Butyl Azodiformate

1-BUTYL AZODIFORMATE (Formic acid, azodi-, di-ferf-butyl ester) 

Submitted by Louis A. Camino and Paul J. Crowley 1 Checked by Virgil Boekelheide and S. J. Cross 

t-Butyl hyirazodiformate. A solution of 28.6 g. (0.2 mole) of i-butyl azidoformate2 and 26.4 g. (0.2 mole) of 1-butyl carba-zate in 60 ml. of pyridine (Note 1) is allowed to stand at room temperature for 1 week and is then diluted with 500 ml. of water. The snow-white microciystalline powder that separates is removed by filtration and is washed with two 50-ml. portions of water. The yield of air-dried hydrazide, m.p. 124-126°, is 35.5-37 g. (77-80%). The product is pure enough for most applications but may be purified by recrystallization from a 1 1 mixture of benzene and ligroin (60-90°) from which it separates as small white needles, m.p. 124-125.5°. The recovery is 92%. 

The pyridine was a pure product, b.p. 113-115°, obtained from Mallinckrodt Chemical Company and used as supplied. The methylene chloride (technical grade) and N-bromosuccin-imide (practical grade) were obtained from the Matheson Company and used as received. 

Unless a 2% excess of N-bromosuccinimide is used, the azo compound is contaminated by an impurity, possibly the original hydrazo compound, which separates along with the desired product in the form of long, easily distinguished needles. The two substances cannot be separated by crystallization from ligroin. 

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Butyl hydrazodiformate has been prepared by acylation of /-butyl carbazate by means of /-butyl azidoformate 3 4 or /-butyl cyanoformate.5 /-Butyl azodiformate has been prepared only by oxidation of the hydrazo compound. ... 

Ethyl azodiformate is a well-known and useful dienophile in the Diels-Alder reaction.8 /-Butyl azodiformate behaves ami-... 

Butyl carbazate is also a key intermediate in the synthesis of 2-butyl azidoformate,5 612 2-butyl hydrazodiformate,8 2-butyl azodiformate,18 and 2-butyl N-hydroxycarbamate,12 14 all of which are valuable synthetic intermediates. 

Butyl azodiformate, 44,18 a-Butyl bromide, preparation of -butyl Grignard reagent from, 41, 61 (-Butyl carbazate, 44, 20 conversion to (-butyl azidoformate, 44,15... 

Diels-Alder dienophiles a-Acetoxyacrylonitrile. Acetylenedicarboxyhc acid. Acrolein (see 1-o-Nitrophenylbutadiene). Allyl alcohol (see Lithium). 1,4-Benzoquinone (see also 1,4-Naphthoquinone, preparation). /rans-l,2-Dibenzoylethylene. Di-(-butyl azodiformate. Dichloroketene. Dicyanoacetylene. Diethyl acetylenedicarboxylate. 1,4-Dihydronaphthalene-... 

A soln. of er butyl azidoformate (s. Synth. Meth. lA, 478) and tert-huiyl carbazate (s. Synth. Meth. 16, 506) in pyridine allowed to stand 1 week at room temp. ter -butyl hydrazodiformate (Y 77-80%) treated according to Synth. Meth. 18, 335 tert-huiyl azodiformate (Y 88-90%). L. A. Garpino and P. J. Growley, Org. Synth. 44, 18 (1964). 

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