pKa Prediction from “Quantum Chemical Topology” Descriptors was written by Harding, A. P.;Wedge, D. C.;Popelier, P. L. A.. And the article was included in Journal of Chemical Information and Modeling in 2009.Name: 2-(4-Methoxyphenoxy)acetic acid This article mentions the following:
Knowing the pKa of a compound gives insight into many properties relevant to many industries, in particular the pharmaceutical industry during drug development processes. In light of this, we have used the theory of Quantum Chem. Topol. (QCT), to provide ab initio descriptors that are able to accurately predict pKa values for 228 carboxylic acids. This Quantum Topol. Mol. Similarity (QTMS) study involved the comparison of 5 increasingly more expensive levels of theory to conclude that HF/6-31G(d) and B3LYP/6-311+G(2d,p) provided an accurate representation of the compounds studies. We created global and subset models for the carboxylic acids using Partial Least Square (PLS), Support Vector Machines (SVM), and Radial Basis Function Neural Networks (RBFNN). The models were extensively validated using 4-, 7-, and 10-fold cross-validation, with the validation sets selected based on systematic and random sampling. HF/6-31G(d) in conjunction with SVM provided the best statistics when taking into account the large increase in CPU time required to optimize the geometries at the B3LYP/6-311+G(2d,p) level. The SVM models provided an average q2 value of 0.886 and an RMSE value of 0.293 for all the carboxylic acids, a q2 of 0.825 and RMSE of 0.378 for the ortho-substituted acids, a q2 of 0.923 and RMSE of 0.112 for the para- and meta-substituted acids, and a q2 of 0.906 and RMSE of 0.268 for the aliphatic acids. Our method compares favorably to ACD/Laboratories, VCCLAB, SPARC, and ChemAxon’s pKa prediction software based of the RMSE calculated by the leave-one-out method. In the experiment, the researchers used many compounds, for example, 2-(4-Methoxyphenoxy)acetic acid (cas: 1877-75-4Name: 2-(4-Methoxyphenoxy)acetic acid).
2-(4-Methoxyphenoxy)acetic acid (cas: 1877-75-4) belongs to ethers. Ether is less polar than esters, alcohols or amines because of the oxygen atom that is unable to participate in hydrogen bonding due to the presence of bulky alkyl groups on both sides of the oxygen atom. Ethers are good solvents partly because they are not very reactive. Most ethers can be cleaved, however, by hydrobromic acid (HBr) to give alkyl bromides or by hydroiodic acid (HI) to give alkyl iodides.Name: 2-(4-Methoxyphenoxy)acetic acid
Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem