Nitration of paraffinic compounds gas phase reaction unlike aromatic compounds the paraffinic compounds are quite inert to nitrating agent. Sulfuric acid is the stronger acid and it protonates the nitric acid on the oh group so that a molecule of water can leave. Stationary points were located and characterized by the dft procedures at. The sulfuric acid behaves as a catalyst, and allows this nitration reaction to proceed at a lower. Nitration of bromobenzene by electrophilic aromatic substitution important concepts electrophilic aromatic substitution reactions nitronium ion as an electrophile activating vs deactivating groups o,pdirectors vs meta directors using resonance structures to predict substitution pattern part a, p. It is generated from a lewis base, nitric acid, in the presence of a lewis acid catalyst, sulfuric acid.
Nitration is important synthetically because it is one of the best ways to add an amino group to a benzene ring. The term is also applied somewhat incorrectly to the different process of forming nitrate esters between alcohol derivatives and nitric acid, as. This video also helps you understand the role of the acid catalyst before and during the reaction. Pdf a theoretical study of the nitration of benzene by acyl nitrates catalyzed by. When benzene is treated with concentrated nitric acid and concentrated sulphuric acid at below 55 o c temperature, nitrobenzene is formed. Nitration is a general class of a chemical process for the introduction of a nitro group into an organic chemical compound. Bromine itself is not electrophilic enough to react with benzene. Directing effects of substituents when a monosubstituted benzene undergoes an electrophilic aromatic substitution reaction, three possible disubstitution products might be obtained. Nitration of methyl benzoate resource rsc education. Full text get a printable copy pdf file of the complete article 993k, or click on a page image below to browse page by page.
The nitration of a benzene ring is an electrophilic aromatic substitution reaction, andits general mechanism is summarized in figure 2. Nitration of benzene firstly involves the formation of a very powerful electrophile, the nitronium ion, which is linear. Benzene reacts with concentrated nitric acid at 323333k in the presence of concentrated sulphuric acid to form nitrobenzene. Dft study on nitration mechanism of benzene with nitronium. All electrophilic aromatic substitution reactions occur by similar mechanisms. Nitration, sulphonation and halogenation class 11 notes. As the aromaticity of benzene is not disturbed in the reaction, these reactions are highly spontaneous in nature. The nitration process is a general class of chemical process for the introduction of a nitro group no 2 into an organic chemical compound. Nitration reactions can proceed via a free radical and an ionic mechanism olah et al. In the second step, this intermediate is deprotonated by water and nitrobenzene is obtained.
More loosely the term also is applied incorrectly to the different process of forming nitrate esters between alcohols and nitric acid, as occurs in the synthesis of nitroglycerin. Nitration is an example of electrophilic aromatic substitution. Mechanism and regioselectivity of electrophilic aromatic. Facts and mechanism for the nitration of benzene an electrophilic substitution reaction between benzene and nitric acid. Nitration methods and mechanisms pdf nitration methods and mechanisms pdf nitration methods and mechanisms pdf download. Benzene reactions sulphonation of benzene and nitration.
Mechanism of nucleophilic addition reaction of aldehyde. Mechanism of aromatic nitration accounts of chemical. A substituent x is said to be activating if the rate of electrophilic aromatic substitution of the substituted benzene c 6h 5x is faster than benzene. Reactions of aromatic compounds rutgers university. Lab report 11 nitration of methylbenzoate ch 238 uab. If you want the nitration mechanism explained to you in detail, there is a link at the bottom of the page. Nitration of toluene electrophilic aromatic substitution. This ion is formed by the reaction between the concentrated nitric acid and concentrated sulphuric acid. A substituent x is said to be deactivating if the rate of electrophilic aromatic substitution of the substituted benzene c 6h 5x is slower than benzene. This is one of many videos provided by clutch prep to prepare you to succeed in your college. A reaction profile for the nitration of benzene with nitronium ion has been successfully calculated for the first time. Because the nitronium ion is a good electrophile, it is attacked by benzene to produce nitrobenzene. Protonation of the hydroxy group of the nitric acid. Mechanism of nucleophilic addition reaction catalysed by alkalis.
As mentioned above, nitration simply means that we are adding a nitro group to an aromatic or benzene ring. Useful as a selective and mild nitration methodfor example, allowing. Eas aromatic nitration reaction and mechanism video. Organic chemistry eas aromatic nitration reaction and mechanism tutorial video this video shows you a step by step mechanism for the formation of nitronium, which is the super electrophile that is attacked by benzene in the nitration reaction. This page gives you the facts and a simple, uncluttered mechanism for the electrophilic substitution reaction between benzene and a mixture of concentrated nitric acid and concentrated sulphuric acid. Mechanism of nucleophilic addition reaction of carbonyl group. Nitration of benzene mechanism in easy steps youtube. The real structure is an intermediate of these structures represented by a resonance hybrid. Benzene reactions sulphonation of benzene and nitration of. Nitration of benzene mechanism electrophilic aromatic substitution reactions duration.
