Showing papers on "Oxalic acid published in 1976"

Foamable resole resin composition

Abstract: This invention relates to an improved foamable resole resin composition comprising a resole resin, a blowing agent and a surfactant wherein said improvement comprises incorporating a particular resole resin catalyzed with alkaline earth metal hydroxides and neutralized with oxalic acid or its acid salts providing inert insoluble oxalate salts dispersed in said resole. Said salts are sized controlled and stabilized in an aqueous resole resin solution having about 60 to 99% resole resin by weight. Methods for preparing and foaming said compositions are disclosed.

Comparison of oxalic acid and phosphoric acid as degumming agents for vegetable oils

Abstract: For many years, phosphoric acid has been used for degumming vegetable oils with high phosphatide content prior to alkali refining. One disadvantage of this technique is the resulting undesirable phosphate waste in streams, a problem which has increased substantially in importance in recent times. We have investigated an alternative degumming technique using oxalic acid that alleviates the pollution problem in cases where water purification by means of a chemical treatment process is not possible.

Etchant for polyimides

Abstract: A composition for etching polyimide based polymers comprised of a tetraalkyl ammonium hydroxide and an organic acid selected from the group of acetic acid, tartaric acid and oxalic acid. The etchant may be used to texture polyimide films or form perforations through polyimide substrates or layers, particularly in the fabrication of printed circuits and semiconductor devices where via holes are required for interconnection of circuitry.

Oxalic Acid: Absorption, Excretion, and Metabolism

Abstract: The incidence of renal stone disease in this country is estimated to be approximately 0.1% of the population. Thus, nephrolithiasis represents one of the most common renal disorders in the United States. It has been documented in a number of previous studies that approximately two thirds of stones collected from patients with nephrolithiasis are composed of calcium oxalate, usually in the monohydrate form, and sometimes mixed with calcium phosphate in the form of apatite. Thus, an understanding of this particular crystalline compound is of importance in defining the pathogenesis of calcium oxalate nephrolithiasis. This discussion will focus on oxalic acid, its physicochemical characteristics, and some of the disorders associated with excess oxalate excretion.

The oxidative metabolism of alpha-chlorohydrin and the chemical induction of spermatocoeles.

Abstract: alpha-Chlorohydrin (I) is oxidatively metabolized to beta-chlorolactic acid (III) and oxalic acid (IV). Deposition of calcium oxalate within the renal tubules is responsible for the toxic effects of alpha-chlorohydrin and a similar action on the epididymis or epididymal blood vessels could initiate the formation of spermatocoeles from this and other male antifertility agents.

CO2 measurement and reagents therefor

Abstract: Reagent compositions for use in CO 2 analysis which comprise certain acids and/or buffered acids together with selected additives. The acids and buffered acids have pH less than 4 and a vapor pressure not in excess of 10mm mercury. Examples of these acids include lactic acid, citric acid, phosphoric acid, sulfuric acid, perchloric acid, malic acid, malonic acid, oxalic acid, naphthalenesulfonic acid, picric acid, sulfamic acid, and nitric acid. The additives, which can be used separately or with one another, are ethers of fatty alcohols and polyoxyethylene (having the structure R--O--(C 2 H 4 --O) n H), glycerin, polyvinyl alcohol, and pH sensitive indicator dyes, including methyl red, p-nitrophenol, neutral red, phenolphthalein, and o-cresolphthalein. An improved method for analysis of CO 2 in body fluids comprises the steps of adding these reagents to body fluid samples to release CO 2 therefrom into a gas space, displacing the released CO 2 to a detector, and measuring the amount of released CO 2 in the detector. Generally, acid reagents including at least one of the ethers of fatty alcohols and polyoxyethylene are preferable for releasing CO 2 from a body fluid sample.

Selectively separating oxalic, tartaric glyoxylic and erythronic acids from aqueous solutions containing the same

Abstract: Mixtures of oxalic, meso tartaric, glyoxylic and erythronic acids derived particularly from the oxidation of cellulose derivatives are separated from aqueous solutions in which they are contained and from each other by stepwise precipitation with calcium ion at controlled pH. The oxalic acid is precipitated as calcium oxalate at a pH of 0.9 to 2.0; the tartaric acid as calcium meso tartrate at a pH of 2.8 to 4.4; and the glyoxylic acid, as calcium glyoxylate at a pH of 4.5 to 5.4. After each precipitation the water insoluble precipitate is separated from the aqueous mixture in which it is contained. The relatively soluble erythronic acid remains in solution as a free acid, or in the form of its calcium salt.

