氮氧自由基的研究VIII. 关于溶剂极性经验参数的讨论

作者测定了有机溶剂-水二元混合溶剂体系中2,2,6,6-四甲基哌啶1-氧自由基(TMPO)的ESRaN 值. 这类混合溶剂体系中aN-m关系可归属有机二元混合溶剂体系的四种典型线关系. 比较了几种溶剂极性经验参数, 说明各种经验极参数-m关系图的差异是特定模型反痘中溶剂分子与溶质分子间相互作用不同的反映. 对二元混合溶剂体系而言, aN-Er(30),aN-Z一般不具有线线性关系, 认为溶剂极性经验参数是溶剂(包括溶剂混合物)对模型化合物溶剂化能力的标度, 给出了在各种溶剂体系中的aN 测定值, 作为溶剂对中性偶极分子相对溶剂化能力的经验标度.     

Zinc porphyrin sensitized redox processes in microemulsions

Photoinduced electron transfer from Zn tetraphenylporphyrin to acceptors solubilized either in the lipid interior or aqueous bulk of anionic oil-in-water microemulsions has been investigated by nanosecond laser photolysis. While intimate cosolubilization appears to decrease the efficiency of electron transfer in the former, enhanced charge separation of the redox products has been observed in the latter.     

Synthesis and structural characterization of [PhE(BNMe2)2]2 (E = P or As): Six-Membered P2B4 and As2B4 Rings with Unusual Structures

The reaction of either Li₂PPh or Li₂AsPh with the diborane(4) derivative B₂(NMe₂)₂Br₂ affords the compounds [PhP(BNMe₂)₂]₂ ( 1 ) or [PhAs(BNMe₂)₂]₂ ( 2 ) in good yield. Both 1 and 2 have cyclic structures featuring non-planar P₂B₄ or As₂B₄ six-membered rings which have chair configurations. Although all four borons in each ring have planar coordination, the two phosphorus or arsenic centers have different degrees of pyramidalization. Bond distances within the rings indicate that the B? B, B? P or B? As bonds are single, whereas the exo-B? N bond lengths are consistent with significant π-bonding. The ring structures of 1 and 2 are in sharp contrast to the related boron-nitrogen species (t-BuN)₂N₄Me₄ which has a nido-N₂B₄ framework. The attempted synthesis of the nitrogen analogue of 1 or 2 by using a similar approach did not result in the isolation of [PhN(BNMe₂)₂]₂, instead the tetramino diborane(4) species [B(NMe₂)NHPh]₂ ( 3 ), which has a structure similar to other tetramine diborane(4) compounds, was isolated.     

1,3-手性转移反应的研究 (4R)-和(4S)-4-甲基(E)-2-辛烯醇的合成

以手性辛烯二醇双酯与甲基锂铜反应, 经1,3手性转移, 分别生成立体选择性高的(4R)和(4S)-4-甲基-辛烯醇酯。     

Tetraarylester der μ-Imidodiphosphorsäure und ihre Thioderivate — Strukturuntersuchungen

Tetraarylesters of μ-Imido-Diphosphoric Acid and its Thio Derivatives — Structure Investigations New O,O′,O″,O?-tetratolyl- and ditolyl-diphenylesters of the μ-imido-diphosphoric acid and its mono and dithio derivatives were synthesized, compared with the corresponding tetraphenylesters and investigated by ¹H, ¹³C, and ³¹P NMR spectroscopy and X-ray crystal structure analysis. Structures of the O,O′,O″,O?-tetrakis-(2-methyl-phenyl)-μ-imidodiphosphate, 1b , as well as of the corresponding ortho-, meta- and para-tolylesters of the μ-imido-monothiodiphosphoric acid ( 2a , 2b , 2c ) were determined. All the compounds form dimers via N? H…?O hydrogen bonds in the crystal as well as in nonpolar solvents. The distances around the phosphorus atoms rise with decreasing electronegativity of the phosphorus substituents. Signs of the ²J_{P? N? P} coupling constants were determined by ¹³C{¹H, ³¹P} triple resonance experiments for some compounds. These constants become more negative owing to substitution of a phosphoryl by a thiophosphoryl group.     

Stereochemistry of cyclic ether formation—II : Intramolecular cyclisation of secondary aliphatic alcohols to tetrahydrofuran-type ethers

The mechanism and stereochemistry of δ-C atom functionalisation in the reactions of secondary straight-chain aliphatic alcohols with lead tetraacetate, ceric ammonium nitrate, and heavy metal (Pb⁴⁺, Hg²⁺, Ag⁺) salts (AcO)^?1, O^2?, CO₃^2?-halogen (I₂, Br₂, Cl₂) combinations are discussed. By demonstrating the intermediacy of 5-bromo-2-hexanol, it was confirmed that the dark silver oxidebromine induced cyclisation of 2-hexanol (and alcohols in general) involves (as the other hypohalite reactions) intramolecular 1,5-hydrogen abstraction by alkoxy radicals and formation of δ-bromohydrins. A novel and simple procedure for obtaining tetrahydrofurans from alcohols by way of the hypochlorite reaction, using silver or mercuric salts and chlorine, is described.     

反-1,2-双[2'-(5'-苯基恶唑基)]乙烯的晶体结构

用X射线单晶衍射法测定了反-1,2-双[2'-(5'-苯基恶唑基)]乙烯(POEOP)的晶体结构,POEOP晶体属单斜晶系, 空间群为P2~1/C, a=0.8268(2), b=0.5977(2), c=1.6292(3)nm;β=100.55(2)°; v=0.7915nm~3; Z=2; d~x=1.319g/cm~3。POEOP分子具有中心对称性,它的两个苯环和两个恶唑环是彼此平行的, 但整个分子却稍有些扭曲成螺旋浆式构型。键长数据表明POEOP分子中苯环与恶唑环以及恶唑环与C'=C双键间均有很大程度共轭。     

A decomposition procedure for the determination of arsenic in marine samples

The use of wet and dry ashing procedures to decompose marine biological tissues and to degrade organoarsenic compounds to inorganic arsenic for analysis by zinc-column arsine generation and atomic-absorption spectrophotometry was investigated. Wet ashing with nitric, sulphuric and perchloric acids (10:2:3 v/v) released the largest percentage of arsenic from fish tissue and quantitatively degraded methylated and other organoarsenic compounds to inorganic arsenic. The arsenic concentrations found when standard reference materials were ashed with this acid mixture were in agreement with the certified values.     

POLYMER-SUPPORTED LEWIS ACID CATALYSTS. Ⅵ. POLYSTYRENE-BONDED STANNIC CHLORIDE CATALYST

A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn (Ⅳ)/g catalyst. The catalyst showed sufficient stability and catalytic activity in organic reaction such as esterification, acetalation and ketal formation, and it could be reused many times without losing its catalytic activity.     

酰亚胺及磺酰苯酰亚胺的氰甲基化新方法

二乙胺基乙腈分別与苯邻二酰亚胺、丁二酰亚胺或邻-磺酰苯酰亚胺反应后,可生成相应的N-氰甲基苯邻二酰亚胺、N-氰甲基丁二酰亚胺,N-氰甲基邻磺酰苯酰亚胺及O-氰甲基邻磺酰苯酰亚胺。酰亚胺或磺酰苯酰亚胺的氰甲基化反应活性,随氮负离子的稳定性及其酸性增强而增大。