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Nitroso

January 01, 1970

In organic chemistry, nitroso refers to a functional group in which the nitric oxide (−N=O) group is 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, RN(−R’)−N=O), and O-nitroso compounds (alkyl nitrites; RO−N=O).

Structural formula of nitroso group

Synthesis edit

Nitroso compounds can be prepared by the reduction of nitro compounds[1] or by the oxidation of hydroxylamines.[2] Ortho-nitrosophenols may be produced by the Baudisch reaction. In the Fischer–Hepp rearrangement aromatic 4-nitrosoanilines are prepared from the corresponding nitrosamines.

Properties edit

 
Structure of 2-nitrosotoluene dimer[3]

Nitrosoarenes typically participate in a monomer–dimer equilibrium. The azobenzene N,N'-dioxide (Ar(–O)N+=+N(O–)Ar) dimers, which are often pale yellow, are generally 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.[4]

When stored in protic media, primary and secondary nitrosoalkanes isomerize to oximes.[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 30–40 kcal/mol (130–170 kJ/mol), while nitrosoarenes have BDEs on the order of 50–60 kcal/mol (210–250 kJ/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 (96 kJ/mol).[6] Organonitroso compounds serve as a ligands giving transition metal nitroso complexes.[7]

Reactions edit

Many reaction exists which make use of an intermediate nitroso compound, such as the Barton reaction and Davis–Beirut reaction, as well as in the synthesis of indoles, for example: Baeyer–Emmerling indole synthesis, Bartoli indole synthesis. In the Saville reaction, mercury is used to replace a nitrosyl from a thiol group.

C-nitroso compounds are used in organic synthesis as synthons in some well-documented chemical reactions such as hetero Diels-Alder (HDA), nitroso-ene and nitroso-aldol reactions.[8]

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 + H+ ⇌ HONO
    HONO + H+ ⇌ 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 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 nitrosyl 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 human health edit

This section is transcluded from Nitrosamine formation during digestion. (edit | history)

Nitroso compounds react with primary amines in acidic environments to form nitrosamines, which human metabolism converts to mutagenic diazo compounds. Small amounts of nitro and nitroso compounds form during meat curing; the toxicity of these compounds preserves the meat against bacterial infection. After curing completes, the concentration of these compounds appears to degrade over time. Their presence in finished products has been tightly regulated since several food-poisoning cases in the early 20th century,[9] but consumption of large quantities of processed meats can still cause a slight elevation in gastric and oesophageal cancer risk today.[10][11][12][13]

For example, during the 1970s, certain Norwegian farm animals began exhibiting elevated levels of liver cancer. These animals had been fed herring meal preserved with sodium nitrite. The sodium nitrite had reacted with dimethylamine in the fish and produced dimethylnitrosamine.[14]

The effects of nitroso compounds vary dramatically across the gastrointestinal tract, and with diet. Nitroso compounds present in stool do not induce nitrosamine formation, because stool has neutral pH.[15][16] Stomach acid does cause nitrosamine compound formation, but the process is inhibited when amine concentration is low (e.g. a low-protein diet or no fermented food). The process may also be inhibited in the case of high vitamin C (ascorbic acid) concentration (e.g. high-fruit diet).[17][18][19] However, when 10% of the meal is fat, the effect reverses, and ascorbic acid markedly increases nitrosamine formation.[20][21]

