Preparation of acetophenone from benzene and acetyl chloride

A Friedel-Crafts acylation reaction between toluene and acetyl chloride produces 4-methyl acetophenone; whereas, the reaction between benzaldehyde and acetylchloride produces 3-acetyl-benzenecarbaldehyde. The reason for the difference in position of where the acetyl group attaches is due to the group already substituted onto the benzene ring.

Both the reactions are electrophilic substitution reactions, but as the benzene ring already has something attached to it, you have the problem of where the incoming group will attach. The group that is already attached is classified as either activating or deactivating towards the aromatic ring, where activating groups tend to stabilise the intermediate by donating electrons into the ring, whilst deactivating groups draw electron density out of the ring.

In the first example, the methyl group of toluene is activating and donates electron density into the ring. These regions are therefore most reactive towards an electron poor electrophile as there is now a higher electron density here.

Generally the highest electron density is at the ortho 2 positionbut in this case, the acetyl group goes to the para 4 position due to steric effects. In the case of benzaldehyde, the opposite is happening. Electron density is pulled out of the ring structure.

THis therefore leaves more electron density around the meta 3 position and so the incoming, electron poor, group is directed here as that is where there is the highest electron density.

The result: with toluene, the acetylation occurs at position 4, and with benzaldehyde it happens at position 3 giving you: 4-methyl acetophenone and 3-acetyl-benzenecarbaldehyde respectively.

Fully explain these reactions. Answer Save. Andrew G. Erika Lv 4. Friedel Crafts Acylation Of Toluene. This Site Might Help You. RE: A Friedel-Crafts acylation reaction? Still have questions? Get your answers by asking now.This page gives details of the Friedel-Crafts reactions of benzene and methylbenzene toluene.

The mechanisms for some of these reactions are covered elsewhere on the site and you will find links to those as you go along.

preparation of acetophenone from benzene and acetyl chloride

An acyl group is an alkyl group attached to a carbon-oxygen double bond. If "R" represents any alkyl group, then an acyl group has the formula RCO.

A Friedel-Crafts acylation reaction...?

Acylation means substituting an acyl group into something - in this case, into a benzene ring. The most commonly used acyl group is CH 3 CO. This is called the ethanoyl group, and in this case the reaction is sometimes called "ethanoylation". In the example which follows we are substituting a CH 3 CO- group into the ring, but you could equally well use any other acyl group.

The most reactive substance containing an acyl group is an acyl chloride also known as an acid chloride.

US6384285B1 - Process for the preparation of 4′-isobutylacetophenone - Google Patents

These have the general formula RCOCl. Benzene is treated with a mixture of ethanoyl chloride, CH 3 COCl, and aluminium chloride as the catalyst.

You may find slight variations on the conditions for this reaction. Various recipes I have found vary the temperature and time - for example by having a slightly lower temperature for a longer time. The aluminium chloride isn't written into these equations because it is acting as a catalyst.

If you wanted to include it, you could write AlCl 3 over the top of the arrow see below. The reaction is just the same with methylbenzene except that you have to worry about where the acyl group attaches to the ring relative to the methyl group.

Normally, the methyl group in methylbenzene directs new groups into the 2- and 4- positions assuming the methyl group is in the 1- position. In acylation, though, virtually all the substitution happens in the 4- position. The reason that you get virtually none of the 2- isomer in this instance is because of the size of the incoming acyl group.

Everything gets too cluttered and therefore less stable if you try to put the acyl group next door to the methyl group. Alkylation means substituting an alkyl group into something - in this case into a benzene ring.

A hydrogen on the ring is replaced by a group like methyl or ethyl and so on. Benzene reacts at room temperature with a chloroalkane for example, chloromethane or chloroethane in the presence of aluminium chloride as a catalyst. On this page, we will look at substituting a methyl group, but any other alkyl group could be used in the same way.

preparation of acetophenone from benzene and acetyl chloride

You get further methyl groups substituted around the ring. You can improve your chances of just getting monosubstitution by using a large excess of benzene. You will find the mechanism for this reaction in the mechanisms section of this site. Again, the reaction is just the same with methylbenzene except that you have to worry about where the alkyl group attaches to the ring relative to the methyl group. Unfortunately this time there is a problem! Where the incoming alkyl group ends up depends to a large extent on the temperature of the reaction.Reaction Mechanism Generation of Electrophile Friedel Crafts Acylation Notes In a Friedel Crafts Acylation Reaction benzene reacts with acyl halides in the presence of a Lewis acid an aluminium halide to give 1-phenolalkanones phenol ketones.

An example of this is the preparation of 1-phenolethanone acetophenone from benzene and acetyl chloride, by using aluminium chloride as the Lewis acid.

The reaction can be stopped at the monosubstitution stage, the acyl group prevents further substitution because of the electron withdrawing effect of the acyl group. In this reaction there is a formation of a complex between the resulting ketone and the aluminium chloride.

