金属酞菁激发态与氧的相互作用

比较了几种金属酞菁光敏产生单重态氧和超氧负离子的能力,结果表明它们产生¹O₂的能力与中心金属的电子结构有关,取决于三重态寿命和量子产率。顺序如下:Zn>Ga>Cu>H₂>Al>Co。产生O₂^·-的能力不仅与三重态寿命和量子产率有关,也与激发能和氧化还原电位有关。其顺序如下:Ga>Al>Cu>Zn。还研究了酪氨酸与镓酞菁激发态相互作用,酪氨酸猝灭镓酞菁荧光。在除氧条件光激发下,酪氨酸猝灭镓酞菁的激发三重态发生电子转移,检测到GaTSPc^-在560nm处的瞬态吸收,在氧的存在下进一步反应生成O₂^·-。     

REACTIONS OF A PHOSPHORANIMINE ANION WITH SOME ORGANIC ELECTROPHILES

Abstract

The reactions of a variety of electrophiles with the N-silyl-P-trifluoroethoxyphosphoranimine anion Me₃Sin°P(Me)(OCH₂CF₃)CH^? ₂ (1a), prepared by the deprotonation of the dimethyl precursor Me₃SiN[dbnd]P(OCH₂CF₃)Me₂ (1) with n-BuLi in Et₂O at-78°C, were studied. Thus, treatment of 1a with alkyl halides, ethyl chloroformate, or bromine afforded the new N-silylphosphoranimine derivatives Me₃SiN[dbnd]P(Me)(OCH₂CF₃)CH₂R [2: R = Me, 3: R = CH₂Ph, 4: R = CH[sbnd]CH₂, 5: R = C(O)OEt, and 6: R = Br]. In another series, when 1a was allowed to react with various carbonyl compounds, 1,2-addition of the anion to the carbonyl group was observed. Quenching with Me₃SiCl gave the O-silylated products Me₃SiN[dbnd]P(Me)(OCH₂CF₃)CH₂°C(OSiMe₃)R¹R² [7: R ¹ = R ² = Me; 8: R ¹ = Me, R ² = Ph; 9: R¹ = Me, R ² = CH[sbnd]CH₂; and 10: R ¹ = H, R ² = Ph]. Compounds 2–10 were obtained as distillable, thermally stable liquids and were characterized by NMR spectroscopy (¹H, ¹³C, and ³¹P) and elemental analysis.     

SOME REACTIONS OF 1,3-THIAZINE DERIVATIVES WITH ALIPHATIC DIAMINES

Abstract

A wide range of 2-substituted-5,6-dihydro-4H-1,3-thiazines (I) and tetrahydro-2H-1,3-thiazines (II) have been found to undergo a facile ring transformation reaction with aliphatic diamines to form the corresponding dinitrogen heterocycles (III) and (IV).     

A SURVEY OF CHEMILUMINESCENCE IN BASE-CATALYZED AUTOXIDATION REACTIONS

Abstract— Relatively bright chemiluminescence has been observed in autoxidation reactions in basic, aprotic, ionizing media for selected acyloins, vinyl carbonyls, vinyl nitriles and polynuclear aromatic compounds. The indoles approach the brightness of the most efficient chemiluminescent compounds. The intensity of acyloin emission correlates qualitatively with the resonance stabilization of the intermediate radical anion. It is suggested that Chandross' oxidative excitation mechanism may be applicable to the acyloins and hydrocarbons.     

SOME REACTIONS OF ALIPHATIC AMIDES WITH SULFUR AND SODIUM POLYSULFIDES

Abstract

Some reactions of the aliphatic amides, CH₃CONH₂, CH₃CONHCH₃, CH₃CON(CH₃)₂ and CH₃CON(C₂H₅)₂ with elemental S and sodium sulfides, Na₂S _n , n ≥ 1, have been studied. The initial reaction product with elemental sulfur appears to be a substituted polysulfane, CH₃COS _n NR, formed by the insertion of the sulfur chain into the C[sbnd]N bond. This product decomposes on further heating, forming COS as the major gas product. In solutions of Na₂S _n in the amides, the reactive material appears to be elemental S, present in equilibrium with S _n ^?2. In the N-dialkyl substituted amides, CH₃CON(CH₃)₂ and CH₃CON(C₂H₅)₂, the tetrasulfide is uniquely stabilized by solvent coordination so that solutions of Na₂S₄ in these amides are stable for long periods of time at 130°C.     

