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1.
During our studies of urea and thiourea adducts, we noticed that no adducts with unsubstituted pyridine had been structurally investigated. The 1:1 adduct of pyridine and urea, C5H5N·CH4N2O, crystallizes in the P21/c space group with Z = 4. The structure is of a standard type for urea adducts, whereby the urea molecules form a ribbon, parallel to the a axis, consisting of linked R22(8) rings, and the pyridine molecules are attached to the periphery of the ribbon by bifurcated (N—H…)2N hydrogen bonds. The 1:1 adduct of pyridine and thiourea, C5H5N·CH4N2S, crystallizes in the P21/n space group, with Z = 32 (Z′ = 8). The structure displays similar ribbons to those of the urea adduct. There are two independent ribbons parallel to the b axis at z ≃ 0 and , and three at z ≃ and ; the latter are crosslinked to form a layer structure by additional long N—H…S interactions, which each formally replace one branch of a bifurcated hydrogen‐bond system.  相似文献   

2.
In the title compound, poly­[sodium‐μ4‐3,5‐di­carboxy­benzene­sulfonato‐κ4O:O′:O′′:O′′′‐μ2‐urea‐κ2O:N] monohydrate], {[Na(C8H5O7S)(CH4N2O)]·H2O}n, the organic anions are arranged almost vertically within (001) monolayers, with the sulfonate and carboxylic acid groups pointing into the interlayer region. The inversion‐related aromatic rings of the anions inside the layers are arrayed via offset face‐to‐face interactions into molecular stacks along the crystallographic a axis. The `up' and `down' arrangement of the aromatic portions makes both faces of the layers ionic and hydro­philic, whereas the interiors of the layers are primarily hydro­phobic. The interleaving of the anions is such that the carboxylic acid groups are oriented more toward the interior than are the sulfonate groups. The aromatic rings in neighbouring layers are arranged in a herring‐bone fashion. The coordination sphere of the Na+ ions contains two sulfonate and two carboxylic acid O atoms, from a total of four different acid anions belonging to two neighbouring anionic monolayers. The urea mol­ecules are positioned between translation‐related anionic stacks inside the (001) layers, serving a triple function, viz. they fill in the large meshes (empty cavities) formed within the anionic–cationic network, and they provide additional Na+ coordination and hydrogen‐bond sites.  相似文献   

3.
Application of the α-Alkynone Cyclization: Total Synthesis of (±)-Albene A synthesis of the racemic form of the natural tricyclic hydrocarbon albene (1) from the Diels-Alder adduct 2 of tiglyl chloride and cyclopentadiene is described (24% yield). The key step 5→6 involves a thermal α-alkynone cyclization (Scheme 3), which is able to establish a new quarternary C-atom at an unactivated position with a high degree of regiospecificity.  相似文献   

4.
The structures of bis(guanidinium) ractrans‐cyclohexane‐1,2‐dicarboxylate, 2CH6N3+·C8H10O42−, (I), guanidinium 3‐carboxybenzoate monohydrate, CH6N3+·C8H5O4·H2O, (II), and bis(guanidinium) benzene‐1,4‐dicarboxylate trihydrate, 2CH6N3+·C8H4O42−·3H2O, (III), all reveal three‐dimensional hydrogen‐bonded framework structures. In anhydrous (I), both guanidinium cations form classic cyclic R22(8) N—H...O,O′carboxylate and asymmetric cyclic R21(6) hydrogen‐bonding interactions, while one cation forms an unusual enlarged cyclic interaction with O‐atom acceptors of separate ortho‐related carboxylate groups [graph set R22(11)]. Cations and anions also associate across inversion centres, giving cyclic R42(8) motifs. In the 1:1 guanidinium salt, (II), the cation forms two separate cyclic R21(6) interactions, one with a carboxyl O‐atom acceptor and the other with the solvent water molecule. The structure is unusual in that both carboxyl groups form short interanion O...H...O contacts, one across a crystallographic inversion centre [O...O = 2.483 (2) Å] and the other about a twofold axis of rotation [O...O = 2.462 (2) Å], representing shared sites on these elements for the single acid H atom. The water molecule links the cation–anion ribbon structures into a three‐dimensional framework. In (III), the repeating molecular unit comprises a benzene‐1,4‐dicarboxylate dianion which lies across a crystallographic inversion centre, two guanidinium cations and two solvent water molecules (each set related by twofold rotational symmetry), and a single water molecule which lies on a twofold axis. Each guanidinium cation forms three types of cyclic interaction with the dianions: one R21(6), the others R32(8) and R33(10) (both of these involving the water molecules), giving a three‐dimensional structure through bridges down the b‐cell direction. The water molecule at the general site also forms an unusual cyclic R22(4) homodimeric association across an inversion centre [O...O = 2.875 (2) Å]. The work described here provides further examples of the common cyclic guanidinium–carboxylate hydrogen‐bonding associations, as well as featuring other less common cyclic motifs.  相似文献   