Because of this more than one mole of Lewis acid is needed per mole of benzene for the reaction to reach completion. Carboxylic acid anhydrides are sometimes used instead of acyl chlorides. Acylation involving acid anhydrides is most useful in the case of cyclic compounds. Uses Monosubstituted alkybenzenes can be synthesised via acylation without the problem of group rearrangement or polysubstitution.This page looks at the reaction of acyl chlorides acid chlorides with benzene in the presence of an aluminium chloride catalyst.

This is known as a Friedel-Crafts acylation. Acylation is the term given to substituting an acyl group such as CH 3 CO- into another molecule. An acyl group is a hydrocarbon group attached to a carbon-oxygen double bond.

For UK A level purposes, the most commonly used example of an acyl group is the ethanoyl group, CH 3 CO- and so that's the one we will stick with throughout. So, if you react benzene with ethanoyl chloride in the presence of an aluminium chloride catalyst, the equation for the reaction is:. In the simplified formula for the product, the phenyl group is usually written on the left-hand side and the alkyl group to the right of the carbon-oxygen double bond - but I doubt if it really matters!

The aluminium chloride isn't written into these equations because it is acting as a catalyst. If you wanted to include it, you could write AlCl 3 over the top of the arrow. Ethanoyl chloride is added carefully to a mixture of benzene and solid aluminium chloride in the cold.

Hydrogen chloride gas is given off. Separating the product from the reaction mixture is fairly long-winded and beyond the scope of this site. You may find slight variations on the temperature and time for this reaction. Friedel-Crafts acylation is a very effective way of attaching a hydrocarbon-based group to a benzene ring. Although the product is a ketone a compound containing a carbon-oxygen double bond with a hydrocarbon group either sideit is easily converted into other things.

The carbon-oxygen double bond can be reduced to give a secondary alcohol, which in turn can undergo a whole lot of other reactions. That page doesn't deal specifically with this particular ketone, but the same principles apply. This is known as the Clemmensen reduction and involves heating the ketone with amalgamated zinc a mixture of zinc and mercury and concentrated hydrochloric acid for a long time.

It is possible to attach an alkyl group directly to the ring, but it is impossible to stop at substituting just one. An alkyl group attached to the ring makes the ring more reactive than the original benzene.

That means that something like ethylbenzene reacts faster than benzene itself. The result is that you get several ethyl groups substituted around the ring rather than just one. Attaching an acyl group to the ring makes the ring so unreactive that it won't substitute a second one.

Use the BACK button on your browser if you want to return to this page. If this is the first set of questions you have done, please read the introductory page before you start.

Friedel-Crafts acylation of benzene Background and equations Acylation is the term given to substituting an acyl group such as CH 3 CO- into another molecule. So, if you react benzene with ethanoyl chloride in the presence of an aluminium chloride catalyst, the equation for the reaction is: Or, simplifying it without drawing the benzene ring: In the simplified formula for the product, the phenyl group is usually written on the left-hand side and the alkyl group to the right of the carbon-oxygen double bond - but I doubt if it really matters!

The product is called phenylethanone old name, acetophenone. Use the BACK button on your browser to return to this page. Doing the reaction Ethanoyl chloride is added carefully to a mixture of benzene and solid aluminium chloride in the cold.

Why the reaction is important Friedel-Crafts acylation is a very effective way of attaching a hydrocarbon-based group to a benzene ring. For example: The carbon-oxygen double bond can be reduced to give a secondary alcohol, which in turn can undergo a whole lot of other reactions.

Phenylethanone can also be reduced to produce ethylbenzene. This indirect route is the best way of getting an alkyl group attached to a benzene ring.An aldol condensation reaction reacted the acetophenone with 4-bromobenzaldehyde. The synthesis scheme is seen below. Introduction Isoxazoles have been of interest to many chemists for many years. Although still relatively new, chemists are finding many different uses for these types of compounds.

One use of isoxazoles are as herbicides. From a patent for a 4-substituted isoxazole herbicide, these compounds are able to inhibit the growth of certain plants. Another interesting use of these compounds is in the medical field. A 3-unsubstituted isoxazole ring is found in the anti-inflammatory drug leflunomide.

Studies have been conducted on the N-O bond cleavage to try to determine what about this ring opening gives rise to its anti-inflammatory properties. These are only two of the many uses of this group of compounds. Equipment and Reagents The masses of the compounds in the synthesis were obtained using a Mettler AE analytical balance.

A Hewlett Packard B mass spectrometer was used to acquire a mass spectrum of the samples to analyze the structural makeup and the atoms present in each product. Each sample was dissolved in methanol in order to be injected into the instrument. Experimental Acylation The week before, the appropriate glassware was set in a drying oven to remove any moisture.

