Epoxide ring opening and related reactivities of cyclopenta polycyclic aromatic hydrocarbonsquantum mechanical studies
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U.S. Environmental Protection Agency , [Washington, D.C
Polycyclic aromatic hydrocarbons -- Analysis., Epoxy compo
|Statement||James R. Rabinowitz and Stephen B. Little.|
|Contributions||Little, Stephen B., United States. Environmental Protection Agency.|
|The Physical Object|
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Oxidized metabolites from cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs). A DFT model study of their carbocations formed by epoxide ring opening. Journal of Physical Organic Chemistry23 (9), Cited by: 4. Epoxide ring opening and related reactivities of cyclopenta polycyclic aromatic hydrocarbons: quantum mechanical studies.
Description Epoxide ring opening and related reactivities of cyclopenta polycyclic aromatic hydrocarbons EPUB
Rabinowitz JR(1), Little SB. Author information: (1)Carcinogenesis and Metabolism Branch, Environmental Protection Agency, Research Triangle Park, North Carolina Cited by: 4. Oxidized metabolites from cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs). A DFT model study of their carbocations formed by epoxide ring opening.
Journal of Physical Organic Chemistry23 (/poc.v), DOI: /pocCited by: A density functional theory (DFT) study aimed at understanding structure–reactivity relationships in the oxidized metabolites of cyclopenta‐fused polycyclic aromatic hydrocarbons (CP‐PAHs) is reported.
Epoxidation at various positions was examined in order to identify the most stable epoxide Cited by: 8.
The half-life of diol epoxide 1 in tissue culture medium was about 30 sec, whereas the half-life of diol epoxide 2 was between 6 and 12 min. 9,Epoxy-7,8,9,tetrahydrobenzo(a)pyrene, which is.
of epoxide formation at the external oleﬁnic bond in the ﬁve-membered ring is substantiated by the bacterial mutagenic response of independently synthesized cyclopenta[cd ]pyrene-3,4-epoxide (9), acephenanthrylene-4,5-epoxide (10), aceanthrylene-1,2-epoxide (11) and cyclopenta[hi]chrysene-4,5-epoxide.
The nonenzymatic ring-opening reactions of epoxides provide a nice overview of many of the concepts we have seen already in this chapter.
Ring-opening reactions can proceed by either S N 2 or S N 1 mechanisms, depending on the nature of the epoxide and on the reaction conditions. If the epoxide is asymmetric, the structure of the product will. ABSTRACT.
β-Amino alcohols are versatile intermediates in the synthesis of various biologically potent compounds, which can also be achieved by ring opening of epoxides by the present review, focus has been placed on the ring opening of epoxides with amines under a variety of reaction parameters reported during – Na+Cp(CO)zFe-; (Bu4N)+Cp(C0)2Fe- even failed to react (f) Methyllithium preferentially adds transannularly, under epoxide ring opening, to 9,lO-didehydrodianthracene 9’, 10’- epoxide.
In the presence of crown ethers or cryptands, addition to the double bond without opening of the epoxide ring becomes the main reaction pathway Polycyclic aromatic hydrocarbons are present in the environment as complex mixtures that are difficult to characterize and measure.
They are generally analyzed using gas chromatography coupled with mass spectrometry (GC-MS) or by using high pressure liquid chromatography (HPLC) with ultraviolet (UV) and fluorescence detectors (Slooff et al., ).
Polycyclic aromatic compounds [electronic resource] The structures & reactions of the aromatic compounds / by G. Badger Epoxide ring opening and related reactivities of cyclopenta polycyclic aromatic hydrocarbons [microform].
The nonenzymatic ring-opening reactions of epoxides provides an oppourtunity to review the nucelophilic substitution mechansims. Ring-opening reactions can proceed by either S N 2 or S N 1 mechanisms, depending on the nature of the epoxide and on the reaction conditions.
If the epoxide is asymmetric, the structure of the product will vary. Epoxides are produced in cells as oxidation products of alkenes and aromatic compounds. These epoxides are formed in the liver by cytochrome P, and they undergo ring-opening reactions with different substances.
If the epoxide reacts with a biological macromolecule, the result is potentially devastating since such reactions disrupt essential biochemical processes. Epoxide ring opening and related reactivities of cyclopenta polycyclic aromatic hydrocarbons: Quantum mechanical studies of 13 cyclopenta polycyclic aromatic hydrocarbons.
The bacterial mutagenic response (Ames-assay, Salmonella typhimurium strain TA98 ± S9-mix) of a series of monocyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs) identified in combustion exhausts, viz. cyclopenta[cd]pyrene (1), acephenanthrylene (2), aceanthrylene (3) and cyclopenta[hi]chrysene (4), is mutagenic effects are compared with those exerted.
Reactions of Epoxides, contd The value of epoxides is the variety of nucleophiles that will open the ring and the combinations of functional groups that can be prepared from them.
Details Epoxide ring opening and related reactivities of cyclopenta polycyclic aromatic hydrocarbons EPUB
Ethers Nomenclature, Synthesis and Reactions 9 H S C H 2 C H O H C H 3 H 2 O / H 3 O + H O C H 2 C H O H C H 3 H 2 C C H O C H 3 H 2 NC H 2 C H O H C H 3 C C H 2 C. opening R OH OH Nu.
Although the most substituted epoxide is favored, the terminal epoxide is more reactive (toward Nu attack). Trans epoxides are more stable than cis-epoxides.
