Search results for "Formic Acid"

Determination of tyrosine through a FIA-direct chemiluminescence procedure.

2003

A new FI-direct chemiluminescence method is proposed for the determination of tyrosine, based on the oxidation of the amino acid by K(3)Fe(CN)(6) in potassium hydroxide medium, at room temperature and enhanced by the presence of beta-cyclodextrin and formic acid. The dynamic range was linear over the range 1.0-10.0 mgl(-1). A large study of the influence of foreign compounds was performed, including amino acids; and, the method showed high selectivity. The reproducibility between days resulted in a rsd (in slope%) of 4.8 and the repeatability with a rsd (n=50, 10.0 mgl(-1)) of 3.1%, the LOD (s/n=3) was 50 mugl(-1) and sample throughput 98 h(-1).

Synthesis of N-methyl alkylaminomethane-1,1-diphosphonic acids and evaluation of their complex-formation abilities towards copper(II)

2015

Abstract A series of N -methyl alkylaminomethane-1,1-diphosphonic acids ( 3a – g ) with a common tertiary nitrogen atom (CH 3 –N–R) bearing linear or branched alkyl, cycloheptyl or phenylalkyl R substituents was synthesized in the reaction of diethylphosphonate with triethyl orthoformate and secondary amine followed by hydrolysis, and by the Eschweiler–Clarke methylation of the alkylaminomethane-1,1-diphosphonic acids with formic acid and formaldehyde. Complex-formation abilities of 3a – g towards copper(II) in solution were studied by means of pH-potentiometry, ESI-MS spectrometry, UV–Vis and EPR methods. Evaluation of stability constants for the Cu(II) complexes of 3a – g has revealed the…

Synthesis of 1H-imidazo[3′,4′:4,5]thieno[2,3-b]pyridines. A new ring system

1984

A facile and convenient synthesis of the title compounds is described, using as starting materials the 2-nitro-3-aminothieno[2,3-b]pyridines. Mass spectral data of the above mentioned compounds are briefly discussed.

Versuche über die oxydation von polyacroleinen mit wasserstoffperoxyd und peressigsäure. Polymer acroleine. 8. Mitt.

1958

Polyacroleine werden durch verdunntes Wasserstoffperoxyd vollstandig abgebaut. Als Abbauprodukte konnten Kohlendioxyd, Ameisensaure und Essigsaure identifiziert werden. Daneben bilden sich noch unbekannte nicht-fluchtige Saren. Polyacrylsaure erleidet unter den gleichen Bedingungen ebenfalls einen Abbau. Die Zusammensetzung der Abbauprodukte ist eine andere. Durch Peressigsaure werden Polyacroleine zu polymeren Sauren oxydiert. Diese gleichen bezuglich der Loslichkeit, der Reaktionen mit Schwermetallsalzen und dem IR- Spektrum weitgehend der Polyacrylsaure. Polyacroleins are completely degraded by the action of dilute hydrogen peroxide. Among the products of degradation carbon dioxyde, form…

HPLC Method for Cyst(e)ine and Methionine in Infant Formulas

1996

Cyst(e)ine and methionine were converted into cysteic acid and methionine sulfone by oxidizing with performic acid. The oxidized samples were then subjected to acid hydrolysis (6N HCl, 105-110°C/24 hr). After derivatization with phenylisothiocyanate, reverse phase HPLC separation was carried out at 48°C and with UV detection. Different gradients and pH values in the eluent were assayed to determine the best resolution. Analytical parameters, detection and quantification limits, linearity, precision and accuracy, were determined. The method was reliable and accurate for measuring cyst(e)ine and methionine in infant formulae.

Electrochemical conversion of Carbon Dioxide: effect of operating parameters and of the reactor on the performances of the process.

2017

Selective hemicellulose hydrolysis of Scots pine sawdust

2019

The depletion of fossil resources is driving forward the search for new and alternative renewable feedstocks in the production of renewable chemicals, which could replace the petroleum-based ones. One such feedstock is pine (Pinus sylvestris) sawdust, which is generated enormous amounts in Finnish sawmills yearly. However, prior to the utilization in high-value applications, it needs to be fractionated into its constituents. In this work, the objective was to produce monomeric hemicellulose sugars from pine sawdust without degrading cellulose or lignin simultaneously. The influence of the reaction temperature and time, as well as acid type and concentration, was studied. Based on the result…

Stereoselective aldol reaction catalyzed by a highly recyclable polystyrene supported substituted prolinamide catalyst

2008

Polystyrene supported substituted prolinamide was used as catalyst in the aldol reaction between cyclohexanone or acetone and several substituted benzaldehydes in chloroform/water. This catalyst afforded aldol products in high yields and stereoselectivities, especially in the case of reactions performed with acetone. The catalyst was easily recovered by filtration and reused, after regeneration with formic acid, up to 22 times.