Table of Contents
Which is a better leaving than OH?
In general,bromide ion(Br-) is better leaving group than hydroxyl ion(OH-). The leaving group tendency depends upon the nucleophilcity. Weak acids conjugate base is stronger than Strong acids conjugate base. Weaker the conjugate base stronger the leaving tendency.
Which is better leaving group NH3 or H2O?
This can be explained by the “thumb rule” of the pKa. NH3 is more basic (pKb(NH3)=4.3) than H2O (pKb(H2O)=15.4) and therefore a worser leaving group.
Which is a better leaving group Br or OH?
OH is a much better nucleophile than Br ; this reaction would revert if it ever happened. So it doesn’t happen.
Is NH2 a good Nucleophile?
“The conjugate base is always a better nucleophile”. NH2(-) is a better nucleophile than NH3. HS(-) is a better nucleophile than H2S. The greater the negative charge, the more likely an atom will give up its pair of electrons to form a bond.
Is OH a good leaving group?
Alcohols have hydroxyl groups (OH) which are not good leaving groups. Because good leaving groups are weak bases, and the hydroxide ion (HO–) is a strong base.
Is NH2 better nucleophile than OH?
Now, since N is less electronegative than O, it’s lone pair is more readily available than that of OH−. So, according to me, NH2− should be more nucleophilic than OH−, but the answer given is the opposite, that is, OH− is more nucleophilic than NH2−.
Which is best leaving group?
Good leaving groups are weak bases. They’re happy and stable on their own. Some examples of weak bases: halide ions (I-, Br-, Cl-) water (OH2), and sulfonates such as p-toluenesulfonate (OTs) and methanesulfonate (OMs). The weaker the base, the better the leaving group.
Is NH2 a good base?
NH2- Acid or Base NH2- is a strong base because it is unstable with its negative charge in a solution so that it wants to take the edge off with a negative charge by accepting a proton and acting as a base.
Is NH2 or NH3 more stable?
The conjugate acid of NH2- is NH3, called ammonia. Ammonia is actually itself a weak base, so its conjugate base NH2- is an incredibly strong base so it can get an extra proton to regenerate NH3 which is much more stable.
What are considered “good” leaving groups?
Triflate, tosylate, and mesylate ions are excellent leaving groups, because the sulfonate ions can stabilize the negative charge via resonance. Good leaving groups are weak bases. These ions are weak bases because they are the conjugate bases of very strong sulfonic acids.
What makes a good leaving group?
Good leaving groups are groups that are stabilized in the reaction medium. In general, the conjugate base for a strong acid is a good leaving group, and indeed, you can apply the same rationale for why something is the conjugate base of a strong acid to why it’s a good leaving group.
What is leaving group organic chemistry?
In organic chemistry we use the term leaving group to refer to a portion of a reactant that will depart the rest of the molecule as a result of reacting with another reagent. This occurs often in organic chemistry reactions.
What is a good “leaving group?
Good leaving groups are weak bases. Consider a general nucleophilic substitution reaction. The second arrow always shows a pair of electrons going toward the leaving group. The best leaving groups “want” those electrons. They don’t want to share them with other atoms. Good leaving groups are weak bases. Weak bases have strong conjugate acids.