Oscillatory gas evolution from the system formic acid-concentrated sulfuric acid-concentrated nitric acid

1978 ◽  
Vol 82 (17) ◽  
pp. 1952-1953 ◽  
Author(s):  
C. J. G. Raw ◽  
J. Frierdich ◽  
F. Perrino ◽  
G. Jex
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Formic Acid ◽  
Gas Evolution ◽  
Concentrated Sulfuric Acid

Gallium Arsenide Integrated Circuits Decapsulation Technique Using Mixed Acid Chemistry For Die-Level Failure Analysis

2018 ◽  
Author(s):  
Harold Jeffrey M. Consigo ◽  
Ricardo S. Calanog ◽  
Melissa O. Caseria
Keyword(s):  
Gallium Arsenide ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Integrated Circuits ◽  
Failure Analysis ◽  
Mixed Acid ◽  
Optimum Parameters ◽  
Plastic Package ◽  
Fuming Nitric Acid ◽  
Concentrated Sulfuric Acid

Abstract Gallium Arsenide (GaAs) integrated circuits have become popular these days with superior speed/power products that permit the development of systems that otherwise would have made it impossible or impractical to construct using silicon semiconductors. However, failure analysis remains to be very challenging as GaAs material is easily dissolved when it is reacted with fuming nitric acid used during standard decapsulation process. By utilizing enhanced chemical decapsulation technique with mixture of fuming nitric acid and concentrated sulfuric acid at a low temperature backed with statistical analysis, successful plastic package decapsulation happens to be reproducible mainly for die level failure analysis purposes. The paper aims to develop a chemical decapsulation process with optimum parameters needed to successfully decapsulate plastic molded GaAs integrated circuits for die level failure analysis.

A Headspace Gas Chromatographic Method for Determination of Formic acid Content in Isosulfan Blue and in Various Drugs

2021 ◽  
Vol 37 (2) ◽  
pp. 321-329
Author(s):  
Nilesh Takale ◽  
Neelakandan Kaliyaperumal ◽  
Gopalakrishnan Mannathusamy ◽  
Rajarajan Govindasamy
Keyword(s):  
Sulfuric Acid ◽  
Formic Acid ◽  
Chromatographic Method ◽  
Isopropyl Alcohol ◽  
Class Iii ◽  
Drug Substances ◽  
Headspace Gas ◽  
Concentrated Sulfuric Acid ◽  
Gas Chromatographic Method

The Pharmaceutical industry uses formic acid in the manufacturing of various drug substances or API. At the time of manufacturing of API formic acid is use as an oxidizing agent. Formic acid is the simplest carboxylic acid. It also called methanoic acid.Formic acid present in API at high concentrations is very hazardous but in low concentrations is very beneficial. The developed and validated method was short, precise, cost effective and reproducible with FID detector and easy to use. The method is a selective and superficial analytical method for determination of formic acid in different drug substances. We report here the development and validation study of headspace gas chromatographic method to determine formic acid in different drug substances we are reported here. As per this method, the drug sample was dissolved in 0.1% (v/v) of concentrated sulfuric acid in isopropyl alcohol (IPA) in a GC headspace vial and 0.1% (v/v) of concentrated sulfuric acid in isopropyl alcohol used as a diluent. A AB-Inowax capillary column (30 m x 0.32 mm I.D. and 0.5 µm film thickness) was used under gradient conditions with FID. The formic acid peak was well separated from all other solvents that are used in synthesis of particular drug substance. The LOD and LOQof the method for formic acid are 82 ppm and 249 ppm respectively. Formic acid are low toxic class-III solvent as per ICH guideline.

