urbaf2

NITRATION AGENTS AND METHODS MORE RARELY USED 107

Stevens and Emmons [82] obtained three compounds: the nitro-nitrates (I) and

(II) as well as a nitro-olefin (III)

(40)

They suggested the following reaction mechanism:

(41)

G. B. Bachman and Hokama [104] have recently found that nitrogen pentoxide

forms a complex with boron trifiuoride: BF 3 .N 2 O 5. The complex is a colourless,

stable liquid in the presence of polychlorinated paraffins and a white solid in nitro-

paraffins. It decomposes at ca. 75°C with evolution of brown fumes.

G. B. Bachman and Dever [105] suggest that the complex has the structure

(F 3 B<-ONO 2 )-NO 2 +

The complex seems to be a somewhat more powerful nitrating agent than an an-

hydrous mixture of HNO 3 -H 2 SO 4.

Nitrobenzene reacts with two moles of the complex in carbon tetrachloride

to give an 86% yield of m- dinitrobenzene after 18 hr at 75°C.

Benzoic acid reacts with three moles of the complex in 36 hr at 70°C to form

3,5-dinitrobenzoic acid (70% yield) and m- nitrobenzoic acid (9.3% yield).

The complex forms an addition molecular compound with m- dinitrobenzene

(m.p. 89.5°C).

NITRYL CHLORIDE (NITRONIUM CHLORIDE, NO 2 Cl)

It was found by Steinkopf and Kühnel [106] that the so-called nitryl chloride

is an agent that both nitrates and chlorinates aromatic hydrocarbons. However,

the reaction could be selective. Thus, only o- nitrophenol was formed when nitryl

chloride interacted with phenol below room temperature, but at room temperature

2,4-dichloro-6-nitrophenol was obtained. Naphthalene was chlorinated and ni-

trated simultaneously to give α− nitro- and α− chloro-naphthalene.