Octane Isomers Research Articles

Analysis of octane isomer properties via topological descriptors of line graphs

Currently, graph-based molecular structure descriptors are frequently used in QSAR (Quantitative Structure-Activity Relationship) and QSPR (Quantitative Structure-Property Relationship) modeling of the properties of chemical compounds. Octane isomers have an important role in the testing of such relationships. In this study, we compute some well-known topological descriptors of the molecular graphs of isomeric octanes and their line graphs, both indices and coindices. Then we analyze the correlation coefficients between the physicochemical properties of the octane isomers and some well-known topological indices and their coindices of the molecular graphs and the line molecular graphs of the octane isomers, to find the particular topological descriptors that have the best predictive values.

Analyzing the modified symmetric division deg index: mathematical bounds and chemical relevance

Abstract The modified symmetric division deg (MSD) index of a graph G is precisely defined as MSD ( G ) = ∑ j ∼ k 1 2 d j d k + d k d j , where d j and d k represent the degrees of j and k respectively. In this paper, we present precise bounds for the modified symmetric division deg index, expressed in the relation to the minimum and maximum degrees, the order and size of the graph, the number of pendant vertices and the minimum degree of a non-pendant vertex, the forgotten topological index, the modified second Zagreb index. We determine the upper bounds for the modified symmetric division deg index of unicyclic, bicyclic and k-cyclic graphs. Moreover, upon analyzing the modified symmetric division deg index, we observe its correlation with other well-known indices and its chemical applicability on the molecular graphs of octane isomers. At the end, we find the chemical applicability of the modified symmetric division deg index on benzenoid hydrocarbons and observe that the modified symmetric division deg index has a very strong correlation with the physical properties of benzenoid hydrocarbons.

A graph theoretical study of porphyrin-cored dendrimers by means of Sombor indices:a computational approach

Topological indices are numerical parameters calculated on the molecular graph of chemical structures which do not depend on the method the molecular graph is labelled or depicted and have no need of energy minimisation of the molecular structure. The Sombor index is a recently established topological index possessing the ability to predict the enthalpy of vaporisation and entropy of octane isomers. Here, we apply the edge-partition technique to study the Sombor index and some of its variants namely delta Sombor index, reduced Sombor index, increased Sombor index, modified Sombor index, reverse Sombor index and Kulli-Gutman Sombor index for four types of dendrimers with porphyrin core. Our results could be helpful in better understanding the physico-chemical characteristics of this family of macromolecules.

Computational insights into zinc silicate MOF structures: topological modeling, structural characterization and chemical predictions

Metal-organic frameworks (MOFs) play a pivotal role in modern material science, offering unique properties such as flexibility, substantial pore space, distinctive structure, and large surface area. Recently, zinc-based MOFs have attracted significant attention, particularly in the biomedical arena, owing to their versatile applications in drug delivery, biosensing, and cancer imaging. However, there remains a crucial need to explore and understand the structural properties of zinc silicate-based MOFs to fully exploit their potential in various applications. The objective of this study is to address this need by employing topological modeling techniques to characterize zinc silicate networks. Utilizing connection number concept of chemical graph theory and novel AL molecular descriptors, we aim to investigate the structural intricacies of these MOFs. More precisely, zinc silicate-based MOF networks are topologically modeled via novel AL topological indices, and derived mathematical closed form formulae for them. By comparing experimental and calculated values and constructing linear regression models, the predictive capabilities of the proposed descriptors are evaluated. Specifically, the performance of derived topological indices against the physico-chemical properties of octane isomers is assessed, which provide valuable insights into their predictive potential. The findings of this study demonstrated the potential of novel AL indices in predicting a wide range of important physico-chemical properties, further enhancing their practicality in materials science and beyond.

Extremal graphs with given parameters in respect of general ABS index

For a graph G=(V,E), the general atom-bond sum-connectivity index is formulated by ABSσ(G)=∑ξζ∈E(G)(dξ+dζ−2dξ+dζ)σ, where dξ indicates the degree of vertex ξ∈V, σ can be arbitrary real number. Several physicochemical features of benzenoid hydrocarbons can be correctly anticipated using the ABSσ index. Researchers go through careful inspection of some ABSσ and reveal that ABS1, ABS−1, ABS12, ABS3 enjoy benefit in foreseeing the boiling point, the standard enthalpy of vaporization, the acentric factor, and the entropy of octane isomers, separately. One significant wellspring of information for exploring the molecular construction is the assessed worth of the reach for topological indices through certain predefined molecular graph parameters. The purpose of the present work is to find the highest values of the ABSσ index for σ≥0 in the set of graphs that were given certain predefined parameters, such as matching number, chromatic number, etc. Furthermore, illustrations of the relevant extremal graphs were provided.

