The effect of pressure on cyclic reactions

1967 ◽  
Vol 20 (7) ◽  
pp. 1335 ◽  
Author(s):  
AH Ewald ◽  
DJ Ottley
Keyword(s):  
Transition States ◽  
Membered Ring ◽  
Aqueous Acetone ◽  
Effect Of Pressure ◽  
Cyclic Reaction

Rates of the cyclization of 4-chlorobutanol and of some analogous non- cyclic solvolysis reactions have been measured in water, methanol, and aqueous acetone at pressures up to 3000 atm. The volume of activation of the cyclic reaction is less negative than those of the linear reactions, in each solvent, but it is suggested that the transition states of both types of reaction may be solvated to about the same extent. The volume of activation for the formation of an eight-membered ring in the cyclization of 4-bromobutylcatechol monoether was also determined.

Theoretical Computations on the Pyrolysis of Alkyl (dithio)acetates

2020 ◽  
Vol 17 (3) ◽  
pp. 224-233
Author(s):  
Xun Zhu ◽  
Chen Jian ◽  
Xiuqin Zhou ◽  
Abdullah M. Asiri ◽  
Khalid A. Alamry ◽  
...  
Keyword(s):  
Transition States ◽  
Membered Ring ◽  
Pyrolysis Process ◽  
Alkyl Esters ◽  
Charge Distributions ◽  
Theoretical Analyses

The pyrolysis of methyl alkyl esters I to III and dithioesters IV to VI were theoretically calculated. All possible pyrolysis paths were considered. Both esters and dithioesters presented three potential paths via six-, four- and five-membered ring transition states, respectively. The calculation processes were calculated using MP2/6-31G(d) set. In-depth theoretical analyses were also presented, including NBO related analyses, synchronicities, and charge distributions, to reveal the detailed pyrolysis process.

Understanding difficulties of irregular number-membered ring transition states for intramolecular proton transfer in excited state

Tetrahedron ◽  
2017 ◽  
Vol 73 (4) ◽  
pp. 403-410 ◽  
Author(s):  
Xiaozhuan Qin ◽  
Ge Ding ◽  
Zhenqiang Wang ◽  
Yulong Gong ◽  
Fang Gao ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Transition States ◽  
Intramolecular Proton Transfer ◽  
Membered Ring

scholarly journals What Differs on the Enzymatic Acetylation Mechanisms for Arylamines and Arylhydrazines Substrates? A Theoretical Study

2009 ◽  
Vol 2009 ◽  
pp. 1-5
Author(s):  
Qing-An Qiao ◽  
Xiao-Min Sun ◽  
Jie Jing ◽  
Xin Chen ◽  
Hua-Yang Wang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Transition States ◽  
Ring Structure ◽  
Membered Ring ◽  
Functional Theory ◽  
Lone Pairs ◽  
The Density Functional Theory

The acetylation mechanisms of several selected typical substrates from experiments, including arylamines and arylhydrazines, are investigated with the density functional theory in this paper. The results indicate that all the transition states are characterized by a four-membered ring structure, and hydralazine (HDZ) is the most potent substrate. The bioactivity for all the compounds is increased in a sequence ofPABA≈4-AS<4-MA<5-AS≈INH<HDZ. The conjunction effect and the delocalization of the lone pairs of N atom play a key role in the reaction. All the results are consistent with the experimental data.

CARBOHYDRATES CONTAINING NITROGEN IN A FIVE-MEMBERED RING AND AN ATTEMPTED SYNTHESIS OF A CARBOHYDRATE WITH NITROGEN IN A SEVEN-MEMBERED RING

1965 ◽  
Vol 43 (8) ◽  
pp. 2345-2356 ◽  
Author(s):  
W. A. Szarek ◽  
J. K. N. Jones
Keyword(s):  
Mercuric Chloride ◽  
Acid Treatment ◽  
Membered Ring ◽  
Aqueous Acetone ◽  
Lead Tetraacetate ◽  
Alkaline Degradation ◽  
Cadmium Carbonate

Lead tetraacetate oxidation of 6-acetamido-6-deoxy-D-galactose (IX) yielded a syrup which was converted to a compound formulated as 4-acetamido-4-deoxy-1,2-O-isopropylidene-D-threofuranose (XII). The same syrup was obtained by alkaline degradation of the product of oxidation of 5-acetamido-5-deoxy-D-xylose diethyl dithioacetal (XVII) with peroxypropionic acid. Treatment of compound XII with p-toluenesulfonyl chloride yielded crystalline 4-acetamido-4-deoxy-1,2-O-isopropylidene-3-O-p-tolylsufonyl-D-threofuranose (XIII).Demercaptalation of 6-acetamido-2,3,4,5-tetra-O-acetyl-6-deoxy-D-galactose diethyl dithioacetal (XX) with mercuric chloride and cadmium carbonate in aqueous acetone did not yield a nitrogen-containing septanose ring but an acyclic derivative.

