Why is i a good leaving group

First we should write the chemical equations for the two processes:. These two equations represent Bronsted acid dissociation and loss of a leaving group in a S N 1 type reaction. For acidity, the more stable A - is, then the more the equilibrium will favour dissociation, and release of protons meaning that HA is more acidic. For the leaving group, the more stable LG - is, the more it favours "leaving".

In some instances, the leaving group is bonded to a carbon center than neighbors a more substituted carbon center. Attack of the methanol hydroxyl group on the carbocation followed by proton abstraction by chloride leads to formation of the 3-methoxymethylpropane product.

The start of first semester organic chemistry can be an information overload. For the first few classes, you will review general chemistry concepts and then… the reactions start coming!

One of the first reactions that will be covered is the SN2 reaction, mainly because it is relatively straight forward and a good tutorial for how to describe reaction mechanisms.

In this article, we will review the important topics of an SN2 reaction. Sign up with StudyOrgo today to get detailed reaction mechanisms and explanations to stay on top of your class! One of the most reactive molecules involving substitution reactions are alkyl halides. However, there are a number of considerations to keep in mind to determine if the SN2 mechanism describes your reaction. The hydroxide will attack the carbon center and form a new bond with carbon which makes it the nucleophile and the chlorine atom will leave the carbon center with the electrons from the C-Cl bond which makes it the leaving group.

Inductive effects of leaving groups: Chloride is a good leaving group because of the inductive effects or electron withdrawing potential of the halogen atom. This is the characteristic of good leaving groups.

The electronegativity of chlorine makes the carbon center slightly electrophilic, meaning it has a partial positive charge, which is strongly attracted to electron-rich nucleophiles. Then you would look at the reaction conditions i. I ve seen alkoxides getting removed during sn2th reactions related to carbonyls. Minor fix needed on the first image: the reactants side is neutral while the products side is positive need to either add a negative formal charge to Nu or take off the negative formal charge from L.

Could u explain why F can become a leaving group when it is attached to a carbonyl carbon or an aromatic ring? Yes, F- is an OK leaving group in those situations nucleophilic aromatic substitution because the rate limiting step is attack of the aromatic ring disrupting aromaticity. Loss of the leaving group is slow compared to that step. Also, because F- is so electron withdrawing, F actually helps to accelerate the reaction by removing electron density from the ring and making it easier to attack.

James, someone mentioned the difference for F- between protic and aprotic solvents, do you mind shedding some light and clarity on this, please? This effect is biggest for fluorides because they are so small and not easily polarisable.

No matter the solvent, F will be a poor leaving group in nucleophilic substitution and elimination reactions. I- is a BLG than F- in aprotic solvents. F- is a BLG than I- in protic solvents. If something is a poor nucleophile it has to be BLG. I am right , right? Ex:F- in protic is much more stable than I- due h bond.

This is absolutely amazing. I will never be able to thank you enough or express how much this has helped me. Seriously, you are a god in my eyes right now. Awesome website, explains the any topic with ease. Thank you Mr. James for your remarkable efforts. You have made learning organic chemistry interesting through this website. For instance Cl- is a better leaving group than NH3. You need to break a bond and to form a relatively stable species. So if the bond is too strong e. C-F or if the leaving group is not very stable by itself stongly basic then the activation energy for this process will be too high for it to happen.

Does F- make an excellent leaving group? So for an E2 reaction it would leave? This might or might not be related to LG but could you please answer: Reaction of chloroform with alc. KOH and p-toluidine forms? This is abs9lutely amazing. I have been struggling since 2 years not being able to understand this. Thank you. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.

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Next 3 Factors That Stabilize Carbocations. So what makes a good leaving group?