超声辐射下某些含官能团化合物与二氯卡宾的反应

超声辐射在有机反应中的应用日趋广泛。我们曾报道了超声辐射与相转移催化相结合产生二氯卡宾和二溴卡宾的方法及其与烯烃加成反应的结果。该法比单纯使用相转移催化剂或超声辐射更为可取。本文进一步将它用于二氯卡宾与某些含官能团化合物的反应,考察超声辐射的影响。反应是在固-液两相条件下进行的,即以粉末状氢氧化钠为碱,氯仿过量兼作溶剂。结果表明,超声辐射对各类化合物反应的影响有相当明显的差异。     

SINGLET OXYGEN REACTIONS WITH 2,7-DIMETHYL-2,6-OCTADIENE

Abstract— Results concerning Rose Bengal sensitized photoxidation of 2,7-dimethyl-2,6-octadiene (A) are discussed. This diolefin may be considered as a model molecule of polyisoprene of polymerization number two with 1,4-4,1 addition mode.
All the mono- and dihydroperoxides apt to occur are actually obtained. One of the occurring hydroperoxides, 2,7-dimethyl-dihydroperoxy-3,5-octadiene, which has the structure of a conjugated diene, does not lead to an endoperoxide. This is contrary to Kaplan and Kelleher's hypothesis. On the other hand, no trihydroperoxide forms as a result of further addition of singlet oxygen (¹O₂).
A complete kinetic study has allowed us to determine the rate constants of all the reactions which take place. The reactivity of (A) is twice that of 2-methyl-2-pentene and the addition of ¹O₂ to one of the double bonds of (A) induces deactivation of the remaining double bond.     

REACTION AND QUENCHING OF SINGLET MOLECULAR OXYGEN WITH ESTERS OF POLYUNSATURATED FATTY ACIDS

Abstract The rate constants for the reactive (k_R) and unreactive (k_Q) interaction of singlet molecular oxygen with three esters of polyunsaturated fatty acids (PUFA: cis-methyl oleate, MO; cis-methyl linoleate, MLA and cis-ethyl linolenate, ELN) are determined. The values of the ratio k_Q/k_R are 0.51, 0.26 and 0.20 for MO, MLA and ELN, respectively. This variation results principally from that of k_R because the values of k_Q are only slightly different (1.24 × 10⁴M^?1 s^?1 for MO and ～1.0 × 10⁴M^?1 s^?1 for MLA and ELN). It is shown that the rate constant k_Q characterizes mainly an interaction with the unreactive part of the molecule rather than with the double bonds (solventlike quenching). Contrary to the already reported case of 1,5-polyenes for which k_Q <<k_R, the present results and those obtained from a number of literature data show that for PUFA and their esters, neither k_R+ k_Q nor k_R are proportional to the total number of double bonds or of methylene groups adjacent to the double bonds. Instead, a linear correlation is observed by plotting k_Rvs the number of methylene groups adjacent to two double bonds. It is deduced that contrary to a common assumption, biallylic hydrogens have a reactivity higher than that of singly allylic hydrogens (reactivity ratio 1.19). The consequence of this result on the estimation of relative contributions of singlet oxygen and radical mechanisms to oxidation processes is discussed. Moreover, the whole of these results allows prediction of the values of k_R and k_Q for all unsaturated fatty acids (and their esters) of similar structure.     

SOME REACTIONS OF DICHLOROPHOSPHINO-METHANETHIOPHOSPHONIC DICHLORIDE

Abstract

The synthesis of the thiophosphonic dichloride Cl₂PCH₂P(S)Cl₂ (1) is reported and some of its reactions are described. A detailed investigation of the aminolysis of 1 and the corresponding F₂PCH₂P(S)F₂ (2) reveals a stepwise substitution pattern.     

