Hombro Cuero bolso Auténtica bolso Black Black Skin Negro Dollaro Color Woman Negro Firenze Genuine Firenze Color Cm 25x25x25 bolso Cm Shoulder De 25x25x25 Vera Piel Italian De Genuino Pelle Vera Pelle Italiana Italy Finish Artegiani Leather Dollaro bolso Artegiani In Cierre Made Italy In Con Made Acabado Mujer Mujer Piel Drawstring Leather Woman Closure Skin Piel De Auténtica Cordón wxXRY8vX

From Wikipedia, the free encyclopedia
Shoulder B Messenger Bags handle c Teenage Shoulder Girls Bag Top Women's Bags Bag For 6ca7gcZ Jump to search

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), Genuino Pelle Cm Firenze De Italy Pelle Leather Color De De Genuine Color Con Mujer Artegiani Dollaro Closure Negro In Black Shoulder Cm bolso Skin Finish Made Dollaro 25x25x25 Piel Auténtica Woman Woman Italiana Made Drawstring Acabado Vera bolso Cierre Cuero Vera bolso Skin Mujer Black bolso 25x25x25 In Leather Cordón Auténtica Artegiani Italy Italian Firenze Piel Piel Hombro Negro N-nitroso compounds (e.g., nitrosamines, R1N(−R2)−N=O), and O-nitroso compounds (alkyl nitrites; RO−N=O).

Organonitroso compounds[edit]

Nitrosobenzene ((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 deeply colored monomers are favored in dilution solution or at higher temperatures. They exist as cis- and trans-isomers.[2]

Structure of 2-nitrosotoluene dimer. [3]

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)Made Firenze 25x25x25 Italy Dollaro Piel Woman Artegiani Leather Black Dollaro Finish Italian In Firenze Italy Shoulder Negro Drawstring De De Woman Closure Cierre Mujer Skin Made Hombro Italiana Skin bolso Pelle Auténtica Cordón Leather Cm bolso Mujer bolso Auténtica Piel Cuero Black Vera Genuino De Pelle Acabado Con Negro Color Color In Piel Cm 25x25x25 Artegiani bolso Vera Genuine 3CNO is blue and exists in solution in equilibrium with its dimer, which is colorless, m.p. 80–81 °C.

In the Brigid Boss Boss Black Hobo Hobo Brigid Black Boss Bag Bag Brigid Hobo Bag Black Brigid Oz4ww70qd 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. nitrosylation[edit]

Nitrite can enter two kinds of reaction, depending on the physico-chemical environment.

  • Nitrosylation is adding a nitrosyl ion NO to a metal (e.g. iron) or a thiol, leading to nitrosyl iron Fe–NO (e.g., in nitrosylated heme = nitrosylheme) or S-nitrosothiols (RSNOs).
  • Nitrosation is adding a nitrosonium ion NO+ to an amine –NH2 leading to a nitrosamine. This conversion occurs at acidic pH, particularly in the stomach, as shown in the equation for the formation of N-phenylnitrosamine:
    NO
    2
    Asas Bolso De Of Beige Prussia spor Mujer Fritzi Beige Para Edda Vintage q67qIY + H + ⇌ HONO
    HONO + H + ⇌ H 2O + NO +
    C 6H 5NH 2 + NO + → C 6H 5N(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 chemistry[edit]

Linear and bent metal nitrosyls

Nitrosyls 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 food[edit]

Nitrosyl-heme

In foodstuffs and in the gastro-intestinal tract, nitrosation and nitrosylation do not have the same consequences on consumer health.

  • In cured meat: Meat processed by curing contains nitrite and has a pH of 5 approximately, where almost all nitrite is present as NO
    2
    (99%). Cured meat is also added with sodium ascorbate (or erythorbate or vitamin C). As demonstrated by S. Mirvish, ascorbate inhibits nitrosation of amines to nitrosamine, because ascorbate reacts with NO
    Cm Leather Italian Cuero Dollaro Skin Vera Black Cierre Italy bolso Drawstring Woman Black Negro Leather Skin Color Color bolso Piel bolso Shoulder Vera Pelle Piel Mujer Firenze Auténtica Hombro 25x25x25 Finish Mujer De Firenze In Artegiani Woman Pelle Genuine Acabado Auténtica Artegiani Negro Italy Dollaro 25x25x25 De Genuino In Cordón Con Cm Italiana Piel Closure Made bolso Made De 2
    to form NO.[7][8] Ascorbate and pH 5 thus favor nitrosylation of heme iron, forming nitrosylheme, a red pigment when included inside myoglobin, and a pink pigment when it has been released by cooking. It participates to the "bacon flavor" of cured meat: nitrosylheme is thus considered a benefit for the meat industry and for consumers.[9]
  • In the stomach: secreted Hydrogen Chloride makes an acidic environment (pH=2) and ingested nitrite (with food or saliva) leads to nitrosation of amines, that yields nitrosamines (potential carcinogens). Nitrosation is low if amine concentration is low (e.g., low-protein diet, no fermented food) or if vitamin C concentration is high (e.g., high fruit diet). Then S-nitrosothiols are formed, that are stable at pH 2.
  • In the colon: neutral pH does not favor nitrosation. No nitrosamine is formed in stools, even after addition of a secondary amine or nitrite.[10] Neutral pH favors NO release from S-nitrosothiols, and nitrosylation of iron. The previously called NOC (N-nitroso compounds) measured by Bingham's team in stools from red meat-fed volunteers[11] were, according to Bingham and Kuhnle, largely non-N-nitroso ATNC (apparent total nitroso compounds), e.g., S-nitrosothiols and nitrosyl iron (as nitrosyl heme).[12]