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. ^ Calder, A.; Forrester, A. R.; Hepburn, S. P. "2-Methyl-2-nitrosopropane and Its Dimer". Organic Syntheses. 52: 77; Collected Volumes, vol. 6, p. 803.
  3. ^ E.Bosch (2014). "Structural Analysis of Methyl-Substituted Nitrosobenzenes and Nitrosoanisoles". J. Chem. Cryst. 98 (2): 44. doi:10.1007/s10870-013-0489-8. S2CID 95291018.
  4. ^ Beaudoin, D.; Wuest, J. D. (2016). "Dimerization of Aromatic C-Nitroso Compounds". Chemical Reviews. 116 (1): 258–286. doi:10.1021/cr500520s. PMID 26730505.
  5. ^ Kirby, G. W. (1977). "Electrophilic C-nitroso-compounds". Chemical Society Reviews. 6: 2. doi:10.1039/CS9770600001 (Tilden lecture).
  6. ^ Luo, Yu-Ran (2007). Comprehensive Handbook of Chemical Bond Energies. Boca Raton, FL: Taylor and Francis. ISBN 9781420007282.
  7. ^ Lee, Jonghyuk; Chen, Li; West, Ann H.; Richter-Addo, George B. (2002). "Interactions of Organic Nitroso Compounds with Metals". Chemical Reviews. 102 (4): 1019–1066. doi:10.1021/cr0000731. PMID 11942786.
  8. ^ Bianchi, P.; Monbaliu, J. C. M. (2022). "Three decades of unveiling the complex chemistry of C-nitroso species with computational chemistry". Organic Chemistry Frontiers. 9: 223–264. doi:10.1039/d1qo01415c.
  9. ^ Honikel, K. O. (2008). "The use an control of nitrate and nitrite for the processing of meat products" (PDF). Meat Science. 78 (1–2): 68–76. doi:10.1016/j.meatsci.2007.05.030. PMID 22062097.
  10. ^ Lunn, J.C.; Kuhnle, G.; Mai, V.; Frankenfeld, C.; Shuker, D.E.G.; Glen, R. C.; Goodman, J.M.; Pollock, J.R.A.; Bingham, S.A. (2006). "The effect of haem in red and processed meat on the endogenous formation of N-nitroso compounds in the upper gastrointestinal tract". Carcinogenesis. 28 (3): 685–690. doi:10.1093/carcin/bgl192. PMID 17052997.
  11. ^ Bastide, Nadia M.; Pierre, Fabrice H.F.; Corpet, Denis E. (2011). "Heme Iron from Meat and Risk of Colorectal Cancer: A Meta-analysis and a Review of the Mechanisms Involved". Cancer Prevention Research. 4 (2): 177–184. doi:10.1158/1940-6207.CAPR-10-0113. PMID 21209396. S2CID 4951579.
  12. ^ Bastide, Nadia M.; Chenni, Fatima; Audebert, Marc; Santarelli, Raphaelle L.; Taché, Sylviane; Naud, Nathalie; Baradat, Maryse; Jouanin, Isabelle; Surya, Reggie; Hobbs, Ditte A.; Kuhnle, Gunter G.; Raymond-Letron, Isabelle; Gueraud, Françoise; Corpet, Denis E.; Pierre, Fabrice H.F. (2015). "A Central Role for Heme Iron in Colon Carcinogenesis Associated with Red Meat Intake". Cancer Research. 75 (5): 870–879. doi:10.1158/0008-5472.CAN-14-2554. PMID 25592152. S2CID 13274953.
  13. ^ Jakszyn, P; Gonzalez, CA (2006). "Nitrosamine and related food intake and gastric and oesophageal cancer risk: A systematic review of the epidemiological evidence". World Journal of Gastroenterology. 12 (27): 4296–4303. doi:10.3748/wjg.v12.i27.4296. PMC 4087738. PMID 16865769.
  14. ^ Joyce I. Boye; Yves Arcand (2012-01-10). Green Technologies in Food Production and Processing. Springer Science & Business Media. p. 573. ISBN 978-1-4614-1586-2.
  15. ^ Lee, L; Archer, MC; Bruce, WR (October 1981). "Absence of volatile nitrosamines in human feces". Cancer Res. 41 (10): 3992–4. PMID 7285009.
  16. ^ 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.
  17. ^ 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. S2CID 26275960.
  18. ^ 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. S2CID 196379002.
  19. ^ Tannenbaum SR, Wishnok JS, Leaf CD (1991). "Inhibition of nitrosamine formation by ascorbic acid". The American Journal of Clinical Nutrition. 53 (1 Suppl): 247S–250S. Bibcode:1987NYASA.498..354T. doi:10.1111/j.1749-6632.1987.tb23774.x. PMID 1985394. S2CID 41045030. Retrieved 2015-06-06. Evidence now exists that ascorbic acid is a limiting factor in nitrosation reactions in people.
  20. ^ Combet, E.; Paterson, S; Iijima, K; Winter, J; Mullen, W; Crozier, A; Preston, T; McColl, K. E. (2007). "Fat transforms ascorbic acid from inhibiting to promoting acid-catalysed N-nitrosation". Gut. 56 (12): 1678–1684. doi:10.1136/gut.2007.128587. PMC 2095705. PMID 17785370.
  21. ^ Combet, E; El Mesmari, A; Preston, T; Crozier, A; McColl, K. E. (2010). "Dietary phenolic acids and ascorbic acid: Influence on acid-catalyzed nitrosative chemistry in the presence and absence of lipids". Free Radical Biology and Medicine. 48 (6): 763–771. doi:10.1016/j.freeradbiomed.2009.12.011. PMID 20026204.

