词条 | Nitroso |
释义 |
Nitroso refers to a functional group in organic chemistry which has the NO group attached to an organic moiety. As such, various nitroso groups can be categorized as C-nitroso compounds (e.g., nitrosoalkanes; R−N=O), S-nitroso compounds (nitrosothiols; RS−N=O), N-nitroso compounds (e.g., nitrosamines, R1N(−R2)−N=O), and O-nitroso compounds (alkyl nitrites; RO−N=O). Organonitroso compoundsNitrosobenzene ((C6H5NO) is prepared by reduction of nitrobenzene to phenylhydroxylamine (C6H5NHOH), which is then oxidized.[1] Nitrosoarenes typically participate in a monomer-dimer equilibrium. The dimers, which are often pale-yellow, are often favored in the solid state, whereas the deep-green monomers are favored in dilute solution or at higher temperatures. They exist as cis- and trans-isomers.[2]Nitroso compounds can be prepared by the reduction of nitro compounds or by the oxidation of hydroxylamines. A good example is (CH3)3CNO, known formally as 2-methyl-2-nitrosopropane, or t-BuNO.[4] (CH3)3CNO is blue and exists in solution in equilibrium with its dimer, which is colorless, m.p. 80–81 °C. In the Fischer–Hepp rearrangement aromatic 4-nitrosoanilines are prepared from the corresponding nitrosamines. Another named reaction involving a nitroso compound is the Barton reaction. Organonitroso compounds serve as a ligands for transition metals.[5] Due to the stability of the nitric oxide free radical, nitroso organyls tend to have very low C–N bond dissociation energies: nitrosoalkanes have BDEs on the order of 30 to 40 kcal/mol, while nitrosoarenes have BDEs on the order of 50 to 60 kcal/mol. As a consequence, they are generally heat- and light-sensitive. Compounds containing O–(NO) or N–(NO) bonds generally have even lower bond dissociation energies. For instance, N-nitrosodiphenylamine, Ph2N–N=O, has a N–N bond dissociation energy of only 23 kcal/mol.[6] Nitrosation vs. nitrosylationNitrite can enter two kinds of reaction, depending on the physico-chemical environment.
{{chem|NO|2|−}} + H+ {{eqm}} HONO HONO + H+ {{eqm}} H2O + NO+ C6H5NH2 + NO+ → C6H5N(H)NO + H+ Many primary alkyl N-nitroso compounds, such as CH3N(H)NO, tend to be unstable with respect to hydrolysis to the alcohol. Those derived from secondary amines (e.g., (CH3)2NNO derived from dimethylamine) are more robust. It is these N-nitrosamines that are carcinogens in rodents. Nitrosyl in inorganic chemistryNitrosyls are non-organic compounds containing the NO group, for example directly bound to the metal via the N atom, giving a metal–NO moiety. Alternatively, a nonmetal example is the common reagent nitrosyl chloride (Cl−N=O). Nitric oxide is a stable radical, having an unpaired electron. Reduction of nitric oxide gives the hyponitrite anion, NO−: NO + e− → NO− Oxidation of NO yields the nitrosonium cation, NO+: NO → NO+ + e− Nitric oxide can serve as a ligand forming metal nitrosyl complexes or just metal nitrosyls. These complexes can be viewed as adducts of NO+, NO−, or some intermediate case. In foodIn foodstuffs and in the gastro-intestinal tract, nitrosation and nitrosylation do not have the same consequences on consumer health.
