Total Hydrolysis with Acid

Subjecting monosaccharides to conditions of acid hydrolysis is only of importance in measuring the expected hydrolysis losses during hydrolysis of oligo- and poly-saccharides. Hydrolysis losses may be predicted, based on either the absolute or the relative decomposition of monosaccharides. Absolute decompositions are based on decomposition of monosaccharides. Relative decompositions are based on studies wherein several methods of hydrolysis were applied to the same samples for various lengths of time in this Section, these are classified under the type of acid that causes the least decomposition (that is the largest yield of monosaccharides liberated), because this acid is usually the one of principal concern in the particular study. 

Recoveries of Galacturonic Acid Subjected to Treatment with 2 M Trifluoroacetic Acid  

Time (h) a Anomer p Anomer Total Relative to time = 0 (%) 

Griggs and coworkers studied hydrolysis with 3 M hydrochloric acid for 3 h at 100° of canine submaxillary mucin (CSM) and CSM mixed with a standard sugar mixture. Sugar recoveries were 76.0% for fucose, 76.6% for mannose, 84.3% for galactose, 82.5% for A -acetylglucosamine, and 87.7% for A -acetylgalactosamine. 

Because the galacturonic acid units of pectin spend a significant portion of the time in the polymerized form, there is less decomposition than that of galacturonic acid standards subjected to the same conditions of hydrolysis. For this reason, correction factors for hydrolysis losses, under any conditions, can never be completely accurate therefore, it is preferable to cleave glycosidic linkages with the minimum of decomposition. 

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IPG and RP-HPLC were useful for separating several monoacetylated forms of rpST but these methods do not yield quantitation for the total level of e-N-acetyllysine. The total amount of e-N-acetyllysine was determined using total enzymatic digestion of the protein followed by amino acid analysis. Normal hydrolysis with acid or base cannot be used since e-N-acetyllysine is not stable to these hydrolysis conditions. A value of 0.42 moles of e-N-acetyllysine per mole of protein was obtained for the low pl rpST (Fig. 2, lane 4) while the normal pi rpST (Fig. 2, lane 3) yielded non-detectable levels (<0.05 mol/mol) of this amino acid. As expected, these data confirmed that e-N-acetyllysine is present only in the low pi components of rpST but not in the normal pi rpST. 

A mixture of diethyl 7-[3-(l-ethyl)indolyl]- -ketopropylphosphonate and aq. KOH refluxed 7 hrs. with stirring ethyl y-[3-(l-ethyl)indolyl]-y-ketopropyl-phosphonate. Y 92%. F. e., also with N-alkylation by 0- N alkyl migration and total hydrolysis by acid, s. J. Szmuszkovicz, Am. Soc. 50, 3782 (1958). 

No hydrolysis occurs with -+amylases, dextianases and other glucanases. Levanase causes partial hydrolysis of the P-(2,6)-backbone in high-polymer 1., but it leaves the branching points unchanged. Total hydrolysis by acids of pH 3.5 leads to almost pure fructose solutions. 

Sulfates having alkyl groups from methyl to pentyl have been examined. With methyl as an example, the hydrolysis rate of dimethyl sulfate iacreases with the concentration of the sulfate. Typical rates ia neutral water are first order and are 1.66 x lO " at 25°C and 6.14 x lO " at 35°C (46,47). Rates with alkaH or acid depend on conditions (42,48). Rates for the monomethyl sulfate [512-42-5] are much slower, and are nearly second order ia base. Values of the rate constant ia dilute solution are 6.5 X 10 L/(mol-s) at 100°C and 4.64 X 10 L/(mol-s) at 138°C (44). At 138°C, first-order solvolysis is ca 2% of the total. Hydrolysis of the monoester is markedly promoted by increasing acid strength and it is first order. The rate at 80°C is 3.65 x lO " ... 

When male Wistar rats were exposed to -hexane at concentrations up to 3,074 ppm for 8 hours, analysis of urine showed that 2-hexanol was the major metabolite, accounting for about 60-70% of the total metabolites collected over the 48-hour collecting period (Fedtke and Bolt 1987). This is in contrast to humans, in which the major urinary metabolite is 2,5-hexanedione (Perbellini et al. 1981). The amounts of metabolites excreted were linearly dependent on the exposure concentration, up to an exposure of about 300 ppm. 2-Hexanol and 2-hexanone were detected in the first sample (obtained during the 8-hour exposure) excretion of 2,5-hexanedione was delayed and was not detected until 8-16 hours after exposure began. The amount of 2,5-hexanedione detected depended on sample treatment total excreted amounts over 48 hours were approximately 350 g/kg 2,5-hexanedione without acid treatment and 3,000 g/kg with total acid hydrolysis, indicating conversion of 4,5-dihydroxy-2-hexanone with acid treatment. 

Ammonium dinitramide has been synthesized from the nitration of ammonium sulfamate with strong mixed acid at -35 to -45 °C followedby neutralization of the resulting dinitraminic acid with ammonia. The yield is 45 % when the mole ratios of sulfuric acid to nitric acid is 2 1 and ammonium sulfamate to total acid is 1 6. The nitration of other sulfonamide derivatives, followed by hydrolysis with metal hydroxides, also yields dinitramide salts. ... 

Pindur et al. reported the synthesis of carazostatin (247) starting from the 2-vinylindole 958, which previously served as the key building block in the total synthesis of carbazoquinocin C (274) (see Scheme 5.130). The 2-vinylindole (958), readily available in four steps starting from Af-(phenylsulfonyl)indole (956), was transformed to the indolylacetic acid (1568) by treatment with KCN and paraformaldehyde followed by alkaline hydrolysis. Subsequent acid-catalyzed polar cyclization of 1568 led to carazostatin (247) (648) (Scheme 6.1). 

Either acid or alkaline hydrolysis can be applied, converting nicotinamide to nicotinic acid. Alkaline hydrolysis releases also the unavailable vitamers providing the estimation of the total niacin content. Acid hydrolysis, instead, is slower than alkaline hydrolysis therefore the former is usually coupled with enzymatic digestion by using takadiastase, papain, and clarase. Extraction with water and dilute sulfuric or hydrochloride acid has been applied to release the vitamers from the matrix without degrading nicotinamide [598]. 

Pantothenic acid occurs in foods both in the free form and bonded to coenzyme (CoA) or acyl carrier protein (ACP) therefore hydrolysis is needed to extract it totally. Since it is degraded by acid and alkaline hydrolysis, only an enzymatic digestion can be applied. Enzyme hydrolysis with papain, diastase, clarase, takadiastase, intestinal phosphatase, pigeon liver pantetheinase, or combination of them has been used. 

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