical, Me2CNCMe₂, has been recorded. A series of 1-aza-allyl radicals have been generated by reaction of 2-alkyl-4,4-dimethyloxazolines with t-butoxyl radicals and their ESR spectra studied. In this reaction 2-alkyl-4,4-dimethyloxazolin-5-yl radicals are also formed.     

Evidence for cyclopropene formation in the reactions of 4,4-dimethyl-4-silacyclohexadienylidene

In the reactions of 4,4-dimethylcyclohexadienylidene no evidence for cyclopropene formation has been found. By contrast, 4,4-dimethyl-4-silacyclohexadienylidene yields a product on reaction with butadiene that is best rationalized by intramolecular cyclopropene formation.     

In situ synthesis and structure of FeCl4(4,4′-diethyl-4,4′-bipyh) (bipy = bipyridine)

A novel viologen(4,4′-bipyridinium)-based compound FeCl₄(4,4′-diethyl-4,4′-bipyH) (1) (bipy = bipyridine), in which 4,4′-diethyl-4,4′-bipyH (MQ ⁺) was generated in situ, is synthesized via the hydrothermal reaction and structurally characterized by single crystal X-ray diffraction. The crystal structure analysis reveals that the title compound features an isolated structure based on 4,4′-diethyl-4,4′-bipyH moieties and an iron atom terminally bound by four chlorine atoms. The 4,4′-diethyl-4,4′-bipyH moieties and (FeCl₄)^? anions are interconnected by hydrogen bonds to form a 3D supramolecular framework.     

4,4-双叠氮联苯光解中间体的多重态研究

本文用顺磁共振和色谱分析等方法,证明了4,4'-双叠氮联苯光解产生的叠氮氮烯和双氮烯都是三重态;而热分解产生的中间体则是由单重态双氮烯所组成。因此4,4'-双叠氮联苯的热分解反应很可能具有和光分解反应完全不同的机理。     

Thorpe-Ingold effect in the reaction of vicinal amino primary alcohol hydrogen sulfates and carbon disulfide

The Thorpe-Ingold effect is a key factor that affects the ring-closure rates and efficiency, as well as the structure of products in some ring-closure reactions. The reaction of vicinal amino primary alcohol hydrogen sulfates and carbon disulfide in the presence of potassium hydroxide produces the desired 4,4-disubstituted thiazolidine-2-thiones, and their isomers 5,5-disubstituted derivatives companying with their oxygen analogues 4,4-disubstituted oxazolidine-2-thiones. The formation of 5,5-disubstituted thiazolidine-2-thiones was rationalized via 2,2-disubstituted aziridine-1-carbodithioate intermediates, which were generated due to the Thorpe-Ingold effect. 4,4-Disubstituted oxazolidine-2-thiones were generated from carbon disulfide and free amino alcohols yielded via basic hydrolysis of active amino alcohol hydrogen sulfates in the reaction system.     

Synthesis and properties of polyether ketones

Polyether ketones were prepared by the nucleophilic reaction of dihaloaromatic ketones with aromatic bisphenols (hydroquinone, resorcinol and 4,4-dihydroxybenzophenone) using various solvents in the presence of anhydrous K₂CO₃. Dihaloaromatic ketones (4,4-difluorobenzophenone/4,4-dichlorobenzophenone) were prepared from the reaction of fluorobenzene/chlorobenzene with carbon tetrachloride in the form of AlCl₃. The polymers were characterized by different physico-chemical techniques. Thermogravimetric studies showed that all the polymers were stable upto 500°C with a char yield above 50% at 900°C in N₂ atmosphere. Isothermal degradation at 400°C under air and N₂ atmosphere reveals about 5% weight loss and about 1% weight loss at 75 min respectively. The effect of solvents, reaction temperature and reaction time on molecular weights are discussed. The effect of the annealing time on crystallinity of the polymers is also discussed.     

Reaction of 4,4-Dimethyl-1,3-dioxane with Dinitriles

The reaction of 4,4-dimethyl-1,3-dioxane with bis(2-cyano)diethyl ether or 1,2-di(beta-cyanoethoxy)ethane yields the corresponding bis[2-(4,4-dimethyl-5,6-dihydro-2-oxazinyl)]diethyl ether and 1,2-di{beta-[2-(4,4-dimethyl-5,6-dihydro-2-oxazinyl)]ethoxy}ethane which are readily hydrolyzed under the action of aqueous alkali to give 3-methyl-3-amino-1-butanol.