Diazoalkanes
Diazomethane
CH2N2
a)basicity and nucleophility at carbon atom
b)decomposition by UV light
A

Diazoalkanes
1. reaction with acids
A

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

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

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

Organic azides
Their preaparation by reaction of azide ion in SN with alkyl halogenide or acyl halogenide
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
very strong nucleophiles and weak bases

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

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

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

Nitro compounds
Fil039
nas N-O 1650 – 1500 cm-1         ns N-O  1370 – 1300 cm-1
nas N-O arom. 1550 cm-1        nsym N-O arom. 1360 cm-1

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

Nitro 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.
REACTIVITY:
1) rather nonreactive group – strong  electronwithdrawing
2) senstitive to reductions under formation of other nitrogen compounds

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