Infrared spectra and thermal decompositions of metal a - PDF document

t.g.a. and d.t.a. Infrared spectra dicarboxylates have Preliminary results dicarboxylates have been Cnnadlal~ Journal of Chernktry, thermal decomposition reaction. There however, little information on the thermal In the present study, thermal decompositions copper acetate, lead di- has long been known to organic cl~emists. While this method was found to be somewllat the preparation some ketones, many the salts Inany have not been identified. It was therefore considered interesting to examine calcium salts of acids (malonic sebacic) employing t.g.a. and d.t.a. and residue left over the lForms part of the Ph.D. Thesis of K. C. F. 2To correspondence should be a pre- been presented. the rare earth acetates in boiling acetic acid were recrystallized - AH values were *IS%. infrared spectra di- a Ferkin-Elmer model-521 KBr in Nujol. vapor phase spectra gas cells (NaC1). Vapor phase chromatographic (v.p.c.) (thermal conductivity detector) fitted with ft, x 1 /8 in. stainless steel packed with fire brick PATIL ET AL.: INFRARED SPECTRA AND THERMAL DECOMPOSlTlONS FIG. 1. The t.g.a. acetates (heating 10 'C/min). The results from the t.g.a. and d.t.a. of the rare earth acetates shown in I1 and 111. Typical t.g.a. and d.t.a. curves are shown in Figs. 1 and 2 respectively. The t.g.a. the rare showed evidence position: the "C corresponding to the decomposition of the an- hydrous acetate, Ln(CH3C02)3, to the oxy- carbonate, Ln20 3. C02 and the second stage corresponding to the formation of the sesqui- oxide, Ln203 (with the the end product non- stoicl~iometric Pr6011)3. for the formation normal carbonate, LII?(CO~)~, in the t.g.a. The formation the oxycarbonate, Ln203. C02, has been found to be the first stage TEMPERATURE ;C FIG. 2. The d.t.a. of anhydrous rare 3P~6011 is found to be the final product of decomposi- earth acetates Ln(CH3C02)3. Curve 1, La; 2, Nd; 3, tion of praseodymium salts. Oxidation of Pr3T accom- Sm; 4, Gd; 5, Dy; and 6, Lu. panies the last stageof decomposition. Infrared frequencies (crn-I), Ln203. COz Srn 1524 1459 1370 1055 873 844 DY 1512 1449 1394 1055 870 844 Gd 1504 1440 1389, 1333 1053 860 844 *Assignment the rare series, possibly metal ion as one various reactions (Table 111) and Copper t.g.a. curve of lead tetraacetate (Fig. 3) distinct stages corresponding carbonate, and (PbO), stages being confirmed by t.g.a. of lead of lead tetra- acetate will involve reactions of the acetoxy radical. The d.t.a. shows two -- ably corresponding the formation d.t.a. products from C02 and methyl acetate by vapor phase infrared spectroscopy. Ethane, formed, must be present in reactions in the decomposi- Pb(CH3C02)4 are : [91 PbC03 + PbO + COz The t.g.a. copper acetate, CU~(CH~CO~)~. 2H20, showed the first stage 6The t.g.a. and d.t.a. curves may corn- parable, particularly the reaction temper- atures, since heating rates not identical. t.g.a. vacuum (3 x 10-2 rnm Hg) while d.t.a. was in alr. - - - - - - PbO I I FIG. 3. The t.g.a. (3 x 10-2 mm Hg) and d.t.a. lead tetraacetate. "C/min in the t.g.a. and 16 "C/rnin in the d.t.a. due to the dehydration at -- 180 "C. After dehydration, there was only stage of -- 310 "C, but the t.g.a. curve showed 550 "C. some oxidation Cu20 formed in -- 350 "C. product at "C is CuO. The t.g.a. from the agree with d.t.a. Hill and co-workers (14), also reported the PATIL ET AL.: Further, the formation CaC03 residue precludes as the initial products decomposi- tion.8 FIG. 5. The d.t.a. curves in dicarboxylates (heating rate 10 "C/min). TABLE VII Differential thermal analysis the thermal calcium dicarboxylates (peak "C) Decom- position to Dehydration CaC03* Decom- position to CaO Malonate. 2H20 Succinate. 2H20 Glu tarate. 4H20 Adipate . Hz0 Pimelate. Hz0 Sebacate. 3H20 *Bettera~reement with t.g.a. the temperatures base line) d.t.a. curves (Fig. of calcium dicar- boxylates showed several "C) dehydration. After the major peak in to the CaC03 and there SAnhydrides been found initially formed thermal decompositions dicarboxylic acids agreement between d.t.a. (Table VII) and t.g.a. (Table VI). case of malonate, there be some exothermic reaction d.t.a. curves show CaC03 to CaO in the 840- 910 "C range, again showing CaC03 only residue left after the decomposition of calcium dicarboxylates. decomposition tem- CaC03 varies slightly t.g.a. of dysprosium that the however, clear evidence for'the elements of CH2 the decomposition the number CH2 endothermic decomposition peak of CaC03 as the internal mole-'), of calcium dicarboxylates CaC03 estimated by measuring areas of the endo- trend in series of position of dicarboxylates varies linearly with increment of - per methylene of decomposition of dicarboxylates is finding indicates obtained in the decompositions of dicarboxylates phase decompositions elements of PATIL ET W. W. HOIBERG. Anal. 12. L. RUZICKA, M. STOLL, andH. SCHINZ. Helv. Chirn. Acta, 28,506 (1963); 29,539 (1963). Acta, 11,670 (1928). 16. L. RUZICKA, W. BRUGGER, M. PFEIFFER, H. SCHINZ, 19. G. A. ROBERTSON. J. Chern. Soc. 119,810 (1921). and M. STOLL. Helv. Chim. Acta, 9,499 (1926). 20. J. F. THORPE and G. A. R. KON. Organic synthesis. 17. L. RUZICKA, W. BRUGGER, C. F. SLIDEL, Helv. Chirn. Acta, 11,496 (1928). 21. F. FEIST. Ber. 28,739 (1898).