An experimental and chemical kinetic modeling study of octane isomer oxidation. Part 1: 2,3,4-trimethyl pentane

2,3,4-trimethyl pentane (234-TMP) is an isomer of octane with the same number of methyl branching groups as 2,2,4-trimethyl pentane (iso-octane). However, there are very few studies of this fuel available in the literature. In this work, a detailed chemical kinetic model is developed to describe the oxidation of 234-TMP using NUIGMech1.3 as the core mechanism. The rate constants for some important reaction classes are updated following a review of literature rate constants. Additionally, the impact of each rate constant on simulated ignition delay times for 234-TMP compared to 2,2,3-trimethyl pentane and 2,2,4-trimethyl pentane (iso-octane) is discussed. The thermodynamic data of the alkanes (RH), alkyl (Ṙ), alkyl peroxy (RȮ2), hydroperoxy-alkyl Q˙OOH, and peroxy hydroperoxyalkyl (Ȯ2QOOH) radicals are newly estimated based on recently updated group values in the literature. Moreover, this study presents the first set of data available for the oxidation of 234-TMP at higher pressures (15 and 30 atm), in the temperature range 600–1600 K, and at fuel/‘air’ equivalence ratios (φ) of 0.5, 1.0 and 2.0. The chemical kinetic model shows general good agreement with the experimental measurements. In addition, flux and sensitivity analyses are conducted to identify the important pathways and reactions controlling fuel oxidation at different temperatures. Furthermore, the reactivity of 234-TMP is compared to that of iso-octane, indicating that 234-TMP is slower to react as it has more tertiary carbon sites compared to iso--octane.

Investigating the properties of octane isomers by novel neighborhood product degree-based topological indices

A topological index is a real number calculated from the structure of a chemical compound to describe its topology. The use of molecular descriptors has been increasing in recent years, helping to determine the physicochemical and biological properties of drugs. The main purpose of this article is to investigate the properties of the octane isomers using the theoretical method. To study the structures of octane isomers, we have introduced a new approach called “neighborhood product degree” to calculate all the classical degree-based topological indices. The np-degree approach is applied to approximate eight properties of octane isomers, such as the acentric factor, density, refractive index, critical volume, molar volume, radius of curvature, critical pressure, and LogP. The np-degree-based topological indices are the estimated values of the properties of octane structures, so the linear and quadratic regression models and correlation coefficients are applied to check the validity of the estimated results. The quantitative structure property relation are obtained by using the linear, quadratic, exponential, logarithmic and sinusoidal regression methods with the help of SPSS. Two models are applied to all the compuations and three regression models are applied to the np-degree Randic index. The computation showed that quadratic regression model is suitable for study octane isomers and np-degree based graph invariants. If the values of the correlation coefficient r ⩾ 0.7, p-values ⩽ 0.05, and F-values ⩾ 2.5, then the results are significant. The results of np-degree-based topological indices satisfy all the criteria for being significant, so these newly introduced indices are valid to study octane isomers. The information determined in this article is beneficial for chemists and pharmacists.

Computation of expected values of some connectivity based topological descriptors of random cyclooctane chains

Cyclooctane is a cycloalkane consisting of carbon and hydrogen atoms arranged in a closed ring structure. Cyclooctane chains can be found in various organic compounds and are significant in the field of organic chemistry due to their diverse reactivity and properties. The atom-bond connectivity index (ABC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{A}\\mathcal{B}\\mathcal{C}$$\\end{document}), the geometric-arithmetic index (GA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{G}\\mathcal{A}$$\\end{document}), the arithmetic–geometric index (AG\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{A}\\mathcal{G}$$\\end{document}) and the forgotten index (F\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{F}$$\\end{document}) are four well-studied molecular descriptors that have found applications in QSPR and QSAR studies. These topological descriptors have shown significant correlations with different physiochemical properties of octane isomers. In this work, the expected values of four degree based topological descriptors for random cyclooctane chains are calculated. An analytical comparison is given between the expected values of ABC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{A}\\mathcal{B}\\mathcal{C}$$\\end{document}, GA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{G}\\mathcal{A}$$\\end{document}, AG\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{A}\\mathcal{G}$$\\end{document}, and F\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{F}$$\\end{document} indices of random cyclooctane chains.

