The salt effect on the yields of trioxane in reaction solution and in distillate

RSC Advances ◽  
2015 ◽  
Vol 5 (47) ◽  
pp. 37697-37702 ◽  
Author(s):  
Liuyi Yin ◽  
Yufeng Hu ◽  
Xianming Zhang ◽  
Jianguang Qi ◽  
Weiting Ma
Keyword(s):  
Sulfuric Acid ◽  
Salt Effect ◽  
Salt Effects ◽  
Reaction Solution ◽  
Acid Catalyzed

The salt effects and the mechanisms that govern such effects on the sulfuric acid catalyzed synthesis of trioxane are reported.

Kinetic salt effects in the hydrolysis of ethyl malonate, methyl glutarate and ethyl adipate semiesters

1986 ◽  
Vol 51 (12) ◽  
pp. 2781-2785 ◽  
Author(s):  
M. Martín Herrera ◽  
J. J. Maraver Puig ◽  
F. Sánchez Burgos
Keyword(s):  
Salt Effect ◽  
Alkaline Media ◽  
Salt Effects ◽  
Coulombic Interaction ◽  
Hydroxide Ion ◽  
Ethyl Malonate ◽  
Hydrolysis Of

A study is made on the kinetic salt effect on the reaction of hydrolysis of several charged esters in alkaline media. The results are interpreted on the basis of the coulombic interaction, the salting in of hydroxide ion and a third component depending on size of the substrate.

scholarly journals Hydrothermal Pretreatment of Wheat Straw: Effects of Temperature and Acidity on Byproduct Formation and Inhibition of Enzymatic Hydrolysis and Ethanolic Fermentation

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 487
Author(s):  
Dimitrios Ilanidis ◽  
Stefan Stagge ◽  
Leif J. Jönsson ◽  
Carlos Martín
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Wheat Straw ◽  
High Performance ◽  
Enzymatic Saccharification ◽  
Hydrothermal Pretreatment ◽  
Gas Chromatography Mass Spectrometry ◽  
Enzymatic Digestibility ◽  
Acid Catalyzed ◽  
Pretreatment Conditions

Biochemical conversion of wheat straw was investigated using hydrothermal pretreatment, enzymatic saccharification, and microbial fermentation. Pretreatment conditions that were compared included autocatalyzed hydrothermal pretreatment at 160, 175, 190, and 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment at 160 and 190 °C. The effects of using different pretreatment conditions were investigated with regard to (i) chemical composition and enzymatic digestibility of pretreated solids, (ii) carbohydrate composition of pretreatment liquids, (iii) inhibitory byproducts in pretreatment liquids, (iv) furfural in condensates, and (v) fermentability using yeast. The methods used included two-step analytical acid hydrolysis combined with high-performance anion-exchange chromatography (HPAEC), HPLC, ultra-high performance liquid chromatography-electrospray ionization-triple quadrupole-mass spectrometry (UHPLC-ESI-QqQ-MS), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Lignin recoveries in the range of 108–119% for autocatalyzed hydrothermal pretreatment at 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment were attributed to pseudolignin formation. Xylose concentration in the pretreatment liquid increased with temperature up to 190 °C and then decreased. Enzymatic digestibility was correlated with the removal of hemicelluloses, which was almost quantitative for the autocatalyzed hydrothermal pretreatment at 205 °C. Except for the pretreatment liquid from the autocatalyzed hydrothermal pretreatment at 205 °C, the inhibitory effects on Saccharomyces cerevisiae yeast were low. The highest combined yield of glucose and xylose was achieved for autocatalyzed hydrothermal pretreatment at 190 °C and the subsequent enzymatic saccharification that resulted in approximately 480 kg/ton (dry weight) raw wheat straw.

Antiaminic agents derived from thieno[2,3-c]-2-benzothiepin: 4-(1-Methyl-4-piperidylidene)-4,9-dihydrothieno[2,3-c]-2-benzothiepin and some related compounds

1983 ◽  
Vol 48 (2) ◽  
pp. 623-641 ◽  
Author(s):  
Zdeněk Polívka ◽  
Miroslav Rajšner ◽  
Jan Metyš ◽  
Jiří Holubek ◽  
Emil Svátek ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Sulfuric Acid ◽  
Title Compound ◽  
Amino Alcohol ◽  
Hydrogen Sulfate ◽  
Geometric Isomers ◽  
Pure Alcohol ◽  
Acid Catalyzed ◽  
Anticataleptic Activity ◽  
Related Compounds

