Nucleophilicity versus Basicity   1 Nickels awarded! Tagged with:  academic    posted on 26 Sep 2008 15:17:32 IST
Nucleophilicity and basicity are very similar properties in that species that are nucleophiles are usually also bases (e.g. HO- , RO-). This is not too surprising since in the LEWIS sense, they are functioning as LONE PAIR donors (i.e. both are LEWIS BASES), compare the two pairs of reactions mechanisms shown below to convince yourself. However, it can avoid confusion by keeping these two types of reactivity separated because there are important differences.... 1. Nucleophilicity:   Both these reactions depict a nucleophile reacting with an electrophilic C atom   Kinetically controlled reactions of lone pair donor with an electrophilic carbon (usually) atom resulting in the formation a new C-X bond. 2. Basicity: Both these reactions depict a base reacting with an electrophilic H atom, a proton Equilibrium (thermodynamic) reaction of the lone pair donor with a proton, forming a new H-X bond The following general reaction mechanisms show you why it is important to appreciate the differences, since an anion that is reacting as a nucleophile will result in a substitution, but if it reacts as a base, then elimination will result, be it on a carbocation (SN1 vs E1) or with the loss of a leaving group (SN2 vs E2).     Substitutions SN1 SN2       Eliminations E1 E2 Comment and rate.................	About the Author: reddevil_2009 (1769) Blazing goIITian  311  [418 rates] total posts: 1007     Offline
this article: 10 points  (with 2    in 2 votes )   [?]   You have to be logged on to rate

Go to:  Select a forum   Physics   General Physics   Mechanics   Optics   Thermal Physics   Electricity   Magnetism   Modern Physics   Mathematics   Algebra   Trignometry   Analytical Geometry   Differential Calculus   Integral Calculus   Vectors   Chemistry   Physical Chemistry   Organic Chemistry   Inorganic Chemistry   Biology - for AIPMT Appearing   Botany   Zoology   Institutes & Courses   Coaching Institutes & Course Material   About IITs and JEE   Non IIT Institutes   Counselling Zone   Parents Corner   Parent Discussion Board   Board Exams - CBSE, ICSE, State Boards   Course Material   Computer Science   Fun Zone   Lounge   Games, Puzzles and Quizzes   General Knowledge   Other Courses   GATE   Commerce Streams   Business Administration   Civil Services   Law Entrance   Banking Careers   Fashion designing   Computer Applications