O-Benzylidene Derivatives of D-Arabinose Diethyl and Dipropyl Dithioacetal

1996 ◽  
Vol 49 (3) ◽  
pp. 273 ◽  
Author(s):  
J Kuszmann ◽  
E Gacsbaitz
Keyword(s):  
Hydrochloric Acid ◽  
Zinc Chloride ◽  
Partial Hydrolysis ◽  
Kinetic Control ◽  
Toluenesulfonic Acid ◽  
Thermodynamic Phase ◽  
Hydrolysis Of ◽  
Derivatives Of

Benzylidenation of D-arabinose diethyl and dipropyl dithioacetals with α,α-dimethoxytoluene in the presence of p-toluenesulfonic acid has been studied in detail. Under kinetic control the two terminal dioxolan -type 4,5-O-(R)- and 4,5-O-(S)-benzylidene diastereomers are formed first which are in equilibrium with each other In the thermodynamic phase of the reaction the corresponding dioxan -type 3,5-O-(R)- benzylidene isomer is formed too, but all three monobenzylidene isomers are gradually converted into the four possible dioxolan -type 2,3 : 4,5-di-O benzylidene diastereomers . The dioxan -type 2,4:3,5-di-O-benzylidene isomer was present only in trace amounts. When benzaldehyde was used as reagent in the presence of hydrochloric acid or zinc chloride only the 2,3: 4,5-di-O-benzylidene diastereomers were formed. Partial hydrolysis of the dibenzylidene derivatives yielded the corresponding 2,3-O-benzylidene diastereomers. Structures, including the chirality of the benzylidene groups, were determined by n.m.r. spectroscopy. A mechanism suggested for the reaction was partially supported by equilibration studies.

Hydrolytic products of 4-aryl-2,3-dicyano-1-naphthol derivatives

1981 ◽  
Vol 46 (9) ◽  
pp. 2207-2216 ◽  
Author(s):  
Jiří Křepelka ◽  
Iva Vančurová ◽  
Jiří Holubek ◽  
Jiří Roubík
Keyword(s):  
Dicarboxylic Acids ◽  
Ring Closure ◽  
Partial Hydrolysis ◽  
H Nmr ◽  
Antiviral Effects ◽  
Hydrolysis Of ◽  
Derivatives Of ◽  
Naphthol Derivatives ◽  
Intramolecular Ring

Depending on the conditions of hydrolysis, vicinal aromatic dicyano derivatives Ia-Ic gave anhydrides IIa-IIe and imides of 4-aryl-1-alkoxynaphthalene-2,3-dicarboxylic acids, IIIa,b, along with products of partial hydrolysis, decarboxylation and demethylation, IVa-IVd, IVf-IVg, and derivatives of benzo(c)fluorene, Va-Vc. The derivatives Va-Vc were also obtained by acid hydrolysis of dicyano derivatives Id-Ig. Methanolysis of the anhydride IId gave a mixture of positional isomers, IVh, which was esterified to the diester IVe. Intramolecular ring closure of the isomers IVh afforded derivatives of benzo(c)fluorene, VIa-VIb. The structures of the selected compounds were corroborated by IR and 1H NMR spectra. The compounds Va-Vc exhibited antiviral effects and interferonogenic activities in vivo.

STUDIES ON REACTIONS RELATING TO CARBOHYDRATES AND POLYSACCHARIDES: XXXIX. STRUCTURE OF THE CELLULOSE SYNTHESIZED BY THE ACTION OF ACETOBACTER XYLINUS ON GLUCOSE

1931 ◽  
Vol 5 (5) ◽  
pp. 580-591 ◽  
Author(s):  
Harold Hibbert ◽  
Jacob Barsha
Keyword(s):  
Hydrochloric Acid ◽  
Methyl Alcohol ◽  
Zinc Chloride ◽  
Cellulose Triacetate ◽  
X Ray Diffraction ◽  
Glucose Yield ◽  
X Ray ◽  
Natural Cellulose ◽  
Hydrolysis Of ◽  
Direct Hydrolysis

