Hydrazone

General structural formula of the hydrazone

Hydrazone (hydrazone) is a group of compounds having structure R¹C(=N-NR³R⁴)R² which carbonyl compounds (R¹C(=O)R²) and hydrazine or hydrazine derivative (H₂N-NR³R⁴) spin-dries it among organic compounds and condensed. I am used as a synthetic intermediate to heterocycle. In addition, I may appear as a reaction intermediate.

Table of contents

Property

Because I have partial structure of imine, I show basicity and coordination characteristics. I get hydrolysis for acid and a basic water solution when I handle it and come back to original ketone and hydrazine, but the reactivity is different by a kind and the steric hindrance of the substituent. The hydrazone that steric hindrance on carbon is small is easy to catch the hydrolysis.

Synthetic

I usually compose it by ketone and dehydration condensation of the hydrazine.

R¹C(=O)^R2 + H₂N-NR³R⁴ → R¹C(=N-NR³R⁴)R²

When アゼン (azene) which a diazonium ion is combined with Cal bunion, and is enacted becomes tautomerism, it becomes the hydrazone.

EE'C^H-+ ⁺N₂Ar → EE'CH-N=N-Ar (アゼン )→ EE'C=N-NHAr (E,E' = 電子求引基)

The upper example is a reaction of the active methylene compound, but the product which 電子求引基 detached when I assume an active methine compound a substrate may be provided and is called Yap クリンゲマン reaction (Japp-Klingemann reaction).

 

Reaction

Because an electron becomes lacking in it, like imine and carbonyl compounds, the carbon top receives the attack of the nucleophilic reagent. The case that a nucleophilic reagent is water and a hydroxyl ion is hydrolysis.

求電子剤 attacks contralateral nitrogen. For example, I can alkylate it with alkyl halide.

I am combined with carbonyl carbon of aldehyde and give azine.

R(R')C=N-N_H2 + R''-CHO → R(R')C=N-N=CHR'' (azine)

I receive hydrogenation when I trigger lithium hydride aluminum to hydrazone and become the hydrazine.

R(R')C=N-N_H2 + LiAlH₄ → R(R')CH-NH-NH₂

I let you make dehydrogenation in silver oxide (I), and there is a reaction to change to the diazo monster.

(H₃C)₂C=N-N_H2 + Ag₂O → (H₃C)₂C=N₂

By the Wolff-Kishner reduction, hydrazone is made from ketone and hydrazine first and nitrogen molecules are detached by the action of the further strong base and change to a methylene compound.

The hydrazone is known as an intermediate of Fischer indole synthesis and the Eschenmoser-Tanabe fragmentation again.

Hydrazone derivative

The hydrazone derivative provided from semi-carbazide (H₂N-NHC(=O)NH₂) and carbonyl compounds is called semi-carbazone (English version).

Compound (R-C(=N-NH₂)-C(=N-NH₂)-R) where two hydrazone group was next to is called オサゾン (English version) in particular.

Like statement above, I call compound (RR'C=N-N=CR''R''') which hydrazine and the carbonyl compounds of 2 molecules condensed azine. Particularly, azine provided from aldehyde calls azine provided from Alda gin (English version), ketone with figure gin (English version).

References

• Smith, M. B.; March, J. March's Advanced Organic Chemistry 5th ed., WILEY, 2001.

Outside link

• hydrazones - IUPAC Gold Book

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