The Chemistry of Powder and Explosives - Sciencemadness Dot Org

278 NITRIC ESTERS
a nitro, or a cyano group is also attached and are in general the
hydrogen atoms which are involved in the phenomena of tautomerism.
The condensation of formaldehyde with acetaldchyde,
with nitromethane, with cyclopentanone, and with cyclohexanone
thus leads to polyhydric primary alcohols the nitric esters of
which are useful explosives.
Pentaerythrite Tetranitrate (PETN, penta, niperyth, penthrit)
Four equivalents of formaldehyde 'in warm aqueous solution
in the presence of calcium hydroxide react with one equivalent
of acetaldehyde to form pentaerythrite. Three of the four
react with the three a-hydrogens of the acetaldehyde, the fourth
acts as a reducing agent, converts the —CHO group to —CH2—
OH, and is itself oxidized to formic acid.
=0 + CH-CHO
y
OH
CH2
H0-CH-C-CH0
CH2
OH
OH
CH2
H-C00H+ HO-CHj-C-CH^OH
CH, PE
OH
0N02
CH2
H•\,
) — 0-CH,—C-CH,-ONO,
H'
CHj PETN
0N02
The name, pentaerythrite, indicates that the substance contains
five carbon atoms and (like erythrite) four hydroxyl groups. In
commercial practice 108 the reaction is carried out at 65-70°. After
2 hours at this temperature, the calcium is precipitated by means
of sulfuric acid, the mixture is filtered, and the filtrate is concentrated
and crystallized by evaporation in vacuum. Penta-
108 For the laboratory preparation see Org. Syntheses, 4, 53 (1912), John
Wiley & Sons, New York. Also Tollens and Wigand, Ann., 265, 316 (1891);
Rave and Tollens, ibid., 276, 58 (1893); Stettbacher, Z. ges. Schiess- u.
Sprengstoffw., 11, 182 (1916).