A description is given of the properties of the cellulose obtained from glucose by the action of Acetobacter xylinus.Acetylation of the product gives a yield of 98.8% of a triacetate identical with cellulose triacetate, and the cellulose regenerated from the acetate is identical with the starting material. The triacetate, when spun dry from solution in chloroform, gives a silk-like fibre which on de-acetylation yields a fibre showing the same X-ray diffraction pattern as natural cellulose. Acetolysis of the acetate yields cellobiose octacetate.Treatment of the triacetate with methyl alcohol containing HCl gives a yield of 94.1% of α- and β-methylglucosides, while on direct hydrolysis of the cellulose with a solution of zinc chloride in hydrochloric acid, a practically quantitative yield (99.5%) of glucose is obtained.Simultaneous de-acetylation and methylation of a partially saponified acetate soluble in acetone gave trimethyl cellulose (yield, 84.6%). The latter, on hydrolysis with methyl alcohol containing HCl, yielded 2:3:6-trimethyl methylglucoside (yield, 92.3%) which, in turn, was converted into crystalline 2:3:6-trimethyl glucose (yield, 83.5%). The last two compounds were found to be identical in every way with the same products prepared from ordinary cotton cellulose. It follows from this that the cellulose obtained by direct bacterial synthesis from glucose is identical with natural cellulose.

Partial hydrolysis of acyl 1,6-anhydro-β-D-glucopyranose

1984 ◽  
Vol 49 (8) ◽  
pp. 1780-1787 ◽  
Author(s):  
Štefan Kučár ◽  
Juraj Zámocký ◽  
Juraj Zemek ◽  
Dušan Anderle ◽  
Mária Matulová
Keyword(s):  
Acid Hydrolysis ◽  
Hydrazine Hydrate ◽  
Hydrogen Chloride ◽  
Ester Group ◽  
The Other ◽  
Hydroxyl Group ◽  
Partial Hydrolysis ◽  
Substantial Influence ◽  
Hydrolysis Of ◽  
Derivatives Of

Partial hydrolysis of per-O-acetyl- and per-O-benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose with methanolic hydrogen chloride and hydrazine hydrate was investigated. The acyl group at C(3) is of substantial influence on the course of hydrolysis. The esterified hydroxyl group at C(3) was found to be most stable on acid hydrolysis with methanolic hydrogen chloride when compared with that at C(2), or C(4); on the other hand, this ester group is the most labile upon hydrolysis with hydrazine hydrate. Selectivity of the respective ester groups towards hydrolysis made it possible to prepare all variations of acetyl and benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose.

The hydrolysis of some N-benzoylamino acids in dilute mineral acid

1967 ◽  
Vol 45 (17) ◽  
pp. 1921-1924 ◽  
Author(s):  
J. B. Capindale ◽  
H. S. Fan
Keyword(s):  
Carboxylic Acid ◽  
Hydrochloric Acid ◽  
Glutamic Acid ◽  
Rate Constants ◽  
Mineral Acid ◽  
Dilute Solution ◽  
Acid Catalyzed ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Derivatives Of

The behavior of N-benzoylaspartic acid and N-benzoylglutamic acid has been investigated at 100° in dilute solution in water and aqueous hydrochloric acid within the pH range 3.1–0.5. Some data are presented concerning the hydrolysis of the N-benzoyl derivatives of alanine, β-alanine, leucine, glycine, serine, and β-ethanolamine in water, 0.1 N hydrochloric acid, and 2 N hydrochloric acid. Benzoylglutamic acid undergoes a pH-independent conversion into pyrrolid-2-one-5-carboxylic acid, which then hydrolyses in mineral acid to glutamic acid; however, N-benzoylaspartic acid, under similar conditions, hydrolyses much more rapidly by a route which does not involve the corresponding lactam as an intermediate. In anhydrous alcohols the solvolysis of N-benzoylaspartic acid gives mixtures of aspartic acid and the β ester.First-order rate constants have been obtained for the acid-catalyzed hydrolysis of pyrrolid-2-one-5-carboxylic acid (I) and azetidin-2-one-4-carboxylic acid (II) in water over this pH range.

