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11.
Summary Existing tests for differentiating carbonate and hydrogen carbonate are shown to be unreliable. New tests have been developed which enable carbonate and hydrogen carbonate to be differentiated readily; cyanate and other anions may also be tested for in the mixture. The recommended tests are applicable in the presence of other anions.Preliminary water extraction is done to remove hydrogen carbonates and soluble carbonates and cyanates. The insoluble portion is then treated with hydrochloric acid; the evolution of carbon dioxide confirms insoluble carbonates or cyanates. The latter are confirmed by making the solution alkaline and testing for ammonia. Insoluble carbonate is tested for by extracting another portion of the sample with water and treating the residue with acetic acid. Cyanates do not react under these conditions.The original water extract is divided into three parts: one portion is treated with hydrochloric acid; the evolution of carbon dioxide indicates that any of the three ions may be present. A further portion is treated with phenolphthalein. The red colour indicates soluble carbonate. Barium chloride is added until the colour is discharged; slow evolution of carbon dioxide in the cold or on gently warming indicates the presence of hydrogen carbonate. The third portion is made alkaline and boiled to expel any ammonia present from ammonium salts. The solution is then acidified, made alkaline again and then tested for ammonia. A positive test indicates that soluble cyanates are present.
Part XIX: Mikrochim. Acta [Wien]1964, 179. 相似文献
Zusammenfassung Bekannte Reaktionen zur Unterscheidung von Carbonat und Hydrogencarbonat erwiesen sich als ungeeignet. Daher wurden neue Tests ausgearbeitet; Cyanat und andere Anionen können dabei gleichfalls nachgewiesen werden.Zunächst wird zur Entfernung von Hydrogencarbonat, löslichen Carbonaten und Cyanaten mit Wasser extrahiert. Der unlösliche Anteil wird mit Salzsäure behandelt; die Freisetzung von Kohlendioxid zeigt unlösliche Carbonate oder Cyanate an. Letztere werden nachgewiesen, indem man alkalisiert und auf Ammoniak prüft. Unlösliche Carbonate sind durch Extraktion einer weiteren Probe mit Wasser und Ansäuern des Rückstandes mit Essigsäure nachweisbar. Cyanate reagieren unter diesen Bedingungen nicht.Der wäßrige Extrakt wird in drei Teile geteilt. Ein Teil wird mit Salzsäure behandelt; Kohlendioxidentwicklung zeigt die Gegenwart einer der drei Ionenarten an. Ein weiterer Teil gibt mit Phenolphthalein Rotfärbung, wenn lösliche Carbonate vorliegen. Man setzt Bariumchlorid bis zur Entfärbung zu: langsame Kohlendioxidentwicklung in der Kälte oder bei leichtem Erwärmen zeigt Hydrogencarbonat an. Der dritte Teil wird alkalisiert und durch Kochen vollständig von Ammoniak aus Ammoniumsalzen befreit. Dann säuert man an, alkalisiert wieder und prüft auf Ammoniak. Ein positives Ergebnis zeigt das Vorhandensein löslicher Cyanate an.
Résumé On montre que les procédés de recherche qui existent actuellement pour différencier le carbonate de l'hydrogéno-carbonate ne sont pas exacts. On a mis au point de nouvelles réactions permettant de distinguer rapidement un carbonate d'un hydrogéno-carbonate; on peut aussi rechercher les cyanates et d'autres anions dans le mélange. Les procédés de recherche que l'on recommande peuvent s'appliquer en présence d'autres anions.On effectue l'extraction préliminaire par l'eau pour séparer les hydrogénocarbonates, les carbonates solubles et les cyanates. La partie insoluble est alors traitée par l'acide chlorhydrique; le dégagement de gaz carbonique indique la présence de carbonates ou de cyanates insolubles. On confirme l'existence de ces derniers en rendant la solution basique et en faisant l'essai á l'ammoniac. On caractérise les carbonates insolubles en extrayant par l'eau une autre portion de l'échantillon et en traitant le résidu par l'acide acétique. Les cyanates ne réagissent pas dans ces conditions.L'extrait par l'eau initial est divisé en trois parties: l'une est traitée par l'acide chlorhydrique; le dégagement de gaz carbonique indique que l'un des trois ions peut être présent. Une autre est traitée par la phénolphtaléine. L'apparition d'une coloration rouge indique un carbonate soluble. On ajoute du chlorure de baryum jusqu'á disparition de la coloration; un faible dégagement de gaz carbonique á froid ou sous chauffage doux montre la présence d'un hydrogéno-carbonate. La troisiéme partie est rendu alcaline et soumise á l'ébullition pour éliminer l'ammoniac des sels d'ammonium. On acidifie alors la solution, on la rend de nouveau alcaline et on fait ensuite l'essai á l'ammoniac. Une réaction positive indique la présence de cyanates solubles.
Part XIX: Mikrochim. Acta [Wien]1964, 179. 相似文献
12.
13.
The energy profiles for the decomposition of the first triplet of acetaldehyde via the reactions: CH3CHOν → CH3CO° + H°, CH3CHO* → CH.3 + HCO., have been computed using a non-empirical LCAO MO SCF procedure. Both reactions were found to have energy barriers of similar height (245 KJ mole ?1) and at similar extensions of the respective rupturing bonds (0.71–0.76 Å). The energy profile for internal rotation about the C-C bond was also calculated and showed a small barrier (3.5 kJ mole?1). 相似文献
14.
