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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head profile="http://gmpg.org/xfn/1"> <title>Computational Organic Chemistry » 2008 » October</title> <meta name="google-site-verification" content="g1Myv4tUVAmqRbwZeBi7IPuSZpP64RWjVJ6itIoouCo"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <style type="text/css" media="screen">@import url( /blog/wp-content/themes/comporg/style.css);</style> <link rel="stylesheet" id="wp-block-library-css" href="/blog/wp-includes/css/dist/block-library/style.min.css?ver=5.6.1" type="text/css" media="all"> <script type="text/javascript">  </script> </head> <body> <div id="header"> <div id="header_img"></div> </div> <div id="link_section"> <div style="float:left"> <a href="/blog/about">About this Blog</a> | <a href="/">Book Homepage</a> | <a href="http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471713422.html">Purchase the Book</a> </div> </div> <div id="after_links"></div> <div id="content"> <div id="main"> <h2 class="post-title">Archive for October, 2008</h2> <div class="box"> <h2><a href="/blog/archives/95" rel="bookmark" title="Permanent Link: Möbius aromaticity">Möbius aromaticity</a></h2> <div class="post-content"> Rzepa has published another study of Möbius aromaticity.<a href="#rzepa2R1">1</a> Here he examines the [14]annulene 1 using the topological method (AIM) and NICS. The B3LYP/6-31G(d) optimized structures of 1, the transition state 3 and product of the 8-e– electroclization 2 are shown in Figure 1. <img src="/blog/wp-content/RZ1.gif"> <table align="center" border="0" cellspacing="0" cellpadding="3"> <tr> <td align="center" valign="middle"> <div class="jmol" id="RZ1"> <a onclick="return false"> <img src="/blog/wp-content/RZ-c1.gif" onclick="insertJmol('RZ1',200,200,'RZ-c1.xyz')"> </a> </div> 1 (0.0) </td> <td align="center" valign="middle"> <div class="jmol" id="RZ3"> <a onclick="return false"> <img src="/blog/wp-content/RZ-c3.gif" onclick="insertJmol('RZ3',200,200,'RZ-c3.xyz')"> </a> </div> 3 (4.56) </td> <td align="center" valign="middle"> <div class="jmol" id="RZ2"> <a onclick="return false"> <img src="/blog/wp-content/RZ-c2.gif" onclick="insertJmol('RZ2',200,200,'RZ-c2.xyz')"> </a> </div> 2 (0.07) </td> </tr> </table> Figure 1. B3LYP/6-31G(d) optimized structures and relative energies (kcal mol-1) of 1-3.<a href="#rzepa2R1">1</a> The topological analysis of 1 reveals a number of interesting features of the density. First, there are two bond critical points that connect the carbon atoms that cross over each other in the lemniscate structure 1 (these bond paths are drawn as the dashed lines in Scheme 1, connecting C1 to C8 and C7 to C14). These bond critical points have a much smaller electron density than for a typical C-C bond. With these added bond critical points come additional ring points, but not the anticipated 3 ring critical points. There is a ring critical point for the quasi-four member ring (C1-C14-C7-C8-C1), but the expected ring point for each of the two 8-member ring bifurcate into two separate ring critical points sandwiching a cage critical point! Scheme 1 <img src="/blog/wp-content/RZ2.gif"> Rzepa argues that the weak bonding interaction across the lemniscates is evidence for Möbius homoaromaticity in each half of 1. The NICS value at the central ring critical point is -18.6 ppm, reflective of overall Möbius aromaticity. But the NICS values at the 8-member ring ring critical points of -8.6 ppm and the cage critical points (-7.9 ppm) provide support for the Möbius homoaromaticity. Transition state 3 corresponds to motion along the bond path of those weak bonds along either C1-C8 or C7-C14. This leads to forming the two fused eight-member rings of 2. An interesting thing to note is that there is only one transition state connecting 1 and 2 – even though one might think of the electrocyclization occurring in either the left or right ring. (Rzepa discusses this in a nice J. Chem. Ed. article.