Electronic Warfare: Electrophilic Substitution

Reactions ◽  
2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Electrophilic Substitution ◽  
Proton Acceptor ◽  
Acid Molecule ◽  
Electronic Warfare ◽  
Hexagonal Ring ◽  
Initial Outcome ◽  
Concentrated Sulfuric Acid ◽  
Electron Clouds

Benzene, 1, is a hard nut to crack. The hexagonal ring of carbon atoms each with one hydrogen atom attached has a much greater stability than its electronic structure, with an alternation of double and single carbon–carbon bonds, might suggest. But for reasons fully understood by chemists, that very alternation, corresponding to a continuous stabilizing cloud of electrons all around the ring, endows the hexagon with great stability and the ring persists unchanged through many reactions. The groups of atoms attached to the ring, though, may come and go, and the reaction type responsible for replacing them is commonly ‘electrophilic substitution’. Whereas the missiles of Reaction 15 sniff out nuclei by responding to their positive electric charge shining through depleted regions of electron clouds, electrophiles, electron lovers, are missiles that do the opposite. They sniff out the denser regions of electron clouds by responding to their negative charge. Let’s suppose you want to make, for purposes you are perhaps unwilling to reveal, some TNT; the initials denote trinitrotoluene. You could start with the common material toluene, which is a benzene ring with a methyl group (–CH3) in place of one H atom, 2. Your task is to replace three of the remaining ring H atoms with nitro groups, –NO2, to achieve 3. And not just any of the H atoms: you need the molecule to have a symmetrical array of these groups because other arrangements are less stable and therefore dangerous. It is known that a mixture of concentrated nitric and sulfuric acids contains the species called the ‘nitronium ion’, NO2+, 4, and this is the reagent you will use. Before we watch the reaction itself, it is instructive to see what happens when concentrated sulfuric acid and nitric acid are mixed. If we stand, suitably protected, in the mixture, we see a sulfuric acid molecule, H2SO4, thrust a proton onto a neighbouring nitric acid molecule, HNO3. (Funnily enough, according to the discussion in Reaction 2, nitric ‘acid’ is now acting as a base, a proton acceptor! I warned you of strange fish in deep waters.) The initial outcome of this transfer is unstable; it spits out an H2O molecule which wanders off into the crowd. We see the result: the formation of a nitronium ion, the agent of nitration and the species that carries out the reaction for you.

ChemInform Abstract: Reaction of 3-Aminobenzo(c)isothiazole and 3-Aminoindazole with Nitrosonium Hydrosulfate and Nitric Acid in Concentrated Sulfuric Acid

ChemInform ◽  
2010 ◽  
Vol 28 (21) ◽  
pp. no-no
Author(s):  
M. V. GORELIK ◽  
V. I. LOMZAKOVA ◽  
E. A. KHAMIDOVA ◽  
M. G. KUZNETSOVA
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Concentrated Sulfuric Acid

scholarly journals A Headspace Gas Chromatographic Method for Determination of Formic Acid Content in Isosulfan Blue and Various Drug Substances

2021 ◽  
Vol 37 (02) ◽  
pp. 321-329
Author(s):  
Nilesh Takale ◽  
Neelakandan Kaliyaperumal ◽  
Gopalakrishnan Mannathusamy ◽  
Rajarajan Govindasamy
Keyword(s):  
Sulfuric Acid ◽  
Formic Acid ◽  
Chromatographic Method ◽  
Isopropyl Alcohol ◽  
Class Iii ◽  
Drug Substances ◽  
Headspace Gas ◽  
Concentrated Sulfuric Acid ◽  
Gas Chromatographic Method

The Pharmaceutical industry uses formic acid in the manufacturing of various drug substances or API. At the time of manufacturing of API formic acid is use as an oxidizing agent. Formic acid is the simplest carboxylic acid. It also called methanoic acid.Formic acid present in API at high concentrations is very hazardous but in low concentrations is very beneficial. The developed and validated method was short, precise, cost effective and reproducible with FID detector and easy to use. The method is a selective and superficial analytical method for determination of formic acid in different drug substances. We report here the development and validation study of headspace gas chromatographic method to determine formic acid in different drug substances we are reported here. As per this method, the drug sample was dissolved in 0.1% (v/v) of concentrated sulfuric acid in isopropyl alcohol (IPA) in a GC headspace vial and 0.1% (v/v) of concentrated sulfuric acid in isopropyl alcohol used as a diluent. A AB-Inowax capillary column (30 m x 0.32 mm I.D. and 0.5 µm film thickness) was used under gradient conditions with FID. The formic acid peak was well separated from all other solvents that are used in synthesis of particular drug substance. The LOD and LOQof the method for formic acid are 82 ppm and 249 ppm respectively. Formic acid are low toxic class-III solvent as per ICH guideline.