The overall reaction for the nitration of methyl benzoate. Nitration of bromobenzene is an electrophilic aromatic substitution reaction. This page gives you the facts and a simple, uncluttered mechanism for the electrophilic substitution reaction between benzene and a mixture of concentrated nitric acid and concentrated sulfuric acid. Electrophilic and free radical nitration of benzene and. The reaction is regioselective and produces predominantly methyl 3nitrobenzoate. Nitration of bromobenzene by electrophilic aromatic. Pdf a dft study of nitration of benzene by acyl nitrate catalyzed. This occurs following the interaction of two strong acids, sulfuric and nitric acid. H 2 so 4 here, h 2 so 4 acts as a an acid and hno 3 as a base entrancei chemistry doubts page consist of more questions for reference. Vogels elementary practical organic chemistry, longman group ltd. To get reaction on the pyridine ring, the noxide can be used as with pyridine itself. In the first step, an intermediate is formed by nucleophilic attack of the benzene to the nitronium ion. Benzene has 2 resonance structures but taken individually none show the delocalisation of electrons and they can exist at the same time as electrons are delocalised. In this experiment the students nitrate methyl benzoate.
If you substitute a nitro group, no 2, into the benzene ring in methylbenzene, you could possibly get any of the following products the carbon with the methyl group attached is thought of as the number 1 carbon, and the ring is then numbered around from 1 to 6. Nitration of benzene mechanism electrophilic aromatic. In aromatic nitration, aromatic organic compounds are nitrated via an electrophilic aromatic substitution mechanism involving the attack of the electronrich benzene ring on the nitronium ion. Mechanism of nucleophilic addition reaction of ketone. Loss of the leaving group, a water molecule provides the nitronium ion, the reactive electrophile. More recently, solid acid catalysts have been used with nitric acid for nitration of aromatic compounds, including pyridine. The nitronium ion acts as an electrophile in the process which further reacts with benzene to form an arenium ion. The mechanism is believed to proceed via an nnitropyridinium nitrate salt similar to the above mentioned nitration using dinitrogen pentoxide scheme 9 1993jcm156, 1995sl383. The elctrophilic substitution reaction mechanism for nitration of benzene. Parrafins can be attacked by certain atoms and free radicals. Nitration methods and mechanisms pdf xii 330 pp, dm. Basic examples of electrophilic substitution reaction of benzene are nitration, sulfonation, halogenation, friedel. The elctrophilic substitution reaction mechanism for nitration of benzene the formation of the electrophile.
Substituents that cause this result are called mdirectors and they usually deactivate the ring. Note that in this reaction and in others that follow, only one of the six benzene hydrogens is shown explicitly to emphasize that one hydrogen is lost in the reaction. In the case of benzene, the hybrid structure is the one below the one you learn at school. In spite of that, the reaction follows a different mechanism from the one in a. This can be done by reducing the nitro group into an amino group through the process of hydrogenation. Nitration and sulfonation of benzene chemistry libretexts. Electrophilic aromatic nitration is one of the most thoroughly studied classes of organic reactions, and its mechanism has been intensely debated over many decades 1,2,3,4,5,6,7. The source of the nitronium ion is through the protonation of nitric acid by sulfuric acid, which causes the loss of a water molecule and formation of a nitronium ion. Electrophilic aromatic substitution nitration ucla chemistry. Nitration of methyl benzoate data and mechanisms ch 238.
Nitric acid accepts a proton from sulphuric acid and then dissociates to form nitronium ion. However, this reaction proceeds slowly, which is inconvenient dangerous since hot, conc. The first step in the nitration of benzene is to activate hno 3with sulfuric acid to produce a stronger electrophile, the nitronium ion. Benzene is highly prone to electrophilic substitution reactions compared to addition. Thermal free radical nitration of benzene and toluene with tetranitromethane in sharp contrast gave nearly statistical product distributions. The formation of a nitronium ion the electrophile from nitric acid and sulfuric acid is shown below. Electrophilic substitution of benzene is the one where an electrophile substitutes the hydrogen atom of benzene. The nitration of benzene is an electrophilic aromatic substitution reaction, in which a nitro group no 2 is introduced onto a benzene ring. This organic chemistry video tutorial provides a basic introduction into the nitration of benzene mechanism which is one of the most common. A good example is acridine, with two benzene rings, which gives four nitration products, all on the benzene rings.
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