Mixture Of Trifluoroacetic Anhydride Research Articles

C6N10O4: Thermally Stable Nitrogen-Rich Inner Bis(diazonium) Zwitterions.

Two nitrogen-rich inner bis(diazonium) salts, the 4,4'-dinitro-5,5'-diazo-2,2'-bisimidazole (2) and the 4,4'-dinitro-5,5'-diazo-3,3'-bispyrazole (4) zwitterions, are described. Compound 2 was synthesized unexpectedly from the nitration of 4,4'-dinitro-5,5'-diamino-1H,1'H-2,2'-bisimidazole (1) in a mixture of trifluoroacetic anhydride and 100% nitric acid. Both 2 and 4 show good thermal stability, especially 2 has a decomposition temperature of 199 °C, which is the highest one in any of the reported hydrogen-free nitrogen-rich diazonium salts.

Microwave‐assisted YBa2Cu3O7 precursors: A fast and reliable method towards chemical precursors for superconducting films

AbstractHighly stable, pure, and anhydrous organometallic YBa2Cu3O7‐δ (YBCO) precursor solutions were prepared by dissolving commercial YBCO powder in acetone by trifluoroacetic anhydride (TFAA) or a mixture of TFAA with propionic acid for low fluorine precursors. It is shown that compared to conventional oil bath heating reported in literature, the reaction to produce YBCO precursor occurs 72 times faster by microwave heating. More importantly, the formation of byproducts is suppressed, as shown by nuclear magnetic resonance (NMR) and mass spectrometry (MS). This approach allows a highly reproducible preparation of superconducting coatings which is of interest for low‐cost manufacturing processes capable of large‐scale production of the coated conductors via chemical solution deposition (CSD). This technology requires reliable and stable precursor solutions for continuous deposition. In this work, we obtained YBCO thin films on single‐crystal substrates ((100)‐LaAlO3) with a high critical current density (Jc) of 3‐4 MA/cm² in self‐field at 77 K using TFA‐based YBCO precursors and Jc of 5‐6 MA/cm² using low fluorine YBCO precursors.

Chemical synthesis of 3β-sulfooxy-7β-hydroxy-24-nor-5-cholenoic acid: An internal standard for mass spectrometric analysis of the abnormal Δ 5-bile acids occurring in Niemann-Pick disease

In Niemann-Pick disease, type C1, increased amounts of 3β,7β-dihydroxy-5-cholenoic acid are reported to be present in urinary bile acids. The compound occurs as a tri-conjugate, sulfated at C-3, N-acetylglucosamidated at C-7, and N-acylamidated with taurine or glycine at C-24. For sensitive LC–MS/MS analysis of this bile acid, a suitable internal standard is needed. We report here the synthesis of a satisfactory internal standard, 3β-sulfooxy-7β-hydroxy-24-nor-5-cholenoic acid (as the disodium salt). The key reactions involved were (1) the so-called “second order” Beckmann rearrangement (one-carbon degradation at C-24) of hyodeoxycholic acid (HDCA) 3,6-diformate with sodium nitrite in a mixture of trifluoroacetic anhydride and trifluoroacetic acid, (2) simultaneous inversion at C-3 and elimination at C-6 of the ditosylate derivatives of the resulting 3α,6α-dihydroxy-24-nor-5β-cholanoic acid with potassium acetate in aqueous N, N-dimethylformamide, and (3) regioselective sulfation at C-3 of an intermediary 3β,7β-dihydroxy-24-nor-Δ 5 derivative using sulfur trioxide–trimethylamine complex. Overall yield of the desired compound was 1.8% in 12 steps from HDCA.

Desenvolvimento e validação de método de análise de glifosato em grãos de soja

The main objective of this work is to develop an efficient procedure to determine glyphosate in soybean grains. The cleanup of the aqueous extracts was done in two steps, beginning with liquid-liquid partitioning and then solid-phase extraction with anion exchange resin. After derivatization with a mixture of trifluoroacetic anhydride (TFAA) and trifluoroethanol (TFE), quantification was done by gas chromatography coupled to mass spectrometry. The mean recovery and RSD of the spiked samples were, respectively, 80.5% and 3.1% at level 0.200 mg kg-1, 93.3% and 18.7% at level 0.500 mg kg-1 and 92% and 3.5% at level 1.000 mg kg-1. The method was linear in the working range (correlation coefficient = 0.9965).