<a href="#rzepa2R2">2</a>) This transition state 3 is stabilized by Möbius aromaticity. As an aside, Rzepa has once again made great use of the web in supplying a great deal of information through the <a href="http://pubs.acs.org/isubscribe/journals/joceah/73/i17/objects/jo801022b/WEO1/index.html">web-enhanced object in the paper</a>. As in the past, ACS continues to put this behind the subscriber firewall instead of considering it to be supporting material, which it most certainly is and should therefore be available to all. <h3>References</h3> (1) Allan, C. S. M.; Rzepa, H. S., "Chiral Aromaticities. AIM and ELF Critical Point and NICS Magnetic Analyses of Moöbius-Type Aromaticity and Homoaromaticity in Lemniscular Annulenes and Hexaphyrins," J. Org. Chem., 2008, 73, 6615-6622, DOI: <a href="http://dx.doi.org/10.1021/jo801022b">10.1021/jo801022b</a>. (2) Rzepa, H. S., "The Aromaticity of Pericyclic Reaction Transition States" J. Chem. Ed. 2007, 84, 1535-1540, <a href="http://www.jce.divched.org/Journal/Issues/2007/Sep/abs1535.html">http://www.jce.divched.org/Journal/Issues/2007/Sep/abs1535.html</a>. <h3>InChIs</h3> 1: InChI=1/C14H14/c1-2-4-6-8-10-12-14-13-11-9-7-5-3-1/h1-14H/b2-1-,3-1-,4-2-,5-3-,6-4-,7-5+,8-6+,9-7-,10-8+,11-9-,12-10+,13-11-,14-12-,14-13- InChIKey= RYQWRHUSMUEYST-YGYPEFQEBU 2: InChI=1/C14H14/c1-2-6-10-14-12-8-4-3-7-11-13(14)9-5-1/h1-14H/b2-1-,4-3-,9-5-,10-6-,11-7-,12-8-/t13-,14+ InChIKey= AMYHCQKNURYOBO-RFCQUTFOBS  </div> <a href="/blog/archives/category/molecules/annulenes" rel="category tag">annulenes</a> &<a href="/blog/archives/category/aromaticity" rel="category tag">Aromaticity</a> Steven Bachrach 28 Oct 2008 <a href="/blog/archives/95#comments">1 Comment</a> </div> <div class="box"> <h2><a href="/blog/archives/94" rel="bookmark" title="Permanent Link: SM8 performance">SM8 performance</a></h2> <div class="post-content"> Cramer and Truhlar have tested their latest solvation model SM8 against a test set of 17 small, drug-like molecules.<a href="#sm8testR1">1</a> Their best result comes with the use of SM8, the MO5-2X functional, the 6-31G(d) basis set and CM4M charge model. This computational model yields a root mean squared error for the solvation free energy of 1.08 kcal mol-1 across this test set. This is the first time these authors have recommended a particular computational model. Another interesting point is that use of solution-phase optimized geometries instead of gas-phase geometries leads to only marginally improved solvation energies, so that the more cost effective use of gas-phase structures is encouraged. These authors note in conclusion that further improvement of solvation prediction rests upon “an infusion of new experimental data for molecules characterized by high degrees of functionality (i.e. druglike)”. <h2>References</h2> <a name="sm8testR1"></a> (1) Chamberlin, A. C.; Cramer, C. J.; Truhlar, D. G., “Performance of SM8 on a Test To Predict Small-Molecule Solvation Free Energies,” J. Phys. Chem. B, 2008, 112, 8651-8655, DOI: <a href="http://dx.doi.org/10.1021/jp8028038">10.1021/jp8028038</a>.  </div> <a href="/blog/archives/category/authors/cramer" rel="category tag">Cramer</a> &<a href="/blog/archives/category/solvation" rel="category tag">Solvation</a> &<a href="/blog/archives/category/authors/truhlar" rel="category tag">Truhlar</a> Steven Bachrach 21 Oct 2008 <a href="/blog/archives/94#respond">No Comments</a> </div> <div class="box"> <h2><a href="/blog/archives/93" rel="bookmark" title="Permanent Link: Rotational barrier of biphenyl">Rotational barrier of biphenyl</a></h2> <div class="post-content"> Just how difficult can it be to compute rotational barriers? Well, it turns out that for biphenyl 1, the answer is “very”! <img src="/blog/wp-content/biphen1.gif"> The experimental barriers for rotation about the C1-C1’ bond of biphenyl are 6.0 ± 2.1 kcal mol-1 at 0° and 6.5 ± 2.0 kJ mol-1 at 90°.<a href="#biphRef1">1</a> CCSD(T) with extrapolated basis set approximation computations by Sancho-Garcı´a and Cornil overestimate both barriers by more than 4 kJ mol-1 and, more critically in error, predict that the 0° barrier is higher in energy than the 90° barrier.<a href="#biphRef2">2</a> Now Johansson and Olsen have reported a comprehensive study of the rotational barrier of biphenyl.<a href="#biphRef3">3</a> They tackled a number of different effects: <ol> <li>Basis sets: The cc-pVDZ basis set is simply too small to give any reasonable estimate (See Table 1).