Trapping nitrous gases during nitric acid leaching of sulfide concentrates

2021 ◽  
pp. 29-36
Author(s):  
E. Yu. Meshkov ◽  
N. A. Bobyrenko ◽  
I. A. Parygin ◽  
A. A. Soloviev
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Nitrogen Oxides ◽  
Nitrogen Oxide ◽  
Acid Leaching ◽  
Process Water ◽  
Nitric Acid Leaching ◽  
Concentrated Sulfuric Acid ◽  
Sulfide Concentrates ◽  
Nitrous Gases

Gas-air mixtures that form in nitric acid leaching of sulfide raw materials possess the following peculiarities making a negative impact on trapping of nitrogen oxides: elevated temperature, different oxidation level of nitrogen oxides, slow oxidation of NO in region of low concentrations, and instability of the resulting gas-air mixture flow. Therefore, well-known methods of trapping nitrous gases shall be adapted to specific sulfide raw material. We propose a process flow diagram for trapping nitrous gases formed during nitric acid leaching of sulfide concentrates at atmospheric pressure on the example of Zhezkazgan concentrate. The paper addresses theoretical aspects of the use of water-ore pulp, concentrated sulfuric acid, process water and alkaline agents for trapping nitrous gases, and typical reactions of interaction of the proposed absorbents with nitrogen oxides. The choice of water-ore pulp as an absorber was made because of similarity between the mechanism of absorption of nitrogen oxides for neutral and alkali ore suspensions and the one for alkali solutions: nitrogen dioxide and nitrous anhydride are absorbed with formation of a solution of nitrates and nitrites. Due to availability in a liquid phase of ferrous iron along with NO2 and N2O3, acidic suspensions are also capable to absorb nitric oxide, to some extent, with formation of Fe(NO)SО4 complex. Process water absorbs only nitrogen dioxide, with formation of nitric and nitrous acids. Nitrous acid is an unstable compound in acidic environments and decomposes with formation of water and nitrogen oxide. At the stages of trapping nitrogen oxides with water-ore pulp and process water (circulating solution), it is recommended conditioning of gas-air mixtures by choosing the volume of additionally introduced air, in an amount to provide the highest rate of nitrogen oxide oxidation. At the stages of sulfuric acid and alkaline trapping of nitrogen oxides, it is recommended conditioning of gas-air mixtures by selecting the volume of additionally introduced air and the oxidation time of nitrogen oxide that provide an equimolecular mixture of NO and NO2. A distinctive feature of the use of water-ore pulp, concentrated sulfuric acid, process water and alkaline agents for trapping nitrous gases is possibility to use the products of absorption at the stage of sulfide concentrate leaching. The extended tests of trapping nitrous gases have been conducted. The plant capacity by the gas-air mixture ranged 17–21 m3/h, and by leached concentrate — 12–15 kg/h. In this case, the degree of capturing nitrous gases reached 96.8%. Return of the products of absorption of nitrous gases in the form of condensate, water-ore pulp, nitrosyl sulfuric acid, nitric acid solution, nitritenitrate lye allows to reduce the nitric acid consumption by 7–10 times relative the values obtained without using the trapping system. In this case, the degree of copper extraction into the leaching solution was 97.7%. The extraction degree of silver, rhenium, zinc was respectively 98.0%, 99.0%; 98.5%.

Color oscillations in the formic acid-nitric acid-sulfuric acid system

1983 ◽  
Vol 60 (11) ◽  
pp. 994
Author(s):  
C. J. G. Raw ◽  
J. P. Kubik ◽  
R. E. Tecklenburg
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Formic Acid ◽  
Acid System
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