Pigments of marine animals. X. Substituted naphthopyrones from the crinoid Comantheria perplexa

1970 ◽  
Vol 23 (11) ◽  
pp. 2325 ◽  
Author(s):  
RA Kent ◽  
IR Smith ◽  
MD Sutherland
Keyword(s):  
Acid Hydrolysis ◽  
Dimethyl Ether ◽  
Sodium Salt ◽  
Crude Extract ◽  
Synthetic Activity ◽  
Marine Animals ◽  
Dehydration Product ◽  
Aromatic Polyketides ◽  
Stalked Crinoids ◽  
Hydrolysis Of

Acetone extraction of the flesh of the comatulid crinoid Comantheria perplexa (H. L. Clark) yields a mixture of substances from which the sodium salt of the sulphuric ester (12) of 8-hydroxy-5,6-dimethoxy-2-methyl-4H-naphtho[2,3-b]pyran-4-one (8) has been isolated. Acid hydrolysis of (12) yields the phenol (8) which on methylation is converted into rubrofusarin dimethyl ether and on partial demethylation yields a product identical with a dehydration product (10) of fonsecin. Hydrolysis of the crude extract from C. perplexa yields (8), (10), and 8-hydroxy-5,6-dimethoxy-2-n-propyl-4H-naphtho[2,3-b]pyran-4-one (13). The structures of the isolated substances suggest a polyketide-type synthetic activity by this species. The stalked crinoids Endoxocrinus parrae (Gervais) and Neocrinus decorus (Wyville Thomson) yield negligible quantities of aromatic polyketides.

Ribonucleosides of 3-amino- and 3,5-diaminopyrazole-4-carboxylic acid and their open-chain analogues: Synthesis and reactions

1986 ◽  
Vol 51 (7) ◽  
pp. 1512-1531 ◽  
Author(s):  
Maria K. Spassova ◽  
Antonín Holý ◽  
Milena Masojídková
Keyword(s):  
Carboxylic Acid ◽  
Acid Hydrolysis ◽  
Carboxylic Acids ◽  
Sodium Salt ◽  
Alkaline Hydrolysis ◽  
Trimethylsilyl Derivative ◽  
Open Chain ◽  
Silyl Derivatives ◽  
Hydrolysis Of

Bis(trimethylsilyl) derivative of ethyl 3-aminopyrazole-4-carboxylate (VI) and tris(trimethylsilyl) derivative of ethyl 3,5-diaminopyrazole-4-carboxylate (VII) on reaction with 2,3,5-tri-O-benzoyl-D-ribofuranolyl chloride and subsequent debenzoylation afforded the respective β-D-ribofuranosyl derivatives VIIIa and Xa. Their alkaline hydrolysis led to 1-(β-D-ribofuranosyl)-3-aminopyrazole-4-carboxylic acid (VIIIc) and 1-(β-D-ribofuranosyl)-3,5-diaminopyrazole-4-carboxylic acid (Xb). The esters VIIIa and Xa were not ammonolyzed under normal conditions. Contrary to nucleosidation of the silyl derivatives VI and VII, sodium salt of ethyl 3-aminopyrazole-4-carboxylate was alkylated with 4-chloromethyl-2,2-dimethyl-1,3-dioxolane (XI) or 5-(p-toluenesulfonyloxy)-1,3-dioxane (XVIIb) to give a mixture of the N-isomeric derivatives XIIIa, XIXa and XIIa, XVIIIa, respectively; sodium salt of the 3,5-diamino derivative V reacted with these synthons under formation of the corresponding compounds XIIIb and XXa. Subsequent alkaline and acid hydrolysis of XIIa and XIIIb gave the open-chain analogs of nucleosides XV and XVI. The N-(1,3-dioxan-5-yl) derivatives XVIIIc and XXa resisted acid hydrolysis, giving rise only to carboxylic acids XVIIIb and XXb.

Hydroboration of 1-allyl-1,2,3,4-tetrahydroquinoline

1985 ◽  
Vol 50 (5) ◽  
pp. 1194-1200 ◽  
Author(s):  
Stanislav Kafka ◽  
Miloslav Ferles ◽  
Miloslav Richter
Keyword(s):  
Hydrogen Peroxide ◽  
Acid Hydrolysis ◽  
Dimethyl Ether ◽  
Diethylene Glycol ◽  
Molar Ratio ◽  
Alkaline Hydrogen Peroxide ◽  
Diethylene Glycol Dimethyl Ether ◽  
Hydrolysis Of ◽  
Subsequent Acid

