Pharmaceutics of Penicillin

Oxygen isotope data are very useful in determining the source rocks of granitic magmas, particularly when used in combination with Sr, Pb, and Nd isotope studies. For example, unusually high δ18O values in magmas (δ18O> +8) require the involvement of some precursor parent material that at some time in the past resided on or near the Earth's surface, either as sedimentary rocks or as weathered or hydrothermally altered rocks. The isotopic systematics which are preserved in the Mesozoic and Cenozoic batholiths of western North America can be explained by grand-scale mixing of three broadly defined end-members: (1) oceanic island-arc magmas derived from a “depleted” (MORB-type?) source in the upper mantle (δ18O c. +6 and 87Sr/86Sr c. 0·703); (2) a high-18O (c. +13 to +17) source with a very uniform 87Sr/86Sr (c. 0·708 to 0·712), derived mainly from eugeosynclinal volcanogenic sediments and (or) hydrothermally altered basalts; and (3) a much more heterogeneous source (87Sr/86Sr c. 0·706 to 0·750, or higher) with a high δ18O (c. +9 to +15) where derived from supracrustal metasedimentary rocks and a much lower δ18O (c. +7 to +9) where derived from the lower continental crust of the craton. These end-members were successively dominant from W to E, respectively, within three elongate N–S geographic zones that can be mapped from Mexico all the way N to Idaho.18O/16O studies (together with D/H analyses) can, however, play a more important and certainly a unique role in determining the origins of the aqueous fluids involved in the formation of granitic and rhyolitic magmas. Fluid-rock interaction effects are most clear-cut when low-18O, low-D meteoric waters are involved in the isotopic exchange and melting processes, but the effects of other waters such as seawater (with a relatively high δD c. 0) can also be recognised. Because of these hydrothermal processes, rocks that ultimately undergo partial melting may exhibit isotopic signatures considerably different from those that they started with. We discuss three broad classes of potential source materials of such “hydrothermal-anatectic” granitic magmas, based mainly on water/rock (w/r), temperature (T), and the length of time (t) that fluid-rock interaction proceeds: (Type 1) epizonal systems with a wide variation in whole-rock δ18O and extreme 18O/16O disequilibrium among coexisting minerals (e.g. quartz and feldspar); (Type 2) deeper-seated and (or) longer-lived systems, also with a wide spectrum of whole-rock δ18O, but with equilibrated 18O/16O ratios among coexisting minerals; (Type 3) thoroughly homogenised and equilibrated systems with relatively uniform δ18O in all lithologies. Low-18O magmas formed by melting of rocks altered in a Type 2 or a Type 3 meteoric-hydrothermal system are the only kinds of “hydrothermal-anatectic” granitic magmas that are readily recognisable in the geological record. Analogous effects produced by other kinds of aqueous fluids may, however, be quite common, particularly in areas of extensional tectonics and large-scale rifting. The greatly enhanced permeabilities in such fractured terranes make possible the deep convective circulation of ground waters and sedimentary pore fluids. The nature and origin of low-18O magmas in the Yellowstone volcanic field and the Seychelles Islands are briefly reviewed in light of these concepts, as is the development of high-D, peraluminous magmas in the Hercynian of the Pyrenees.

Oxygen, hydrogen, and strontium isotope constraints on the origin of granites

Solid-state structural transformation of two polymorphic forms of [Ag(8-HqH)(8-Hq)]n (1α and 1β, where 8-HqH = 8-hydroxyquinoline and 8-Hq– = 8-hydroxyquinolate) to {[Ag(8-HqH)2]NO3}n (2) has been observed upon solid–gas reaction of compounds 1α and 1β with HNO3 vapors. Solid–gas reaction of compound 2 with hydrated vapors of NH3 results in the formation of only the 1β polymorph, while solid–solid reaction of compound 2 with KOH results in the formation of a 1α and 1β mixture with chiral and achiral space groups of P212121 and Pbcn, respectively.

Solid-State Structural Transformations of Two AgI Supramolecular Polymorphs to Another Polymer upon Absorption of HNO3 Vapors

Studies on EDTA complexes—VIII

CHAPTER 3 – Bidentate Chelates

ONE of the least-studied aspects of co-ordination chemistry is the thermal properties of metal complexes with organic chelating agents. With such easily available instruments as the automatic recording thermobalance and differential thermal analysis apparatus, physical parameters such as minimum and maximum temperature limits for dehydration and pyrolysis reactions, rate-studies of thermal decomposition reactions1, and detection of intermediate compounds formed during pyrolysis are easily attainable. Such information is needed in order to understand more fully the nature of certain types of thermal rearrangements and in synthesis work.

Differential thermal analysis of some transition metal ethylenediamine tetraacetic acid chelates.

SILVER (I) ion reacts with 8-quinolinol to give a metal chelate having the formula, Ag(C9H6NO)C9H6NOH (ref. 1). Two forms of the chelate are known: (a) a yellow form, prepared at temperatures below 60° C.2; (b) a green form prepared at temperatures above 60° C.2. Nakatsuka2 reported that the green form contained silver in the Ag (II) oxidation state, a deduction based on a bromometric titration procedure. However, it was shown later by Block et al.3 that the green form was diamagnetic and contained silver in the Ag (I) oxidation state. Although both the yellow and green forms were prepared by the latter investigators, the differences between these two forms were not elucidated.

Yellow and Green Forms of Silver (I) 8-Quinolinolate

As part of our programme on the thermal decomposition of antibiotics1, additional studies have been made to include the antibiotics, aureomycin (chlortetracycline), terramycin and tetracycline.

Thermal Decomposition of Some Antibiotics

Thermal decomposition of antibitoics

ALTHOUGH the silver (I) complexes of 8-quinolinol (8-hydroxyquinoline) have been the subject of several investigations1–4, little is known about the complexes formed with 2-quinolinol and its derivatives. The 8-quinolinol complexes of silver are rather unusual in that two chelating groups, per metal ion, are present in the complex, or Ag(C9H6NO)·C9H6NOH. To complicate matters, both a yellow and a green form of the above are known. However, we have recently shown that the green form is identical to the yellow except that it contains a small amount of free silver5. With the above information available, it was thought that the silver (I) 2-quinolinol complexes would be similar to those of 8-quinolinol.

Wesley W. Wendlandt

Papers

Differential thermal analysis of some transition metal ethylenediamine tetraacetic acid chelates.

Yellow and Green Forms of Silver (I) 8-Quinolinolate

Thermal Decomposition of Some Antibiotics

Thermal decomposition of antibitoics

Silver (I) Complexes with 2-Quinolinol and 4-Methyl-2-Quinolinol: a Possible 4-Membered Ring Chelate System