ON THE REACTION OF SINGLET MOLECULAR OXYGEN WITH N-ALLYLTHIOUREA IN AQUEOUS SOLUTION

Abstract— Experiments on the photooxidation of N -allylthiourea, thiourea, and N-allylurea sensitized by the dye phenosafranine show that in N -allylthiourea the thiourea group is the site of singlet oxygen attack, while the allyl moiety neither reacts with nor quenches this metastable form of O₂ (in neutral aqueous solutions). Low concentrations of N^-₃ (a known quencher of singlet oxygen) strongly reduce the photooxidation of allylthiourea by a mechanism which apparently obeys simple competition kinetics. From these results the rate constant of the reaction between allylthiourea and singlet oxygen is obtained ( k = 4 × 10⁶ M ^-1 s^-1; pH = 7.1).     

DETECTION OF OXYGEN RADICALS IN BIOLOGICAL REACTIONS

Abstract— Recent data are presented on the mechanisms or selected assay procedures for superoxide anions (O₂^-) and hydroxyl radicals (OH). The systems discussed include the autoxidation of adrenalin to adrenochrome and other indole compounds, the oxidation of hydroxylamine to nitrite, the generation of ethylene from methional, and the scavenging of OH radicals by p -nitroso-dimethylaniline. The results are compared with other assay procedures to aid in the search for absolute and specific tests for these oxygen radicals. Particular emphasis is placed on the interrelation of 0₂^- OH and hydrogen peroxide.     

PRODUCTS AND RELATIVE REACTION RATES OF THE OXIDATION OF TOCOPHEROLS WITH SINGLET MOLECULAR OXYGEN

Abstract— The relative reactivity of singlet molecular oxygen, 0₂(¹Δ_g), α-,β-,Γ-and δ with -tocopherol (vitamin E) was investigated using microwave discharge generation as a uniquely clean source of singlet oxygen and using a hydrocarbon solvent to approximate the membrane environment. The relative efficiencies of the tocopherols for O₂(¹Δg) were found to decrease in the order: D-α-tocopherol > D-β-tocopheroI > D–Γ-tocopherol > D-δ-tocopherol. The reaction products in all cases were found to be mixtures of quinone and quinone epoxides apparently resulting from decomposition of the primary product, the hydroperoxydienone.     

SOME INTERESTING REACTIONS OF AN N－BROMOMETHYL QUATERNARY AMMONIUM SALT WITH HALOPHILIC REAGENTS

ＳＯＭＥＩＮＴＥＲＥＳＴＩＮＧＲＥＡＣＴＩＯＮＳＯＦＡＮＮ－ＢＲＯＭＯＭＥＴＨＹＬＱＵＡＴＥＲＮＡＲＹＡＭＭＯＮＩＵＭＳＡＬＴＷＩＴＨＨＡＬＯＰＨＩＬＩＣＲＥＡＧＥＮＴＳ￥ＧｕｏＦｅｎｇＨＵＡＮＧａｎｄＸｉａｏＴｉａｎＬＩＡＮＧ（Ｉｎｓｔｉｔｕｔｅｏ...     

THE REACTIONS OF HYDROXYL RADICAL WITH SOME TRANSITION-METAL COMPOUNDS CONTAINING ORGANIC MOLECULES

Abstract— Recent reports that have appeared in the literature concerning the reactions in aqueous media of hydroxyl radical with some transition-metal compounds containing bound organic molecules are discussed and experimental results on the reactions of hydroxyl radical with some platinum complex ions are presented. Emphasis is placed on the comparison of the behavior of the free ligand relative to that of the complexed and protonated forms. The occurrence of metal-ion complexation can modify to varying degrees the reactivity of organic entities towards hydroxyl radical and the subsequent behavior of the products. The influence of the metal center is considered to involve its Lewis acidity, π-bonding capabilities as well as features such as its formal oxidation state.     

