With strong sterically hindered bases: Elimination occurs by an E2 mechanism 2º Alkyl Halides With strong bases and nucleophiles: A mixture of S N 2 and E2 reaction products are formed With strong sterically hindered bases: Elimination occurs by an E2 mechanism With weak nucleophiles or bases: A mixture of S N 1 and E1 products results
Nucleophile: A good nucleophile is needed. Remember from chapter 5: 1. Nucleophilicity roughly parallels Case 2: Weak Base: Strong bases favor elimination. If the nucleophile is a weak base...
Simple question but I’m having trouble Examples of weak nucleophiles. Does Hydrogen act as an electrophile or nucleophile in H30+? I first expected the Hydrogen atoms to act as nucleophiles seeing that H3O+ is positively charged; however, when looking at an electrostatic potential map even though the molecule is positively charged it still shows the Oxygen atom as . .
Strong Nucleophiles – • Usually anions with a full negative charge (easily recognizable by the presence of sodium, lithium or potassium counterions) • Participate in SN2-type substitutions Examples: NaOCH3 (any NaOR), LiCH3 (any RLi), NaOH or KOH, NaCN or KCN, NaCCR (acetylide anion), NaNH2, NaNHR, NaNR2, NaI, LiBr, KI, NaN3
Strong nucleophiles: This is VERY important throughout organic chemistry, but will be especially important when trying to determine the products of elimination and substitution (E1, E2, SN1, SN2)...
strong base, hindered nucleophile methoxide anion smaller, attacks more easily What Makes a Good Nucleophile? solvent hinders nucleophile from approaching electrophile. 4.Not obscured by too polar a solvent. So, SN2 reactions are usually run in medium polarity solvents; polar enough to dissolve ionic species, not so polar to cage the nucleophile.
Only a few acids and bases are strong. Therefore, the key to master this topic is to learn the list of strong acids and bases that you can find below. If you are presented with an acid or base that is not on this list, that means that acid or base is weak.
2. If p H of a solution is less than ‘7’ then it is acidic.. 3. If p H of a solution is greater than ‘7’ then it is alkaline.. 4. If p H is ‘7’ then the solution is neutral.