</li> <li>Correlation effects: HF, MP2, SCS-MP2 and CCSD overestimate the barriers and get the relative energies of the two barriers wrong, regardless of the basis set. While CCSD(T) does properly predict the barrier at 0° is lower than that at 90°, even this level overestimates the barrier heights (Table 1). </li> Table 1. Computed torsional barriers in kJ mol-1. <table border="0" cellspacing="1" cellpadding="4" align="center"> <tr> <td colspan="5"> <hr> </td> </tr> <tr> <td>   </td> <td colspan="2"> MP2 </td> <td colspan="2"> CCSD(T) </td> </tr> <tr> <td>   </td> <td> 0° </td> <td> 90° </td> <td> 0° </td> <td> 90° </td> </tr> <tr> <td> cc-pVDZ </td> <td> 12.23 </td> <td> 7.68 </td> <td> 10.89 </td> <td> 7.23 </td> </tr> <tr> <td> aug-cc-pVDZ </td> <td> 9.68 </td> <td> 7.45 </td> <td> 9.23 </td> <td> 6.67 </td> </tr> <tr> <td> cc-pVTZ </td> <td> 9.86 </td> <td> 9.13 </td> <td> 8.85 </td> <td> 8.50 </td> </tr> <tr> <td> aug-cc-pVTZ </td> <td> 9.78 </td> <td> 9.43 </td> <td> 8.83 </td> <td> 8.86 </td> </tr> <tr> <td> cc-pVQZ </td> <td> 9.65 </td> <td> 9.33 </td> <td> 8.68 </td> <td> 8.74 </td> </tr> <tr> <td> aug-cc-pVQZ </td> <td> 9.35 </td> <td> 9.31 </td> <td> 8.39 </td> <td> 8.76 </td> </tr> <tr> <td colspan="5"> <hr> </td> </tr> </table> <li>Their best CCSD(T) energy using a procedure to extrapolate to infinite basis set still gives barriers that are too high, though in the right relative order: E(0°)=7.97 and E(90°) = 8.79 kJ mol-1.</li> <li>Inclusion of Core-Core and Core-Valence correlation energy reduces the 0° barrier and raises the 90° barrier a small amount. With an extrapolation for completeness in the coupled clusters expansion, their best estimates for the two barriers are 7.88 and 8.94 for the 0° and 90° barriers, respectively.</li> <li>Relativity has no effect on the barrier heights. (This is a great result – it suggests that we don’t have to worry about relativistic corrections for normal organics!)</li> <li>Intramolecular basis set superposition error might be responsible for as much a 0.4 kJ difference in the energies of the two barriers.</li> <li>Inclusion of vibrational energies along with all of the other corrections listed above leads to their best estimate of the two barriers: E(0°)=8.0 and E(90°) = 8.3 kJ mol-1, which are at least in the correct order and within the experimental error bars.</li> </ol> Who would have thought this problem was so difficult? <h3>References</h3> <a name="#biphRef1"></a> (1) Bastiansen, O.; Samdal, S., "Structure and barrier of internal rotation of biphenyl derivatives in the gaseous state: Part 4. Barrier of internal rotation in biphenyl, perdeuterated biphenyl and seven non-ortho-substituted halogen derivatives," J. Mol. Struct., 1985, 128, 115-125, DOI: <a href="http://dx.doi.org/10.1016/0022-2860(85)85044-4">10.1016/0022-2860(85)85044-4</a>. <a name="#biphRef2"></a> (2) Sancho-Garcia, J. C.; Cornil, J., "Anchoring the Torsional Potential of Biphenyl at the ab Initio Level: The Role of Basis Set versus Correlation Effects," J. Chem. Theory Comput., 2005, 1, 581-589, DOI: <a href="http://dx.doi.org/10.1021/ct0500242">10.1021/ct0500242</a>. <a name="#biphRef3"></a> (3) Johansson, M. P.; Olsen, J., "Torsional Barriers and Equilibrium Angle of Biphenyl: Reconciling Theory with Experiment," J. Chem. Theory Comput., 2008, 4, 1460-1471, DOI: <a href="http://dx.doi.org/10.1021/ct800182e">10.1021/ct800182e</a>. <h3>InChIs</h3> Biphenyl 1: InChI=1/C12H10/c1-3-7-11(8-4-1)12-9-5-2-6-10-12/h1-10H InChIKey: ZUOUZKKEUPVFJK-UHFFFAOYAV  </div> <a href="/blog/archives/category/molecules/biphenyl" rel="category tag">biphenyl</a> Steven Bachrach 15 Oct 2008 <a href="/blog/archives/93#comments">4 Comments</a> </div> <div class="box"> <h2><a href="/blog/archives/92" rel="bookmark" title="Permanent Link: Dihydroxycarbene">Dihydroxycarbene</a></h2> <div class="post-content"> Following on the great study of hydroxycarbene<a href="#ho2cRef1">1</a> (see my blog <a href="http://hackberry.chem.trinity.edu/blog/?p=148">post</a>), Schreiner now reports on the synthesis and characterization of dihydroxycarbene 1.