Abstraction:The intent of this experiment was to nitrate naphthalene with nitronium ion, which is formed at low concentration from a reaction of azotic acid and sulphuric acid. The percent output from the experiment was 54.4 % of the merchandise, and the runing point of the possible consequences were 59 °C for 1-nitronaphthalene, and 78°C for 2-nitronaphthalene.
Introduction:Polynuclear aromatic hydrocarbons such as naphthalene can be nitrated by the same methods as benzine derived functions, including the well-known “mixed acid” method that utilizes a mixture of azotic acid and sulphuric acid. The electrophile is the nitronium ion, NO2+ , which is formed at low concentration by a reaction of the two acids. The mononitration of naphthalene could take to either one of two merchandises, 1-nitronaphthalene or 2-nitronaphthalene. The intent of this experiment was to nitrate naphthalene with nitronium ion, which is formed at low concentration from a reaction of azotic acid and sulphuric acid. Chemical reaction:
Chemical reaction mechanism:
Safety Notes:Sulphuric acid and azotic acid can do really serious Burnss, and they react violently with H2O and other chemicals. Nitric acerb produces toxic N dioxide fumes during the reaction. Use baseball mitts and a goon, avoid contact with the acids, and do non take a breath their bluess. The nitro naphthalene is a suspected carcinogen ; avoid contact. The mixture of hexanes is really flammable ; maintain fires off. Procedure:
Into a 5-ml conelike phial, 1.0 milliliter of assorted 1:1 sulphuric acid and azotic acid was added. Approximately, 0.610 g of finely divided naphthalene was added in little parts to the solution while stirring after each add-on, and chilling to maintain the temperature around 45-50°C. The reaction mixture was so stirred in a 60°C H2O bath for 20minutes after the add-on of naphthalene. When the reaction cooled to room temperature, the solution was transferred to a beaker incorporating 20 milliliter of ice-cold H2O with stirring. Yellow crystals were allowed to organize, and so the liquid content was removed with filter-tip pipet.
The solid was so boiled with 10ml of fresh H2O for 10minutes. The mixture was cooled in ice and the merchandise was collected by vacuity filtration. 0.1 of the rough merchandise was so recrystallized for 5minutes with 5ml of hexane under reflux. The hot solution was filtered utilizing a preheated filtering paper. Crystallization occurred, and so the merchandise was cod by vacuity filtration. The merchandise was dried and the thaw and mass were measured of the merchandise, nitro naphthalene.
Discussion:The per centum output from the experiment was 54.4 % of the merchandise, which was low. This low per centum output might happen due to loss of the merchandise during reassigning or weighing. The runing point of the possible consequences were 59 °C for 1-nitronaphthalene, and 78°C for 2-nitronaphthalene. Even though there was disagreement in the consequences obtained from the experiment, the merchandise is more likely to be 1-nitonaphthalene because its thaw point was closer to that of the merchandise obtained. The disagreement in the consequence obtained may hold been from assorted beginnings during the experiment. During vacuity filtering, if non decently performed, some of the merchandise might hold been lost, hence diminishing the sum of the merchandise obtained. Another beginning might hold been from the add-on of naphthalene to the 1:1 mixture of azotic acid and sulphuric acid. The reaction likely did non to the full respond if the naphthalene was added at one time without stirring. Again, this might hold caused the disagreement in consequence. Decision:
The intent of the experiment, which was to synthesise nitro naphthalene, was accomplished through the method implemented in this experiment because of the similarity between the obtained merchandise and the predicted result. This experiment can be improved by cagily following the process, carefully adding the finely divided naphthalene in small sums in order to ease a good reaction between the nitronium ion and naphthalene.
Multiscale operational organic chemical science, by John W. Lehman, custom edition.