John L. Holmes Alexander D. Osborne Gwyneth M. Weese 《Journal of mass spectrometry : JMS》1975,10(10):867-873
Composite metastable peaks are generated in the unimolecular fragmentations (i) [C3H5]+ → [C3H3]+ + H2 (flat-top upon flat-top) and (ii) [C4H9]+ → [C3H5]+ + CH4 (flat-top and gaussian). The measurement of appearance potentials and kinetic energy releases lead us to conclude, in agreement with earlier proposals, that in (i) the components can arise from the generation of the isomeric cyclopropenium and propargyl daughter cations. In (ii) the components are proposed to arise from the fragmentation of tert- and sec-butyl cations yielding allyl as the common daughter ion. The composite peak observed in the fragmentation (iii) [C3H4]+· → [C3H3]+ + H· is shown to be present only if the decomposing molecular ion is large enough to also produce [C6H8]2+ ions. The second component in (iii) then arises from the reaction [C6H8]2+ → [C6H6]2+ + H2. 相似文献
15.
A.G. Osborne A.J. Blake R.E. Hollands R.F. Bryan S. Lockhart 《Journal of organometallic chemistry》1985,287(1):39-47
A series of [3]ferrocenophanes of general formula Fe(C5H4X)2YCl2 and the spiro compounds [Fe(C5H4X)2]2Ge (X = S, Se; Y = Ge, Sn) have been prepared by the reaction of ferrocene 1,1′-dithiol and ferrocene 1,1′-diselenol with tetrahalides of germanium and tin. Spectroscopic properties of the compounds are reported. In solution, the compounds are fluxional by a bridge reversal process. The crystal structure of 1,3-diselena-2,2-dichlorogermyl-[3]ferrocenophane at 163 K. has been determined by X-ray diffraction methods. At that temperature, crystals have space group P21/n with a 6.222(3), b 16.156(13), c 12.968(4) Å, β 97.53(1)° and Z = 4. Least-squares refinement gave R = 0.033 for 2834 unique significant reflections whose intensities were measured by counter diffractometry. The two SeGe bond lengths are 2.323 and 2.325(1) Å, with GeCl 2.148 and 2.161(1) Å. The SeGeSe bond angle is 118.2(1)°, ClGeCl 104.7(1)°, and SeGeCl angles range from 106.2 to 109.8(1)°. The SeC bond lengths are 1.901 and 1.904(5) Å, with CSeGe angles of 95.8 and 96.5(2)°. The cyclopentadienyl rings are in an eclipsed conformation with a mean twist angle of 2.7°, and are inclined to one another at 6.1°. The Se atoms are displaced from the ring planes by 0.17 and 0.20 Å yielding a non-bonded intramolecular Se…Se contact of 3.99 Å. 相似文献
16.
17.
Bogert D Burnstein R Fisk R Fuess S Morfin J Ohska Stutte L Walker JK Bofill J Busza W Eldridge T Friedman JI Goodman MC Kendall HW Kostoulas IG Lyons T Magahiz R Mattison T Mukherjee A Osborne L Pitt R Rosenson L Sandacz A Tartaglia M Taylor FE Verdier R Whitaker S Yeh GP Abolins M Brock R Cohen A Ernwein J Owen D Slate J Weerts H 《Physical review letters》1985,55(6):574-577
18.
We study the class \({\mathcal{M}}\) of functions meromorphic outside a countable closed set of essential singularities. We show that if a function in \({\mathcal{M}}\), with at least one essential singularity, permutes with a non-constant rational map g, then g is a Möbius map that is not conjugate to an irrational rotation. For a given function \({f \in\mathcal{M}}\) which is not a Möbius map, we show that the set of functions in \({\mathcal{M}}\) that permute with f is countably infinite. Finally, we show that there exist transcendental meromorphic functions \({f : \mathbb{C} \to \mathbb{C}}\) such that, among functions meromorphic in the plane, f permutes only with itself and with the identity map. 相似文献
19.
This paper is concerned with the implementation and testing of an algorithm for solving constrained least-squares problems. The algorithm is an adaptation to the least-squares case of sequential quadratic programming (SQP) trust-region methods for solving general constrained optimization problems. At each iteration, our local quadratic subproblem includes the use of the Gauss–Newton approximation but also encompasses a structured secant approximation along with tests of when to use this approximation. This method has been tested on a selection of standard problems. The results indicate that, for least-squares problems, the approach taken here is a viable alternative to standard general optimization methods such as the Byrd–Omojokun trust-region method and the Powell damped BFGS line search method. 相似文献
20.
Osborne TJ 《Physical review letters》2008,101(14):140503
In this Letter we make progress on a long-standing open problem of Aaronson and Ambainis [Theory Comput. 1, 47 (2005)]: we show that if U is a sparse unitary operator with a gap Delta in its spectrum, then there exists an approximate logarithm H of U which is also sparse. The sparsity pattern of H gets more dense as 1/Delta increases. This result can be interpreted as a way to convert between local continuous-time and local discrete-time quantum processes. As an example we show that the discrete-time coined quantum walk can be realized stroboscopically from an approximately local continuous-time quantum walk. 相似文献