Use Of Sulfamic Acid Research Articles

Eco‐friendly Pretreatment of Oil with High Free Fatty Acid Content Using a Sulfamic Acid/Ethanol System

AbstractIn recent years, sulfamic acid (SA, NH2SO3H) has emerged as a novel green catalyst for organic synthesis because of several advantages, including its non‐volatility, non‐hygroscopicity, non‐corrosivity, and low cost. This work reports the use of sulfamic acid as a catalyst in the pretreatment of oil with a high content of free fatty acids (10 and 20 % FFA) in ethanol or methanol. The process (esterification reaction) used in the pretreatment of the oil was carried out under a variety of conditions, initial fatty acid content, temperature, type of alcohol, and % catalyst. The experiments using an NH2SO3H/ethanol system resulted in a high fatty acid ethyl ester conversion, 88.53 % (±0.95) from an initial acidity of 40 mg KOH/g (20 % FFA), using 8 % NH2SO3H as the catalyst. According to the results, the methodology using sulfamic acid and ethanol demonstrated elevated potential for a environmentally‐friendly means of biodiesel production.

Expeditious Synthesis of Thiadiazolo Benzodiazepines Under Conventional Method and Microwave Irradiation

This article explores the use of sulfamic acid as an efficient catalyst for the one-pot synthesis of thiadiazolo 1, 5 benzodiazepines by using benzo[c][1,2,5]thiadiazole-4,5-diamine and various types of ketones in the presence of chloroform as a solvent under conventional methods and microwave irradiation. Our method is more advantageous than current methods. The catalyst (sulfamic acid) is cost effective, readily available and gives excellent yields with high purity. In comparison, the microwave irradiation method is equally as effective with a shorter reaction time and still maintaining high yields.

Inter‐ and Intramolecular Imino Diels—Alder Reactions Catalyzed by Sulfamic Acid: A Mild and Efficient Catalyst for a One‐Pot Synthesis of Tetrahydroquinolines.

The successful use of sulfamic acid as a catalyst in the inter- and intramolecular Inverse Electron Demand Diels-Alder reactions of iminodienes is described. A one-pot synthesis of tetrahydroquinolines was achieved by three component coupling of benzaldehyde and anilines with electron-rich dienophiles such as 2,3-dihydrofuran, dihydropyran and cyclopentadiene catalyzed by sulfamic acid (H 2 NSO 3 H). The intramolecular cycloaddition of imines, derived from O-prenylsalicylaldehyde with anilines catalyzed by sulfamic acid proceeds smoothly and yielded the diastereomeric tetrahydrochromanoquinolines in good yields.

Inter- and Intramolecular Imino Diels-Alder Reactions Catalyzed by Sulfamic Acid: A Mild and Efficient Catalyst for a One-Pot Synthesis of Tetrahydroquinolines

The successful use of sulfamic acid as a catalyst in the inter- and intramolecular Inverse Electron Demand Diels-Alder reactions of iminodienes is described. A one-pot synthesis of tetrahydroquinolines was achieved by three component coupling of benzaldehyde and anilines with electron-rich dienophiles such as 2,3-dihydrofuran, dihydropyran and cyclopentadiene catalyzed by sulfamic acid (H 2 NSO 3 H). The intramolecular cycloaddition of imines, derived from O-prenylsalicylaldehyde with anilines catalyzed by sulfamic acid proceeds smoothly and yielded the diastereomeric tetrahydrochromanoquinolines in good yields.

Effect of additives on the flow-analysis determination of weak-acid-dissociable and total cyanide.

