Proton magnetic resonance spectra and conformation of mevalonolactone and 3,3-dimethylvalerolactone

1971 ◽  
Vol 24 (8) ◽  
pp. 1659 ◽  
Author(s):  
RN Johnson ◽  
NV Riggs
Keyword(s):  
Energy Difference ◽  
Equilibrium Mixture ◽  
Hydroxyl Group ◽  
Proton Spectrum ◽  
Hydroxyl Groups ◽  
Methylene Proton ◽  
Ring Proton ◽  
Starting Point ◽  
Methylene Groups ◽  
The Difference

The ring-proton spectrum at 60 MHz of mevalonolactone (3-hydroxy-3- methylvalerolactone) has been examined in a range of solvents and that of 3,3- dimethylvalerolactone in deuterochloroform a t 30°. All the spectra are complicated by long-range coupling between the 2- and 4-methylene protons, but a complete set of magnetic parameters, for the MM'XX' spectrum of the 4- and 5-methylene groups of 3,3-dimethylvalerolactone may be extracted from the spectrum of the 5-methylene (XX') protons alone. Such parameters as can be extracted for mevalonolactone suggest there is little dependence of conformation on solvent. At 100 MHz in hexa- deuteroacetone alone, or in mixtures with benzene, the 2-methylene protons show only a small internal chemical shift and are readily completely decoupled; the residual 4,5-methylene-proton four-spin spectrum gave a set of parameters used as the starting point for iterative analysis of the complete six-spin ring-proton spectrum. I t is proposed that mevalonolactone in solution is a rapidly inverting equilibrium mixture of half-chair conformers in which the conformer having the hydroxyl group axial is favoured c. 4.5 : 1 at 30°. The corresponding free-energy difference (c. 750 cal mol-1) is close to the difference of conformational free-energies of methyl and hydroxyl groups in cyclohexane systems, which suggests that no special polar factor is operating in the mevalonolactone equilibrium.

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XVI. PHENOL LIGNIN FROM SPRUCE WOOD, FROM FREUDENBERG SPRUCE LIGNIN AND WILLSTÄTTER SPRUCE LIGNIN

1935 ◽  
Vol 13b (2) ◽  
pp. 61-77 ◽  
Author(s):  
Irene Koerber Buckland ◽  
Fritz Brauns ◽  
Harold Hibbert
Keyword(s):  
Condensation Product ◽  
Analytical Data ◽  
Insoluble Fraction ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Condensation Products ◽  
Building Unit ◽  
Spruce Wood ◽  
Analytical Results ◽  
The Difference

The condensation of lignin with phenol by treatment of spruce wood meal with this solvent, using hydrogen chloride as catalyst, yields two chemically different phenol lignins, namely, an ether-insoluble and an ether-dioxane–soluble phenol lignin, in a ratio of approximately 3 to 1. Duplicate preparations gave the same yields of these two fractions, analyses of which gave concordant results, indicating homogeneity and constancy of composition.The analytical results of the ether-insoluble phenol lignin, and of its methylated and acetylated derivatives, can be interpreted on the basis of the Brauns–Hibbert formula for the "native" lignin unit. It is found, in this way, that the ether-insoluble phenol lignin contains three new free phenolic hydroxyl groups capable of methylation with diazomethane, while one phenol group has reacted with one hydroxyl group in the lignin unit with formation of a phenyl-oxygen ether linkage.The analytical results of the ether-dioxane–soluble phenol lignin indicate that a much larger quantity of phenol has condensed with the "native" lignin building unit than in the case of the ether-insoluble fraction. The exact number of phenol molecules reacting to form this condensation product has not been determined experimentally although calculations based on analytical data point to a number as large as 15 or 21.The phenol condensation products were obtained from Freudenberg and Willstätter lignins in nearly quantitative yield and found to differ from the directly extracted phenol lignin in that neither of them could be resolved into two fractions, thus indicating that some change had taken place in the native lignin during the isolation process. The Brauns-Hibbert formula can also be applied to interpret the experimental data in both cases. These lignins appear to contain the same fundamental building unit as the ether-insoluble phenol lignin fraction isolated directly from spruce wood, with the difference that the former probably have one additional hydroxyl group capable of acetylation and diazomethane-methylation.The correlation found to exist in the present investigation between the phenol condensation products from native spruce lignin, isolated Freudenberg lignin and Willstätter lignin is regarded as providing definite experimental evidence indicating the presence of a chemical unit common to various lignins. The phenol condensation products, it is considered, may serve as valuable reference compounds for proving the identity of lignins obtained from different sources and by use of different chemical reagents.