Estudo de recuperação de glifosato e AMPA derivados em solo utilizando-se resinas nacionais

In the present paper we studied the recoveries of glyphosate, N-(phosphonomethyl)glycine (GLY) and its major metabolite, (aminomethyl)phosphonic acid (AMPA) in soil using national (Brazilian) ion-exchange resins, derivatization by a mixture of trifluoroacetic anhydride and trifluoroethanol and analyses by GC-MS. The quantification limits were 12 ng.g-1 for both compounds and the methodology showed a range of recuperation from 85 to 94% with coefficients of variation (CV) ranging from 4.07 to 6.91% for GLY. For AMPA, the mean recoveries ranged from 87 to 102% with CVs ranging from 5.81 to 6.99%. Additional studies showed that, due to the instability of the derivatized compounds, they must be analysed keeping constant time between derivatization and analysis, preferably less than 24 h.

A ‘cold synthesis’ of heroin and implications in heroin signature analysis: Utility of trifluoroacetic/acetic anhydride in the acetylation of morphine

Treatment of morphine, at room temperature, with a mixture of trifluoroacetic anhydride (TFAA) and acetic acid (20–30 min) affords good yields of heroin. GC–MS and HPLC examination shows that heroin produced by this route to be extremely clean, but the product contains slightly less heroin than observed via the more traditional acetic anhydride (AA) route (76.1% versus 83.55%); and greater quantities of 3-MAM and 6-MAM (6.9% versus 0.75% and 7.13% versus 0.63%). The concentration ratios of the major alkaloid impurities were found to be both production method (TFAA and AA) as well as morphine extraction methodology dependant. Data contained herein describe the impact of this new production method on current intelligence efforts, largely by-passing existing heroin signature programs and the UNDCP's efforts to restrict access to key synthetic precursors. Given the methodology dependency we find that examination of the major alkaloid ratios is unsuitable for the development of a new heroin signature program. Further examination of the TFAA methodology allowed the identification of TFAA specific marker compounds, namely bis-trifluoroacetylmorphine ( 30), 3-trifluoroacetyl-6-acetylmorphine ( 31), 3-acetyl-6-trifluoroacetylmorphine ( 32) and trifluoroacetylcodeine ( 33). However, the hydrolytic lability of trifluroacetyl esters requires careful treatment of suspect samples, thus we propose a modification to existing HSP's in instances were the 6-MAM/WM ratio falls within the average minimum and maximum values of 6.17 and 17.32.

Oxazolinone derivative of leucine for GC-MS: a sensitive and robust method for stable isotope kinetic studies of lipoproteins

Stable isotope labeled amino acids are commonly used as endogenous tracers to study the metabolism of lipoproteins. The determination of isotopic enrichment of particular amino acids in apolipoproteins is carried out by gas chromatography mass spectrometry (GC-MS). This report describes a robust and sensitive derivative for analysis of d3-leucine by GC-MS and its utility in studying the metabolism of human lipoproteins. The trifluoromethyloxazolinone (oxazolinone) derivative of leucine was formed in a rapid single step procedure using a mixture of trifluoroacetic anhydride (TFAA) and trifluoroacetic acid (TFA). Analysis of the oxazolinone by negative ion chemical ionization GC-MS gave excellent sensitivity and precision, which enabled accurate determination of low levels of isotopic enrichment from small amounts of protein. For example, enrichments between 0.05% and 100% in 100 pg leucine can be measured with a coefficient of variation of <3%. To demonstrate the utility of this procedure, we measured d3-leucine enrichment in apolipoprotein B (apoB) isolated from VLDL and LDL as well as apoA-I isolated from HDL by gel electrophoresis and western blotting. The derivatization procedure gave excellent enrichment data from a single intravenous bolus dose of 5 mg/kg, from which the fractional catabolic rate and production rate of the lipoproteins were calculated. In conclusion, the oxazolinone derivative provides a robust and simple procedure for the sensitive analysis of isotopic enrichment for metabolic studies of human lipoproteins.—Dwyer, K. P., P. H. R. Barrett, D. Chan, J. I. Foo, G. F. Watts, and K. D. Croft. Oxazolinone derivative of leucine for GC-MS: a sensitive and robust method for stable isotope kinetic studies of lipoproteins.