<a href="#ho2cRef2">2</a> It is prepared by high-vacuum flash pyrolysis of oxalic acid (Scheme 1). Scheme 1 <img src="/blog/wp-content/ho2c1.gif"> Dihydroxycarbene can exist in three different conformations characterized by the relationship about the C-O bond, either s-cis or s-trans. The three conformations are shown in Figure 1, and the s-trans,s-trans structure is the local energy minimum (computed at CCSD(T)/cc-pVTZ). <table border="0" cellspacing="0" cellpadding="3" align="center"> <tr> <td align="center"> <div class="jmol" id="1tt"> <a onclick="return false"> <img src="/blog/wp-content/ho2c-1tt.gif" onclick="insertJmol('1tt',200,200,'ho2c-1tt.xyz')"> </a> </div> 1tt (0.0) </td> <td align="center"> <div class="jmol" id="1ct"> <a onclick="return false"> <img src="/blog/wp-content/ho2c-1ct.gif" onclick="insertJmol('1ct',200,200,'ho2c-1ct.xyz')"> </a> </div> 1ct (0.1) </td> <td align="center"> <div class="jmol" id="1cc"> <a onclick="return false"> <img src="/blog/wp-content/ho2c-1cc.gif" onclick="insertJmol('1cc',200,200,'ho2c-1cc.xyz')"> </a> </div> 1cc (6.7) </td> </tr> </table> Figure 1. CCSD(T)/cc-pVTZ optimized geometries and relative energies (kcal mol-1) of the conformers of 1.<a href="#ho2cRef2">2</a> Identification of the 1 is made through comparison of the experimental and computed IR vibrational frequencies. As an example, the experimental and computed frequencies for the s-trans,s-trans conformer are listed in Table 1. The agreement is excellent. Table 1. Computed and experimental vibrational frequencies (cm-1) and intensities (in parentheses) of the s-trans,s-trans conformation of 1.<a href="#ho2cRef2">2</a> <table align="center" border="0" cellspacing="2" cellpadding="3"> <tr> <td colspan="3"> <hr> </td> </tr> <tr> <td> vibration </td> <td> computed </td> <td> experiment </td> </tr> <tr> <td> 1 </td> <td> 3876.4 (23.5) </td> <td> 3633.2 / 3628.6 (w) </td> </tr> <tr> <td> 2 </td> <td> 3871.4 (234.1) </td> <td> 3625.1 (s) </td> </tr> <tr> <td> 3 </td> <td> 1443.1 (124.4) </td> <td> 1386.2 (m) </td> </tr> <tr> <td> 4 </td> <td> 1370.5 (58.3) </td> <td> 1289.0 / 1287.4 (w) </td> </tr> <tr> <td> 5 </td> <td> 1157.8 (470.6) </td> <td> 1110.3 / 1109.3 (vs) </td> </tr> <tr> <td> 6 </td> <td> 1156.6 (1.4) </td> <td>   </td> </tr> <tr> <td> 7 </td> <td> 742.4 (178.8) </td> <td> 706.6 (s) </td> </tr> <tr> <td> 8 </td> <td> 672.4 (0.0) </td> <td>   </td> </tr> <tr> <td> 9 </td> <td> 641.6 (11.2) </td> <td>   </td> </tr> <tr> <td colspan="3"> <hr> </td> </tr> </table> Unlike hydroxycarbene, dihydroxycarbene is stable. The amazing instability of hydroxycarbene is due to tunneling through a large barrier: nearly 30 kcal mol-1.<a href="#ho2cRef1">1</a> The tunneling route for the decomposition of 1 is more difficult for two reasons. First, its C-O bond is quite strong; the C-O distance is quite short, 1.325 Å. This makes a long distance that must be traversed in the tunneling mode. (The strong bond is due to π-donation from the oxygen lone pair into the empty carbon p orbital; this is noted by the large rotational barrier about the C-O bonds of 17 kcal mol-1!) Second, the activation barrier for decomposition is very high, at least 34 kcal mol-1. <h3>References</h3> <a name="ho2cRef1"></a> (1) Schreiner, P. R.; Reisenauer, H. P.; Pickard Iv, F. C.; Simmonett, A. C.; Allen, W. D.; Matyus, E.; Csaszar, A. G., "Capture of hydroxymethylene and its fast disappearance through tunnelling," Nature, 2008, 453, 906-909, DOI: <a href="http://dx.doi.org/10.1038/nature07010">10.1038/nature07010</a>. <a name="ho2cRef2"></a> (2) Schreiner, P. R.; Reisenauer, H. P., "Spectroscopic Identification of Dihydroxycarbene13," Angew. Chem. Int. Ed., 2008, 47, 7071-7074, DOI: <a href="http://dx.doi.org/10.1002/anie.200802105">10.1002/anie.200802105</a> <h3>InChIs</h3> 1: InChI=1/CH2O2/c2-1-3/h2-3H  </div> <a href="/blog/archives/category/molecules/carbenes" rel="category tag">carbenes</a> &<a href="/blog/archives/category/authors/schreiner" rel="category tag">Schreiner</a> &<a href="/blog/archives/category/tunneling" rel="category tag">Tunneling</a> Steven Bachrach 06 Oct 2008 <a href="/blog/archives/92#comments">2 Comments</a> </div> </div> <div id="sidebar"> <ul> <li class="box"> <h2> Categories </h2> <ul> <li class="cat-item cat-item-25"> <a