5.
In the 1:1 adduct formed between l ‐phenyl­alanine and 4‐nitro­phenol [alternative IUPAC name: (2S)‐2‐ammonio‐3‐phenyl­propanoate–4‐nitro­phenol (1/1)], C9H11NO2·C6H5NO3, the l ‐phenyl­alanine mol­ecule is in the zwitterionic state. The overall structure is stabilized via strong hydrogen bonding between polar zones and van der Waals inter­actions between non‐polar zones, which alternate with the polar zones.  相似文献   

6.
The reaction between homophthalic anhydride and cyclohexanone was examined both in the presence of DMAP or BF3·Et2O complex as a catalyst. The latter yielded (±)‐1‐oxo‐1H‐spiro[benzo[c]pyran‐3(4H), 1′‐cyclohexane]‐4‐carboxylic acid ( 3 ) in a higher yield (82 %). A series of new (±)‐4‐(N,N‐disubstituted‐1‐carbamoyl)‐1H‐spiro[benzo[c]pyran‐3(4H),1′‐cyclohexane]‐1‐ones ( 5a‐h ) were synthesized from the parent acid 3 by a two‐step reaction. Differentiating microbial screening was performed for most of the synthesized compounds against twelve microorganisms belonging to different taxonomic groups. The spiro acid 3 was active against all bacterial strains with MIC ≥ 20 μg/ml against B. subtillis and P. vulgaris. E. coli was the most sensitive strain to the antibacterial effect of the tested compounds.  相似文献   

7.
Half-crystallization times t½, enthalpies of fusion ΔH, melting temperatures Tf glass transition temperatures Tg x-ray patterns, and morphologies were obtained for nine samples of poly(α-methyl-α-n-propyl-β-propiolactones) prepared from different homogeneous or heterogeneous initiators. The bulk of the results indicates that all samples can be classified into two categories: Polymers A having t½?, 100 min, ΔH ? 26 J/g, T ? 376 K, Tg ? 275 K, and Polymers B having t½ ? 10 min, ΔH ? 14.5 J/g T ? 425 K and Tg ? 271 K. Polymers A were prepared with homogeneous initiators while polymers B were polymerized with heterogeneous intiators. The difference in crystallization behavior between polymers A and polymers B is certainly due to a difference in microstructure, brought about by the initiators, which has been qualitatively observed by NMR.  相似文献   

8.
Zusammenfassung Während die Kondensation von Dimedon mit Aldehyden ausschließlich zuMichaeladditionsprodukten (Molverhältnis 2:1) führt, erhält man aus dem Natriumsalz des Dimedons und Aldehyden die entsprechenden Äthylene (1:1-Produkte); diese sind starke organischeLewissäuren.
(1:1)-Condensation products of aldehydes with dimedone (Organic Lewis acids, XXII)
Michael reaction-type condensations of aldehydes with dimedone generally lead to reaction products which are made up from 2 moles of aldehyde and 1 mole of dimedone. However, if the sodium salt of dimedone is used, reaction products corresponding to a molar ratio 1:1 are obtained. These substituted ethylenes are strong organicLewis acids.


21. Mitt.:P. Margaretha, Mh. Chem.101, 811 (1970).  相似文献   

9.
Hexa­methyl­ene­tetramine and ractrans‐1,2‐cyclo­hexane­di­carboxylic acid crystallize in a 1:1 ratio as a neutral molecular adduct, C6H12N4·C8H12O4. Two di­carboxylic acid mol­ecules and two tetr­amine mol­ecules form a hydrogen‐bonded ring, in the shape of a rhombus, which lies on a crystallographic twofold axis bisecting the two diacid mol­ecules. The O—H⋯N hydrogen bonds have lengths 2.6808 (19) and 2.6518 (19) Å, and, in each ring, both acid mol­ecules have the same handedness.  相似文献   

10.
In flow tube studies of the quenching of O2(b1Σ), broad band emission of O2(b):M collision complexes was found to appear under the discrete rotational lines of the 0–0 band of the b1Σ → a1Δg electric quadrupole transition at higher oxygen pressures and on addition of foreign gases. Bimolecular rate constants for the collision-induced emission processes have been derived from the ratio of the intensities of the discrete lines and the continuum as well as from low-resolution measurements of the relative intensities of the ba and bX bands as a function of O2 and added gas pressure. They range from ≈10?21 cm3 s?1 for He to ≈4 × 10?19 cm3 s?1 for PCl3 vapor.  相似文献   

