Trifluoroacetic acid hydrolysis

Neutral sugars were quantified by trifluoroacetic acid hydrolysis (3) and gas chormatography of alditol acetates (4). Uronic acids were determined by Blumenkrantz method... 

Basic Protocol 2 Determination of Noncellulosic Neutral Sugars and Cellulose Content by Trifluoroacetic Acid Hydrolysis Followed by Sulfuric Acid Hydrolysis E3.2.4... 

DETERMINATION OF NONCELLULOSIC NEUTRAL SUGARS AND CELLULOSE CONTENT BY TRIFLUOROACETIC ACID HYDROLYSIS FOLLOWED BY SULFURIC ACID HYDROLYSIS... 

A Tsugita, T Uchida, HW Mewes, T Ataka. Rapid vapor-phase acid (hydrochloric acid and trifluoroacetic acid) hydrolysis of peptide and protein. J Biochem 102 1593-1597, 1987. 

The characterization and quantitative determination of uronic acid components in polysaccharides faces the problem of complete release of the uronic acids without accompanying decomposition. This is a difficult task because of the acid resistance of the glycosiduronic bond. From a comparison of several methods, it was shown that methanolysis combined with trifluoroacetic acid hydrolysis is the best for the liberation of uronic acids.204 The identification can be performed by gas chromatography of the trimethylsilyl derivatives.205... 

The 5,6,7,8-tetrahydro-7,7-dimethyl-2,5-dioxo-2H-l-benzopyran-4-carboxylic ester 435 was prepared from 1 and sodium diethyl oxalacetate in trifluoroacetic acid. Hydrolysis of the ester group in 435 gave 436 whose decarboxylation afforded the 7,8-dihydrobenzopyran 437 (72JOC1337). 

Trifluoroacetic acid hydrolysis of the isopropylidene protecting group in 79 without loss of the tosyl group provides (25,3 5)-1-0-tosyl-L-threitol (116), which can be cyclized with basic resin to afford (25,3 S)-l,4-anhydro-L-threitol (117) in good overall yield. Treating 117 with triphenylphosphine in pyridine affords the chiral diphosphinite diphin (118), which has been utilized as a ligand in asymmetric hydrogenation, hydrocyanation, and hydroformylation reactions [48] (Scheme 26). 

Trifluoroethanol was first prepared by the catalytic reduction of trifluoroacetic anhydride [407-25-0] (58). Other methods iaclude the catalytic hydrogeaatioa of trifluoroacetamide [354-38-1] (59), the lithium aluminum hydride reductioa of trifluoroacetyl chloride [354-32-5] (60) or of trifluoroacetic acid or its esters (61,62), and the acetolysis of 2-chloro-l,l,l-trifluoroethane [75-88-7] followed by hydrolysis (60). More recently, the hydrogenation of... 

Many carbamates have been used as protective groups. They are arranged in this chapter in order of increasing complexity of stmcture. The most useful compounds do not necessarily have the simplest stmctures, but are /-butyl (BOC), readily cleaved by acidic hydrolysis benzyl (Cbz or Z), cleaved by catalytic hy-drogenolysis 2,4-dichlorobenzyl, stable to the acid-catalyzed hydrolysis of benzyl and /-butyl carbamates 2-(biphenylyl)isopropyl, cleaved more easily than /-butyl carbamate by dilute acetic acid 9-fluorenylmethyl, cleaved by /3-elimination with base isonicotinyl, cleaved by reduction with zinc in acetic acid 1-adamantyl, readily cleaved by trifluoroacetic acid and ally], readily cleaved by Pd-catalyzed isomerisation. 

The aromatization of the oxepin structure can be accompanied by other acid-catalyzed reactions such as the hydrolysis of ketals. Dimethyl 11 -oxo-6-oxabicyclo[5.4.0]undeca-l (7),2,4-triene-2,3-dicarboxylate ethylene ketal reacts in the presence of trifluoroacetic acid to give the tetralone system 3.133... 

For the extraction of colourants from Rubia tinctorum (Figure 13.2) roots, mostly methanol, [42] water-methanol (with the addition of n-amyl alcohol in the case of lake extraction)[19,20] or water-ethanol solutions[38] are used. Additional hydrolysis can be performed with hydrochloric acid[8,19,20,34] and trifluoroacetic acid,[42] but also with madder root enzymes,[42] responsible for cleavage of anthraquinone glycosides into the corresponding aglycones and sugars. 

Other electrophilic substitution reactions on aromatic and heteroaromatic systems are summarized in Scheme 6.143. Friedel-Crafts alkylation of N,N-dimethyl-aniline with squaric acid dichloride was accomplished by heating the two components in dichloromethane at 120 °C in the absence of a Lewis acid catalyst to provide a 23% yield of the 2-aryl-l-chlorocydobut-l-ene-3,4-dione product (Scheme 6.143 a) [281]. Hydrolysis of the monochloride provided a 2-aryl-l-hydroxycyclobut-l-ene-3,4-dione, an inhibitor of protein tyrosine phosphatases [281], Formylation of 4-chloro-3-nitrophenol with hexamethylenetetramine and trifluoroacetic acid (TFA) at 115 °C for 5 h furnished the corresponding benzaldehyde in 43% yield, which was further manipulated into a benzofuran derivative (Scheme 6.143b) [282]. 4-Chloro-5-bromo-pyrazolopyrimidine is an important intermediate in the synthesis of pyrazolopyrimi-dine derivatives showing activity against multiple kinase subfamilies (see also Scheme 6.20) and can be rapidly prepared from 4-chloropyrazolopyrimidine and N-bromosuccinimide (NBS) by microwave irradiation in acetonitrile (Scheme... 

Under certain conditions, the trifluoroacetic acid catalyzed reduction of ketones can result in reductive esterification to form the trifluoroacetate of the alcohol. These reactions are usually accompanied by the formation of side products, which can include the alcohol, alkenes resulting from dehydration, ethers, and methylene compounds from over-reduction.68,70,207,208,313,386 These mixtures may be converted into alcohol products if hydrolysis is employed as part of the reaction workup. An example is the reduction of cyclohexanone to cyclohexanol in 74% yield when treated with a two-fold excess of both trifluoroacetic acid and triethylsilane for 24 hours at 55° and followed by hydrolytic workup (Eq. 205).203... 

Note that the traces are somewhat ragged (individual spectra have different intensities due to fluctuations in spray quality). Addition of trifluoroacetic acid caused a huge boost in ion current at 30 s, due to its ability to protonate neutrals to form [M + H]+ ions (as well as catalyze the hydrolysis)—the ion count per data point jumped from 3000 to a momentary value of 48,000 (Fig. 3 shows only 0-15,000 counts, to keep the rest of the data on scale). To smooth out these fluctuations and to focus in on the relative abundances of the ions of interest, we normalized the data to the total intensity of the three key ions (Fig. 4) the product traces disregard the other product, to take account of the different ionization efficiencies of these two ions. 

Groves and Swan tried unsuccessfully to cyclize Af-2-(indol-3-yl)ethyl aminomethylenemalonate (1413) to tetrah ydro-/3-carboline-1 -acetate (1414) by the action of an acid or base. Instead of cyclization, hydrolysis of 1413 occurred to yield tryptamine (52JCS650). Later, Maclaren obtained 3,4-dihydro-/3-carboline when he treated 1413 with trifluoroacetic acid or boron trifluoride (87AJC1617). 

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