An integrated gas chromatographic method towards the simultaneous determination of phosphoric and amino acid group containing pesticides

Ampropylfos, glyphosate, glufosinate and bialaphos are water soluble pesticides that contain phosphoric and amino acid groups in their molecules. Their polar nature and high water solubility make extraction difficult and limit the options for using the various derivatization techniques often employed for gas chromatographic analysis. A multiresidue method is proposed that allows the simultaneous determination of six analytes (pesticides and some of their metabolites) in environmental waters down to sub-μb L−1 levels. A mixture of trifluoroacetic anhydride and trifluoroethanol converts them in a single-step reaction to derivatives that are sufficiently volatile for gas chromatographic analysis. Electron capture and mass-selective detection are used for quantitation purposes, and their analytical characteristics are presented. Under the chromatographic conditions employed, acceptable separation is attained for the derivatized analytes, with both glufosinate and bialaphos emerging as double peaks. Recoveries of spiked environmental water samples range from 88 to 106%. The mean relative standard deviation of the method does not exceed 3.0%, whereas, depending on the detection system, the limits of detection for the analytes are in the range of 0.09–65 μg L−1, the upper value being the bialaphos detection limit.

Determination of Glyphosate and Its Metabolite, (Aminomethyl)phosphonic Acid, in River Water

Abstract A procedure for extracting glyphosate and its meta bolite, (aminomethyl)phosphonic acid, from river water and for determining these 2 compounds by gas chromatography/ion trap mass spectrometry is described. Both compounds were extracted with Bio-Rad AG 1-X8 anion-exchange resin (formate form) prior to derivatization with a mixture of trifluoroacetic anhydride and trifluoroethanol. Limits of detection for glyphosate and its metabolite were 1 ppb even when as little as 10 mL water was analyzed. Recoveries of both compounds from river water fortified at 50 ppb were &amp;gt;90%.

Inhibitors of sterol synthesis. Metabolism-based design and construction of a new analog of 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one and its effects in cultured mammalian cells and in rats.

3 beta-Hydroxy-5 alpha-cholest-8(14)-en-15-one (I) is a potent regulator of cholesterol metabolism. In the present study, the 7 alpha-methyl-25,26,26,26,27,27,27-heptafluoro analog (X) of I has been synthesized with the goal of blocking not only the side chain oxidation of I but also its conversion to cholesterol. X was prepared in seven steps from the known 7 alpha-methyl analog (IX) of I. Treatment of the acetate of IX with a mixture of trifluoroacetic anhydride, hydrogen peroxide, and sulfuric acid gave 3 beta-acetoxy-7 alpha-methyl-24-hydroxy-5 alpha-chol-8(14)-en-15-one (XII) in remarkably high (68%) yield. Dehydration of XII via the orthonitrophenylselenide to the 23-ene, followed by addition of (CF3)2CFI gave (23R)-3 beta-acetoxy-7 alpha-methyl-23-iodo-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholest-8(14)-en-15-one (XV). Reductive deiodination of XV with tributyltin hydride, followed by hydrolysis of the acetate gave 3 beta-hydroxy-7 alpha-methyl-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholest-8(14)-en-15-one (X). The F7-7 alpha-methyl-15-ketosterol X lowered the levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in CHO-K1 cells with a potency equivalent to that of I. X showed significant hypocholesterolemic action upon oral administration to rats, with a potency far in excess of the 7 alpha-methyl-15-ketosterol IX lacking the F7 substitution. In marked contrast to I, X showed little or no suppression of food consumption in rats. Upon oral administration of X to rats, low levels of X (relative to cholesterol), characterized by chromatographic and gas chromatography-mass spectrometric methodologies, were observed in serum, liver, and small intestine. No material was observed with the expected properties of F7-7-methylcholesterol (or potential intermediates in its possible formation from X). In contrast to I, X lowered serum cholesterol levels at dosages at which no effect on food consumption was observed.

Inhibitors of sterol synthesis. A highly efficient and specific side-chain oxidation of 3 beta-acetoxy-5 alpha-cholest-8(14)-en-15-one for construction of metabolites and analogs of the 15-ketosterol.