11.
Copper(II)-Chloride Catalyzed ‘Carbene Dimerization’ of 1-Halogeno-1-lithiocyclopropanes: A Simple Access to Bi(cyclopropylidenes) A series of 13 bi(cyclopropylidenes) 11 are prepared in a simple one-pot reaction by halogeno-lithio exchange between 1,1-dibromocyclopropanes 1a – n and BuLi, in most cases at ?95°, to give 1-bromo-1-lithiocyclopropanes 2a – n , followed by treatment with CuCl2 at low temperature and a simple workup at room temperature (Scheme 3c and Table 1). The yields of bi(cyclopropylidenes) 11 strongly depend on reaction parameters, as explicitly shown for the conversion 1f →→ 11f (Tables 2–8). Mixed couplings between two different carbenoids are possible (Scheme 4), while diastereoselectivity of the active transition-metal complex seems to be low. The structures of bi(cyclopropylidenes) 11 are confirmed by spectroscopic data as well as by X-ray analysis of an isolated crystalline diastereoisomer of 11k (Fig. 1).  相似文献   

12.
Short Total Syntheses of (±)-Sativene and (±)-cis-Sativenediol Our approach to (±)-sativene (7) and (±)-cis-sdtivenediol (9) involves: (a) reaction of 3-methylbutanoyl chloride with Et3N/cyclopentadiene to give the endo-isopropyl-ketone 1 (here improved to 71%), (b) NBS bromination of 1 to a 5:1 mixture (87%) of the bromo-ketones 2 and 3 , (c) NFD-reaction sequence initiated by the attack of 1,2-butadienyl titanate (complex of 15 , obtained from 2-butine) on 2/3 to afford 52% of the brexenone derivative 4 (along with 8% of its epimer 16 ), (d) addition of dibromomethane to 4 forming 63% of the diene-alcohol 5 (along with 13% of the diene-carbaldehyde 38 ), and (e) carbenoid ring-expansion with MeLi applied to 5 resulting in 41% the diene-ketone 6 (along with 15% of a 1:3 mixture of the diene-ketones 32 and 33 ). Wolff-Kishner reduction of 6 led to 81% of (±)-sativene (7), when enough O2 was present, but to 97% of the diene 8 in the strict absence of O2. (±)-cis-Sativenediol (9) was obrained (86%) by OsO4 hydroxylation of 8 . The brexenone derivatives 4 and 16 (6:1, 50%) were also produced when the NFD-reaction sequence was applied to the isomeric bromo-ketone mixture 13/13 (1:3). The latter was obtained by NBS bromination of 10 , which in turn was available by base epimerization of 1 , followed by destructive removal of unreacted 1 by repeated gas-flow thermolysis. An analogous (less convenient) route to (±)-sativene (7) passed through a series of dihydro compounds (the ene series) it started with the methylidene-ketone 36 , which was the product (97%) of a partial hydrogenation of 4 . Addition of dibromomethane to 36 led t 62% of the methylidene-alcohol 39 (along with a little tetracyclic ether 40 ). Carbenoid ring expansion of 39 with MeLi afforded ca. 42% of the methylidene-ketone 41 (along with 7% of the methylidene-ketone 43 or, under slightly different condition, along with 9% of the methylidene-ketone 42 and 10% of the methylidene-carabaldehyde 44 ). The methylidene-alcohol 39 and the methylidene-ketone 43 were also obtained by partial hydrogenation of 5 and 33 , respectively. Wolff-Kisher reduction converted 41 into (±)-sativene ( 7 99%); the same conditons applied to 42 afforded only ca. 8% 7 (along with three other hydrocarbons, one of them (ca. 21%) probably being (±)-copacamphene (45)). In the diene series, the two succeeding reactions ( 4→5 and 5→6 ) competed with the same side reaction, a rearrangement leading to the brendene-aldehyde 38. In the ene series, the corresponding dihydro-by-product 44 was found in the reacton 39→41 , but not during 36→39. These side reactons could largely be suppressed by keeping the reaction temperature low. An explanation is proposed.  相似文献   

