{"id":23062,"date":"2020-12-04T05:35:39","date_gmt":"2020-12-04T05:35:39","guid":{"rendered":"https:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=23062"},"modified":"2020-12-04T05:53:00","modified_gmt":"2020-12-04T05:53:00","slug":"is-cyanogen-chloride-fluoride-a-source-of-c%e2%a9%b8n-more-mechanistic-insights","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23062","title":{"rendered":"Is cyanogen chloride (fluoride) a source of C\u2a78N(+)? More mechanistic insights."},"content":{"rendered":"
\n

I asked the question in my previous post<\/a>. A computational mechanism revealed that AlCl3<\/sub> or its dimer Al2<\/sub>Cl6<\/sub> could catalyse a concerted 1,1-substitution reaction at the carbon of Cl-C\u2261N, with benzene displacing chloride which is in turn captured by the Al. Unfortunately the calculated barrier for this simple process was too high for a reaction apparently occuring at ~room temperatures. Comments on the post suggested using either a second AlCl3<\/sub> or a proton to activate the carbon of the C\u2261N group by coordination on to nitrogen. A second suggestion was to involve di-cationic electrophiles. Here I report the result of implementing the N-coordinated model below.<\/p>\n

\"\"

Click on image for \u00a03D model<\/p><\/div>\n

The free energy barrier \u0394G\u2021<\/sup>298<\/sub> is 20.8 kcal\/mol (FAIR Data DOI: 10.14469\/hpc\/7584<\/a>), which corresponds to a facile reaction at room temperatures. There does not seem to be any need to invoke super-reactive di-cationic electrophiles in this instance.\u00a0This is yet another illustration that computational modelling nowadays is good enough to flag unviable mechanisms, and hence to instigate a search for a better model.<\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

I asked the question in my previous post. A computational mechanism revealed that AlCl3 or its dimer Al2Cl6 could catalyse a concerted 1,1-substitution reaction at the carbon of Cl-C\u2261N, with benzene displacing chloride which is in turn captured by the Al. Unfortunately the calculated barrier for this simple process was too high for a reaction […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":5,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"","footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1086],"tags":[],"ppma_author":[2661],"class_list":["post-23062","post","type-post","status-publish","format-standard","hentry","category-reaction-mechanism-2"],"yoast_head":"\nIs cyanogen chloride (fluoride) a source of C\u2a78N(+)? More mechanistic insights. - Henry Rzepa's Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23062\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Is cyanogen chloride (fluoride) a source of C\u2a78N(+)? More mechanistic insights. - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"I asked the question in my previous post. A computational mechanism revealed that AlCl3 or its dimer Al2Cl6 could catalyse a concerted 1,1-substitution reaction at the carbon of Cl-C\u2261N, with benzene displacing chloride which is in turn captured by the Al. Unfortunately the calculated barrier for this simple process was too high for a reaction […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23062\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2020-12-04T05:35:39+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2020-12-04T05:53:00+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/12\/CNAl-1024x889.jpg\" \/>\n<meta name=\"author\" content=\"Henry Rzepa\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Henry Rzepa\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Is cyanogen chloride (fluoride) a source of C\u2a78N(+)? More mechanistic insights. - Henry Rzepa's Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23062","og_locale":"en_GB","og_type":"article","og_title":"Is cyanogen chloride (fluoride) a source of C\u2a78N(+)? More mechanistic insights. - Henry Rzepa's Blog","og_description":"I asked the question in my previous post. A computational mechanism revealed that AlCl3 or its dimer Al2Cl6 could catalyse a concerted 1,1-substitution reaction at the carbon of Cl-C\u2261N, with benzene displacing chloride which is in turn captured by the Al. 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The expected answer was to generate a nitronium ion to nitrate benzonitrile, but can one invert this by generating a C\u2a78N+ ion to cyanate nitrobenzene? The\u2026","rel":"","context":"In "reaction mechanism"","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2020\/11\/TS-CN-254x300.gif?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":14902,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=14902","url_meta":{"origin":23062,"position":1},"title":"A tutorial problem in stereoelectronic control. The Tiffeneau-Demjanov rearrangement as part of a prostaglandin synthesis.","author":"Henry Rzepa","date":"November 23, 2015","format":false,"excerpt":"This reaction emerged a few years ago (thanks Alan!) as a tutorial problem in organic chemistry, in which students had to devise a mechanism for the reaction and use this to predict the stereochemical outcome at the two chiral centres indicated with *. \u00a0It originates in a brief report from\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"Click for 3D","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2015\/11\/green.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":26272,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=26272","url_meta":{"origin":23062,"position":2},"title":"Pre-mechanism for the Swern Oxidation: formation of chlorodimethylsulfonium chloride.","author":"Henry Rzepa","date":"August 25, 2023","format":false,"excerpt":"The Swern oxidation is a class of \"activated\" dimethyl sulfoxide (DMSO) reaction in which the active species is a chlorodimethylsulfonium chloride salt. The mechanism of this transformation as shown in e.g. Wikipedia is illustrated below.\u2021 However, an interesting and important aspect of chemistry is not apparent in this schematic mechanism\u2026","rel":"","context":"In "Curly arrows"","block_context":{"text":"Curly arrows","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2327"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":20560,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=20560","url_meta":{"origin":23062,"position":3},"title":"Smoke and mirrors. All is not what it seems with this Sn2 reaction!","author":"Henry Rzepa","date":"April 4, 2019","format":false,"excerpt":"Previously, I explored the Graham reaction to form a diazirine. The second phase of the reaction involved an Sn2' displacement of N-Cl forming C-Cl. Here I ask how facile the simpler displacement of C-Cl by another chlorine might be and whether the mechanism is Sn2 or the alternative Sn1. The\u2026","rel":"","context":"In "reaction mechanism"","block_context":{"text":"reaction mechanism","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=1086"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":26523,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=26523","url_meta":{"origin":23062,"position":4},"title":"More examples of “double-headed” curly arrows: S and C Nucleophiles attacking acetyl chloride","author":"Henry Rzepa","date":"October 12, 2023","format":false,"excerpt":"In an earlier post on this topic,\u2021 I described how the curly-arrows describing the mechanism of a nucleophilic addition at a carbonyl group choreograph in two distinct ways, as seen in red or blue below. The arrows in red can be described as firstly addition to the carbonyl group to\u2026","rel":"","context":"In \"Interesting chemistry\"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?tag=interesting-chemistry"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":63,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=63","url_meta":{"origin":23062,"position":5},"title":"The SN-1 Reaction live!","author":"Henry Rzepa","date":"April 3, 2009","format":false,"excerpt":"The ionization of a C-X bond (X=halogen) to form what we call a carbocation and which is known as the SN-1 reaction goes way back in the history of chemistry. Julius Steglitz was probably the first person to suggest such an ionization, back in 1899 (Steglitz, J.; Am. Chem. J.,\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"SN-1 Reaction. 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