scholarly journals Studies of lipid A fractions from the lipopolysaccharides of Pseudomonas aeruginosa and Pseudomonas alcaligenes

1973 ◽  
Vol 133 (3) ◽  
pp. 563-572 ◽  
Author(s):  
David T. Drewry ◽  
James A. Lomax ◽  
George W. Gray ◽  
Stephen G. Wilkinson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lipid A ◽  
Gel Filtration ◽  
Structural Features ◽  
Partial Hydrolysis ◽  
Hexadecanoic Acid ◽  
Alkaline Methanolysis ◽  
Pseudomonas Alcaligenes ◽  
Hydrolysis Of ◽  
Derivatives Of

Lipid A fractions from Pseudomonas aeruginosa and Pseudomonas alcaligenes have similar compositions and structural features. By means of hydrazinolysis of the parent lipopolysaccharides and partial hydrolysis of the deacylation products, it was established that both lipids are derived from the β-(1→6)-linked disaccharide of glucosamine. Phosphorylated derivatives of the disaccharide from Ps. aeruginosa were also characterized. The lipids differ mainly in the absence of hexadecanoic acid and 2-hydroxydodecanoic acid from the lipid from Ps. alcaligenes. Evidence that in Ps. aeruginosa these acids are ester-linked to residues of 3-hydroxyalkanoic acids (including 3-hydroxydecanoic acid) was obtained. Heterogeneity of lipid A fractions was indicated by t.l.c., and by gel filtration of de-O-acylation products from mild alkaline methanolysis of the lipids.

scholarly journals Metabolism of the diacetyl derivatives of stereoisomeric monoacyl-sn-glycerols by rat adipocytes in vitro

1986 ◽  
Vol 235 (3) ◽  
pp. 833-838 ◽  
Author(s):  
W W Christie ◽  
M L Hunter
Keyword(s):  
Oleic Acid ◽  
Significant Degree ◽  
Partial Hydrolysis ◽  
Unesterified Fatty Acid ◽  
Triacylglycerol Biosynthesis ◽  
Bonded Phase ◽  
High Degree ◽  
Hydrolysis Of ◽  
Derivatives Of

Diacetyl long-chain 1(3)- and 2-acyl-sn-glycerols containing either [9,10-3H]oleic acid or [1-14C]palmitic acid were synthesized by partial hydrolysis of the corresponding labelled triacylglycerols and acetylation. They were obtained in a high degree of stereochemical purity by preparative h.p.l.c. on a column containing a diol bonded phase. Each compound was rapidly metabolized by adipocyte preparations in vitro, and a high proportion of the label was recovered in the unesterified fatty acid and triacylglycerol fractions. Negligible amounts of intermediate products of hydrolysis were detected. Triacylglycerols were formed from [9,10-3H]oleic acid and from diacetyl-1(3)-[9,10-3H]oleoyl glycerol precursors at about the same rate, but the 2-isomer was metabolized rather more slowly. The results were consistent with the hypothesis that essentially complete hydrolysis occurred in the medium or at the plasma membrane, through the actions of lipoprotein lipase and monoacylglycerol lipase, and that subsequent esterification took place within the cell. To confirm that no putative intermediate monoacylglycerols were utilized for triacylglycerol biosynthesis via the monacylglycerol pathway, the positional distributions of fatty acids in triacylglycerols from each substrate were determined. No positional selectivity was observed. It was concluded that monoacylglycerols, of an origin exogenous to the tissue, e.g. those derived from plasma triacylglycerols, were not utilized to a significant degree for triacylglycerol biosynthesis in adipose tissue. The diacetyl derivatives of monoacylglycerols may serve as useful stereochemical probes in studies of triacylglycerol biosynthesis via the monoacylglycerol pathway in other tissues.