href="/blog/archives/category/acidity">Acidity</a> (12) </li> <li class="cat-item cat-item-3"> <a href="/blog/archives/category/aromaticity">Aromaticity</a> (91) </li> <li class="cat-item cat-item-53"> <a href="/blog/archives/category/authors">Authors</a> (153) <ul class="children"> <li class="cat-item cat-item-42"> <a href="/blog/archives/category/authors/borden">Borden</a> (12) </li> 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href="/blog/archives/category/molecules/biphenyl">biphenyl</a> (1) </li> <li class="cat-item cat-item-70"> <a href="/blog/archives/category/molecules/calixarenes">calixarenes</a> (1) </li> <li class="cat-item cat-item-33"> <a href="/blog/archives/category/molecules/carbenes">carbenes</a> (13) </li> <li class="cat-item cat-item-72"> <a href="/blog/archives/category/molecules/cyclobutadiene">cyclobutadiene</a> (4) </li> <li class="cat-item cat-item-62"> <a href="/blog/archives/category/molecules/dendralenes">dendralenes</a> (1) </li> <li class="cat-item cat-item-66"> <a href="/blog/archives/category/molecules/dewar-benzene">Dewar benzene</a> (1) </li> <li class="cat-item cat-item-39"> <a href="/blog/archives/category/molecules/diradicals">diradicals</a> (8) </li> <li class="cat-item cat-item-59"> <a href="/blog/archives/category/molecules/ephedrine">ephedrine</a> (1) </li> <li class="cat-item cat-item-37"> <a href="/blog/archives/category/molecules/ethyl-cation">ethyl cation</a> (2) </li> <li class="cat-item cat-item-90"> <a href="/blog/archives/category/molecules/fullerene">fullerene</a> (6) </li> <li class="cat-item cat-item-51"> <a href="/blog/archives/category/molecules/fulvalenes">fulvalenes</a> (1) </li> <li class="cat-item cat-item-21"> <a href="/blog/archives/category/molecules/hexacyclinol">hexacyclinol</a> (2) </li> <li class="cat-item cat-item-78"> <a href="/blog/archives/category/molecules/nanohoops">nanohoops</a> (4) </li> <li class="cat-item cat-item-41"> <a href="/blog/archives/category/molecules/non-classical">non-classical</a> (4) </li> <li class="cat-item cat-item-34"> <a href="/blog/archives/category/molecules/norbornyl-cation">norbornyl cation</a> (2) </li> <li class="cat-item cat-item-49"> <a href="/blog/archives/category/molecules/nucleic-acids">nucleic acids</a> (4) </li> <li class="cat-item cat-item-36"> <a href="/blog/archives/category/molecules/oximes">oximes</a> (1) </li> <li class="cat-item cat-item-75"> <a href="/blog/archives/category/molecules/phenyloxenium">phenyloxenium</a> (1) </li> <li class="cat-item cat-item-8"> <a href="/blog/archives/category/molecules/polycyclic-aromatics">polycyclic aromatics</a> (7) </li> <li class="cat-item cat-item-50"> <a href="/blog/archives/category/molecules/propellane">propellane</a> (2) </li> <li class="cat-item cat-item-79"> <a href="/blog/archives/category/molecules/stilbene">stilbene</a> (1) </li> <li class="cat-item cat-item-80"> <a href="/blog/archives/category/molecules/sugars">sugars</a> (5) </li> <li class="cat-item cat-item-85"> <a href="/blog/archives/category/molecules/terpenes">terpenes</a> (2) </li> <li class="cat-item cat-item-89"> <a href="/blog/archives/category/molecules/twistane">twistane</a> (1) </li> </ul> </li> <li class="cat-item cat-item-22"> <a href="/blog/archives/category/nmr">NMR</a> (40) </li> <li class="cat-item cat-item-31"> <a href="/blog/archives/category/optical-rotation">Optical Rotation</a> (16) </li> <li class="cat-item cat-item-28"> <a href="/blog/archives/category/qm-method">QM Method</a> (96) <ul class="children"> <li class="cat-item cat-item-20"> <a href="/blog/archives/category/qm-method/caspt2">CASPT2</a> (1) </li> <li class="cat-item cat-item-7"> <a href="/blog/archives/category/qm-method/dft">DFT</a> (71) </li> <li class="cat-item cat-item-45"> <a href="/blog/archives/category/qm-method/focal-point">focal point</a> (7) </li> <li class="cat-item cat-item-14"> <a href="/blog/archives/category/qm-method/g3">G3</a> (3) </li> <li class="cat-item cat-item-60"> <a href="/blog/archives/category/qm-method/mp">MP</a> (11) </li> </ul> </li> <li class="cat-item cat-item-56"> <a href="/blog/archives/category/reactions">Reactions</a> (83) <ul class="children"> <li class="cat-item cat-item-13"> <a