The apparatus in Figure 1 was assembled. Figure 1: Apparatus for Friedel-Crafts acylation3. In a hood, The aluminum chloride was transferred into the mL three-necked flask and 15 mL dichloromethane was used to transfer any remaining traces and rinse the neck of the flask.

A stir bar was added to the flask and the stopper was replaced. A steady flow of water was circulated through the condenser throughout the reaction. Approximately 7. The acetyl chloride solution was slowly added over twenty minutes to the aluminum chloride.Reference may be made to a publication by Baddley et al.

Reference may be made to a U. The draw-backs in the above processes are the use of stoichiometric amounts of anhydrous aluminium chloride, an hazardous material that leaves large amount of solid wastes after the reaction and tedious separation process from the alumina gel to obtain the product.

Reference may be made to a Japanese patent publication Early disclosure No. Reference may be made to U. The draw-bracks in the above processes are hydrogen fluoride is extremely toxic, corrosive, generation of large amount of solid wastes after the reaction and need for industrially expensive equipment to work with hydrofluoric acid.

Friedel Crafts Alkylation of Benzene Reaction Mechanism - Tons of Examples!

The inherent disadvantages in the use of conventional Lewis acid metal chlorides for Friedel-Crafts acylation are that they are non-regenerable and require more than stoichiometric amounts because of complexation with the carbonyl product formed. Work-up to decompose the resultant intermediate complex by hydrolysis forms a large amount of waste product and separation is lengthy and expensive.

Moreover the catalyst should be simple to separate and reusable. Another object of the present invention is the use of the nano- and microcrystalline and metal exchanged nano- and microcrystalline zeolite beta as catalysts.

Still another object of the present invention is the use of acetic anhydride as an acylating agent. Still another object of the present invention is the use of isobutylbenzene as the reaction solvent.

Still another object of the present invention is the ratio of isobutylbenzene and acylating agent is to The novelty of the present invention lies in the use of nanocrystalline and microcrystalline and metal exchanged nano- and microcrystalline zeolite beta for the acylation of isobutyl benzene for the first time. Decrease in particle size of zeolite beta, enhances the density of acidic sites and surface area of zeolites, which are essential factors to increase the activity of acylation reaction.

In fact the activity of these nano-and microcrystalline forms increases manifold over normal zeolites. As a result of this, the acylation of isobutyl benzene is effected successfully in reasonable yields for the first time. In an embodiment of the present invention metal exchanged, nanocrystalline and microcrystalline zeolite beta are used as the catalysts. In yet another embodiment of the present invention acetic anhydride is used as an acylating agent.

In still another embodiment of the present invention the catalyst is separated by filtration from the reaction mixture. In the nano- and microcrystalline zeolite by the density of the acidic sites increases because of increased number of broken edges resulted from the broken aluminium silicate rings.

Synthesis of aspirin from salicylic acid using acetyl chloride and pyridine

The surface area of these particles is also increased due to reduction of the particle size of zeolites. The higher density of acidic sites eventually increases number of acyl cations generated in the reaction in the electrophilic substitution of the Freidel-Crafts acylation and thus enhances activity of the reaction.

Thus the higher density of acid sites present in nano- microcrystalline, metal exchanged zeolite beta are responsible for the Friedel-Crafts acylation of isobutyl benzene for the first time. Nanocrystalline, microcrystalline and metal exchanged zeolite beta were prepared as described in example 1 and employed them in the acylation of isobutylbenzene with acetic anhydride as an acylating agent as described in examples.

The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the invention. Water is added to tetraethylortho silicate and stirred. To this solution aluminium nitrate, nonahydrate in tetraethylammonium hydroxide solution is added dropwise by a pressure regulating funnel under stirring.

Then the solid was filtered and air dried. Nanocrystalline zeolite beta was synthesised with different particle size 10 nm to nm from the homogenised solution prepared in the first step of zeolite beta which is kept for crystallisation at different times by decreasing ageing time to control the nucleation growth of zeolite during the synthesis.

A mixture of isobutylbenzene 40 mmolacetic anhydride 10 mmol and zeolite beta catalyst 0.

preparation of acetophenone from benzene and acetyl chloride

After completion of the reaction followed by G. Yield: 0. A mixture of isobutylbenzene 1. Yield A mixture of isobutylbenzene 40 mmolacetic anhydride 10 mmol and microcrystalline zeolite beta-II catalyst 0.

Example Time Isolated yield No. The present process eliminates the use of corrosive and stoichiometric quantities of aluminium chloride.Remember me. Method of preparation. Email based Chemistry assignment help - homework help at Expertsmind. Are you searching chemistry expert for help with Acetophenone or Acetyl Benzene questions? Acetophenone or Acetyl Benzene topic is not easier to learn without external help? Live tutors are available for 24x7 hours helping students in their Acetophenone or Acetyl Benzene related problems.

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