urbaf2

NITRATION AGENTS AND METHODS MORE RARELY USED 123

sodium alcoholates. This is a generally known method for obtaining phenylnitro-

methane from benzyl cyanide (Wislicenus and Endres [175] ; Meisenheimer [175a]).

The reaction proceeds as follows:

C 6 H 5 CH 2 + C 2 H 5 ONO 2 + C 2 H 5 ONa -> C 6 H 5 C=NOONa + 2C 2 H 5 OH

I I

CN CN

(78)

C 6 H 5 C=NOONa

NaOH H+

-> C 6 H 5 C=NOONa ->C 6 H 5 C=NOOH

I I I

CN COONa COOH

C 6 H 5 CH 2 NO 2 <- C 6 H 5 CH=NOOH (78a)

The use of acetone cyanohydrin nitrate has recently been proposed for reactions

of this type:

(Anbar, Dostrovsky, Samuel and Yoffe [176]; Emmons [177]; Emmons and Free-

man [178]).
The advantage of this compound over simple alcohol esters is that the O-N
bond is weakened by the highly electronegative nitrile group. Besides, the com-
pound does not contain α− atoms of hydrogen and in this way the oxidation to
an aldehyde or ketone by the NO 2 groups can be avoided. According to Emmons,
McCallum and Freeman [179], this reagent has proved to be particularly useful
in the nitration of amines:

(79)

The yield amounts to 80% for the nitration of secondary amines, and 60% for

primary ones.

Nitrates of cyclopentanone or cyclohexanone cyanohydrin (I and II) may also

be nitrating agents.

I II

ACYL NITRATES (MIXED ANHYDRIDES)

Acyl nitrates are rather powerful nitrating agents. The simplest of them, acetyl

nitrate, CH 3 COONO 2 (b. p. 22°C at 70 mm Hg), is formed by reacting acetic an-

hydride with N 2 O 5. It is presumably present in nitrating mixtures consisting of

nitric acid and acetic anhydride (Pictet and Khotinsky [180]). The aromatic hydro-