See also
References1. ^{{cite journal| author = G. H. Coleman, C. M. McCloskey, F. A. Stuart | title = Nitrosobenzene | journal=Org. Synth.|volume = 25 | pages = 80| year = 1945 | doi=10.15227/orgsyn.025.0080}} {{Functional Groups}}{{Nitric oxide signaling}}{{Authority control}}2. ^{{cite journal|authors=Beaudoin, D.; Wuest, J. D.|title=Dimerization of Aromatic C-Nitroso Compounds|journal=Chemical Reviews|year=2016|volume=116|pages=258-286|doi=10.1021/cr500520s}} 3. ^{{cite journal|author=E.Bosch|title=Structural Analysis of Methyl-Substituted Nitrosobenzenes and Nitrosoanisoles|journal=J. Chem. Cryst.|year=2014|volume=98|page=44| doi=10.1007/s10870-013-0489-8}} 4. ^{{OrgSynth|first1=A. |last1=Calder |first2=A. R. |last2=Forrester |first3=S. P. |last3=Hepburn |title=2-Methyl-2-nitrosopropane and Its Dimer |collvol=6, |collvolpages=803 |volume=52 |page=77 |prep=cv6p0803}} 5. ^{{cite journal|last1=Pilato |first1=R. S. |last2=McGettigan |first2=C. |last3=Geoffroy |first3=G. L. |last4=Rheingold |first4=A. L.|last5=Geib |first5=S. J. |title=tert-Butylnitroso complexes. Structural characterization of W(CO)5(N(O)Bu-tert) and [CpFe(CO)(PPh3)(N(O)Bu-tert)]+ |journal=Organometallics |date=1990 |volume=9 |pages=312–17 |doi=10.1021/om00116a004}} 6. ^{{Cite book|title=Comprehensive Handbook of Chemical Bond Energies|last=Luo|first=Yu-Ran|publisher=Taylor and Francis|year=2007|isbn=9781420007282|location=Boca Raton, Fl.|pages=}} 7. ^{{cite journal | pmid = 5041776 | volume=177 | issue=4043 | title=Ascorbate–nitrite reaction: possible means of blocking the formation of carcinogenic N-nitroso compounds |date=July 1972 | journal=Science | pages=65–8 | doi=10.1126/science.177.4043.65|bibcode = 1972Sci...177...65M | last1 = Mirvish | first1 = SS | last2 = Wallcave | first2 = L | last3 = Eagen | first3 = M | last4 = Shubik | first4 = P}} 8. ^{{cite journal | pmid = 3756808 | volume=58 | issue=8 Suppl | title=Effects of vitamins C and E on N-nitroso compound formation, carcinogenesis, and cancer |date=October 1986 | journal=Cancer | pages=1842–50 | doi=10.1002/1097-0142(19861015)58:8+<1842::aid-cncr2820581410>3.0.co;2-# | last1 = Mirvish | first1 = SS}} 9. ^{{cite journal | last1 = Honikel | first1 = K. O. | year = 2008 | title = The use an control of nitrate and nitrite for the processing of meat products | url = | journal = Meat Science | volume = 78 | issue = | pages = 68–76 | doi = 10.1016/j.meatsci.2007.05.030 | pmid=22062097}} 10. ^{{cite journal | pmid = 7285009 | volume=41 | issue=10 | title=Absence of volatile nitrosamines in human feces |date=October 1981 | journal=Cancer Res. | pages=3992–4 | last1 = Lee | first1 = L | last2 = Archer | first2 = MC | last3 = Bruce | first3 = WR}} 11. ^{{cite journal | pmid = 8631138 | volume=17 | issue=3 | title=Does increased endogenous formation of N-nitroso compounds in the human colon explain the association between red meat and colon cancer? |date=March 1996 | journal=Carcinogenesis | pages=515–23 | doi=10.1093/carcin/17.3.515 | last1 = Bingham | first1 = SA | last2 = Pignatelli | first2 = B | last3 = Pollock | first3 = JR |display-authors=etal }} 12. ^{{cite journal | doi = 10.1016/j.freeradbiomed.2007.03.011 | pmid = 17761300 | volume=43 | issue=7 | title=Diet-induced endogenous formation of nitroso compounds in the GI tract |date=October 2007 | journal=Free Radic. Biol. Med. | pages=1040–7 | last1 = Kuhnle | first1 = GG | last2 = Story | first2 = GW | last3 = Reda | first3 = T |display-authors=etal }} 3 : Functional groups|Nitroso compounds|Nitrosyl compounds |
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