Connection based novel AL topological descriptors and structural property of the zinc oxide metal organic frameworks

Metal organic frameworks (MOFs) play a vital role in a variety of processes such as heterogeneous catalysis, heterogeneous gas purification and division, biocompatibility, toxicity, and biomedical applications. The Zinc-based MOFs, particularly, have gained prominence in the biomedical industry for applications such as drug delivery, biosensing, and cancer imaging, which has attracted the interest of researchers from around the world. Given the significant influence of molecular structure on the properties of MOFs, it is imperative to model and characterize this structure comprehensively to deepen our understanding and explore avenues for property enhancement. Topological indices are numerical parameters derived from the graph representation of molecules that quantify specific structural features. These indices provide insights into the connectivity and arrangement of atoms or nodes within the structure, offering information about its chemical, physical, or biological properties. In this study, the Zinc Oxide network structures are topologically modeled via connection numbers, and some novel topological descriptors viz. AL 1, AL 2, AL3, AL4, AL5, AL6, AL7andAL8 are computed by deriving mathematical closed form expressions for them. Based on the numerical results, a comparative analysis of the computed topological descriptors is also performed. The prediction potential and chemical applicability of these indices are investigated using the benchmark dataset of Octane Isomers and corresponding experimental values, correlating experimental and computed values through regression models.

Comparative study of GQ and QG indices as potentially favorable molecular descriptors

AbstractIn chemical graph theory, several degree‐based topological indices are introduced and put forward in the development of quantitative structure‐property relationships (QSPR)/quantitative structure‐activity relationships (QSAR) studies. However, only a few of them are considered employable in the prediction of physical and chemical properties and biological activities of molecular compounds. Here, we focus our attention on some foremost characteristics of newly defined Geometric–Quadratic and Quadratic–Geometric indices such as prediction power, degeneracy and structure sensitivity. Based on these attributes, we discuss their comparison with other well‐established degree‐based topological indices with the help of statistical analysis and computational techniques on the data sets of octane, nonane and decane isomers. Some of the graphical approaches, statistical outcomes and computational tests exhibit the dominating nature of the and indices over other topological indices.

Some novel neighborhood degree sum‐based versus degree‐based topological indices in QSPR analysis of alkanes from n‐butane to nonanes

AbstractThe topological indices are reported to be very useful in various QSPR studies as these indices can be utilized as a tool to predict the physicochemical properties of a diverse set of chemical compounds. The objective of this communication is twofold. First, to introduce some neighborhood degree sum‐based topological indices and perform a comparative QSPR analysis of the indices with their corresponding degree‐based topological indices to analyze the usefulness of the new indices. Second, to investigate isomer discrimination ability of the newly defined indices on the basis of degeneracy test. Neighborhood degree sum‐based topological indices not only consider the degree of each atom in the molecule but also the degrees of its neighboring atoms. Moreover, these indices are expected to provide information about how connected and dense the neighborhoods of atoms are within the molecule. In this study, we observe that the proposed neighborhood degree sum‐based topological indices exhibit better correlation with some physicochemical properties of Octane Isomers and 66 alkanes as compared to their corresponding degree‐based topological indices. Also, the supremacy in terms of sensitivity of the neighbourhood degree sum‐based topological indices as compared to the classical degree‐based ones is established.

Enfoque químico “estructura-conformación” de la gasolina regular en el mercado de combustibles ecuatoriano

A source of chemical energy storage is fossil fuels that in Ecuador are represented by two derivatives: regular gasoline -EcoPlus- (89 octanes), premium -EcoPremium- (96 octanes), and diesel. This shows that the market is not only focused on automobiles but also on agricultural and industrial machinery. There is currently a remission of the sale price to the public as there are subsidies from the Ecuadorian government. Regular 89-octane gasoline is the most widely used for the abovementioned purposes and for implementing and adapting new proposals in modifying 4-stroke engines. This gasoline mixture's composition and octane isomers were analyzed for physicochemical properties related to its liquid state and intermolecular interactions concerning variables such as boiling points and volatility. With the three-dimensional conformation obtained, it was possible to correlate the variables, as mentioned earlier, with the stabilized structures in the gasoline mixtures.