Hydroboration of 1-allyl-1,2,3,4-tetrahydroquinoline (I) with triethylamine-borane in the molar ratio 1 : 1 afforded a product from which 6,7-benzo-5-aza-1-boraspiro[4,5]decane (II) was isolated. Ethanolysis of II gave diethyl 3-(1,2,3,4-tetrahydro-1-quinolyl)propylboronate (III). Acid hydrolysis of the crude hydroboration product and subsequent oxidation with alkaline hydrogen peroxide led to a mixture of 3-(1,2,3,4-tetrahydro-1-quinolyl)-1-propanol (IV), 1,2,3,4-tetrahydroquinoline (V) and 1-propyl-1,2,3,4-tetrahydroquinoline (VI). Hydroboration of I with triethylamine-borane in the molar ratio 3 : 1, followed by oxidation, gave a mixture of IV, V, VI and 1-(1,2,3,4-tetrahydro-1-quinolyl)-2-propanol (VIII). Hydroboration of I with diborane in situ in diethylene glycol dimethyl ether at 20 °C and subsequent acid hydrolysis and oxidation with alkaline hydrogen peroxide afforded a mixture of IV, V and VIII when the hydroboration product was first heated to 150 °C and then subjected to the above-mentioned processing, only compounds IVand V were formed.

Branched-chain derivatives of acyclic adenosine analogs: Alkyl and hydroxymethyl derivatives of S-adenosyl-L-homocysteinase inhibitors substituted at the 2- and 3-position of the side chain

1989 ◽  
Vol 54 (1) ◽  
pp. 248-265
Author(s):  
Antonín Holý
Keyword(s):  
Acid Hydrolysis ◽  
Sodium Borohydride ◽  
Sodium Salt ◽  
Osmium Tetroxide ◽  
Sodium Perchlorate ◽  
Side Chain ◽  
Isopropylidene Derivative ◽  
Branched Chain ◽  
Hydrolysis Of ◽  
Derivatives Of

Reaction of 1,3-dichloro-2-propanone (VII) with methylmagnesium chloride, followed by alkaline hydrolysis, afforded 2-methylpropane-1,2,3-triol (VIII) which on treatment with 2,2-dimethoxypropane and subsequent tosylation gave 4-(p-toluenesulfonyloxymethyl)-2,2,4-trimethyl-1,3-dioxolane (IXb). Compound IXb was condensed with sodium salt of adenine and the intermediate X was acid-hydrolysed to give 9-(RS)-(2,3-dihydroxy-2-methylpropyl)adenine (XI). Oxidation of XI with sodium periodate led to 9-(2-oxopropyl)adenine (XII). 9-(RS)-(2-Hydroxy-2-hydroxymethyloctyl)adenine (XVI) was obtained analogously from compound VII and hexylmagnesium bromide via triol XIV. Methyl 2-bromomethyl-2-propenoate (XVII) reacted with sodium salt of adenine and the resulting methyl 2-(adenin-9-ylmethyl)-2-propenoate (XVIII) was hydroxylated with sodium perchlorate and osmium tetroxide. The obtained methyl (RS)-2-(adenin-9-ylmethyl)-2,3-dihydroxypropanoate (XIX) was alkali-hydrolysed to give sodium salt of the acid XX. Reduction of ester XIX with sodium borohydride furnished 9-(RS)-(2,3-dihydroxy-2-hydroxymethylpropyl)adenine (XXI). 1-Nonen-3-ol (XXIII), obtained by reaction of propenal with hexylmagnesium bromide, was converted by hydroxylation with osmium tetroxide into nonane-1,2,3-triol (XXIVa) and further into its 1-O-p-toluenesulfonate XXIVb which reacted with 2,2-dimethoxypropane to give 2,2-dimethyl-4-hexyl-5-(p-toluenesulfonyloxymethyl)-1,3-dioxolane (XXV). Compound XXV reacted with adenine and the resulting intermediate XXVI was converted into 9-(RS)-(2,3-dihydroxynonyl)adenine (XXVII) by acid hydrolysis. 9-(3-Methyl-2-buten-1-yl)adenine (XXVIII), obtained by alkylation of sodium salt of adenine with 1-bromo-3-methyl-2-butene, was oxidized with potassium permanganate in an acid medium to give 9-(3-hydroxy-2-oxo-3-methylbutyl)adenine (XXIX). This compound was converted into 9-(RS)-(2,3-dihydroxy-3-methylbutyl)adenine (XXX) by reduction with sodium borohydride. 4-C-Hydroxymethyl-1,2-O-isopropylidene-α-D-xylofuranose (XXXII) reacted with 2,2-dimethoxypropane under formation of 4-C-hydroxymethyl-1,2:3,5-di-O-isopropylidene derivative XXXIIIa whose p-toluenesulfonyl derivative XXXIIIb on treatment with adenine afforded 4-C-(adenin-9-yl)methyl-1,2:3,5-di-O-isopropylidene-α-D-xylofuranose (XXXIV). Acid hydrolysis of this compound, followed by oxidation in an alkaline medium, gave (2S,3R)-4-(adenin-9-yl)-3-hydroxymethyl-2,3-dihydroxybutanoic acid, isolated as its ethyl ester XXXVI.

