NOVEMBER, 1948
PREPARATION OF ANTU (a-NAPHTHYLTHIOUREA) FROM NAPHTHALENE 1. M. BERKEBILE and ARTHUR H. FRIES McPherson College, McPherson, Kansas CONSIDERABLE interest has been shown in the rodenticide l-(l-naphthy1)-2-thiourea also known as ornaphthylthiourea and abbreviated for common usage to ANTU. Much has been written concerning its use and effectiveness. However, there is little literature available to many of the smaller schools concerning its synthesis. The following series of reactions involve chemicals and rragents common to all laboratories. It is of interest to most students that the wellknown and cheap chemical, naphthalene, is one of the main starting materials. The making of the cu-nitronaphthalene, the ornaphthylamine, and finally the or-naphthylthiourea involves few difficulties. These three reactions serve as an effective teaching dwice for three fundamental reactions of organic chemistry, and also give the experience of using several of the common means of purification of compounds. The immediate and prartical use to which the product can be put creates an incentive for carrying out a series of reactions and provides a sustaining interest in its progress. Modifications of some of the common chemical procedures are used in making the intermediates and the final product. The naphthalene is nitrated by the usual methodlJ and the nitronaphthalene resulting are The reduced with iron and hydrochloric acid a a-naphthylamine is then used with ammonium thio-
cyanate in the presence of hydrochloric acid to produce the ANTU.6 The ANTU can be used effectively as a rodenticide by mixing 10 g. of the pulverized material with 50 g of powdered sugar, and the resulting mixture blended intimately with 400 g. of flour. A little cream or lard added to the flour mixture above, sufficient to make a paste, produces a bait much more inviting than the dry powder. Corn meal, ground meat, or peanut butter can be substituted for the flour. Sufficient bait should be placed at one time to poison all the rats in the area concerned because the rat that is unable to get the bait, or very little of it, refrains from taking the same bait again. A different base can be used if a second set is required. For instance, if flour is used the first time, meat can be used the second time. The rat seems to suspect the main constituent rather than the poison. Two milligrams of the a-naphthylthiourea are sufficient to kill a rt.6 EXPERIMENTAL
"
WITT, 0. N., Chem. Ind., 10, 216 (1887).
' THORPE, J. F., AND R. R. LINSTEAD, "The Synthetic Dye-
stuffs," 7th ed., Charles Griffin and Company, Ltd., London. 1933, p. 341. a WITT, 0. N., Chem. Ind., 10, 215(1887). ' P.