As part of a program directed towards the chemical syntheses of potential metabolites and analogs of 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one (I), a potent regulator of cholesterol metabolism, several routes have been explored for the preparation of 3 beta-hydroxy-15-keto-5 alpha-chol-8(14)-en-24-oic acid (IV). These investigations led to a remarkably specific and efficient side-chain oxidation of I. For example, treatment of the acetate of I with a mixture of trifluoroacetic anhydride, hydrogen peroxide, and sulfuric acid for 3.5 h at -2 degrees C gave a crude product consisting of 3 beta-acetoxy-24-trifluoroacetoxy-5 alpha-chol-8(14)-en-15-one (XI), 3 beta-acetoxy-24-hydroxy-5 alpha-chol-8(14)-en-15-one (XII), and 3 beta, 24-diacetoxy-5 alpha-chol-8(14)-en-15-one (XIII) in yields of 58%, 8%, and 3%, respectively, by HPLC analysis. XI was readily hydrolyzed to XII upon treatment with triethylamine in methanol at room temperature. Oxidation of XII with Jones reagent gave 3 beta-acetoxy-15-keto-5 alpha-chol-8(14)-en-24-oic acid (XVIII) from which its methyl ester (IX) was prepared by treatment with diazomethane. Mild alkaline hydrolysis of XVIII gave the 3 beta-hydroxy-delta 8(14)-15-keto C24 acid (IV). Hydrolysis of the crude product of the side-chain oxidation with K2CO3 in methanol gave 3 beta,24-dihydroxy-5 alpha-chol-8(14)-en-15-one (XIV) which was oxidized with Jones reagent to yield 3,15-diketo-5 alpha-chol-8(14)-en-24-oic acid (XV). Treatment of XV with diazomethane gave its methyl ester (XVI) which, upon controlled reduction with NaBH4, yielded methyl 3 beta-hydroxy-15-keto-5 alpha-chol-8(14)-en-24-oate (XVII). Compound IX was also prepared by an independent route. Full 1H and 13C NMR assignments are presented for 12 new compounds. IV caused a approximately 56% reduction of the level of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in CHO-K1 cells at a concentration of 2.5 microM. In contrast, the corresponding 3,15-diketo acid XV had no detectable effect on reductase activity under the same conditions.

1,1,4,4-Tetranitrobutane-2,3-diol and its derivatives. 3. Synthesis of 1,4-dichloro- and 1,4-dibromo-1,1,4,4-tetranitrobutane-2,3-diol dinitrates and their crystalline structure

1,4-Dichloro- (1) and 1,4-dibromo-1,1,4,4-tetranitrobutane-2,3-diol dinitrates (2) were synthesized by nitration of the corresponding diols with a mixture of trifluoroacetic anhydride and nitric acid. The x-ray diffraction investigations of 1 and 2 that have been carried out showed the influence of the intramolecular interactions of the nitro and nitrate groups on the packing of the molecules in the crystal.

High-sensitivity FAB-MS strategies for O-GlcNAc characterization

In this paper we report the first application of fast atom bombardment mass spectrometry (FAB-MS) to O-linked N-acetylglucosamine (O-GlcNAc)-bearing glycopeptides. Using N-acetylgalactosamine (GalNAc)- and Gal-GalNAc-containing glycopeptides (isolated from Tn glycophorin and desialylated normal glycophorin, respectively) as readily available model compounds, rapid and sensitive derivatization/FAB-MS strategies applicable to serine/threonine-rich glycopeptides have been devised. Peptides and glycopeptides were propionylated in a 1 min reaction using a mixture of trifluoroacetic anhydride and propionic acid, and the product mixtures were analysed directly by FAB-MS. Glycopeptides and peptides rich in hydroxylated residues afforded characteristic clusters of molecular ions at high sensitivity. Additional sensitivity enhancement was achieved by prior esterification of carboxyl groups. These methods were used in a study of O-GlcNAc glycopeptides produced by purified O-GlcNAc transferase addition of GlcNAc to the synthetic peptides YSDSPSTST and YSGSPSTST in which Y is tyrosine, S is serine, D is aspartic acid, P is proline, T is threonine and G is glycine. The propionyl derivatives afforded high-quality spectra which unequivocally showed that the majority of the glycopeptides were substituted with a single GlcNAc residue. Low pmol quantities of material gave detectable signals. The propionylation/FAB-MS procedure has been combined with gas-phase sequencing strategies and shows promise for defining the sites of glycosylation of O-GlcNAc glycopeptides that are available in limited quantities.