Determination of Phenolic Hydroxyl Groups in Lignin by Combined Use of 1H NMR and UV Spectroscopy

Holzforschung ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 529-533 ◽  
Author(s):  
Eija Tiainen ◽  
Torbjörn Drakenberg ◽  
Tarja Tamminen ◽  
Kirsi Kataja ◽  
Anneli Hase
Keyword(s):  
Uv Spectroscopy ◽  
Spectroscopic Properties ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Model Compounds ◽  
H Nmr ◽  
Combined Use ◽  
Phenolic Hydroxyl Groups ◽  
The Difference

Summary Two independent spectroscopic methods are presented and compared for the quantitation of the phenolic hydroxyl groups in lignins. The combined information is used to further elucidate the character of the lignin samples examined. The UV method is based on the difference of the spectroscopic properties of the ionised and the nonionised phenol. The method using 1H NMR spectroscopy is based on the exchange of phenolic protons in D2O. The difference in integrated proton intensities in the sample dissolved in DMSO and the sample with additional 20% D2O is proportional to the phenolic protons. The method based on UV spectroscopy uses differences in the maxima close to 300 nm and 350 nm of the sample dissolved in alkali and the neutral sample. The results using the two independent methods are in agreement for milled wood lignin, for kraft lignin and for model compounds carrying one aromatic hydroxyl group. For modified lignins and for model compounds with more than one aromatic hydroxyl group, the UV method gives too low values for phenolic hydroxyl groups. The combined results obtained by the two methods however provide information of the total amount of the phenolic groups and of the nature of the phenolic structure formed by the lignin refining.

scholarly journals Interaction of Refractory Dibenzothiophenes and Polymerizable Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jose L. Rivera ◽  
Pedro Navarro-Santos ◽  
Roberto Guerra-Gonzalez ◽  
Enrique Lima
Keyword(s):  
Hydrogen Bonds ◽  
First Principles ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
First Principles Calculations ◽  
Amino Groups ◽  
Hydrogen Atoms ◽  
Methylene Groups ◽  
Monomeric Structure ◽  
Additional Hydrogen

We carried out first principles calculations to show that polymerizable structures containing hydroxyl (alcoholic chain) and amino groups are suitable to form stable complexes with dibenzothiophene (DBT) and its alkyl derivates. These sulfur pollutants are very difficult to eliminate through traditional catalytic processes. Spontaneous and exothermic interactions at 0 K primarily occur through the formation of stable complexes of organosulfur molecules with monomeric structures by hydrogen bonds. The bonds are formed between the sulfur atom and the hydrogen of the hydroxyl group; additional hydrogen bonds are formed between the hydrogen atoms of the organosulfur molecule and the nitrogen atoms of the monomers. We vary the number of methylene groups in the alcoholic chain containing the hydroxyl group of the monomer and find that the monomeric structure with four methylene groups has the best selectivity towards the interaction with the methyl derivates with reference to the interaction with DBT. Even this study does not consider solvent and competitive adsorption effects; our results show that monomeric structures containing amino and hydroxyl groups can be used to develop adsorbents to eliminate organosulfur pollutants from oil and its derivates.

scholarly journals Analysis of the Structural Aspects of Tannin-Based Adhesives by 2D-NMR

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5479
Author(s):  
Sachikazu Omura ◽  
Yoshinori Kawazoe ◽  
Daisuke Uemura
Keyword(s):  
Benzene Ring ◽  
Water Resistance ◽  
Multiple Bond ◽  
2D Nmr ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Chemical Structures ◽  
Correlation Spectrum ◽  
The Difference ◽  
Structural Aspects