January 01, 1970
nitroso, organic, chemistry, nitroso, refers, functional, group, which, nitric, oxide, group, attached, organic, moiety, such, various, nitroso, groups, categorized, nitroso, compounds, nitrosoalkanes, nitroso, compounds, nitrosothiols, nitroso, compounds, nit. In organic chemistry nitroso refers to a functional group in which the nitric oxide N O group is 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 RN R N O and O nitroso compounds alkyl nitrites RO N O Structural formula of nitroso group Contents 1 Synthesis 2 Properties 3 Reactions 4 Nitrosation vs nitrosylation 5 Nitrosyl in inorganic chemistry 6 In human health 7 See also 8 ReferencesSynthesis editNitroso compounds can be prepared by the reduction of nitro compounds 1 or by the oxidation of hydroxylamines 2 Ortho nitrosophenols may be produced by the Baudisch reaction In the Fischer Hepp rearrangement aromatic 4 nitrosoanilines are prepared from the corresponding nitrosamines Properties edit nbsp Structure of 2 nitrosotoluene dimer 3 Nitrosoarenes typically participate in a monomer dimer equilibrium The azobenzene N N dioxide Ar O N N O Ar dimers which are often pale yellow are generally 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 4 When stored in protic media primary and secondary nitrosoalkanes isomerize to oximes 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 40 kcal mol 130 170 kJ mol while nitrosoarenes have BDEs on the order of 50 60 kcal mol 210 250 kJ 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 96 kJ mol 6 Organonitroso compounds serve as a ligands giving transition metal nitroso complexes 7 Reactions editMany reaction exists which make use of an intermediate nitroso compound such as the Barton reaction and Davis Beirut reaction as well as in the synthesis of indoles for example Baeyer Emmerling indole synthesis Bartoli indole synthesis In the Saville reaction mercury is used to replace a nitrosyl from a thiol group C nitroso compounds are used in organic synthesis as synthons in some well documented chemical reactions such as hetero Diels Alder HDA nitroso ene and nitroso aldol reactions 8 Nitrosation vs nitrosylation editNitrite 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 H HONO HONO H 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 chemistry edit nbsp 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 nitrosyl 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 human health editThis section is transcluded from Nitrosamine formation during digestion edit history Nitroso compounds react with primary amines in acidic environments to form nitrosamines which human metabolism converts to mutagenic diazo compounds Small amounts of nitro and nitroso compounds form during meat curing the toxicity of these compounds preserves the meat against bacterial infection After curing completes the concentration of these compounds appears to degrade over time Their presence in finished products has been tightly regulated since several food poisoning cases in the early 20th century 9 but consumption of large quantities of processed meats can still cause a slight elevation in gastric and oesophageal cancer risk today 10 11 12 13 For example during the 1970s certain Norwegian farm animals began exhibiting elevated levels of liver cancer These animals had been fed herring meal preserved with sodium nitrite The sodium nitrite had reacted with dimethylamine in the fish and produced dimethylnitrosamine 14 The effects of nitroso compounds vary dramatically across the gastrointestinal tract and with diet Nitroso compounds present in stool do not induce nitrosamine formation because stool has neutral pH 15 16 Stomach acid does cause nitrosamine compound formation but the process is inhibited when amine concentration is low e g a low protein diet or no fermented food The process may also be inhibited in the case of high vitamin C ascorbic acid concentration e g high fruit diet 17 18 19 However when 10 of the meal is fat the effect reverses and ascorbic acid markedly increases nitrosamine formation 20 21 See also editNitrosamine the functional group with the NO attached to an amine such as R2N NO Nitrosobenzene