Matches in DBpedia 2015-10 for { <http://dbpedia.org/resource/SNi> ?p ?o }
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- SNi abstract "SNi or Substitution Nucleophilic internal stands for a specific but not often encountered nucleophilic aliphatic substitution reaction mechanism. The name was introduced by Cowdrey et al. in 1937 to label nucleophilic reactions which occur with retention of configuration, but later was employed to describe various reactions that proceed with similar mechanism. A typical representative organic reaction displaying this mechanism is the chlorination of alcohols with thionyl chloride, or the decomposition of alkyl chloroformates, the main feature is retention of stereochemical configuration. Some examples for this reaction were reported by Edward S. Lewis and Charles E. Boozer in 1952. Mechanistic and kinetic studies were reported few years later by various researchers.Thionyl chloride first reacts with the alcohol to form an alkyl chloro sulfite, actually forming an intimate ion pair. The second step is the concerted loss of a sulfur dioxide molecule and its replacement by the chloride, which was attached to the sulphite group. The difference between SN1 and SNi is actually that the ion pair is not completely dissociated, and therefore no real carbocation is formed, which else would lead to a racemisation. This reaction type is linked to many forms of neighbouring group participation, for instance the reaction of the sulfur or nitrogen lone pair in sulfur mustard or nitrogen mustard to form the cationic intermediate.This reaction mechanism is supported by the observation that addition of pyridine to the reaction leads to inversion. The reasoning behind this finding is that pyridine reacts with the intermediate sulfite replacing chlorine. The dislodged chlorine has to resort to nucleophilic attack from the rear as in a regular nucleophilic substitution.In the complete picture for this reaction the sulfite reacts with a chlorine ion in a standard SN2 reaction with inversion of configuration. When the solvent is also a nucleophile such as dioxane two successive SN2 reactions take place and the stereochemistry is again retention. With standard SN1 reaction conditions the reaction outcome is retention via a competing SNi mechanism and not racemization and with pyridine added the result is again inversion.".
- SNi thumbnail SNi_reaction_mechanism.gif?width=300.
- SNi wikiPageID "2726466".
- SNi wikiPageLength "4415".
- SNi wikiPageOutDegree "26".
- SNi wikiPageRevisionID "671530961".
- SNi wikiPageWikiLink 1,4-Dioxane.
- SNi wikiPageWikiLink Alcohol.
- SNi wikiPageWikiLink Category:Reaction_mechanisms.
- SNi wikiPageWikiLink Category:Substitution_reactions.
- SNi wikiPageWikiLink Cation.
- SNi wikiPageWikiLink Dioxane.
- SNi wikiPageWikiLink Halogenation.
- SNi wikiPageWikiLink Intimate_ion_pair.
- SNi wikiPageWikiLink Ion.
- SNi wikiPageWikiLink Lone_pair.
- SNi wikiPageWikiLink Neighbouring_group_participation.
- SNi wikiPageWikiLink Nitrogen.
- SNi wikiPageWikiLink Nitrogen_mustard.
- SNi wikiPageWikiLink Nucleophile.
- SNi wikiPageWikiLink Nucleophilic_acyl_substitution.
- SNi wikiPageWikiLink Nucleophilic_aliphatic_Substitution.
- SNi wikiPageWikiLink Nucleophilic_substitution.
- SNi wikiPageWikiLink Organic_reaction.
- SNi wikiPageWikiLink Pyridine.
- SNi wikiPageWikiLink Reaction_mechanism.
- SNi wikiPageWikiLink Reactive_intermediate.
- SNi wikiPageWikiLink SN2_reaction.
- SNi wikiPageWikiLink Sulfite.
- SNi wikiPageWikiLink Sulfur.
- SNi wikiPageWikiLink Sulfur_dioxide.
- SNi wikiPageWikiLink Sulfur_mustard.
- SNi wikiPageWikiLink Thionyl_chloride.
- SNi wikiPageWikiLink Walden_inversion.
- SNi wikiPageWikiLink File:SNi_reaction_mechanism.gif.
- SNi wikiPageWikiLinkText "SNi".
- SNi hasPhotoCollection SNi.
- SNi wikiPageUsesTemplate Template:Other_uses.
- SNi wikiPageUsesTemplate Template:Reaction_mechanisms.
- SNi wikiPageUsesTemplate Template:Reflist.
- SNi subject Category:Reaction_mechanisms.
- SNi subject Category:Substitution_reactions.
- SNi type Process.
- SNi type Reaction.
- SNi comment "SNi or Substitution Nucleophilic internal stands for a specific but not often encountered nucleophilic aliphatic substitution reaction mechanism. The name was introduced by Cowdrey et al. in 1937 to label nucleophilic reactions which occur with retention of configuration, but later was employed to describe various reactions that proceed with similar mechanism.".
- SNi label "SNi".
- SNi sameAs SNi_reaktsioon.
- SNi sameAs Interne_nucleofiele_substitutie.
- SNi sameAs m.07_7sg.
- SNi sameAs Q1092165.
- SNi sameAs Q1092165.
- SNi sameAs 分子内亲核取代反应.
- SNi wasDerivedFrom SNi?oldid=671530961.
- SNi depiction SNi_reaction_mechanism.gif.
- SNi isPrimaryTopicOf SNi.