DETERMINATION OF MICRO-AMOUNTS OF 5β-PREGNAN-3α-OL-20-ONE IN URINE USING INFRARED-SPECTROMETRY

1962 ◽  
Vol 41 (2) ◽  
pp. 234-246 ◽  
Author(s):  
H. J. van der Molen
Keyword(s):  
Infrared Spectrum ◽  
Quantitative Determination ◽  
Acid Hydrolysis ◽  
Chromatographic Separation ◽  
Pure Form ◽  
Infrared Spectrometry ◽  
Hydrolysis Of

ABSTRACT A procedure for the quantitative determination of 5β-pregnan-3α-ol-20-one in urine is described. After acid hydrolysis of the pregnanolone-conjugates in urine, the free steroids are extracted with toluene. Pregnanolone is isolated in a pure form as its acetate; after chromatographic separation of the free steroids on alumina, the fraction containing pregnanolone is acetylated and rechromatographed on alumina. Quantitative determination of the isolated pregnanolone-acetate is carried out with the aid of the infrared spectrum recorded by a micro KBr-wafermethod. The reliability of the method under various conditions is discussed under the headings, specificity, accuracy, precision and sensitivity. It is possible to determine 30–40 μg pregnanolone in a 24-hours urine portion with a precision of 25%.

Optimization of technological modes of cold acid hydrolysis of potato starch

2020 ◽  
Vol 26 (3) ◽  
pp. 222-233
Author(s):  
M. Alekseenko ◽  
V. Litvyak ◽  
A. Sysa ◽  
E. Hrabovska ◽  
O. Galenko
Keyword(s):  
Acid Hydrolysis ◽  
Potato Starch ◽  
Hydrolysis Of

FLOWTHROUGH ACID HYDROLYSIS OF RAPESEED STALKS

2012 ◽  
Vol 11 (12) ◽  
pp. 2313-2318
Author(s):  
Theodor Malutan ◽  
Adina Elena Panzariu
Keyword(s):  
Acid Hydrolysis ◽  
Hydrolysis Of

scholarly journals Tagasaste, leucaena and paulownia: three industrial crops for energy and hemicelluloses production

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Alberto Palma ◽  
Javier Mauricio Loaiza ◽  
Manuel J. Díaz ◽  
Juan Carlos García ◽  
Inmaculada Giráldez ◽  
...  
Keyword(s):  
Activation Energy ◽  
Acid Hydrolysis ◽  
Energy Production ◽  
Combustion Process ◽  
Operating Conditions ◽  
Raw Material ◽  
Energy Of Combustion ◽  
Increasing Temperature ◽  
Hydrolysis Of ◽  
Chamaecytisus Proliferus

Abstract Background Burning fast-growing trees for energy production can be an effective alternative to coal combustion. Thus, lignocellulosic material, which can be used to obtain chemicals with a high added value, is highly abundant, easily renewed and usually inexpensive. In this work, hemicellulose extraction by acid hydrolysis of plant biomass from three different crops (Chamaecytisus proliferus, Leucaena diversifolia and Paulownia trihybrid) was modelled and the resulting solid residues were used for energy production. Results The influence of the nature of the lignocellulosic raw material and the operating conditions used to extract the hemicellulose fraction on the heat capacity and activation energy of the subsequent combustion process was examined. The heat power and the activation energy of the combustion process were found to depend markedly on the hemicellulose content of the raw material. Thus, a low content in hemicelluloses resulted in a lower increased energy yield after acid hydrolysis stage. The process was also influenced by the operating conditions of the acid hydrolysis treatment, which increased the gross calorific value (GCV) of the solid residue by 0.6–9.7% relative to the starting material. In addition, the activation energy of combustion of the acid hydrolysis residues from Chamaecytisus proliferus (Tagasaste) and Paulownia trihybrid (Paulownia) was considerably lower than that for the starting materials, the difference increasing with increasing degree of conversion as well as with increasing temperature and acid concentration in the acid hydrolysis. The activation energy of combustion of the solid residues from acid hydrolysis of tagasaste and paulownia decreased markedly with increasing degree of conversion, and also with increasing temperature and acid concentration in the acid hydrolysis treatment. No similar trend was observed in Leucaena diversifolia (Leucaena) owing to its low content in hemicelluloses. Conclusions Acid hydrolysis of tagasaste, leucaena and paulownia provided a valorizable liquor containing a large amount of hemicelluloses and a solid residue with an increased heat power amenable to efficient valorization by combustion. There are many potential applications of the hemicelluloses-rich and lignin-rich fraction, for example as multi-components of bio-based feedstocks for 3D printing, for energy and other value-added chemicals.

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