Pyrolysis of (thio)carbonates via computation analysis

2018 ◽  
Vol 17 (06) ◽  
pp. 1850041
Author(s):  
Jingjing Xia ◽  
Abdullah M. Asiri ◽  
Khalid A. Alamry ◽  
Ping Wu ◽  
Zhihao Huang
Keyword(s):  
Transition States ◽  
Membered Ring ◽  
The Other ◽  
Energy Barriers ◽  
Calculation Results ◽  
Computation Analysis ◽  
Step Mechanism ◽  
Pyrolysis Processes

The regioselective production of alkenes from (thio)carbonates was calculated by MP2/6-31G(d) method via pyrolysis processes. Four (thio)carbonates were calculated in this paper. They are S-sec-butyl O-methyl thiocarbonate (I), O-sec-butyl S-methyl thiocarbonate (II), sec-butyl methyl thioncarbonate (III), and sec-butyl methyl dithiocarbonate (IV). Thirteen potential thermolysis routes were revealed for the pyrolysis of each substance, including nine routes to produce regioselective alkenes and four rearrangement/decompose alternatives. Among nine alkene generation routes, six-membered ring transition states via a two-step mechanism required the lowest energy, while the other routes exhibited higher energy barriers. The calculation results demonstrated an alkene distribution hierarchy of 1-butene [Formula: see text] E-butene [Formula: see text] Z-butene for substances I and II, and an order of E-butene [Formula: see text] 1-butene [Formula: see text] Z-butene for substances III and IV.

REGIOSELECTIVITY INVESTIGATION FOR THE PYROLYSIS OF XANTHATES: A COMPUTATIONAL STUDY

2013 ◽  
Vol 12 (07) ◽  
pp. 1350064 ◽  
Author(s):  
PING WU ◽  
JOHNNY TRUONG ◽  
YONGSHUN HUANG ◽  
JIAXING LI
Keyword(s):  
Oxygen Atom ◽  
Computational Study ◽  
Transition States ◽  
Major Product ◽  
Membered Ring ◽  
Computational Results ◽  
Atomic Size ◽  
Rate Determining Step ◽  
Ring Transition State ◽  
Step Mechanism

MP2/6-31+G(d,p)//MP2/6-31G(d) method was employed to investigate the pyrolyses of O -sec-butyl S -methyl xanthate (Chugeav reaction) and S -sec-butyl O -methyl xanthate, which gave regioselective products of E-butene, Z-butene and 1-butene. Both procedures were found to have 13 possible pathways, of which nine pathways would generate the alkene products. For O -sec-butyl S -methyl xanthate, the computational results indicated that the most favorable three pathways corresponded to a two-step mechanism, with the rate-determining step to be a thion sulfur atom involved six-membered ring transition states. The calculated products distribution was consistent with the experimental observations. However, for S -sec-butyl O -methyl xanthate, thiol-participated four-membered ring transition states were found to be more energetically favored than the six-membered ring transition state to produce 1-butene, which can be attributed to a larger sulfur atomic size than an oxygen atom. As the calculation result, only trace amount of 1-butene could be obtained with a major product being E-butene and Z-butene as a minority.

PRESSURE EFFECT AND MECHANISM IN THE ACID-CATALYZED HYDRATION OF PROPYLENE AND ISOBUTYLENE

1964 ◽  
Vol 42 (5) ◽  
pp. 1019-1026 ◽  
Author(s):  
B. T. Baliga ◽  
E. Whalley
Keyword(s):  
Molecular Structure ◽  
Strong Evidence ◽  
Pressure Effect ◽  
Transition States ◽  
Effect Of Temperature ◽  
Kcal Mole ◽  
Effect Of Pressure ◽  
Entropy Of Activation ◽  
Acid Catalyzed ◽  
Arrhenius Energy

The effect of pressure up to 3 kbar on the rate of the acid-catalyzed hydration of propylene and isobutylene has been measured. The volumes of activation are: for propylene at 100 °C−9.6 ± ~1.0 cm3 mole−1, and for isobutylene at 35 °C− 11.5 ± ~1.0 cm3 mole−1. The effect of temperature in the range 90–120 °C on the rate of hydration of propylene at 100 bar was measured. At 100 °C the Arrhenius energy is 27.1 ± ~1.0 kcal mole−1 and the entropy of activation is −5.4 ± ~2.5 cal deg−1 mole−1. Both the volumes and entropies of activation strongly indicate that a molecule of water is present in the transition states, which can therefore be represented as [olefin. H+•H2O]≠. There appears to be no strong evidence regarding the molecular structure of the transition states.

The crystal and molecular structure of syn-[4.4.3]propella-2,4,12-trien-11-ol 3,5-dinitrobenzoate

1985 ◽  
Vol 63 (4) ◽  
pp. 862-865 ◽  
Author(s):  
Judith C. Gallucci ◽  
Katsuo Ohkata ◽  
Leo A. Paquette
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Molecular Geometry ◽  
Chair Conformation ◽  
Membered Ring ◽  
Aqueous Acetone ◽  
X Ray Diffraction ◽  
X Ray ◽  
R Value

The crystal structure of syn-[4.4.3]propella-2,4,12-trien-11-ol 3,5-dinitrobenzoate, 2, has been determined by single crystal X-ray diffraction and refined to an R value of 0.051. The crystal structure is triclinic with a = 10.208(2), b = 13.355(2), c = 7.068(1) Å, α = 99.35(1)°, β = 100.63(1)°, γ = 100.79(1)°, and the space group is [Formula: see text] with two molecules per cell, D(calcd) = 1.39 g cm−3. The unsaturated five-membered ring resides in an envelope conformation with C6—C11—C12—C13 lying essentially in a plane. The fifth atom, C1, is positioned 0.47 Å out of this plane on the side opposite O1. The latter is situated 1.38 Å away and projects the 3,5-dinitrobenzoate group above the central portion of the cyclohexadiene unit. Four contiguous carbon atoms in the latter ring are mutually coplanar and the fused cyclohexane ring adopts a chair conformation. The overall molecular geometry is reconcilable with its solvolytic behavior in aqueous acetone.

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