Use of Tert-Butyl Sulfoxides as Latent Sulfenyl Cation Equivalents

Abstract This paper reports a new and practical method of trifluoro-acetoxysulfenylation of olefins, starting from t-butyl sulfoxides. The latter, in a mixture of trifluoroacetic anhydride and trifluoroacetic acid, do not undergo the Pummerer reaction. Instead, sulfenyltrifluoroacetates 2 are formed and they add in situ to olefins.

Synthesis of 24-nor-5 beta-cholan-23-oic acid derivatives: a convenient and efficient one-carbon degradation of the side chain of natural bile acids

An efficient procedure for obtaining nor-bile acids from natural (C24) bile acids is described. Treatment of formylated bile acids with sodium nitrite in a mixture of trifluoroacetic anhydride with trifluoroacetic acid gives, through a "second order" Beckmann rearrangement, 24-nor-23-nitriles. These compounds, on alkaline hydrolysis, afford the corresponding nor-bile acids in high yields. The sequence was successfully applied to the synthesis of 3 alpha-hydroxy-24-nor-5 beta-cholan-23-oic (norlithocholic) acid, 3 alpha,6 alpha- (norhyodeoxycholic), 3 alpha,7 alpha- (norchenodeoxycholic), 3 alpha,7 beta- (norursodeoxycholic), and 3 alpha,12 alpha-dihydroxy-24-nor-5 beta-cholan-23-oic (nordeoxycholic) acids, as well as 3 alpha,7 alpha,12 alpha-trihydroxy-24-nor-5 beta-cholan-23-oic (norcholic) acid. 13C-NMR spectra of their methyl esters are reported. The procedure provides a more rapid alternative to the Barbier-Wieland degradation for shortening by one methylene group the side chain of natural (C24) bile acids.

A new method for degradation of the protein part of glycoproteins: isolation of the carbohydrate chains of asialofetuin

A new method has been developed for degrading the protein part of several glycoproteins, whilst leaving the carbohydrate portion virtually intact apart from partial degradation at the reducing end. The method is based upon stabilization of the glycosidic linkages of the sugar residues by trifluoroacetyl groups and subsequent cleavage of the peptide bonds by transamidation. The two reactions are carried out in a mixture of trifluoroacetic anhydride and trifluoroacetic acid. After O- and N-detrifluoroacetylation, the carbohydrate portion can be isolated and re- N-acetylated. The applicability of the method is demonstrated by the isolation from asialofetuin of the carbohydrate chains that are attached by N- and O-glycosyl links.

Ring scission of cyclic acetals. Part III. Reaction of acetyl trifluoroacetate with 1,3:2,5:4,6-tri-O-methylene-D-mannitol

The ring fission reaction of 1,3:2,5:4,6-tri-O-methylene-D-mannitol has been studied with the acetylating reagent formed from the 1 : 1 molar mixture of trifluoroacetic anhydride and acetic acid. Among a variety of acetals which have been identified are an O-acetoxymethyl-O-acetyl-1,3:2,5-di-O-methylene-, a di-O-acetoxymethyl-di-O-acetyl-2,5-O-methylene-, an O-acetyl-1,3:2,5-di-O-methylene-, 1,6-di-O-acetyl-2,5-O-methylene-, 1,6-di-O-acetyl-2,5-O-methylene-3,4-O-oxydimethylene-, and 1-O-acetyl-3-O-alkoxymethyl-2,5:4,6-di-O-methylene-compounds. Mechanisms put forward to interpret the formation of these products are based on a ring-opening reaction with the formation of an O-acetyl and an O-trifluoroacetoxymethyl reaction intermediate.

Synthesis of (±)-Hydroxytremetone

(±)Hydroxytremetone (III) has been synthesized from 2-(α-hydoxyisopropyl)-6-hydroxycoumaran (V b) via its O-acetate V c by dehydration with phosphorus tribromide in pyridine solution, followed by acylation with a mixture of trifluoroacetic anhydride and acetic acid. Isohydroxytremetone (IX b) was also synthesized.

Synthesis of (±)-Hydroxytremetone

(±) Hydroxytremetone (III) has been synthesized from 2-(α-hydoxyisopropyl)-6-hydroxy-coumaran (V b) via its 0-acetate V c by dehydration with phosphorus tribromide in pyridine solution, followed by acylation with a mixture of trifluoroacetic anhydride and acetic acid. Isohydroxytremetone (IX b) was also synthesized.