urbaf2

NITRATION AGENTS AND METHODS MORE RARELY USED 87

This is seen clearly in Table 10, which shows the results of nitration of butane at

various temperatures.

TABLE 10

COMPOSITION OF THE PRODUCTS OF THE BUTANE NITRATION AT VARIOUS TEMPERATURES

Temperature Nitromethane Nitroethane 1-Nitropropane 2-Nitropropane 1-Nitrobutaue

°C % % % % %

395 2.1 12.7 4.9 4.9 30.5

393 6.0 19.0 7.0 41.0 27.0

445 5.9 18.2 6.5 37.0 31.8

450 9.0 25.0 7.0 28.0 31.0

Apart from this, at higher temperatures the amount of primary nitropropane

increases as compared with the secondary derivative.

Similar experiments have been carried out by Grundmann [30]. He found

160-180°C to be the best temperature for the reaction. The products of nitration

of long-chain paraffins were mono- and polynitro compounds.

Thus n-dodecane was nitrated at 180-190°C to yield the products shown in

Table 11.

TABLE 11

NITRATION OF n-DODECANE

Products

Mol. ratio

n-dodecane:HNO 3 Unreacted Mononitro Polynitro

n-dodecane dodecane dodecane Fatty acids

2:l 58 36 5 1

1:l / 43 40 15 2

1:2 33 25 38 4

1:4 (^2444725)
Hass and Alexander [31] and G. B. Bachman, Hass and Addison [32] described
the positive influence of oxygen on the yield in gas-phase nitration. Bachman and
his co-workers also discovered that the addition of halogens had a positive effect
on the yield of the nitration.
Hass and Shechter [33] have formulated thirteen general rules governing the
vapour-phase nitration of paraffins (and cycloparaffins). Here they are in a sum-
marized form :
(1) Polynitro compounds can probably be formed only from paraffins of
fairly high molecular weight.
(2) Any hydrogen atom in the hydrocarbon is capable of replacement by a
nitro group, and the ease of replacement is: tertiary > secondary > primary
group. As the temperature rises, however, the ease of replacement tends to
become equal.