href="/blog/archives/category/reactions/12-addition">1,2-addition</a> (1) </li> <li class="cat-item cat-item-35"> <a href="/blog/archives/category/reactions/aldol">aldol</a> (4) </li> <li class="cat-item cat-item-32"> <a href="/blog/archives/category/reactions/bergman-cyclization">Bergman cyclization</a> (6) </li> <li class="cat-item cat-item-44"> <a href="/blog/archives/category/reactions/claisen-rearrangement">Claisen rearrangement</a> (2) </li> <li class="cat-item cat-item-10"> <a href="/blog/archives/category/reactions/cope-rearrangement">Cope Rearrangement</a> (5) </li> <li class="cat-item cat-item-69"> <a href="/blog/archives/category/reactions/cycloadditions">cycloadditions</a> (12) </li> <li class="cat-item cat-item-23"> <a href="/blog/archives/category/reactions/diels-alder">Diels-Alder</a> (26) </li> <li class="cat-item cat-item-47"> <a href="/blog/archives/category/reactions/electrocyclization">electrocyclization</a> (11) </li> <li class="cat-item cat-item-76"> <a href="/blog/archives/category/reactions/electrophilic-aromatic-substitution">electrophilic aromatic substitution</a> (1) </li> <li class="cat-item cat-item-5"> <a href="/blog/archives/category/reactions/ene-reaction">ene reaction</a> (1) </li> <li class="cat-item cat-item-52"> <a href="/blog/archives/category/reactions/hajos-parrish-reaction">Hajos-Parrish Reaction</a> (1) </li> <li class="cat-item cat-item-61"> <a href="/blog/archives/category/reactions/mannich">Mannich</a> (2) </li> <li class="cat-item cat-item-64"> <a href="/blog/archives/category/reactions/michael-addition">Michael addition</a> (5) </li> <li class="cat-item cat-item-40"> <a href="/blog/archives/category/reactions/ozonolysis">ozonolysis</a> (1) </li> <li class="cat-item cat-item-43"> <a href="/blog/archives/category/reactions/proton-transfer">proton transfer</a> (1) </li> <li class="cat-item cat-item-38"> <a href="/blog/archives/category/reactions/pseudopericyclic">pseudopericyclic</a> (4) </li> <li class="cat-item cat-item-63"> <a href="/blog/archives/category/reactions/strecker">Strecker</a> (1) </li> <li class="cat-item cat-item-24"> <a href="/blog/archives/category/reactions/substitution">Substitution</a> (6) </li> <li class="cat-item cat-item-93"> <a href="/blog/archives/category/reactions/wittig">Wittig</a> (1) </li> </ul> </li> <li class="cat-item cat-item-87"> <a href="/blog/archives/category/second-edition">Second Edition</a> (3) </li> <li class="cat-item cat-item-11"> <a href="/blog/archives/category/solvation">Solvation</a> (17) </li> <li class="cat-item cat-item-77"> <a href="/blog/archives/category/stereochemistry">Stereochemistry</a> (2) </li> <li class="cat-item cat-item-68"> <a href="/blog/archives/category/stereoinduction">stereoinduction</a> (4) </li> <li class="cat-item cat-item-71"> <a href="/blog/archives/category/tunneling">Tunneling</a> (26) </li> <li class="cat-item cat-item-1"> <a href="/blog/archives/category/uncategorized">Uncategorized</a> (57) </li> <li class="cat-item cat-item-82"> <a href="/blog/archives/category/vibrational-frequencies">vibrational frequencies</a> (3) </li> </ul> </li> <li class="box"> <h2> Monthly </h2> <ul> <li><a href="/blog/archives/date/2019/06">June 2019</a></li> <li><a href="/blog/archives/date/2019/04">April 2019</a></li> <li><a href="/blog/archives/date/2019/03">March 2019</a></li> <li><a href="/blog/archives/date/2019/02">February 2019</a></li> <li><a href="/blog/archives/date/2019/01">January 2019</a></li> <li><a href="/blog/archives/date/2018/12">December 2018</a></li> <li><a href="/blog/archives/date/2018/11">November 2018</a></li> <li><a href="/blog/archives/date/2018/10">October 2018</a></li> <li><a href="/blog/archives/date/2018/09">September 2018</a></li> <li><a href="/blog/archives/date/2018/08">August 2018</a></li> <li><a href="/blog/archives/date/2018/07">July 2018</a></li> <li><a href="/blog/archives/date/2018/06">June 2018</a></li> <li><a href="/blog/archives/date/2018/05">May 2018</a></li> <li><a href="/blog/archives/date/2018/04">April 2018</a></li> <li><a href="/blog/archives/date/2018/03">March 2018</a></li> <li><a href="/blog/archives/date/2018/02">February 2018</a></li> <li><a href="/blog/archives/date/2018/01">January 2018</a></li> <li><a