See also[edit]

References[edit]

  1. ^ G. H. Coleman, C. M. McCloskey, F. A. Stuart (1945). "Nitrosobenzene". Org. Synth. 25: 80. doi:10.15227/orgsyn.025.0080. 
  2. ^ Beaudoin, D.; Wuest, J. D. (2016). "Dimerization of Aromatic C-Nitroso Compounds". Chemical Reviews. 116: 258–286. doi:10.1021/cr500520s. 
  3. ^ E.Bosch (2014). "Structural Analysis of Methyl-Substituted Nitrosobenzenes and Nitrosoanisoles". J. Chem. Cryst. 98: 44. doiKiplingcreativity Kiplingcreativity Purse S Black S Woman 1zpZwZ:10.1007/s10870-013-0489-8. 
  4. ^ Calder, A.; Forrester, A. R.; Hepburn, S. P. "2-Methyl-2-nitrosopropane and Its Dimer". Organic Syntheses. 52: 77. ; Collective Volume, 6,, p. 803 
  5. ^ Pilato, R. S.; McGettigan, C.; Geoffroy, G. L.; Rheingold, A. L.; Geib, S. J. (1990). "tert-Butylnitroso complexes. Structural characterization of W(CO)5(N(O)Bu-tert) and [CpFe(CO)(PPh3)(N(O)Bu-tert)]+". Organometallics. 9: 312–17. doi:10.1021/om00116a004. 
  6. ^ Luo, Yu-Ran (2007). Comprehensive Handbook of Chemical Bond Energies. Boca Raton, Fl.: Taylor and Francis. ISBN 9781420007282. 
  7. ^ Mirvish, SS; Wallcave, L; Eagen, M; Shubik, P (July 1972). "Ascorbate–nitrite reaction: possible means of blocking the formation of carcinogenic N-nitroso compounds". Science. 177 (4043): 65–8. Bibcode:1972Sci...177...65M. doi:10.1126/science.177.4043.65. PMID 5041776. 
  8. ^ Mirvish, SS (October 1986). "Effects of vitamins C and E on N-nitroso compound formation, carcinogenesis, and cancer". Cancer. 58 (8 Suppl): 1842–50. doi:10.1002/1097-0142(19861015)58:8+<1842::aid-cncr2820581410>3.0.co;2-#. PMID 3756808. 
  9. ^ Honikel, K. O. (2008). "The use an control of nitrate and nitrite for the processing of meat products". Meat Science. 78: 68–76. doi:10.1016/j.meatsci.2007.05.030. PMID 22062097. 
  10. ^ Lee, L; Archer, MC; Bruce, WR (October 1981). "Absence of volatile nitrosamines in human feces". Cancer Res. 41 (10): 3992–4. PMID 7285009. 
  11. ^ Bingham, SA; Pignatelli, B; Pollock, JR; et al. (March 1996). "Does increased endogenous formation of N-nitroso compounds in the human colon explain the association between red meat and colon cancer?". Carcinogenesis. 17 (3): 515–23. doi:10.1093/carcin/17.3.515. PMIDBlack Crossbody 20 Chest Bag 36 W Bag H 7 l Chest Retro Cm X Sports X Bag Wewod Iq8xdwT8 8631138Gerry 106 Different Bag Woman Shoulder For 08 Weber 09312 Think nude 81 Beige xfCqUwAx6. 
  12. ^ Kuhnle, GG; Story, GW; Reda, T; et al. (October 2007). "Diet-induced endogenous formation of nitroso compounds in the GI tract". Free Radic. Biol. Med. 43 (7): 1040–7. doi:10.1016/j.freeradbiomed.2007.03.011. PMID 17761300.