The synthesis of methyl tetrosides and their methyl ethers

1980 ◽  
Vol 45 (12) ◽  
pp. 3571-3582 ◽  
Author(s):  
Jiří Jarý ◽  
Miroslav Marek
Keyword(s):  
Partial Methylation ◽  
Starting Compound

Methyl α- and β-D-threofuranosides (I and II) and methyl α- and β-D-erythrofuranosides (VII and VIII) were prepared in a modified manner. For the preparation of monomethyl ethers of compounds I and II 1,2-O-isopropylidene-β-D-threofuranose (IV) was prepared as the starting compound. For the synthesis of monomethyl ethers of compounds VII and VIII partial methylation of these diols was made use of.

Partial methylation of methyl 4,6-dideoxy-α-D-arabino-hexopyranoside

1977 ◽  
Vol 42 (11) ◽  
pp. 3180-3185 ◽  
Author(s):  
K. Kefurt ◽  
Z. Kefurtová ◽  
V. Ineman ◽  
J. Jarý
Keyword(s):  
Partial Methylation

Preparation, properties and structure of some intermediate nido- and arachno-monocarbaboranes

1981 ◽  
Vol 46 (10) ◽  
pp. 2345-2353 ◽  
Author(s):  
Karel Baše ◽  
Bohumil Štíbr ◽  
Jiří Dolanský ◽  
Josef Duben
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Nmr Spectra ◽  
Liquid Ammonia ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Starting Compound

The 6-N(CH3)3-6-CB9H11 carbaborane reacts with sodium in liquid ammonia with the formation of 6-CB9H12- which was used as a starting compound for preparing the 4-CB8H14, 9-L-6-CB9H13 (L = (CH3)2S, CH3CN and P(C6H5)3), 1-(η5-C5H5)-1,2-FeCB9H10-, and 2,3-(η5-C5H5)2-2,31-Co2CB9H10- carboranes. The 4-CB8H14 compound was dehydrogenated at 623 K to give 4-(7)-CB8H12 carborane. Base degradation of 6-N(CH3)3-6-CB9H11 in methanol resulted in the formation of 3,4-μ-N(CH3)3CH-B5H10. The structure of all compounds was proposed on the basis of their 11B and 1H NMR spectra and X-ray diffraction was used in the case of the transition metal complexes.

Monomethyl and dimethyl ethers of methyl β-D-xylopyranoside

1984 ◽  
Vol 49 (12) ◽  
pp. 2922-2931 ◽  
Author(s):  
Jan Staněk ◽  
Jana Jeřábková ◽  
Jiří Jarý
Keyword(s):  
Partial Methylation ◽  
Separation Of Isomers ◽  
Subsequent Separation ◽  
Single Reaction

The preparative advantages of partial methylation with subsequent separation of isomers over standard syntheses of individual derivatives are presented on the case of the methylation of methyl β-D-xylopyranoside (I). All seven possible methyl ethers were isolated in reasonable yields from a single reaction. Literature data concerning methyl 2,3-di-O-methyl-β-D-xylopyranoside (V) and methyl 2,4-di-O-methyl-β-D-xylopyranoside (VI) have been revised.

Oxidation scheme of symmetrically disulphonated naphthidines with cerium(IV) sulphate

1981 ◽  
Vol 46 (3) ◽  
pp. 561-572 ◽  
Author(s):  
Karel Komers
Keyword(s):  
Sulphuric Acid ◽  
Rate Constants ◽  
Oxidation Product ◽  
Side Reaction ◽  
Reaction Scheme ◽  
Second Order ◽  
Intermediate Products ◽  
Stable Intermediate ◽  
Starting Compound ◽  
Oxidation Agent

The author derived theoretical dependences of preasymptotic slopes of the currentless E-t curves (potential of an indicator redox electrode against time) on the number of equivalents, n, of added oxidation agent, assuming a reaction scheme of two consecutive concurrent second-order reactions involving the formation of intermediate products ( a side reaction of the starting compound with the final oxidation product leading to an adduct, which undergoes consecutive bimolecular oxidations leading again to the final product). The dependences enable to determine the type of the relatively stable intermediate products and the ratios of the rate constants. The theory was applied to the oxidation of four symmetrically disulphonated naphthidines with cerium(IV) sulphate in aqueous sulphuric acid and the results were substantiated spectrophotometrically

Understanding of Lithium Insertion into λ-MnO2 Compounds

1998 ◽  
Vol 548 ◽  
Author(s):  
S. Sarciaux ◽  
A. Le Gal La Salle ◽  
A. Verbaere ◽  
Y Piffard ◽  
D. Guyomard
Keyword(s):  
Oxygen Content ◽  
Structural Parameters ◽  
Reversible Capacity ◽  
Rechargeable Batteries ◽  
Structural Water ◽  
Synthesis Conditions ◽  
Starting Compound ◽  
Physico Chemical ◽  
New Compounds

ABSTRACTA large variety of EMD and HTMD samples with various oxygen and water contents and various structural parameters Pr and Mt has been prepared. We show that the physico-chemical and structural parameters of the λ-MnO2 compounds are related to the synthesis conditions. New compounds were obtained with unusual amounts of intergrowth and twinning defects.The Li insertion study focuses on a comprehensive investigation of the relationships between the material characteristics of the samples and their Li insertion behavior, and on the structural characterization of selected compounds after cycling. The oxygen content drastically affects the shape of the discharge curve after the first cycle and the total reversible capacity. The amount of structural water has an influence on the transformation kinetics of the starting phase. For optimized oxygen content (y= 2 in MnOY), the intrinsic reversible Li insertion capacity is maximum when the amount of microtwinning defects is minimum and when the structure is either mostly Ramsdellite or faulted Pyrolusite. Results show that, upon cycling, the λ-MnO2 structure seems to evoluate towards less Pyrolusite defects together with the apparition of new kinds of defects.This work shows that λ-MnO2, compounds could be good candidates for the cathode application of Li-metal rechargeable batteries, provided that the physico-chemical and structural parameters of the starting compound are well chosen.