In the reaction of thieno[2,3c]-2-benzothiepin-4(9H)-one (VI) with 1-methyl-4-piperidylmagnesium chloride 7-(1-methyl-4-piperidyl)thieno[2,3-c]-2-benzothiepin-4(9H)-one (VIII) is formed in addition to the expected amino alcohol VII. The title compound I was obtained by the acid catalyzed dehydration of the pure alcohol VII. Compound I (pipethiadene) has outstanding antihistamine, antiserotonin, antireserpine and anticataleptic activity and was recommended to clinical trials as a potential antimigraine agent. For pharmacokinetic and metabolic studies there were prepared the NC2H3 analogue of pipethiadene IV and further, as potential metabolites, the demethyl analogue III, S-oxide X, demethyl S-oxide XI, N-oxide XIII and N,S-dioxide XIV. The Witting reaction of the ketone VI with 3-dimethylaminopropylidenetriphenylphosphorane resulted in a mixture of geometric isomers of 4-(3-dimethylamino-propylidene)-4,9-dihydrothieno[2,3-c]-2-benzothiepin with the strongly predominating Z-isomer XVI which was isolated from the mixture by crystallization of the hydrogen maleate. The mixture with the predominating Z-isomer XVI was converted by the treatment with 80% sulfuric acid and dilution with water to a mixture with the predominating E-isomer XV (dithiadene) which was isolated by crystallization of the hydrogen sulfate. Some further new thieno[2,3-c]-2-benzothiepin derivatives were synthesized as potential intermediates.

Jervine. V. The Sulfuric Acid-catalyzed Acetolysis of Diacetyltetrahydrojervine

1954 ◽  
Vol 76 (22) ◽  
pp. 5609-5616 ◽  
Author(s):  
O. Wintersteiner ◽  
M. Moore ◽  
B. M. Iselin
Keyword(s):  
Sulfuric Acid ◽  
Acid Catalyzed

The decomposition of aliphatic N-nitro amines in aqueous sulfuric acid. Bisulfate as a nucleophile

1996 ◽  
Vol 74 (10) ◽  
pp. 1774-1778 ◽  
Author(s):  
Robin A. Cox
Keyword(s):  
Sulfuric Acid ◽  
Water Molecule ◽  
Rate Constants ◽  
Activation Parameters ◽  
Standard State ◽  
Aqueous Sulfuric Acid ◽  
Alkyl Groups ◽  
Different Temperatures ◽  
State Rate ◽  
Acid Catalyzed

In aqueous sulfuric acid, aliphatic N-nitro amines decompose to N2O and alcohols. An excess acidity analysis of the observed rate constants for the reaction shows that free carbocations are not formed. The reaction is an acid-catalyzed SN2 displacement from the protonated aci-nitro tautomer, the nucleophile being a water molecule at acidities below 82–85% H2SO4, and a bisulfate ion at higher acidities. Bisulfate is the poorer nucleophile by a factor of about 1000. Twelve compounds were studied, of which results obtained for nine at several different temperatures enabled calculation of activation parameters for both nucleophiles. The reaction appears to be mainly enthalpy controlled. The intercept standard-state rate constants are well correlated by the σ* values for the alkyl groups; the slopes are negative, with a more negative value for the slower bisulfate reaction. Interestingly the m≠m* slopes also correlate with σ*, although the scatter is bad. Key words: N-nitro amines, excess acidity, bisulfate, nucleophiles, acid-catalyzed, kinetics.

scholarly journals Acid-catalyzed reactions of hexanal on sulfuric acid particles: Identification of reaction products

2006 ◽  
Vol 40 (35) ◽  
pp. 6863-6878 ◽  
Author(s):  
Rebecca M. Garland ◽  
Matthew J. Elrod ◽  
Kristi Kincaid ◽  
Melinda R. Beaver ◽  
Jose L. Jimenez ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Reaction Products ◽  
Acid Catalyzed ◽  
Catalyzed Reactions

Study of the Wallach rearrangement and related processes in the 100% sulfuric acid region

1970 ◽  
Vol 48 (2) ◽  
pp. 377-382 ◽  
Author(s):  
E. Buncel ◽  
W. M. J. Strachan
Keyword(s):  
Sulfuric Acid ◽  
Proton Transfer ◽  
Kinetic Method ◽  
Rate Data ◽  
Upper Limit ◽  
Transfer Step ◽  
Rearrangement Process ◽  
Equilibrium Process ◽  
Acid Catalyzed ◽  
Acid Region

Study of the acid-catalyzed Wallach rearrangement of azoxybenzene is extended into the 100% H2SO4 region. The rate of formation of 4-hydroxyazobenzene can be followed spectrally in a straight-forward manner until close to 99% H2SO4, but in higher acidities sulfonation of this product becomes kinetically important. The advent of second equilibrium protonations of 4-hydroxyazobenzene and of 4-hydroxyazobenzene-4′-slfonic acid further complicate the azoxybenzene rearrangement as followed spectrally. Above 100% H2SO4 a second sulfonation is also observed. A method is given for dissecting the rate data for the primary rearrangement process from the first of the sulfonation reactions.The rate of the azoxybenzene rearrangement is observed to increase continuously up to 99.99% H2SO4 (the upper limit of the present kinetic method). This suggests that the second proton transfer step to azoxybenzene is rate-determining and not an equilibrium process. These results permit a clarification of a previously proposed mechanism (1).

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