13.
The structures of diastereomeric pairs consisting of (S)‐ and (R)‐2‐methylpiperazine with (2S,3S)‐tartaric acid are both 1:1 salts, namely (S)‐2‐methylpiperazinium (2S,3S)‐tartrate dihydrate, C5H14N22+·C4H4O62−·2H2O, (I), and (R)‐2‐methylpiperazinium (2S,3S)‐tartrate dihydrate, C5H14N22+·C4H4O62−·2H2O, (II), which reveal the formation of well defined ammonium carboxylate salts linked via strong intermolecular hydrogen bonds. Unlike the situation in the more soluble salt (II), the alternating columns of tartrate and ammonium ions of the less soluble salt (I) are packed neatly in a grid around the a axis, which incorporates water molecules at regular intervals. The increased efficiency of packing for (I) is evident in its lower `packing coefficient', and the hydrogen‐bond contribution is stronger in the more soluble salt (II).  相似文献   

14.
Group 12 halides and 2,2′‐dithiobis(pyridine N‐oxide) (dtpo) form the crystalline the 1D coordination polymers [ZnX2(μ‐dtpo‐κ2O:O′)]n [X = Cl ( 1 ), Br ( 2 ), I ( 3 )], [Cd3(μ‐Cl)4Cl2(μ‐dtpo‐κ2O:O′)2(CH3OH)2]n ( 4 ), [(CdBr2)23‐dtpo‐κ3O,O:O′)2(H2O)2]n ( 5 ), and [(CdI2)2(μ‐dtpo‐κ2O:O′)3]n ( 6 ) in methanol. The compounds were structurally characterized by single‐crystal X‐ray analysis. Compounds 1 – 3 represent an isomorphous series of single‐stranded coordination polymers, whereas the CdII derivatives are structurally diverse. The metal nodes in 4 and 5 are trinuclear and dinuclear cadmium clusters, respectively. In 4 and 5 , the metal nodes are linked into double‐stranded 1D coordination polymers by two dtpo bridging ligands. Compound 6 contains mononuclear CdI2 units as nodes and can be viewed as an alternating copolymer of CdI2(μ‐dtpo‐κ2O:O′)2 and CdI2(μ‐dtpo‐κ2O:O′) entities. Owing to the disulfide moiety, the dtpo bridging ligand inevitably exhibits an axially chiral angular structure. The dtpo ligand adopts various coordination modes through the pyridine N‐oxide oxygen atoms.  相似文献   

15.
Triad and tetrad tacticities of poly(methyl α-chloroacrylate) and poly(methyl α-chloroacrylate-β-d1) were determined by nuclear magnetic resonance (NMR) spectroscopy. Methyl α-chloroacrylate-β-d1 and its polymer were first synthesized. Isotactic poly(methyl α-chloroacrylate) was prepared with ethylmagnesium chloride-benzal-acetophenone in combination as catalyst. The syndiotacticity of radically polymerized polymers increased with decreasing polymerization temperature. For radical polymerization, enthalpy and entropy differences between isotactic and syndiotactic additions were calculated to give ΔH ? ΔH = 850 cal/mole and ΔS ? ΔS = 0.93 eu. The stereoregularity of the polymer prepared with phenylmagnesium bromide catalyst was analyzed in fairly good agreement with first-order Markov statistics, while polymerization with fluorenyllithium seems predominantly to proceed by a mechanism similar to free-radical mechanism. Stereoregularity-controlling power for individual substituents is briefly discussed.  相似文献   

16.
(Acetonitrile‐1κN)[μ‐1H‐benzimidazole‐2(3H)‐thione‐1:2κ2S:S][1H‐benzimidazole‐2(3H)‐thione‐2κS]bis(μ‐1,1‐dioxo‐1λ6,2‐benzothiazole‐3‐thiolato)‐1:2κ2S3:N;1:2κ2S3:S3‐dicopper(I)(CuCu), [Cu2(C7H4NO2S2)2(C7H6N2S)2(CH3CN)] or [Cu2(tsac)2(Sbim)2(CH3CN)] [tsac is thiosaccharinate and Sbim is 1H‐benzimidazole‐2(3H)‐thione], (I), is a new copper(I) compound that consists of a triply bridged dinuclear Cu—Cu unit. In the complex molecule, two tsac anions and one neutral Sbim ligand bind the metals. One anion bridges via the endocyclic N and exocyclic S atoms (μ‐S:N). The other anion and one of the mercaptobenzimidazole molecules bridge the metals through their exocyclic S atoms (μ‐S:S). The second Sbim ligand coordinates in a monodentate fashion (κS) to one Cu atom, while an acetonitrile molecule coordinates to the other Cu atom. The CuI—CuI distance [2.6286 (6) Å] can be considered a strong `cuprophilic' interaction. In the case of [μ‐1H‐benzimidazole‐2(3H)‐thione‐1:2κ2S:S]bis[1H‐benzimidazole‐2(3H)‐thione]‐1κS;2κS‐bis(μ‐1,1‐dioxo‐1λ6,2‐benzothiazole‐3‐thiolato)‐1:2κ2S3:N;1:2κ2S3:S3‐dicopper(I)(CuCu), [Cu2(C7H4NO2S2)2(C7H6N2S)3] or [Cu2(tsac)2(Sbim)3], (II), the acetonitrile molecule is substituted by an additional Sbim ligand, which binds one Cu atom via the exocylic S atom. In this case, the CuI—CuI distance is 2.6068 (11) Å.  相似文献   

