Acid hydrolysis determination

In conditions of acidic hydrolysis, determination of cephem analogs took place. Vanadium(IV) after reduction from vanadium(V), reacted with forming degradation products. Colored complexes of some cephem analogs (cephalexin, cephaprine sodium, cefazolin sodium, cefotaxime) were found, absorbing at 515, 512, 518 and 523 nm, respectively (Fig. 19) [59]... 

Group 1 or group 2 with group 4. SDS or NaTPB in alkaline solution (0.1 M alkali) if the imidazoline contains a ring structure. SDS in alkaline solution after acid hydrolysis (all cases). Either of these determines group 1 or 2. Extraction and determination of fatty acid after acid hydrolysis determines group 4. 

International Organization for Standardization, Surface active agents—detergents—anionic-active matter stable to acid hydrolysis—determination of trace amounts, ISO 2868 1973. Geneva, Switzerland. 

Complete hydrolysis of a peptide gives a mixture of ammo acids An ammo acid analyzer identifies the individual ammo acids and determines their molar ratios... 

The sequence of each different peptide or protein is important for understanding the activity of peptides and proteins and for enabling their independent synthesis, since the natural ones may be difficult to obtain in small quantities. To obtain the sequence, the numbers of each type of amino acid are determined by breaking down the protein into its individual amino acids using concentrated acid (hydrolysis). For example, hydrolysis of the tetrapeptide shown in Figure 45.3 would give one unit of glycine, two units of alanine, and one unit of phenylalanine. Of course, information as to which amino acid was linked to which others is lost. 

Mechanistically the rate-determining step is nucleophilic attack involving the hydroxide ion and the more positive siUcon atom in the Si—H bond. This attack has been related to the Lewis acid strength of the corresponding silane, ie, to the abiUty to act as an acceptor for a given attacking base. Similar inductive and steric effects apply for acid hydrolysis of organosilanes (106). 

Aminopteridine is the most sensitive to acid hydrolysis, and 6-amino- and 6-dimethyl-amino-pteridine are also hydrolyzed, even by cold 0.0IN hydrochloric acid, too rapidly for accurate determination of the cation form (52JCS1620). 2-Amino- and 4-amino-pteridine are not readily attacked by IN HCl at 20 °C but at 100 °C the former compound is destroyed and the latter converted into pteridin-4-one (5UCS474). 2,4-Diaminopteridine can be hydrolyzed by refluxing in 6N HCl for 30 minutes to 2-aminopteridin-4-one (pterin 2) and after... 

NaHC03 H2O, dry (MgS04), filter, evaporate and distil residue. Identified by hydrolysis to the acid and determining the neutralisation equiv (theor 80.0). The acid has m 155-157° efferv [Hauser, Abramovitch and Adams J Am Chem Soc 64 2715 1 942 Bush and Beauchamp J Am Chem Soc 75 2949 1953]. 

Most reactions of nucleic acid hydrolysis break bonds in the polynucleotide backbone. Such reactions are important because they can be used to manipulate these polymeric molecules. For example, hydrolysis of polynucleotides generates smaller fragments whose nucleotide sequence can be more easily determined. 

The absolute configuration of C-3 of the chromophore 4 of an isopyoverdin was determined as S from the CD spectrum (Cotton effect -1-242 nm, —290nm, - -358nm) of 420 obtained from isopyoverdin by acidic hydrolysis (01T1019). 

It is well known that the 1-phosphates of the ketoses, L-fuculose (51) and L-rhamnulose (52) have considerable biochemical interest. Their chemical synthesis has not been described as far as is known to the writer, but the rate of acid hydrolysis of L-fuculose 1-phosphate, obtained by enzymatic synthesis, has been determined by Heath and Ghalambor (20) and that of L-rhamnulose 1-phosphate by H. Sawada (48) and by Chiu and Feingold (II). They found that the rate of... 

The ee is determined by liberution of (3S)-3-hydroxy-5-nicthylhcxanoic acid by acidic hydrolysis, which is then derivalized by heating with isopropylisocyanatc and analyzed 011 a chiral capillary GC column (Chirasil-L-Val, 50 m, 190 C, carrier 90 kPa) (,V)-cnantiomcr / 9.35 min 97% (fJ)-enantiomer 9.58 min 3% 94% ee. Material of 99% optical purity is obtained by rccrystallization. 

Glycosyl-linkages were determined by GC-EIMS of the partially methylated alditol acetates. RG-II samples (2 mg) were methylated using sodium methyl sulfmyl carbanion and methyl iodide in dimethyl sulfoxide [24] followed by reduction of the uronosyl groups with lithium triethylborodeuteride (Superdeuteride , Aldrich) [23,25]. Methylated and carboxyl-reduced samples were then submitted to acid hydrolysis, NaBIlt reduction and acetylation, partially methylated alditol acetates being analysed by EIMS on two fused-silica capillary columns (DB-1 and DB-225) [20]. 

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

The content of neutral monosaccharides was determined after an acid hydrolysis, performed as follows with 72 % sulphuric acid for 1 hr at 30°C and then, after dilution to IM sulphuric acid, for another 3 hr s at 100°C. The determination was performed by GC analysis of the prepared alditol acetates (13,14)... 

Rates of hydrolysis may be influenced by the presence of dissolved organic carbon, or organic components of soil and sediment. The magnitude of the effect is determined by the structure of the compound and by the kinetics of its association with these components. For example, whereas the neutral hydrolysis of chlorpyrifos was unaffected by sorption to sediments, the rate of alkaline hydrolysis was considerably slower (Macalady and Wolf 1985) humic acid also reduced the rate of alkaline hydrolysis of 1-octyl 2,4-dichlo-rophenoxyacetate (Perdue and Wolfe 1982). Conversely, sediment sorption had no effect on the neutral hydrolysis of 4-chlorostilbene oxide, although the rate below pH 5 where acid hydrolysis dominates was reduced (Metwally and Wolfe 1990). 

A structural study on lipid A and the O-specific polysaccharide of the lipopoly-saccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn s disease was conducted by Hashimoto and coworkers [39]. They separated two potent virulence factors, capsular polysaccharide (CPS) and lipopolysaccharide (LPS), from a clinical isolate of B. vulgatus and characterized the structure of CPS. Next, they elucidated the strucmres of O-antigen polysaccharide (OPS) and lipid A in the LPS. LPS was subjected to weak acid hydrolysis to produce the lipid A fraction and polysaccharide fraction. Lipid A was isolated by PLC, and its structure was determined by MS and NMR. 

A method to determine nabam by HPLC after acidic hydrolysis to ethylenediamine and post-column derivatization with o-phthalaldehyde-mercaptoethanol has also been reported. " ... 

The most suitable routine analytical method for the determination of alkylenebis-(dithiocarbamate) residues in fruits and vegetables is hot acid hydrolysis with stannnous chloride and concentrated hydrochloric acid, followed by determination of the evolved carbon disulfide by spectrophotometry or GC. 

Hydrolysis of polyamide-based formulations with 6 N HC1 followed by TLC allows differentiation between a-aminocaproic acid (ACA) and hexamethylenedi-amine (HMD) (hydrolysis products of PA6 and PA6.6, respectively), even at low levels. The monomer composition (PA6/PA6.6 ratio) can be derived after chromatographic determination of the adipic acid (AA) content. Extraction of the hydrolysate with ether and derivatisa-tion allow the quantitative determination of fatty acids (from lubricants) by means of GC (Figure 3.27). Further HC1/HF treatment of the hydrolysis residue, which is composed of mineral fillers, CB and nonhydrolysable polymers (e.g. impact modifiers) permits determination of total IM and CB contents CB is measured quantitatively by means of TGA [157]. Acid hydrolysis of flame retarded polyamides allows to determine the adipic acid content (indicative of PA6.6) by means of HPLC, HCN content (indicative of melamine cyanurate) and fatty acid (indicative of a stearate) by means of GC [640]. Determination of ethylene oxide-based antistatic agents... 

In order to elucidate the causes of the increased stability of the hydrolyzed cluster ions compared with the unhydrolyzed ions, further studies were made of the behaviour of [Te2X8]3 (where X = Cl,Br, or I) in solutions of hydrogen halides [43,52,80,87]. The studies were performed mainly in relation to the most stable and most readily synthesized [Tc2C18]3- ion (Fig. la) kinetic methods with optical recording were employed. The identity of the reaction products was in most cases confirmed by their isolation in the solid phase. The studies showed that the stability of the [Tc2X8]3 ions (where X = Cl, Br, or I) in aqueous solutions is determined by the sum of competing processes acid hydrolysis complex formation with subsequent disproportionation and dissociation of the M-M bonds, and oxidative addition of atmospheric oxygen to the Tc-Tc multiple bond. 

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