Remove the flask containing the reaction mixture from the ice bath and set in on the bench top. Your sample should be a free flowing slurry, meaning that there is enough liquid to keep the solid moving around. What factors are responsible for producing this as the only dialkylation product? How the alkyl cation is produced is not important. Show the product to the instructor when you turn in your lab notebook for grading on the day you complete the experiment. In order to collect your solid material, you will do a vacuum filtration.
Allow the reaction mixture to gradually warm up to room temperature. The purpose of this cooling is to prevent a large increase in temperature when the concentrated sulfuric acid is added. Very carefully, add a drop of water to the mixture. The reaction we will be performing actually takes advantage of that fact, as the dialkylation product shown above is not only the desired product, but it is the only product. Day 1: This is a small scale experiment, so it is crucial that you are careful, or you will end up with no product.
The purpose of this experiment is to synthesize 1, 4-Di-t-butyl-2, 5 — dimethoxybenzene by reacting 1, 4 — dimethoxybenzene w ith tertiary-butyl alcoho l in the presence of sulfuric acid as a Lew is acid catalyst. Also, when a Pasteur pipet was used to remov e the solvent from the reactio n tube, many crystals were lost. While addition reactions occur for compounds containing either double or triple bonds, most reactions actually occur when one chemical or atom replaces something already on the molecule. Dramatic Enhancement of Catalytic Activity in an Ionic Liquid: Highly Practical Friedel-Crafts Alkenylation of Arenes with Alkynes Catalyzed by Metal Triflates C. Further Information Related Reactions Friedel-Crafts Alkylation This Lewis acid-catalyzed electrophilic aromatic substitution allows the synthesis of alkylated products via the reaction of arenes with alkyl halides or alkenes. These amounts will be your yield of both the crude and re-crystallized material.
You can use a little bit of methanol to add to the filter prior to adding your solid, but do not use water. Be sure to remove all plastic parts from your glassware, including graduated cylinder bases before heating. For aromatic compounds, where the aromaticity of the compound is maintained, electrophilic substitutions take place. Procedure Safety: Concentrated sulfuric acid is a strong oxidizer, and both it and acetic acid are highly corrosivewear gloves while handling them, and avoid breathing their vapors. You do not want to add too much methanol, but if you do, you can always evaporate some of it away.
The ob served melting point of the product was 96 - 98°C, which is considerably lower than the literature value of 104 — 105°C. Therefore, when an electron releasing group is added, it activates the ring for additional alkylation reactions. In the current experiment, we will use a different electrophile the t-butyl cation to alkylate 1,4-dimethoxybenzene. Wash the solid chemical collected on the filter with water in order to remove any water-soluble chemicals e. When you add your filter paper to the Buchner Funnel, do not wet with water, you must keep it dry. A valuable, two-step alternative is Friedel-Crafts Acylation followed by a carbonyl reduction. Add the cold sulfuric acid drop wise about 1 drop per second or slower to the cooled reaction mixture from above.
This is a Friedel-Crafts Alkylation reaction. The only real difference is how to produce the appropriate electrophile for reaction. Addition of Arylboronic Acids to Arylpropargyl Alcohols en Route to Indenes and Quinolines J. Electrophilic Aromatic Substitution: Friedel-Crafts Alkylation Objectives Substitution reactions are really at the heart of most organic reactions. Use a dry and clean 125-mL Erhlenmeyer flask for this reaction. This was lower due to the fact that many of the crystals were stuck in the reaction tube and could not be removed for weighing. After this 15-min period of drying your sample, you can use the crystalline material directly in a melt temp.
The important part is that a carbocation is used for this reaction. Iron-Catalyzed Synthesis of Tetrahydronaphthalenes via 3,4-Dihydro-2 H-pyran Intermediates R. Add enough methanol to dissolve the product. Stir with a glass stirring rod, then continue to add water dropwise with both cooling and mixing until 2. Dicationic Electrophiles from Olefinic Amines in Superacid Y. The t-butyl cation, which is used as the electrophile in this reaction, is a 3° carbocation which cannot rearrange, so it works quite well.
If the methanol is boiling, and all the solid has not dissolved add more methanol in 2-mL quantities until the boiling mixture is free of solid material. Remove the beaker and let it sit again at room temperature until crystals form. Continue to swirl the mixture occasionally during the warming up process. Allow the tube to remain at 20-25°C for approximately 10 minutes in order to complete the reaction. Let the vacuum continue to draw air over your sample, letting it dry by evaporating all of the methanol about 15 min.