href="/blog/archives/date/2017/12">December 2017</a></li> <li><a href="/blog/archives/date/2017/11">November 2017</a></li> <li><a href="/blog/archives/date/2017/10">October 2017</a></li> <li><a href="/blog/archives/date/2017/09">September 2017</a></li> <li><a href="/blog/archives/date/2017/08">August 2017</a></li> <li><a href="/blog/archives/date/2017/07">July 2017</a></li> <li><a href="/blog/archives/date/2017/06">June 2017</a></li> <li><a href="/blog/archives/date/2017/05">May 2017</a></li> <li><a href="/blog/archives/date/2017/04">April 2017</a></li> <li><a href="/blog/archives/date/2017/03">March 2017</a></li> <li><a href="/blog/archives/date/2017/02">February 2017</a></li> <li><a href="/blog/archives/date/2017/01">January 2017</a></li> <li><a href="/blog/archives/date/2016/12">December 2016</a></li> <li><a href="/blog/archives/date/2016/11">November 2016</a></li> <li><a href="/blog/archives/date/2016/10">October 2016</a></li> <li><a href="/blog/archives/date/2016/09">September 2016</a></li> <li><a href="/blog/archives/date/2016/08">August 2016</a></li> <li><a href="/blog/archives/date/2016/07">July 2016</a></li> <li><a href="/blog/archives/date/2016/06">June 2016</a></li> <li><a href="/blog/archives/date/2016/05">May 2016</a></li> <li><a href="/blog/archives/date/2016/04">April 2016</a></li> <li><a href="/blog/archives/date/2016/03">March 2016</a></li> <li><a href="/blog/archives/date/2016/02">February 2016</a></li> <li><a href="/blog/archives/date/2016/01">January 2016</a></li> <li><a href="/blog/archives/date/2015/12">December 2015</a></li> <li><a href="/blog/archives/date/2015/11">November 2015</a></li> <li><a href="/blog/archives/date/2015/10">October 2015</a></li> <li><a href="/blog/archives/date/2015/09">September 2015</a></li> <li><a href="/blog/archives/date/2015/08">August 2015</a></li> <li><a href="/blog/archives/date/2015/07">July 2015</a></li> <li><a href="/blog/archives/date/2015/06">June 2015</a></li> <li><a href="/blog/archives/date/2015/05">May 2015</a></li> <li><a href="/blog/archives/date/2015/04">April 2015</a></li> <li><a href="/blog/archives/date/2015/03">March 2015</a></li> <li><a href="/blog/archives/date/2015/02">February 2015</a></li> <li><a href="/blog/archives/date/2015/01">January 2015</a></li> <li><a href="/blog/archives/date/2014/12">December 2014</a></li> <li><a href="/blog/archives/date/2014/11">November 2014</a></li> <li><a href="/blog/archives/date/2014/10">October 2014</a></li> <li><a href="/blog/archives/date/2014/09">September 2014</a></li> <li><a href="/blog/archives/date/2014/08">August 2014</a></li> <li><a href="/blog/archives/date/2014/07">July 2014</a></li> <li><a href="/blog/archives/date/2014/06">June 2014</a></li> <li><a href="/blog/archives/date/2014/05">May 2014</a></li> <li><a href="/blog/archives/date/2014/04">April 2014</a></li> <li><a href="/blog/archives/date/2014/03">March 2014</a></li> <li><a href="/blog/archives/date/2014/02">February 2014</a></li> <li><a href="/blog/archives/date/2014/01">January 2014</a></li> <li><a href="/blog/archives/date/2013/12">December 2013</a></li> <li><a href="/blog/archives/date/2013/11">November 2013</a></li> <li><a href="/blog/archives/date/2013/10">October 2013</a></li> <li><a href="/blog/archives/date/2013/09">September 2013</a></li> <li><a href="/blog/archives/date/2013/08">August 2013</a></li> <li><a href="/blog/archives/date/2013/07">July 2013</a></li> <li><a href="/blog/archives/date/2013/06">June 2013</a></li> <li><a href="/blog/archives/date/2013/05">May 2013</a></li> <li><a href="/blog/archives/date/2013/04">April 2013</a></li> <li><a href="/blog/archives/date/2013/03">March 2013</a></li> <li><a href="/blog/archives/date/2013/02">February 2013</a></li> <li><a href="/blog/archives/date/2013/01">January 2013</a></li> <li><a href="/blog/archives/date/2012/12">December 2012</a></li> <li><a href="/blog/archives/date/2012/11">November 2012</a></li> <li><a href="/blog/archives/date/2012/10">October 2012</a></li> <li><a href="/blog/archives/date/2012/09">September 2012</a></li> <li><a href="/blog/archives/date/2012/08">August 2012</a></li> <li><a href="/blog/archives/date/2012/07">July 2012</a></li> <li><a href="/blog/archives/date/2012/06">June 2012</a></li> <li><a