17.
Acid-catalyzed methanolysis of N-hydroxy-α-oxobenzeneethanimidoyl chloride ( 1 ), a 2-(hydroxyimino)-1-phenylethan-1-one derivative obtained in one step from acetophenone, leads to a constant ratio of methyl α-oxobenzeneacetate ( 2 ) and methyl α-(hydroxyimino)benzeneacetate ( 3 ). 13C(α) Labelled [13C]- 1 affords 13C(α) labelled [13C]- 3 , thus discarding the hypothesis of its formation via 1,2-arene migration. The reported sequence opens a novel approach to phenylglyoxylic and mandelic acid esters (=α-oxobenzeneacetic and α-hydroxybenzeneacetic acid esters), from acetophenone. The molecular structures of 1 and 3 were determined by X-ray structure analysis and compared with previously reported crystallographic data of α-oxo-oximes (=α-(hydroxyimino) ketones) 4 and 6 – 8 . The unique stereoelectronic characteristics of the α-oxo-oxime moiety are discussed. All α-oxo-oximes share the following structural characteristics: (E)-configuration of the oxime C=N−OH bond (i.e. OH and C=O trans), the s-trans conformation of the oxo and imino moieties about the C(α)-C(=NOH) single bond, and intermolecular H-bonding. They differ from the isostructural β-diketone enols by the absence of resonance-assisted intramolecular H-bonding.  相似文献   

18.
In the crystalline 1:1 molecular complex of tri­phenyl­methanol (TPMeOH) and tri­phenyl­phosphine oxide (TPPO), C19H16O·C18H15OP, molecular dimers are formed which are linked by O—H?O=P hydrogen bonds. The dimers are aligned by sixfold phenyl embraces to form columns. The structure is disordered with half a dimer per asymmetric crystal unit, i.e. with only one molecular site which is half‐occupied by both TPMeOH and TPPO.  相似文献   

19.
Cocrystallization of 1,1′‐(p‐phenylene)dipyridin‐4(1H)‐one (4,4′‐dpy) and terephthalic acid (tpa) affords the hydrogen‐bonded 1:1 title complex, C16H12N2O2·C8H6O4. Both mol­ecules are symmetrically disposed about independent symmetry centers. Strong O—H⋯O hydrogen bonds between tpa carboxyl groups and 4,4′‐dpy carbonyl groups produce one‐dimensional zigzag infinite chains. Each chain is linked to four surrounding chains via weak C—H⋯O inter­actions, resulting in a three‐dimensional mol­ecular framework.  相似文献   

20.
Two europium(III) coordination polymers (CPs), namely, poly[[diaquabis(μ4‐1H‐benzimidazole‐5,6‐dicarboxylato‐κ6N3:O5,O5′:O5,O6:O6′)(μ2‐oxalato‐κ4O1,O2:O1′,O2′)dieuropium(III)] dihydrate], {[Eu2(C9H4N2O4)2(C2O4)(H2O)2]·2H2O}n ( 1 ), and poly[(μ3‐1H‐benzimidazol‐3‐ium‐5,6‐dicarboxylato‐κ5O5:O5′,O6:O6,O6′)(μ3‐sulfato‐κ3O:O′:O′′)europium(III)], [Eu(C9H5N2O4)(SO4)]n ( 2 ), have been synthesized via the hydrothermal method and structurally characterized. CP 1 shows a three‐dimensional network, in which the oxalate ligand acts as a pillar, while CP 2 has a two‐dimensional network based on a europium(III)–sulfate skeleton, further extended into a three‐dimensional framework by hydrogen‐bonding interactions. The structural diversity in the two compounds can be attributed to the different acidification abilities and geometries of the anionic ligands. The luminescence properties of 1 display the characteristic europium red emission with CIE chromaticity coordinates (2/3, 0.34). Interestingly, CP 2 shows the characteristic red emission with CIE chromaticity coordinates (0.60, 0.34) when excited at 280 nm and a near‐white emission with CIE chromaticity coordinates (0.38, 0.29) when excited at 340 nm.  相似文献   

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