Nitric oxide NitroxylReferences edit G H Coleman C M McCloskey F A Stuart 1945 Nitrosobenzene Org Synth 25 80 doi 10 15227 orgsyn 025 0080 Calder A Forrester A R Hepburn S P 2 Methyl 2 nitrosopropane and Its Dimer Organic Syntheses 52 77 Collected Volumes vol 6 p 803 E Bosch 2014 Structural Analysis of Methyl Substituted Nitrosobenzenes and Nitrosoanisoles J Chem Cryst 98 2 44 doi 10 1007 s10870 013 0489 8 S2CID 95291018 Beaudoin D Wuest J D 2016 Dimerization of Aromatic C Nitroso Compounds Chemical Reviews 116 1 258 286 doi 10 1021 cr500520s PMID 26730505 Kirby G W 1977 Electrophilic C nitroso compounds Chemical Society Reviews 6 2 doi 10 1039 CS9770600001 Tilden lecture Luo Yu Ran 2007 Comprehensive Handbook of Chemical Bond Energies Boca Raton FL Taylor and Francis ISBN 9781420007282 Lee Jonghyuk Chen Li West Ann H Richter Addo George B 2002 Interactions of Organic Nitroso Compounds with Metals Chemical Reviews 102 4 1019 1066 doi 10 1021 cr0000731 PMID 11942786 Bianchi P Monbaliu J C M 2022 Three decades of unveiling the complex chemistry of C nitroso species with computational chemistry Organic Chemistry Frontiers 9 223 264 doi 10 1039 d1qo01415c Honikel K O 2008 The use an control of nitrate and nitrite for the processing of meat products PDF Meat Science 78 1 2 68 76 doi 10 1016 j meatsci 2007 05 030 PMID 22062097 Lunn J C Kuhnle G Mai V Frankenfeld C Shuker D E G Glen R C Goodman J M Pollock J R A Bingham S A 2006 The effect of haem in red and processed meat on the endogenous formation of N nitroso compounds in the upper gastrointestinal tract Carcinogenesis 28 3 685 690 doi 10 1093 carcin bgl192 PMID 17052997 Bastide Nadia M Pierre Fabrice H F Corpet Denis E 2011 Heme Iron from Meat and Risk of Colorectal Cancer A Meta analysis and a Review of the Mechanisms Involved Cancer Prevention Research 4 2 177 184 doi 10 1158 1940 6207 CAPR 10 0113 PMID 21209396 S2CID 4951579 Bastide Nadia M Chenni Fatima Audebert Marc Santarelli Raphaelle L Tache Sylviane Naud Nathalie Baradat Maryse Jouanin Isabelle Surya Reggie Hobbs Ditte A Kuhnle Gunter G Raymond Letron Isabelle Gueraud Francoise Corpet Denis E Pierre Fabrice H F 2015 A Central Role for Heme Iron in Colon Carcinogenesis Associated with Red Meat Intake Cancer Research 75 5 870 879 doi 10 1158 0008 5472 CAN 14 2554 PMID 25592152 S2CID 13274953 Jakszyn P Gonzalez CA 2006 Nitrosamine and related food intake and gastric and oesophageal cancer risk A systematic review of the epidemiological evidence World Journal of Gastroenterology 12 27 4296 4303 doi 10 3748 wjg v12 i27 4296 PMC 4087738 PMID 16865769 Joyce I Boye Yves Arcand 2012 01 10 Green Technologies in Food Production and Processing Springer Science amp Business Media p 573 ISBN 978 1 4614 1586 2 Lee L Archer MC Bruce WR October 1981 Absence of volatile nitrosamines in human feces Cancer Res 41 10 3992 4 PMID 7285009 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 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 S2CID 26275960 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 lt 1842 aid cncr2820581410 gt 3 0 co 2 PMID 3756808 S2CID 196379002 Tannenbaum SR Wishnok JS Leaf CD 1991 Inhibition of nitrosamine formation by ascorbic acid The American Journal of Clinical Nutrition 53 1 Suppl 247S 250S Bibcode 1987NYASA 498 354T doi 10 1111 j 1749 6632 1987 tb23774 x PMID 1985394 S2CID 41045030 Retrieved 2015 06 06 Evidence now exists that ascorbic acid is a limiting factor in nitrosation reactions in people Combet E Paterson S Iijima K Winter J Mullen W Crozier A Preston T McColl K E 2007 Fat transforms ascorbic acid from inhibiting to promoting acid catalysed N nitrosation Gut 56 12 1678 1684 doi 10 1136 gut 2007 128587 PMC 2095705 PMID 17785370 Combet E El Mesmari A Preston T Crozier A McColl K E 2010 Dietary phenolic acids and ascorbic acid Influence on acid catalyzed nitrosative chemistry in the presence and absence of lipids Free Radical Biology and Medicine 48 6 763 771 doi 10 1016 j freeradbiomed 2009 12 011 PMID 20026204 Retrieved from https en wikipedia org w index php title Nitroso amp oldid 1208617213, wikipedia, wiki, book, books, library,

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