href="/blog/archives/date/2012/05">May 2012</a></li> <li><a href="/blog/archives/date/2012/04">April 2012</a></li> <li><a href="/blog/archives/date/2012/03">March 2012</a></li> <li><a href="/blog/archives/date/2012/02">February 2012</a></li> <li><a href="/blog/archives/date/2012/01">January 2012</a></li> <li><a href="/blog/archives/date/2011/12">December 2011</a></li> <li><a href="/blog/archives/date/2011/11">November 2011</a></li> <li><a href="/blog/archives/date/2011/10">October 2011</a></li> <li><a href="/blog/archives/date/2011/09">September 2011</a></li> <li><a href="/blog/archives/date/2011/08">August 2011</a></li> <li><a href="/blog/archives/date/2011/07">July 2011</a></li> <li><a href="/blog/archives/date/2011/06">June 2011</a></li> <li><a href="/blog/archives/date/2011/05">May 2011</a></li> <li><a href="/blog/archives/date/2011/04">April 2011</a></li> <li><a href="/blog/archives/date/2011/03">March 2011</a></li> <li><a href="/blog/archives/date/2011/02">February 2011</a></li> <li><a href="/blog/archives/date/2011/01">January 2011</a></li> <li><a href="/blog/archives/date/2010/12">December 2010</a></li> <li><a href="/blog/archives/date/2010/11">November 2010</a></li> <li><a href="/blog/archives/date/2010/10">October 2010</a></li> <li><a href="/blog/archives/date/2010/09">September 2010</a></li> <li><a href="/blog/archives/date/2010/08">August 2010</a></li> <li><a href="/blog/archives/date/2010/07">July 2010</a></li> <li><a href="/blog/archives/date/2010/06">June 2010</a></li> <li><a href="/blog/archives/date/2010/05">May 2010</a></li> <li><a href="/blog/archives/date/2010/04">April 2010</a></li> <li><a href="/blog/archives/date/2010/03">March 2010</a></li> <li><a href="/blog/archives/date/2010/02">February 2010</a></li> <li><a href="/blog/archives/date/2010/01">January 2010</a></li> <li><a href="/blog/archives/date/2009/12">December 2009</a></li> <li><a href="/blog/archives/date/2009/11">November 2009</a></li> <li><a href="/blog/archives/date/2009/10">October 2009</a></li> <li><a href="/blog/archives/date/2009/09">September 2009</a></li> <li><a href="/blog/archives/date/2009/08">August 2009</a></li> <li><a href="/blog/archives/date/2009/07">July 2009</a></li> <li><a href="/blog/archives/date/2009/06">June 2009</a></li> <li><a href="/blog/archives/date/2009/05">May 2009</a></li> <li><a href="/blog/archives/date/2009/04">April 2009</a></li> <li><a href="/blog/archives/date/2009/03">March 2009</a></li> <li><a href="/blog/archives/date/2009/02">February 2009</a></li> <li><a href="/blog/archives/date/2009/01">January 2009</a></li> <li><a href="/blog/archives/date/2008/12">December 2008</a></li> <li><a href="/blog/archives/date/2008/11">November 2008</a></li> <li><a href="/blog/archives/date/2008/10" aria-current="page">October 2008</a></li> <li><a href="/blog/archives/date/2008/09">September 2008</a></li> <li><a href="/blog/archives/date/2008/08">August 2008</a></li> <li><a href="/blog/archives/date/2008/07">July 2008</a></li> <li><a href="/blog/archives/date/2008/06">June 2008</a></li> <li><a href="/blog/archives/date/2008/05">May 2008</a></li> <li><a href="/blog/archives/date/2008/04">April 2008</a></li> <li><a href="/blog/archives/date/2008/03">March 2008</a></li> <li><a href="/blog/archives/date/2008/02">February 2008</a></li> <li><a href="/blog/archives/date/2008/01">January 2008</a></li> <li><a href="/blog/archives/date/2007/12">December 2007</a></li> <li><a href="/blog/archives/date/2007/11">November 2007</a></li> <li><a href="/blog/archives/date/2007/10">October 2007</a></li> <li><a href="/blog/archives/date/2007/09">September 2007</a></li> <li><a href="/blog/archives/date/2007/08">August 2007</a></li> <li><a href="/blog/archives/date/2007/07">July 2007</a></li> </ul> </li> </ul> <a rel="license" href="https://creativecommons.org/licenses/by-nd/3.0/"> <img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nd/3.0/88x31.png"> </a> This work is licensed under a <a rel="license" href="https://creativecommons.org/licenses/by-nd/3.0/">Creative Commons Attribution-No Derivative Works 3.0 Unported License</a>. </div>  <div class="clear"></div> </div>  <div id="footer"> Copyright © 2021 Computational Organic Chemistry. </div> </body> </html>