The effect of partial methylation of the glycine amino group on crystal structure inN,N-dimethylglycine and its hemihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o283-o287 ◽  
Author(s):  
Vasily S. Minkov ◽  
Elena V. Boldyreva
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Water Molecules ◽  
Amino Group ◽  
Asymmetric Unit ◽  
Partial Methylation ◽  
Space Groups ◽  
Carboxylate Groups ◽  
Anhydrous Compound ◽  
Additional Hydrogen

N,N-Dimethylglycine, C4H9NO2, and its hemihydrate, C4H9NO2·0.5H2O, are discussed in order to follow the effect of the methylation of the glycine amino group (and thus its ability to form several hydrogen bonds) on crystal structure, in particular on the possibility of the formation of hydrogen-bonded `head-to-tail' chains, which are typical for the crystal structures of amino acids and essential for considering amino acid crystals as mimics of peptide chains. Both compounds crystallize in centrosymmetric space groups (PbcaandC2/c, respectively) and have twoN,N-dimethylglycine zwitterions in the asymmetric unit. In the anhydrous compound, there are no head-to-tail chains but the zwitterions formR44(20) ring motifs, which are not bonded to each other by any hydrogen bonds. In contrast, in the crystal structure ofN,N-dimethylglycinium hemihydrate, the zwitterions are linked to each other by N—H...O hydrogen bonds into infiniteC22(10) head-to-tail chains, while the water molecules outside the chains provide additional hydrogen bonds to the carboxylate groups.

Medium-sized cyclophanes, part 59:1 Nitration of [3.3]- and [3.3.3]metacyclophanes — Through-space electronic interactions between two or three benzene rings

2002 ◽  
Vol 80 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Takehiko Yamato ◽  
Koji Tsuchihashi ◽  
Noriko Nakamura ◽  
Mai Hirahara ◽  
Hirohisa Tsuzuki
Keyword(s):  
Acetic Anhydride ◽  
Electronic Interaction ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Mixed Acid ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Starting Compound ◽  
Nitration Product ◽  
Fuming Nitric Acid

The two tert-butyl groups of anti-6,15-di-tert-butyl-9,18-dimethoxy[3.3]metacyclophane (anti-4) are both ipso-nitrated even under mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of the decreased deactivation of the second aromatic ring by the introduced nitro group. On the other hand, anti-5,13-di-tert-butyl-8,16-dimethoxy[2.2]metacyclophane (anti-1) undergoes replacement of only one tert-butyl group under the same reaction conditions. The higher yields of the twofold ipso-nitration product anti-7 were obtained in nitration of anti-4 with fuming nitric acid or mixed acid (HNO3–H2SO4). Thus, the number of ipso-nitrations at the tert-butyl groups of anti-4 was strongly affected by the reactivity of the nitration reagent. Nitration of the corresponding syn-conformer syn-4 with copper(II) nitrate in an acetic anhydride solution, however, led only to the recovery of the starting compound. The presently developed procedure was further applied to the direct removal of the tert-butyl group by electrophilic substitution of the larger-sized ring macrocyclic metacyclophanes, cone- and partial-cone-tri-tert-butyl[3.3.3]metacyclophanes 11.Key words: [3n]metacyclophanes, conformation, ipso-nitration, through-space electronic interaction, crystal structure.

The use of a feed additive on the base of beekeeping products «Vinivet» in the feeding of juveniles of Steelhead salmon

2021 ◽  
pp. 19-27
Author(s):  
D. S. Dementiev ◽  
M. L. Kalayda ◽  
A. V. Zhigin
Keyword(s):  
Rapid Development ◽  
Feed Consumption ◽  
Feed Additive ◽  
Control Group ◽  
Recirculating Aquaculture System ◽  
Recirculating Aquaculture ◽  
Aquaculture System ◽  
Starting Compound ◽  
Effective Use ◽  
Experimental Group

Currently, there is a rapid development of commercial salmon farming in Russia, which has grown almost 3 times in terms of production since 2013 and exceeded 116 thousand tons in 2020. In turn, this requires the appropriate development of the feed base and the development of methods for the effective use of fairly expensive fi sh feed. From these positions the involvement of the feed additive “Vinivet”, which is a waste of beekeeping in the feed production for fi sh as a protein additive is relevant. The feed additive “Vinivet” contains bee products such as bee bread and slumgum, a significant complex of vitamins, amino acids, macro- and microelements. The purpose of the work was to assess the influence of the feed additive “Vinivet” on the livability of juveniles, growth rate and feed consumption of rainbow trout of Steelhead salmon breed when growing in a recirculating aquaculture system. For the experiment juveniles with an average juvenile weight of 2,37±0,72 g have been selected, from which the control and 3 experimental groups have been formed. The control group has received a standard starting compound feed as the main diet, the 1st experimental group in addition to the main diet has received the additive “Vinivet” in the amount of 2,5 % of the mass of the main diet, the 2nd experimental group has received 5,0 % of the additive, and the 3rd experimental group in the first week received 2,5 % of the additive, and from the second week of studies the dose of the additive was increased to 5 %. The conducted studies have shown that the inclusion of the feed additive “Vinivet” in the feed when growing juveniles of Steelhead salmon is most advisable by introducing it at the dosage of 2,5 % of the mass of the main diet in the first week of cultivation, followed by the increase in the dose to 5,0 %, which allows achieving the highest fi sh productivity of pools in the recirculating aquaculture system compared to all variants of the experiment and by 24 % compared to the control group.

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