Condensed Phosphates and Arsenates

Dehydration behavior of the superprotonic conductor CsH2PO4 at moderate temperatures: 230 to 260 °C

“…We attribute this to the polymorphic behavior of CsPO 3 , which is known to crystallize in long-chain, cyclic and other forms depending on the details of the thermal history and preparation methods. 15 On the basis of the work of Osterheld and Markowitz, 10 who used the Jones method 16 to analyze the dehydration products of CsH 2 PO 4 obtained under similar dry conditions, we conclude that the product phase generated in this study is long-chain CsPO 3 .…”

“…15 It is reasonable to assume that the dehydration of CsH 2 PO 4 occurs similarly, with slow diffusion of gasphase H 2 O through the product layer limiting the rate of transformation of the un-reacted shrinking core. It can be shown for such a process that the lag, DT, in the dehydration temperature from its equilibrium value is proportional to the square root of the heating rate.…”

Growth and thermal studies on pure ADP, KDP and mixed K1‐x(NH4)xH2PO4 crystals

“…There are, however, large discrepancies in the literature concerning the nature of this transition, as well as regarding the number of additional transitions at higher temperatures. For example, a structural phase transition from tetragonal to monoclinic symmetry has been proposed for KDP at 180 °C [7,8]. Other researchers have proposed that when the KDP-type compounds are heated above room temperature, loss of water will take place, as in the following chemical reaction [10];…”

Influence of Imidazole and Hydrocyanic Acid Derivatives on the ‘Possible Prebiotic’ polyphosphate induced peptide synthesis in aqueous solution

“…This result is not surprising since the ultimate products of the thermal condensation of dihydrogenphosphates are the metaphosphates, particularly trimetaphosphate [2]; furthermore, the properties of linear polyphosphates 1 become closer to those of trimetaphosphate 2 when n is large, i.e. when the ratio (n-l)/n is close to 1 [2].…”

“…Besides sodium cyanide and cyanamide we have chosen imidazole for the following reasons: a) imidazole and imidazole derivatives are produced in simulated prebiotic reactions [ 121, b) imidazole plays a catalytic role in acyl [ 131 and phosphory12) [ 141 transfer reactions (l-phosphonatoimidazole 6 and 1 -triphosphonato-imidazole 7 transfer very easily the phosphoryl group to other sites and are often formed in model biochemical reactions as 'energy rich' intermediates [ 15]), and c) 1-(a-aminoacy1)imidazoles 8 give rise to peptides in aqueous solutions, the best yields of tripeptide (and higher peptides) being achieved precisely in the pH range 6-9 [16] which is of interest to us. Magnesium ion was also added in one experiment because of its catalysis of pyrophosphate breakdown in aqueous solutions [2], its catalysis of the synthesis of amino acid adenylate anhydride [17] and its use (together with imidazole) in simultaneous peptide and oligonucleotide formation in mixtures of amino acids and nucleoside-triphosphates [ 181. We hoped therefore to obtain more significant amounts of tripeptide by adding imidazole (or imidazole and MgC12) to our aqueous system of polyphosphate and amino acid, and by working at pH 9 or below.…”