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Chemistry of Diazoalkanes and Organic Azides

Explore the reactivity, preparation methods, and reactions of diazoalkanes, diazocompounds, and organic azides. Learn about basicity, nucleophility, decomposition, and rearrangements in these compounds.

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Chemistry of Diazoalkanes and Organic Azides

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  1. Diazoalkanes Diazomethane CH2N2 • basicity and nucleophility at carbon atom • decomposition by UV light A

  2. Diazoalkanes A 1. reaction with acids

  3. Diazoalkanes Arndt, Eistert, Wolf rearrangement Diazoketones acid + 1 carbon atom amide ester

  4. Diazoalkanes Preparation N-nitroso-N-methylurea + NaOH = diazomethane N-nitroso-N-methylacylamide N-nitroso-N-methylurethane Preparation of diazoesters diazotation of aminoacid esters

  5. Diazoalkanes B Diazocompounds under UV irradiation: electrophile reacts with p electrones isolated from tropical plants oil

  6. Organic azides Their preaparation by reaction of azide ion in SN with alkyl halogenide or acyl halogenide very strong nucleophiles and weak bases Azides are sensitive to thermal decomposition (sometimes with explosion) decomposition of alkyl ayide is non-selective to mixture of products and therefore has no aplication acylazides are sources of nitrenes Azides may be reduced either under catalytic conditions (H2 / Pt) or by LiAlH4 products are amines

  7. Organic azides Tepelný rozklad acyl azidů - Curtiův přesmyk (odbourání) azidů AMIN AMINE

  8. Organic azides Similar is also Schmidt rearrangement, diference only in the preparation. Azide is preparted by sulfuric acid with N3H Lossen decomposition is starting from hydroxamic acids

  9. Nitro compounds Nomenclature only prefix nitro- dinitro- …atc. nitromethane nitrobenzene 3-nitropropanal 2-nitrobenzoic acid

  10. Nitro compounds nas N-O 1650 – 1500 cm-1 nsN-O 1370 – 1300 cm-1 nas N-O arom. 1550 cm-1nsym N-O arom. 1360 cm-1

  11. Nitro compounds REACTIVITY: 1) rather nonreactive group – strong electronwithdrawing 2) senstitive to reductions under formation of other nitrogen compounds a-hydrogen atoms are acidic pKa CH3NO2 10,2 CH3CH2NO2 8,5 CH3CH2CH2NO2 7,8 O2N-CH2-NO2 3,57

  12. Nitro compounds REACTIVITY: 1) rather nonreactive group – strong electronwithdrawing 2) senstitive to reductions under formation of other nitrogen compounds Nitro group is electronwithdrawing group and at aromatic ring is causing deminishing electrondensity and this way unables SEAr HAMMETT CONSTANT sm= 0,71-I a – M efekt sp = 0,81 reaction proceed only with strong electrophiles and at harsh conditions (they do not react in F.C. alkylation, acylation, azocopulation etc.

  13. Nitro compounds REACTIVITY: 1) rather nonreactive group – strong electronwithdrawing 2) senstitive to reductions under formation of other nitrogen compounds reactions are pH dependent and are important at aromatic systems

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