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class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p>The <b>Thorpe–Ingold effect</b>, <b>gem-dimethyl effect</b>, or <b>angle compression</b> is an effect observed in <a href="/wiki/Chemistry" title="Chemistry">chemistry</a> where increasing <a href="/wiki/Steric_hindrance" class="mw-redirect" title="Steric hindrance">steric hindrance</a> favours ring closure and intramolecular reactions. The effect was first reported by Beesley, <a href="/wiki/Jocelyn_Field_Thorpe" title="Jocelyn Field Thorpe">Thorpe</a>, and <a href="/wiki/Christopher_Kelk_Ingold" title="Christopher Kelk Ingold">Ingold</a> in 1915 as part of a study of <a href="/wiki/Cyclization_reaction" class="mw-redirect" title="Cyclization reaction">cyclization reactions</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> It has since been generalized to many areas of chemistry.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>The comparative rates of <a href="/wiki/Lactone" title="Lactone">lactone</a> formation (lactonization) of various 2-hydroxybenzenepropionic acids illustrate the effect. The placement of an increasing number of methyl groups accelerates the cyclization process.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span typeof="mw:File"><a href="/wiki/File:LactonizationRates.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/72/LactonizationRates.png/440px-LactonizationRates.png" decoding="async" width="440" height="116" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/72/LactonizationRates.png/660px-LactonizationRates.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/72/LactonizationRates.png/880px-LactonizationRates.png 2x" data-file-width="1505" data-file-height="398" /></a></span></dd></dl> <p>One application of this effect is addition of a <a href="/wiki/Quaternary_carbon" title="Quaternary carbon">quaternary carbon</a> (e.g., a <a href="/wiki/Geminal" title="Geminal">gem</a>-di<a href="/wiki/Methyl_group" title="Methyl group">methyl group</a>) in an <a href="/wiki/Alkyl" class="mw-redirect" title="Alkyl">alkyl</a> chain to increase the <a href="/wiki/Reaction_rate" title="Reaction rate">reaction rate</a> and/or <a href="/wiki/Equilibrium_constant" title="Equilibrium constant">equilibrium constant</a> of cyclization reactions. An example of this is an <a href="/wiki/Olefin_metathesis" title="Olefin metathesis">olefin metathesis</a> reaction:<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> In the field of <a href="/wiki/Peptide" title="Peptide">peptide</a> <a href="/wiki/Foldamer" title="Foldamer">foldamers</a>, <a href="/wiki/Amino_acid" title="Amino acid">amino acid</a> <a href="/wiki/Residue_(chemistry)#Biochemistry" title="Residue (chemistry)">residues</a> containing <a href="/wiki/Quaternary_carbon" title="Quaternary carbon">quaternary carbons</a> such as <a href="/wiki/2-aminoisobutyric_acid" class="mw-redirect" title="2-aminoisobutyric acid">2-aminoisobutyric acid</a> are used to promote formation of certain types of helices.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span class="mw-default-size" typeof="mw:File"><a href="/wiki/File:Tiemethathesis.PNG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/2/21/Tiemethathesis.PNG" decoding="async" width="312" height="111" class="mw-file-element" data-file-width="312" data-file-height="111" /></a></span></dd></dl> <p>One proposed explanation for this effect is that the increased size of the substituents increases the angle between them. As a result, the angle between the other two substituents decreases. By moving them closer together, reactions between them are accelerated. It is thus a kinetic effect. </p> <dl><dd><span class="mw-default-size" typeof="mw:File"><a href="/wiki/File:Thorpeingoldeffect.PNG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/3/32/Thorpeingoldeffect.PNG" decoding="async" width="231" height="65" class="mw-file-element" data-file-width="231" data-file-height="65" /></a></span></dd></dl> <p>The effect also has some thermodynamic contribution as the <a href="/wiki/In_silico" title="In silico">in silico</a> <a href="/wiki/Strain_energy" title="Strain energy">strain energy</a> decreases on going from <a href="/wiki/Cyclobutane" title="Cyclobutane">cyclobutane</a> to 1-methylcyclobutane and 1,1-dimethylcyclobutane by a value between 8 kcal/mole<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> and 1.5 kcal/mole.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> A noteworthy example of the Thorpe-Ingold effect in <a href="/wiki/Supramolecular_catalysis" title="Supramolecular catalysis">supramolecular catalysis</a> is given by diphenylmethane derivatives provided with guanidinium groups.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> These compounds are active in the cleavage of the RNA model compound HPNP. Substitution of the methylene group of the parent diphenylmethane spacer with cyclohexylidene and adamantylidene moieties enhances catalytic efficiency, with gem dialkyl effect accelerations of 4.5 and 9.1, respectively. </p> <dl><dd><span typeof="mw:File"><a href="/wiki/File:DPMThorpeIngold.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1a/DPMThorpeIngold.png/550px-DPMThorpeIngold.png" decoding="async" width="550" height="207" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1a/DPMThorpeIngold.png/825px-DPMThorpeIngold.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1a/DPMThorpeIngold.png/1100px-DPMThorpeIngold.png 2x" data-file-width="1373" data-file-height="517" /></a></span></dd></dl> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Thorpe%E2%80%93Ingold_effect&action=edit&section=1" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Chelate_effect" class="mw-redirect" title="Chelate effect">Chelate effect</a></li> <li><a href="/wiki/Flippin-Lodge_angle" class="mw-redirect" title="Flippin-Lodge angle">Flippin-Lodge angle</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Thorpe%E2%80%93Ingold_effect&action=edit&section=2" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist 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cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and 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"Guanidine–Guanidinium Cooperation in Bifunctional Artificial Phosphodiesterases Based on Diphenylmethane Spacers; gem -Dialkyl Effect on Catalytic Efficiency". <i>The Journal of Organic Chemistry</i>. <b>78</b> (14): 7259–7263. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fjo401085z">10.1021/jo401085z</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/23772969">23772969</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Journal+of+Organic+Chemistry&rft.atitle=Guanidine%E2%80%93Guanidinium+Cooperation+in+Bifunctional+Artificial+Phosphodiesterases+Based+on+Diphenylmethane+Spacers%3B+gem+-Dialkyl+Effect+on+Catalytic+Efficiency&rft.volume=78&rft.issue=14&rft.pages=7259-7263&rft.date=2013-07-19&rft_id=info%3Adoi%2F10.1021%2Fjo401085z&rft_id=info%3Apmid%2F23772969&rft.aulast=Salvio&rft.aufirst=Riccardo&rft.au=Mandolini%2C+Luigi&rft.au=Savelli%2C+Claudia&rfr_id=info%3Asid%2Fen.wikipedia.org%3AThorpe%E2%80%93Ingold+effect" class="Z3988"></span></span> </li> </ol></div></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Thorpe–Ingold_effect&oldid=1131696241">https://en.wikipedia.org/w/index.php?title=Thorpe–Ingold_effect&oldid=1131696241</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Physical_organic_chemistry" title="Category:Physical organic chemistry">Physical organic chemistry</a></li><li><a href="/wiki/Category:Chemical_kinetics" title="Category:Chemical kinetics">Chemical kinetics</a></li><li><a href="/wiki/Category:Stereochemistry" title="Category:Stereochemistry">Stereochemistry</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 5 January 2023, at 09:27<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. 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