On Structure Sensitivity and Chemical Applicability of Some Novel Degree-Based Topological Indices

Numerous quantitative graph invariant-based topological indices have been developed in the literature and employed for correlation analysis in chemical graph theory. Among them, the degree-based topological indices are the most investigated molecular descriptors and have proven their usability in this area. Here, we focus on testing the structural properties and prediction potential of some novel degree-based topological indices. At the outset, computer testing for the considered topological indices is performed to calibrate their structure sensitivity and abruptness. After that, the correlation among the topological indices is also executed. In addition, QSPR analysis is performed for the octane isomers molecular database to investigate the physical and chemical significance of the considered topological indices.

Degree-weighted Wiener index of a graph

<abstract><p>From geometric point of view, we introduced the Sombor-Wiener index of a graph and studied the basic properties of the new index. It was shown that the Sombor-Wiener index was useful in predicting the acentric factor of octane isomers. In addition, we proposed a degree-weighted Wiener index to generalize the Schultz index, the Gutman index, and the Sombor-Wiener index. Meanwhile, we gave the calculation formula of degree-weighted Wiener index for generalized Bethe trees.</p></abstract>

Chemical Applicability of Second Order Sombor Index

In this paper, we introduce the higher-order Sombor index of a molecular graph. In addtition, we compute the second order Sombor index of some standard class of graphs and line graph of subdivision graph of 2D-lattice, nanotube and nanotorus of TUC_4C_8[p,q] and also we obtain the expressions of the second order Sombor index of the line graph of subdivision graph of tadpole graph, wheel graph, ladder graph and chain silicate network CSn. Further, we study the linear regression analysis of the second order Sombor index with the entropy, acentric factor, enthalpy of vaporization and standard enthalpy of vaporization of an octane isomers.

On the Hyper Zagreb Index of Trees with a Specified Degree of Vertices

Topological indices are the numerical descriptors that correspond to some certain physicochemical properties of a chemical compound such as the boiling point, acentric factor, enthalpy of vaporisation, heat of fusion, etc. Among these topological indices, the Hyper Zagreb index, is the most effectively used topological index to predict the acentric factor of some octane isomers. In the current work, we investigate the extremal values of the Hyper Zagreb index for some classes of trees.

Neighbour Degree Connectivity Indices of Graphs and Its Applications to the Octane Isomers

Neighbour Degree Connectivity Indices of Graphs and Its Applications to the Octane Isomers

On maximum Zagreb connection indices for trees with fixed domination number

The Zagreb connection indices of a graph are notable topological descriptors constructed from the connection number of every vertex (cardinality of set of vertices with distance two from that vertex). In 1972, these indices were presented to determine the total electron energy of the alternate hydrocarbons. The Zagreb connection indices give finer values for the correlation coefficient for the 13 physico-chemical characteristics of the octane isomers compared to basic Zagreb indices. For many years, all these connection indices have been ignored by researchers for further work. Recently, determining the extremal bounds for the topological indices in terms of graph parameters has turned out to be an interesting direction in extremal graph theory, and numerous related results have been acquired in the literature. This article presents sharp bounds on the first, second, and modified Zagreb connection indices of trees with a fixed domination number. These bounds are strict, and the trees which attained these bounds are characterized.

TRANSIT ISOMORPHISM AND ITS STUDY ON OCTANE ISOMERS

Having defined and studied, the transit index and transit decomposition of a connected graph, we introduce the concept of transit isomorphism. In this paper we discuss the transit isomorphism between certain graphs and its line graphs. Construction of transit isomorphic graphs is also dealt with. Finally we discuss how transit isomorphism relates to chemical properties of octane isomers.

Expected value of first Zagreb connection index in random cyclooctatetraene chain, random polyphenyls chain, and random chain network.

The Zagreb connection indices are the known topological descriptors of the graphs that are constructed from the connection cardinality (degree of given nodes lying at a distance 2) presented in 1972 to determine the total electron energy of the alternate hydrocarbons. For a long time, these connection indices did not receive much research attention. Ali and Trinajstić [Mol. Inform. 37, Art. No. 1800008, 2018] examined the Zagreb connection indices and found that they compared to basic Zagreb indices and that they provide a finer value for the correlation coefficient for the 13 physico-chemical characteristics of the octane isomers. This article acquires the formulae of expected values of the first Zagreb connection index of a random cyclooctatetraene chain, a random polyphenyls chain, and a random chain network with l number of octagons, hexagons, and pentagons, respectively. The article presents extreme and average values of all the above random chains concerning a set of special chains, including the meta-chain, the ortho-chain, and the para-chain.