NEAR-INFRARED DETECTION OF SINGLET MOLECULAR OXYGEN PRODUCED BY PHOTOSENSITIZATION WITH PROMAZINE and CHLORPROMAZINE

A sensitive near-infrared detection system has been used to study the steady-state emission of ¹O₂ at 1268 nra produced by promazine (PZ) and chlorpromazine (CPZ) during photo-illumination. Singlet molecular oxygen could be detected in a variety of ordinary and perdeuterated organic solvents, but was not detectable in water or deuterium oxide. The emission was enhanced in the perdeuterated organic solvents and could be eliminated by rigorous degassing or by addition of the singlet oxygen scavenger 2,3-dimethylfuran. Singlet oxygen could not be detected in any of the solvents during irradiation of the sulfoxides of PZ and CPZ. We conclude that in biological systems ¹O₂ production is not a major pathway to phototoxicity for the sulfoxides, while for the parent phenothiazines the formation of ¹O₂ is much more likely to be important in nonpolar environments such as cell membranes than in the aqueous parts of the cell.     

POLYMER BOUND TRANSITION METAL COMPLEXES FOR CATALYTIC OXIDATION OF CYCLOHEXENE WITH MOLECULAR OXYGEN

Polymer-bound Schiff-base ligand （PS-Sal-Cys） was prepared from the polystyrene-bound salicylaldehyde and L-cysteine, its complex （PS-Sal-Cys-Mn） was also synthesized. The polymer ligand and its complex were characterized by infrared spectra （IR）, small area X-ray photoelectron spectroscopy （XPS）, and inductively coupled plasma-atomic emission spectro （ICP-AES）. In the presence of complex, cyclohexane can be effectively oxidized by molecular oxygen without a reductant. The major products of the reaction are 2-cyclohexen-1-ol, 2-cyclohexen-1-one, and 2-cyclohexen-1-hydroperoxide, which is different from the typical oxidation of cyclohexene. The mechanism of cyclohexene oxidation is also discussed.     

HYDROGEN PEROXIDE-DEPENDENT GENERATION OF SINGLET MOLECULAR OXYGEN BY HUMAN SALIVA: ITS DETECTION BY CHEMILUMINESCENCE FROM A Cypridina LUCIFERIN ANALOG

By the addition of hydrogen peroxide to human saliva, chemiluminescence from Cypridina luciferin analog (CCLA) and oxygen evolution were observed. Chemiluminescence was inhibited by inhibitors of salivary peroxidase, azide and cyanide and by a singlet oxygen quencher, crocin. Deuterium oxide (99.75%) stimulated the initial increase of CCLA by15–50% and the integrated CCLA 2.1-3.6-fold. The result suggest that the generation of singlet oxygen by peroxidase in human saliva depends on hydrogen peroxide.     

RAPID EQUILIBRATION OF OXYGEN IN FLUORESCENCE QUENCHING REACTIONS

A simple means is described for the rapid equilibration of oxygen in fluorescence quenching reactions. This involves bubbling the gas through experimental solutions. With this procedure, data for Stern-Volmer plots can be obtained in 1–2 h, without bubbling it takes approximately ten times as long to collect such data.     

ON SOME PROBLEMS CONCERNING INVESTIGATION OF LIQUID-PHASE CHEMILUMINESCENCE

Abstract— Some features of chemiluminescence important for quantitative studies of the phenomenon are discussed. Parallel excitation reactions may lead to several sorts of emitters. Energy transfer from and quenching of excited states may be responsible for the peculiar behaviour of chemiluminescent systems. These points are illustrated by results for a model reaction: thermal decomposition of dicyclohexylperoxydicarbonate (DCHPC) in the presence of O₂ with or without methylethylketone and an activator, 9,10-dibromoanthracene.     

液相化学发光法测定水中溶解氧

以碘－鲁米诺化学发光反应作指示反应,与碘量法相结合,提出了测定水中溶解氧的新方法。该方法具有试样用量较钞,准确度较高的特点,用于水样中溶解氧的测定,结果满意。