Antiandrogenic A-homo-B,19-dinor-analogues of androgens from 6β-chloro-5-methyl-19-nor-5β-androst-9-enes

1989 ◽  
Vol 54 (5) ◽  
pp. 1318-1326 ◽  
Author(s):  
Alexander Kasal
Keyword(s):  
Partial Hydrolysis ◽  
Lithium Aluminium Hydride ◽  
Lithium Aluminium ◽  
Selective Acylation ◽  
Chloro Derivatives ◽  
Hydrolysis Of ◽  
Derivatives Of ◽  
Antiandrogenic Activity

6β-Chloro derivatives of 5-methyl-19-nor-5β-androst-9-enes (Westphalen diol type) with oxygen functionalities in positions 3 and 17 were converted into diene VI by treatment with lithium aluminium hydride. The lipophilic product of hydrogenation of VI was shown to be 4aα-methyl-A-homo-B,19-dinor-5β,10α-androstane-3β,17β-diol (IX). Various paths leading to dihydrotestosteron analogues, e.g. selective acylation or oxidation of diol IX and partial hydrolysis of diacetate X, have been realized. 17β-Hydroxy-4aα-methyl-A-homo-B,19-dinor-5β,10α-androstan-3-one (XVI) has been found to exhibit antiandrogenic activity.

ACYLATION OF HYDROQUINONES ESTERS AND THEIR TRANSFORMATIONS PRODUCTS

1970 ◽  
Author(s):  
Valekh M. Ismailov ◽  
Gezal G. Ibragimova ◽  
Nurlana D. Sadykhova ◽  
Farid N. Nagiyev ◽  
Rakif A. Qasimov ◽  
...  
Keyword(s):  
Carbonyl Group ◽  
Aromatic Hydrocarbons ◽  
Nucleophilic Addition ◽  
Electrophilic Substitution ◽  
Guanidine Hydrochloride ◽  
Biologically Active ◽  
Partial Hydrolysis ◽  
Rearrangement Reaction ◽  
Hydrolysis Of ◽  
Derivatives Of

The high synthetic potential of the functionalized aromatic diketones makes it possible to use them as "multi-side" intermediates, in the synthesis of heterocyclic compounds and potentially biologically active molecules.   Friedel-Crafts acylation of aromatic hydrocarbons is the most important method of synthesis of acylaromatic ketones, which allows the introduction of only one carbonyl group into the aromatic ring. The application of the Friedel-Crafts acylation reaction is not so often used to obtain aromatic diketones.      Have been investigated the possibilities of synthesis functionalized diketones by the Friedel-Crafts acylation of aromatic hydrocarbons on the basis of 1,4-diacetyl- and 1-acetyl-4-methylhydroquinones in the presence of AlCl3 in dichloroethane. 2,6-diacetyl derivatives of hydroquinone and the products of their hydrolysis were obtained.  Have been studied the dependence of the yield of the products on the reaction conditions.    The properties of synthesized ketones in the reactions with electrophilic and nucleophilic reagents have also been studied.   The reaction of 2,6-diacetylhydroquinone and its esters with hydroxylamine produced dioximes. The reaction of acetylhydroquinone and its derivatives with urea produces the corresponding imine that forms by the nucleophilic addition of urea to the carbonyl group.  These ketones with guanidine hydrochloride give the corresponding guanidinium derivatives. Ketones with guanidine hydrochloride give the corresponding guanidinium derivatives, the formation of which refers to the reactions of nucleophilic addition to the carbonyl group.  It was shown that this reaction with 1,4-dimethoxybenzene proceeds according to the scheme of electrophilic substitution in the aromatic nucleus, followed by destruction, forming a mixture of nitriles. These ketones are readily nitrated with partial hydrolysis of the methoxy group giving 1-(2-hydroxy-5-metoksi-3-nitrofenil)propan-1-ona.     Unconventional electrophilic substitution reaction was observed at the Beckmann rearrangement of  the oxime (E)-1-(2-hydroxy-5-methylphenyl)etan-1-one proceeds by sulfonation and hydrolysis of the rearrangement reaction product to form 3-amino-2-hydroxy-5-methylbenzensulfonat. Have been shown the conditions and suggested mechanisms of carried out reactions.

Partial hydrolysis of a benzonitrile

10.1039/sp710 ◽  
2013 ◽  
Author(s):  
John MacMillan
Keyword(s):  
Partial Hydrolysis ◽  
Hydrolysis Of
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