Hydrazine-hydroquinone inclusion

Keywords anhydrous hydrazine, hydroquinone, dimethyl terephthalate, inclusion crystal, terephthalic acid dihydrazide... 

A further variation is the reaction of isothiocyanates (e.g., 162f) with hydrazine that has been solidified by inclusion into the host hydroquinone (163). Ball-milling of the solids leads to a quantitative reaction and the auxiliary 165 is washed away with water [79] (Scheme 20). 

A mixture of powdered dimethyl terephthalate la (19.4 g, 0.1 mol) and 1 1 inclusion complex of hydroquinone and hydrazine (58.5 g, 0.4 mol) was kept under a nitrogen atmosphere at 100-125 °C for 25 h. To the reaction mixture was added MeOH and MeOH insoluble terephthalic acid dihydrazide 2a was obtained by filtration (17.1 g, 88.1% yield). 

The inclusion complex of an unstable reactant or reagent is sometimes useful in organic synthesis in the solid state. For example, very reactive anhydrous hydrazine can be trapped as a 1 1 inclusion complex with hydroquinone (24). This 1 1 inclusion compound (24) is a stable white powder that can easily be prepared by mixing aqueous hydrazine with powdered hydroquinone. Compound 24 is... 

Anhydrous N2Hi can be made by distillation of aqueous hydrazine over NaOH but the procedure is hazardous since explosions can occur the most concentrated product that is made is N2HcH20. Pure N2H4 can be obtained from aqueous solutions in the form of inclusion compounds with hydroquinone or p-methoxyphenol and these solids can be used in synthetic reactions.21... 

Hydrazine can be stabilized by formation of an inclusion compound with hydroquinone.58 Uncomplexed anhydrous hydrazine can be explosive. Highly toxic dimethyl sulfate can be handled more easily as an inclusion compound with toxic 18-crown-6. Both of these toxic compounds could be avoided through the use of dimethyl carbonate (as described in Chap. 2). Reactive intermediates, such as benzyne, have been stabilized by generating them inside hosts.59 Even the noble gas xenon can be trapped reversibly by hosts such as a cryptophane, 4-ferf-butyl-calix[4]arene or a-cyclodextrin.60... 

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