Table of Contents
What is a meta director?
Meta director: In electrophilic aromatic substitution, a substituent that favors electrophilic attack meta to the substituent. Most meta directors are also deactivators. Bromination of nitrobenzene gives meta-bromonitrobenzene as the major product because the nitro group is a meta director. aq.
How can you tell if an ortho para or meta director?
If the relative yield of the ortho product and that of the para product are higher than that of the meta product, the substituent on the benzene ring in the monosubstituted benzene is called an ortho, para directing group. If the opposite is observed, the substituent is called a meta directing group.
What are ortho para and meta directing groups?
The groups that promote substitution at the ortho/para or meta positions are, respectively, called ortho/para and meta directing groups, which are often characterized by their capability to donate electrons to or withdraw electrons from the ring.
What are op directing groups?
Most o,p-directing groups are Activating Group. If electrophilic aromatic substitution of a monosubstituted benzene is faster than that of benzene under identical conditions, the substituent in the monosubstituted benzene is called an Activating Group.
Is Oh op directing?
since OH is +R/+M group thus provides e- to the benzene ring thus creates +ve charge on meta position and -ve charge on ortho and para position thus it is ortho para directing group…
Which groups are meta directors?
Examples of meta– directors include nitriles, carbonyl compounds (such as aldehydes, ketones, and esters), sulfones, electron-deficient alkyl groups, nitro groups, and alkylammoniums. Specific example: nitration of trifluoromethylbenzene gives the meta product in about 90% yield.
Is COOH a meta director?
Therefore, COOH is a strong meta director.
Why is no2 a meta director?
–NO2 group is meta directing because it is an electron withdrawing group. It decreases electron density at ortho– and para–positions thereby directs the incoming group towards meta-position.
Is meta directing group?
−CCl3 is a meta directing group. Because chlorine is more electronegative than carbon. So, it pulls the electron density towards itself and acts as a deactivating group on Benzene ring which gives generally meta substituents.
Are EWG meta directors?
Electron donating groups are generally ortho/para directors for electrophilic aromatic substitutions, while electron withdrawing groups are generally meta directors with the exception of the halogens which are also ortho/para directors as they have lone pairs of electrons that are shared with the aromatic ring.
Why is CHO group meta directing?
In other words -CHO group is deactivating in nature. Further the decrease in electron density is more at the o and p-positions therefore electrophilic substitution occurs only at m-position. Thus we can say that -CHO group in benzaldehyde is m-directing and deactivating.
Is nitro group op directing?
Yes, Nitro-group is meta-directing. The nitro group strongly deactivates the benzene ring towards electrophilic substitution. Nitro group is electron withdrawing group and thus causes electron deficiency at ortho and para positrons as is clear from the resonating structures of nitro benzene.
Why is COOH a meta director?
For example, a carboxylic acid is a meta director because it experiences resonance, a delocalization of electrons.
Why is meta deactivating?
The deactivating group directs the reaction to the meta position, which means the electrophile substitute the hydrogen that is on carbon 3 with the exception of the halogens that is a deactivating group but directs the ortho or para substitution.
Is COOH group meta directing?
Is meta a directing group?
Are all deactivating groups meta directors?
Deactivating group (meta directors) Halogens are an exception of the deactivating group that directs the ortho or para substitution. The halogens deactivate the ring by inductive effect not by the resonance even though they have an unpaired pair of electrons.
Is CN meta directing?
Meta-directing: Substituents which draw electron density from the ortho and para positions, hence increasing reaction on the meta position. Examples: -CF3, -NO2, -CN, Donation or withdrawal of electrons can occur via either a conjugative or an inductive effect.
What is the difference between meta directors and ortho/para directors?
Ortho/para directors are alkyl group or generally have lone pairs on the element attached to the benzene ring. Meta directors usually have an element with a double bond o attached to the benzene ring. When there are multiple substituents on the benzene ring, how do we know where the next one will go?
What is an example of a meta director?
We call the substituents which lead to this result “ meta- directors”. Examples of meta – directors include nitriles, carbonyl compounds (such as aldehydes, ketones, and esters), sulfones, electron-deficient alkyl groups, nitro groups, and alkylammoniums.
What are the examples of ortho para and meta products?
Examples of ortho-, para – directors are hydroxyl groups, ethers, amines, alkyl groups, thiols, and halogens. Here’s a concrete example: the nitration of methoxybenzene (also known as anisole). ortho- and para- products dominate, while meta – products comprise less than 3%. 2. meta- Directors
Are activating groups meta directors?
First: no activating groups are meta directors. Second: what’s up with the halogens? Yes indeed. What isup with the halogens, and how is it that they can be deactivating (i.e. slow down the reaction rate) and yetlead to ortho-, para- products?