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AROMATIC NITRO COMPOUNDS 201

be added relatively easily to the methyl group of trinitrotoluene, resulting in the

formation of the trinitro derivative of phenylethyl alcohol (Vol. II).

The methyl group in nitrotoluenes reacts with benzaldehyde much more read-

ily than that of toluene itself, giving the corresponding derivatives of stilbene.

Mono-, di- and tri-nitrotoluenes also react with p- nitrosodimethylaniline to form

the corresponding anils. Such a product is not obtained in the case of toluene (Sachs
and Kempf [34]). The methyl group of 2,4-dinitrotoluene also reacts with pyridine

N-oxide in the presence of iodine to yield 2,4-dinitrobenzaldehyde [155]. Poray-

Koshits and Chizhevskaya [35] found that di- and trinitrotoluenes react with
phthalic anhydride to form nitro derivatives of benzylidenephthalide:

Mononitrotoluene is not subject to this reaction.

The compounds obtained are crystalline products and may be utilized for the

identification of di- and tri-nitro compounds containing a methyl group.

On heating with an aqueous solution of NaOH the benzylidenephthalide de-

rivatives hydrolyse to form ketoacids:

2,4-Dinitrotoluene also reacts with pyridine and iodine to yield 2,4-dinitroben-

zylpyridinium iodide [156].

On boiling nitro derivatives of toluene with sodium hydroxide, their methyl

group is readily oxidized, forming a methine group and nitro derivatives of stil-

bene.

One of the typical reactions of aromatic nitro compounds with two or more
nitro groups is that with sodium sulphite. Here one of the nitro groups is replaced

by a sulphonic group (as its sodium salt) and sodium nitrate is formed:

(18)

The reaction occurs particularly readily with nitro groups that are in the o-

and p- position to each other, i.e. with “mobile nitro groups”. As to meta- nitro

groups they react less readily and require a higher temperature. Nitro derivatives

of higher homologues of benzene with two or three nitro groups (such as di- and

tri-nitro derivatives of m- xylene also react less readily, and trinitromesitylene
does not react with sodium sulphite [35a].