1 / 41

Nitrite Ion, Nitrous Acid, and Nitrosyl Cation

+. H. –. ••. ••. ••. ••. ••. ••. O. O. N. O. N. O. H. • •. • •. • •. ••. ••. +. H. H. H. +. ••. ••. ••. ••. O. N. O. O. N. O. • •. • •. • •. • •. • •. +. H. H. Nitrite Ion, Nitrous Acid, and Nitrosyl Cation. +. ••. ••. N. O. • •. +.

nan
Download Presentation

Nitrite Ion, Nitrous Acid, and Nitrosyl Cation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. + H – •• •• •• •• •• •• O O N O N O H •• •• •• •• •• + H H H + •• •• •• •• O N O O N O •• •• •• •• •• + H H Nitrite Ion, Nitrous Acid, and Nitrosyl Cation +

  2. •• •• N O •• + Nitrosyl Cation and Nitrosation

  3. + •• •• N N O •• •• •• N N O •• •• + Nitrosyl Cation and Nitrosation +

  4. + •• •• •• •• N N N O N O •• •• •• R H •• •• N N O •• •• + H Nitrosation of Primary Alkylamines R R H • analogous to nitrosation of secondary amines to this point + H H + H +

  5. •• •• N N O •• •• Nitrosation of Primary Alkylamines R • this species reacts further H

  6. R + H •• •• •• •• + N N N O N O •• •• •• H H Nitrosation of Primary Alkylamines R H

  7. R •• •• + N N O •• H H R •• •• N N O •• •• H + H Nitrosation of Primary Alkylamines

  8. R H + H •• •• N N O •• •• H Nitrosation of Primary Alkylamines R •• N N O •• •• + H

  9. R H •• N N O •• •• + H Nitrosation of Primary Alkylamines

  10. H + O N N R •• •• •• H R H •• N N O •• •• + H Nitrosation of Primary Alkylamines • nitrosation of a primary alkylamine gives an alkyl diazonium ion • process is called diazotization +

  11. + + N N N R R N •• •• •• Alkyl Diazonium Ions • alkyl diazonium ions readily lose N2 to give carbocations +

  12. Nitrosation of Primary Arylamines • gives aryl diazonium ions • aryl diazonium ions are much more stable thanalkyl diazonium ions • most aryl diazonium ions are stable under the conditions of their formation (0-10°C)

  13. + + + R N2 RN N + N ArN Nitrosation of Primary Arylamines • gives aryl diazonium ions • aryl diazonium ions are much more stable thanalkyl diazonium ions • most aryl diazonium ions are stable under the conditions of their formation (0-10°C) fast slow + + Ar N2

  14. NH2 (CH3)2CH NaNO2, H2SO4 H2O, 0-5°C + N (CH3)2CH N Example: HSO4–

  15. H Ar NO2 Ar NH2 Ar + N N Ar Synthetic Origin of Aryl Diazonium Salts

  16. 22.18Synthetic Transformations of Aryl Diazonium Salts

  17. Cl Br Ar Ar F Ar CN Ar + N N Ar H I Ar Ar OH Ar Transformations of Aryl Diazonium Salts

  18. + N N Ar OH Ar Preparation of Phenols • hydrolysis of a diazonium salt H2O, heat

  19. NH2 (CH3)2CH OH (CH3)2CH Example 1. NaNO2, H2SO4 H2O, 0-5°C 2. H2O, heat (73%)

  20. Cl Br Ar Ar F Ar CN Ar + N N Ar H I Ar Ar OH Ar Transformations of Aryl Diazonium Salts

  21. + N N Ar I Ar Preparation of Aryl Iodides • reaction of an aryl diazonium salt with potassium iodide KI

  22. NH2 Br Example I 1. NaNO2, HCl H2O, 0-5°C Br 2. KI, room temp. (72-83%)

  23. Cl Br Ar Ar F Ar CN Ar + N N Ar H I Ar Ar OH Ar Transformations of Aryl Diazonium Salts

  24. F Ar + N N Ar Preparation of Aryl Fluorides • heat the tetrafluoroborate salt of a diazonium ion; • process is called the Schiemann reaction

  25. NH2 F CCH2CH3 CCH2CH3 O O Example 1. NaNO2, HCl, H2O, 0-5°C 2. HBF4 3. heat (68%)

  26. Cl Br Ar Ar F Ar CN Ar + N N Ar H I Ar Ar OH Ar Transformations of Aryl Diazonium Salts

  27. Cl Br Ar Ar + N N Ar Preparation of Aryl Chlorides and Bromides • aryl chlorides and aryl bromides are prepared by heating a diazonium salt with copper(I) chloride or bromide • substitutions of diazonium salts that use copper(I) halides are called Sandmeyerreactions

  28. Example NH2 Cl 1. NaNO2, HCl, H2O, 0-5°C 2. CuCl, heat NO2 NO2 (68-71%)

  29. NH2 Cl Example 1. NaNO2, HBr, H2O, 0-10°C Br Cl 2. CuBr, heat (89-95%)

  30. Cl Br Ar Ar F Ar CN Ar + N N Ar H I Ar Ar OH Ar Transformations of Aryl Diazonium Salts

  31. CN Ar + N N Ar Preparation of Aryl Nitriles • aryl nitriles are prepared by heating a diazonium salt with copper(I) cyanide • this is another type of Sandmeyer reaction

  32. NH2 CH3 Example 1. NaNO2, HCl, H2O, 0°C CN CH3 2. CuCN, heat (64-70%)

  33. Cl Br Ar Ar F Ar CN Ar + N N Ar H I Ar Ar OH Ar Transformations of Aryl Diazonium Salts

  34. + N N Ar H Ar Transformations of Aryl Diazonium Salts • hypophosphorous acid (H3PO2) reduces diazonium salts; ethanol does the same thing • this is called reductive deamination

  35. NH2 CH3 CH3 Example NaNO2, H2SO4, H3PO2 (70-75%)

  36. Value of Diazonium Salts • 1) allows introduction of substituents such as OH, F, I, and CN on the ring • 2) allows preparation of otherwise difficultly accessible substitution patterns

  37. NH2 NH2 Br Br Br2 H2O Br Br Br Br Example NaNO2, H2SO4,H2O, CH3CH2OH (100%) (74-77%)

  38. 22.19Azo Coupling

  39. Azo Coupling • Diazonium salts are weak electrophiles. • React with strongly activated aromatic compounds by electrophilic aromatic substitution.

  40. + H N N N N Ar' Ar Ar Ar' Azo Coupling • Diazonium salts are weak electrophiles. • React with strongly activated aromatic compounds by electrophilic aromatic substitution. + an azo compound Ar' must bear a strongly electron-releasing group such as OH, OR, or NR2.

  41. OH + N C6H5N OH N NC6H5 Example + Cl–

More Related