Process for preparing oxalic acid and esters of same

Abstract: OF THE DISCLOSURE: The present invention relates to a process for pre-paring oxalic acid and esters of same. More particularly, this invention relates to a catalytic process for preparing oxalic acid and esters of same by oxidative reaction in a liquid phase of carbon monoxide and water or alcohols with oxygen in the presence of redox systems. The catalyst systems used in accordance with this invention comprises a redox catalyst con-sisting essentially of a salt of Pd (II) and salts of a metal more electropositive than Pd having at least two oxidation states and, optionally, salts of alkaline metals, and co-catalytic amounts of at least one base having the formula R2NH in which the groups R which may be like or unlike are selected from the group con-sisting of hydrogen and alkyl radicals having from 1 to 10 car-bon atoms.

Behaviour of oxalic acid in the anodic oxidation of aluminium. The role of anodically initiated reduction processes in coloration and photoluminescence

Abstract: Anodization of aluminium in aqueous oxalic acid produces a yellow to dark red anodic film and anolyte, both of which luminesce under 365 nm excitation. The luminous substances separated from the anodic film and anolyte by means of paper chromatography showed an e.s.r. signal and have been identified as Al[Al(C2O4)3]nH2O (n= 3 or 4). Yellowish coloration, luminescence and the existence of radicals, however, are not inherent to Al[Al(C2O4)3]nH2O. These phenomena have been explained by the formation of C2O2[graphic omitted]4 produced by intramolecular charge transfer between the low valency aluminium ion and oxalato ligand within the complex. Reduction of oxalic acid at the anode was observed and a reduced product, glyoxylic acid, was isolated from the anolyte. This reductive process has also been explained by an intramolecular charge transfer reaction which gives rise to H atoms.

Photopolymerizable composition with oxalic acid photoinitiator

Abstract: The subject invention relates to photopolymerizable compositions useful for making plastic printing elements for use in photolithography and other photomechanical processes. The photopolymerizable compositions comprise an aqueous mixture of a water-insoluble resin, a water-soluble binder, a crosslinking agent, and a photopolymerization initiator having an alpha-keto ester linkage. In particular, photopolymerization initiators include oxalic acid, sodium oxalate, potassium oxalate, lithium oxalate and urea oxalate. The printing plates prepared from the compositions herein disclosed have improved ink receptivity, good retention of such ink, receptivity even after long continued use, greater durability and excellent binding qualities.

Stability constants of oxalate complexes of copper (II) and nickel (II) by paper electrophoresis

Abstract: Stability constants of copper (II) and nickel (II) oxalates have been determined by paper electrophoresis. Oxalic acid (0.005 mol dm−3) was added to the background electrolyte: 0.1 mol dm−3 HClO4. The proportions of HC2O4− and C2O42− were varied by changing the pH of the electrolyte, these anions yielding the complex ions MHC2O4+ and M(C2O4)22−, average values of the stability constants for which are 102.4 and 107.6 respectively for Cu(II), and 102.3 and 106.5 for Ni(II) (μ=0.1,30°).

An automated colorimetric method for determining oxalic acid in plant material

Abstract: A simple, automated colorimetric method for determining oxalic acid in plant material is based on the quantitative reduction in colour of a zirconium/3,4-dihydroxyazobenzene-2′-carboxylic acid complex by microgram quantities of oxalic acid. It is suitable for use over a wide range of oxalic acid concentrations. Interference from phosphate, sulphate, citric acid and malic acid was encountered but by appropriate sample dilution this problem was resolved.

Aqueous resole resin solutions having dispersed inert salts

Abstract: This invention relates to resoles catalyzed with alkaline earth metal hydroxides and neutralized with oxalic acid or its acid salts providing inert insoluble oxalate salts dispersed in said resoles. Said salts are size controlled and stabilized in aqueous resole resin solution having about 40 to 95 percent resole resin by weight. A method for manufacture is disclosed.

Dilutable resole resin solutions having stabilized dispersed inert salts

Abstract: This invention relates to stable water dilutable resoles. Said resoles are catalyzed with alkaline earth metal hydroxides and neutralized with oxalic acid or its acid salts providing inert insoluble oxalate salts dispersed in said resoles. Said salts are size controlled and stabilized by the presence of particular anionic type dispersing agents. A method for manufacture is disclosed.