Directing group (heteroatom- oxygen) was essential for optimal reactivity Sharpless, K. et al. Pure & Appl. Chem. 55, R OH O R HO O OH O BnO NH2Ts, NaOH. Book, Author: Snyder, James P., Description: New York: Academic Press, Epoxide ring opening and related reactivities of cyclopenta polycyclic aromatic hydrocarbons [microform] Explore.
Find in other libraries; Preview at Google Books; Check eResources and Research Guides. Epoxide Formation and Ring Opening Reactions. Epoxides are more reactive than open chain ethers due to their highly strained ring structure, and are therefore used in a variety of synthetic reactions.
Epoxides are synthesized either by treatment of alkenes by peroxyacids, or by the base-promoted cyclization of halohydrins. Theoretical study of aza-polycyclic aromatic hydrocarbons The epoxide ring opening mode is also greatly influenced by N-protonation. the covalent adducts (syn and anti) formed by reaction of the benzylic carbocations derived from diol epoxides and dihydrodiols with methoxide and methanethiolate anions were studied.
Overview of the Reactions of Epoxides Reaction type: Nucleophilic Substitution. Summary. Epoxides are much more reactive than simple ethers due to ring strain.
Nucleophiles attack the electrophilic C of the C-O bond causing it to break, resulting in ring opening. Opening the ring relieves the ring strain. The products are typically 2. This documentation is based mainly on the monograph on selected polycyclic aromatic hydrocarbons by the International Programme on Chemical Safety (WHO ) and on extracts from contributions to the research report “Polycyclische Aromatische Kohlenwasserstoffe (PAH)” (DFG ) of the ad hoc working group “PAH” of the MAK Commission.
The tables with individual data taken from WHO A density functional theory (DFT) study aimed at understanding structure–reactivity relationships in the oxidized metabolites of cyclopenta‐fused polycyclic aromatic hydrocarbons (CP‐PAHs) is reported. Epoxidation at various positions was examined in order to identify the most stable epoxide in each class of CP‐PAHs.
Relative energies of the carbocations resulting from O‐protonation. Abstract. Polycyclic aromatic hydrocarbons (PAH) are formed as products of the incomplete pyrolysis of organic materials and are present in considerable quantities in fossil fuel from which they are released by a variety of combustion processes (see Guerin ).
Sources of environmental PAH therefore include, in the wider sense, power plants, domestic heating systems, petrol and diesel. The reaction of different types of aromatic and aliphatic epoxides with sodium azide to give vicinal azido alcohols was studied in a microreactor with and without pillars in the channels.
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Dependent on the substrate, the regioselectivity of the ring opening is affected by the used solvent system, viz.
acetonitrile–water (sometimes with 10%. Epoxide, cyclic ether with a three-membered ring. The basic structure of an epoxide contains an oxygen atom attached to two adjacent carbon atoms of a hydrocarbon. The strain of the three-membered ring makes an epoxide much more reactive than a typical acyclic ether.
Ethylene oxide is economically. Polycyclic aromatic hydrocarbons Synthesis of cyclopenta(cd)pyrene-3,4-epoxide, the ultimate mutagenic metabolite of the environmental carcinogen cyclopenta(cd)pyrene. Chem. Soc. Chem. Commun. – Google Scholar. Gold, A., J.
Schultz, and E. Eisenstadt. Relative reactivities of pyrene ring positions: cyclopenta(cd)pyrene via. Complexation of Ag(I) cation to a series of substituted anthracenes (AN), phenanthrenes (PH), pyrenes (PY) and cyclopenta[a]phenanthrenes (CPaPH) was studied in competitive experiments by allowing PAHs to react in pairs with resulting complexes were examined by electrospray mass spectrometry (ES-MS) to determine relative abundances of the corresponding monomeric and dimeric.
Aromatic hydrocarbons are defined by having 6-membered ring structures with alternating double bonds (Fig ). Figure Aromatic Hydrocarbons. Aromatic hydrocarbons contain the 6-membered benzene ring structure (A) that is characterized by alternating double bonds. Ultradur, PBT is a plastic polymer that contains an aromatic functional group.
Polycyclic aromatic hydrocarbons (PAHs) are major organic pollutants in the environment, which are toxic to humans and biota, given their carcinogenic, mutagenic and teratogenic nature.
In this chapter, we carried out an overview of the sources and toxicity of PAHs, their common analytical methods of determination in the water and sediment samples, and also their global trend of.
Polycyclic aromatic hydrocarbons (PAHs, also polyaromatic hydrocarbons or polynuclear aromatic hydrocarbons) are hydrocarbons—organic compounds containing only carbon and hydrogen—that are composed of multiple aromatic rings (organic rings in which the electrons are delocalized).The simplest such chemicals are naphthalene, having two aromatic rings, and the three-ring compounds .Borosky, Gabriela, L.; Laali, Kenneth, K.
Oxidized Metabolites from Cyclopenta-Fused Polycylic Aromatic Hydrocarbons (CP-PAHs). A DFT Model Study of Their Carbocations Formed by Epoxide Ring Opening. J.
Phys. Org. Chem. (), 23(9), Nitrated polycyclic aromatic hydrocarbons (N-PAHs) are an important category of derivations of PAHs and are of special interest because they include potential mutagens and carcinogens.
They have been recognized as direct-acting mutagens and carcinogens to mammalian systems and are, thus, considered to have far greater toxicity than.
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