Forming Methyl Orange an Azo Die
An synthetic azo dye was created by reaction of diazonium salt with N,N-Dimethylanaline. The final product created was 4-dimethylaminoazobenzene-4-sulfonic acid, an orange clay-like substance. Sulfanilic acid was chemically manipulated by using sodium carbonate followed by cooled sodium nitrate and hydrochloric acid to form the diazonium salt used in the reaction. The products were washed in ethanol. The product was obtained at an 84% yield and was characterized by its physical attributes.
Results and Discussion:
An adequate percent yield of 84% was obtained. These good yields are attributed to a efficient procedure. The 16% that was lost during the reaction can be attributed to experimental error as well as the possibility for side reaction. If the solutions were not properly cooled different materials could have been formed and is explained later in the discussion. To create the Diazonium salt, which reacted with N,N-Dimethylanaline to form the product both sodium carbonate and concentrated HCl was added to sulfanilic acid. The sodium carbonate accepts a hydrogen from sulfanilic acid a zwitterion therefore making it much more reactive later in the reaction. The concentrated HCl was used to form a nitrosonium ion from sodium nitrate. The oxygen attacks two hydrogen ions in solution and leaves as a water molecule. This process created the nitrosonium ion that reacts with the activated sulfanilic acid to create the diazonium salt. If an aqueous solution of diazotized sulfanilic acid were not kept below 5 degrees centigrade, the acid would quickly hydrolize to form a corresponding phenol. The lower temperature decreases the kinetic activity and the subsequent reaction rate of the diazotized salt, which allows for the HCl to react with sodium nitrate. At room temperature, the oxygen would attack the hydrogen of HCl and the Na molecule would form an ionic bond with Cl. This unwanted reaction would...
References: 1. Carl T. Wigal, Organic Chemistry Laboratory Manual: Chemistry Signature Labs. Mason Ohio: Thomson Brookes and Cole, 2007. 242-245
Please join StudyMode to read the full document