Hydrazide

Hydrazides in organic chemistry are a class of organic compounds with the formula R−NR¹−NR²R³ where R is acyl (R'−C(=O)−), sulfonyl (R'−S(=O)₂−), phosphoryl ((R'−)₂P(=O)−), phosphonyl ((R'−O−)₂P(=O)−), etc. and R¹, R², R³ and R' are any groups (typically hydrogen or organyl). Unlike hydrazine and alkylhydrazines, hydrazides are nonbasic owing to the inductive influence of the acyl, sulfonyl, or phosphoryl substituent.

Sulfonyl hydrazides

A common sulfonyl hydrazide is p-toluenesulfonyl hydrazide, a white air-stable solid. They are also widely used as organic reagents.

Toluenesulfonyl hydrazide is used to generate toluenesulfonyl hydrazones. Derived from ketones, these hydrazones participate in the Shapiro reaction and the Eschenmoser–Tanabe fragmentation.

2,4,6-Triisopropylbenzenesulfonylhydrazide is a useful source of diimide.

Acyl hydrazides

Acylhydrazines are derivatives of carboxylic acids, although they are typically prepared by the reaction of esters with hydrazine.

Transamidation is possible but requires long-duration heat, and acyl moieties rarely migrate off another hydrazide.^{: 527, 543} An exception are the chloral hydrazones, which deacylate easily.^: 570

Alternatively, bromine oxidizes aldehydic hydrazones to a hydrazoyl bromide, which then hydrolyzes to an acyl hydrazide.^{: 525–526}

Lithium aluminum hydride reduces acylhydrazides to the hydrazine only if the hydrazide lacks a labile proton.^{: 550–552}

They are also the product of the Schestakov rearrangement.

See also

• Hydrazide imide – tautomeric form of amidrazone

References

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