The initial chemical changes in the pyrolysis of the five alkali metal (M) chlorates under a slowly rising temperature program involve the reactions: (a) MC1O3 -. t MC1 + 1.502, and (b) hfC103 -0.75hIC104 + 0.25MCl; subsequent phenomena are associated with the decompositions of the more thermally stable perchlorates, (c) MC1o4 + SIC1 + 20a.The extent of conversion of ;\tClOa per reaction b increases in the order Li (40%) < Na (6770) < E(, Rb, Cs (87%) a t the expense of reaction a. The increasing order of thermal stabilities of these metal chlorates follows the decreasing polarizing powers of X f though the stability differences among I(c103, RbC103, and CsC103 are rather small. Each of the MClO3 compounds appears to possess a congruent melting point in contrast to the corresponding Mc10.1 salts which, except for LiC104, undergo simultaneous fusion and rapid decomposition. The catalytic effects of MnO2 additions to MC103 salts result primarily in the acceleration of reaction a. The general trends in thermal stability among compounds of the type MC10, (x = 1, 2, 3, 4) as a function of M and ~t: are discussed briefly.

The normal course of pyrolysis of L1CIO4, NaClOt, and KClCh to the metal chlorides is altered to varying degrees to yield effectively the metal oxides in the presence of the corresponding metaphosphates. This behavior reflects an acid displacement reaction which is accompanied by depolymerization of the metaphosphates to simpler anionic species. In this respect the perchlorates are bases relative to the isopolyphosphate anionic acids. The extent of metaphosphate depolymerization is found to be a function of the cationic environment such that for perchlorate-metaphosphate mixtures the order of extent of depolymerization is Li > Na K. NaCICh and KCIO4, unlike LÍCIO4, do not depolymerize their corresponding pyrophosphates to orthophosphates. Of interest is the fact that these elevated temperature reactions do not involve mutual oxidation and reduction of the perchlorate and condensed phosphate reactants. The stoichiometry and course of the reactions were studied by means of thermogravimetry, differential thermal analysis, Cl2 evolution measurements, and chemical and X-ray analyses.

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NOTES 1325The procedure used in determining intensities is described elsewhere.3 The integration interval chosen was 100 cm.-'. Overlapping from adjacent bands was considered negligible, since the absorption fell to nearly zero at the edges of the integration interval. Solution concentrations were in the range 0.005-0.017 molar. At least three separate intensity determinations were made on each compound, and the results were averaged. Chloroform was used as solvent rather than carbon tetrachloride, because the compounds were not sufficiently soluble in the latter.

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