The effect of reductants, complexants, and nitrite eliminators on the flow-analysis determination of weak-acid-dissociable and total cyanide has been studied for: 1. cyanide recovery from copper, nickel, and iron complexes; 2. cyanide generation from the reagents in the presence of common interferents; and 3. cyanide consumption by the reagents in the presence of those interferents. In the absence of additives the UV-assisted recovery of (total) cyanide from the iron complexes (using a succinate buffer) was insufficient. Arsenite and hypophosphite had no measurable effect on the recovery, ascorbic acid resulted in total recovery but under these conditions nitrite and sulfite seemed to destroy cyanide. Phenanthroline promoted the recovery of cyanide from iron complexes but led to formation of cyanide from thiocyanate. Citrate resulted in good recovery but in the presence of nitrite cyanide was formed; the recovery with EDTA was also good. It proved necessary to destroy nitrite by use of sulfamic acid. If a combination of EDTA, citrate, and sulfamic acid is used rather high concentrations of thiocyanate, nitrite, thiosulfate, and sulfite can be tolerated in the samples. It is strongly advisable to test modifications of the cyanide determination comprehensively, because some surprising results have been obtained.

Biological monitoring of workers exposed to 4,4'-methylene-bis-(2-orthochloroaniline) (MOCA). I. A new and easy determination of "free" and "total" MOCA in urine.

The objective of the study was to validate a new and simple method to determine MOCA in the urine of exposed workers. The separation, identification and quantification of urinary MOCA were performed in spiked urines by a sensitive and practical high-performance liquid chromatography (HPLC) method and applied to urine samples of 11 workers occupationally exposed to MOCA; the postshift urinary levels of MOCA in their urine samples with and without hydrolysis, "total" and "free" MOCA respectively, were determined. In addition, we investigated the use of citric or sulfamic acid as preservatives of urine samples. The "total" and "free" MOCA were extracted with isooctane from hydrolysed and nonhydrolysed 20-ml urine samples respectively. After evaporation, the residue was dissolved in 4 ml of 2.10(-2) M aqueous hydrochloric acid and analysed by an isocratic HPLC system using both ultraviolet (UV) detection at 244 nm and electrochemical detection working in oxidation mode (0.9 V) with an Ag/AgCl reference electrode. Mobile phase (50% acetonitrile in water containing 0.4% acetate buffer solution pH = 4.6) was used to complete the 20-min analysis. "Free" and "total" MOCA were chromatographed on a reversed-phase C8 column (5 microns, 250 mm x 4 mm). The standard curve of MOCA was linear over the range 5-500 micrograms/l in human urine. The detection limit was 1 microgram/l for a 20-microliter injection volume; the repeatability ranged from 5.6 to 1.3% (n = 6) for spiked urines at 5 and 500 micrograms/l, with a percentage recovery of 94 +/- 3%. The reproducibility of the method was 7.3% (n = 4) for spiked urine at 10 micrograms/l. The use of sulfamic acid as a preservative of urine samples is important to improve the precision and accuracy of the analysis. The results indicate that these analytical procedures using conventional apparatus may be used routinely and reliably with large numbers of urine samples for biological monitoring of the exposure to MOCA. The occupational exposure to MOCA in some factories in France is studied in the second part of this work.

Steroid conjugates I. The use of sulfamic acid for the preparation of steroid sulfates

The utility of sulfamic acid for the preparation of diverse steroid sulfates has been investigated. Sulfates of the following steroids were prepared and characterized: testosterone, choleseterol, pregnenolone, dehydroisoandrosterone, estrone, 2-methyoxyestrone, ethynylestradiol and ethynylesteradiol-3-methyl ether.

The use of sulfamic acid as a primary standard in nonaqueous titrimetry

A method has been developed for the standardization of a typical nonaqueous base lithium methoxide, with an inorganic primary standard, sulfamic acid. 'T'his acid was found to dissolve readily in four independant basic solvents, dimethyl formamide, ethylenediamine, n-butylamine and dimethyl sulfoxide. Sulfamic acid could be titrated in each of these solvents, by both visual and potentiometric means with lithium methoxide dissolved in benzene-methanol. No gels nor precipitates resulted in the course of the titrations and the accuracy of the method was comparable to that obtained using benzoic acid as the primary standard. Conductometric titrations were also performed using sulfamic acid dissolved in two systems, dimethyl formamide and glacial acetic acid. In the latter solvent it was possible to titrate sulfamic acid with perchloric acid in glacial acetic acid.