We developed non-toxic, harmless adhesives composed of all-natural and renewable resources, of which one was composed of tannin and gelatin, which unfortunately was lacking water resistance, and the other of tannin and ε-poly-l-lysine. In this study, we analyzed the chemical structures of these adhesives by two-dimensional nuclear magnetic resonance (2D-NMR) to explain the difference in water-resistance of the two glues. The results showed that only one proton was left in the benzene ring of tannin after mixing. This suggests that the amino group of the protein was directly attached to the benzene ring by a Michael addition-type reaction, and not to the hydroxyl group. In addition, the heteronuclear multiple bond correlation spectrum of the tannin-poly-l-lysine compound indicated that the hydroxyl groups of the tannin oxidized, suggesting the improvement of its water resistance.

Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

2004 ◽  
Vol 82 (8) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vanessa Renée Little ◽  
Keith Vaughan
Keyword(s):  
Free Energy ◽  
Chemical Shifts ◽  
Linear Free Energy Relationship ◽  
Piperazine Ring ◽  
Linear Free Energy ◽  
In Series ◽  
Methylene Groups ◽  
Diazonium Coupling ◽  
The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

scholarly journals Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2131
Author(s):  
Leonardo Dalseno Antonino ◽  
Júlia Rocha Gouveia ◽  
Rogério Ramos de Sousa Júnior ◽  
Guilherme Elias Saltarelli Garcia ◽  
Luara Carneiro Gobbo ◽  
...  
Keyword(s):  
Experimental Work ◽  
Chemical Structure ◽  
31P Nmr ◽  
Kraft Lignin ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Diphenylmethane Diisocyanate ◽  
Complex Chemical ◽  
Heterogeneous Reactivity ◽  
Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

scholarly journals Finite Pure Plane Strain Bending of Inhomogeneous Anisotropic Sheets

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 145
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Yeong-Maw Hwang
Keyword(s):  
Plane Strain ◽  
Yield Criterion ◽  
Large Strains ◽  
Rigid Plastic ◽  
Plastic Properties ◽  
Elastic Plastic ◽  
Starting Point ◽  
The Difference ◽  
Inside Radius ◽  
Elastic Unloading

The present paper concerns the general solution for finite plane strain pure bending of incompressible, orthotropic sheets. In contrast to available solutions, the new solution is valid for inhomogeneous distributions of plastic properties. The solution is semi-analytic. A numerical treatment is only necessary for solving transcendent equations and evaluating ordinary integrals. The solution’s starting point is a transformation between Eulerian and Lagrangian coordinates that is valid for a wide class of constitutive equations. The symmetric distribution relative to the center line of the sheet is separately treated where it is advantageous. It is shown that this type of symmetry simplifies the solution. Hill’s quadratic yield criterion is adopted. Both elastic/plastic and rigid/plastic solutions are derived. Elastic unloading is also considered, and it is shown that reverse plastic yielding occurs at a relatively large inside radius. An illustrative example uses real experimental data. The distribution of plastic properties is symmetric in this example. It is shown that the difference between the elastic/plastic and rigid/plastic solutions is negligible, except at the very beginning of the process. However, the rigid/plastic solution is much simpler and, therefore, can be recommended for practical use at large strains, including calculating the residual stresses.

scholarly journals Enhancement of Antioxidant and Hydrophobic Properties of Alginate via Aromatic Derivatization: Preparation, Characterization, and Evaluation

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2575
Author(s):  
Smaher M. Elbayomi ◽  
Haili Wang ◽  
Tamer M. Tamer ◽  
Yezi You
Keyword(s):  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Benzoyl Group ◽  
Antioxidant Evaluation ◽  
Thermo Stability

The preparation of bioactive polymeric molecules requires the attention of scientists as it has a potential function in biomedical applications. In the current study, functional substitution of alginate with a benzoyl group was prepared via coupling its hydroxyl group with benzoyl chloride. Fourier transform infrared spectroscopy indicated the characteristic peaks of aromatic C=C in alginate derivative at 1431 cm−1. HNMR analysis demonstrated the aromatic protons at 7.5 ppm assigned to benzoyl groups attached to alginate hydroxyl groups. Wetting analysis showed a decrease in hydrophilicity in the new alginate derivative. Differential scanning calorimetry and thermal gravimetric analysis showed that the designed aromatic alginate derivative demonstrated higher thermo-stability than alginates. The aromatic alginate derivative displayed high anti-inflammatory properties compared to alginate. Finally, the in vitro antioxidant evaluation of the aromatic alginate derivative showed a significant increase in free radical scavenging activity compared to neat alginate against DPPH (2,2-diphenyll-picrylhydrazyl) and ABTS free radicals. The obtained results proposed that the new alginate derivative could be employed for gene and drug delivery applications.

Bisquaternary ammonium salts derived from 3α,12α-Diamino-5β-cholane and 3α,12α-Diamino-24-nor-5β-cholane

1971 ◽  
Vol 24 (3) ◽  
pp. 521 ◽  
Author(s):  
S Ahmed ◽  
M Alauddin ◽  
B Caddy ◽  
M Martin-Smith ◽  
WTL Sidwell ◽  
...  
Keyword(s):  
Deoxycholic Acid ◽  
Ammonium Salts ◽  
Hydroxyl Group ◽  
Amino Compound ◽  
Hydroxyl Groups ◽  
Lithium Aluminium Hydride ◽  
Lithium Aluminium ◽  
Polyhydric Alcohols ◽  
Methane Sulphonate ◽  
Methylene Group

The preparation of 3α,12α-bisdimethylamino-5β-cholane dimethiodide, 3α,12α-bisdimethylamino-5β-cholane dimethiodide, 3α,12α- bisdimethylamino-24-nor-5β-cholanedimethiodide, and 3α,12α- bisdimethylamino-24-nor-5β-cholanediethiodide, from deoxycholic acid are described. During this work it was found that attempted copper- quinoline decarboxylation of dehydrocholic acid gives rise to lactol formation, and that what had previously been considered to be 3α,12α- dihydroxy-5β-cholane is a mixture of this compound and 12α,24- dihydroxy-5β-cholane. Comparable selectivity of attack by methanesulphonyl chloride and toluene-p-sulphonyl chloride occurs with various polyhydric alcohols derived from bile acids, as evidenced from the products of reduction of the sulphonates with lithium aluminium hydride. With both 5α- and 5β-cholane derivatives, a C 3 equatorial hydroxyl group exhibits comparable reactivity to the terminal primary hydroxyl group, generated from the bile acid carboxylic group, towards both sulphonyl chlorides. With axial hydroxyl groups at C 7 and C 12, toluene-p-sulphonate formation is much more difficult than methane- sulphonate formation. Reduction by means of lithium aluminium hydride of equatorial sulphonate esters at C 7 and C 12 gives rise to a methylene group, but the axial sulphonates under the same conditions give the axial alcohol. The same clear distinction between equatorial and axial sulphonate esters is not observed at C 3 and C 6, but 17α- methanesulphonyloxy-5α-androstane gives 5α-androstane and the 17β- ester gives 17β-hydroxy-5α-androstane. Reduction of 12-oximino groups in both 5α- and 5β-cholanes with sodium and ethanol, hydrogen in the presence of a catalyst, or lithium aluminium hydride gives solely the 12α-amino compound.

Reduction of Computing Time and Improvement of Convergence Stability of the Monte Carlo Method Applied to Radiative Heat Transfer With Variable Properties

1989 ◽  
Vol 111 (1) ◽  
pp. 135-140 ◽  
Author(s):  
M. Kobiyama
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Computing Time ◽  
Energy Difference ◽  
Radiative Properties ◽  
Radiative Energy ◽  
Control Element ◽  
The Monte Carlo Method ◽  
The Difference ◽  
Convergence Stability

A modified Monte Carlo method is suggested to reduce the computing time and improve the convergence stability of iterative calculations without losing other excellent features of the conventional Monte Carlo method. In this method, two kinds of radiative bundle are used: energy correcting bundles and property correcting bundles. The energy correcting bundles are used for correcting the radiative energy difference between two successive iterative cycles, and the property correcting bundles are used for correcting the radiative properties. The number of radiative energy bundles emitted from each control element is proportional to the difference in emissive energy between two successive iterative cycles.

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