Preparation of Identification by Ir and Nmr Spectroscopy free essay sample

The reactive acid chloride can then be treated with a primary or secondary amine to give the amide along with HCl, which reacts with the excess amine to give an alkylammonium chloride salt. The mechanism of this process is shown on the following page in Scheme 22: [pic] Scheme 2 To carry out this reaction, the apparatus shown in Figure 1 will be assembled. The apparatus must be dry, since thionyl chloride will react with water to give sulfur dioxide and hydrogen chloride. The acid chloride will then be cooled to room temperature and dissolved in anhydrous ether. Ice-cold diethylamine will be added as a solution in anhydrous ether to form the amide. The resulting ether mixture will washed with aqueous sodium hydroxide (to remove any excess acid chloride), then washed with hydrochloric acid (to remove any excess diethylamine). The resulting ether solution of DEET will be dried and evaporated to yield the crude product, which will then be purified by column chromatography to afford pure DEET. We will write a custom essay sample on Preparation of Identification by Ir and Nmr Spectroscopy or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page The percent yield from m-toluic acid will be determined and the product will be analyzed by transmission infrared spectroscopy (IR) as a neat sample using NaCl plates5 to confirm its structure by (1) looking at the major absorptions and comparing them to a correlation table6 and (2) by comparing the spectrum to that of an authentic sample. Thionyl chloride is toxic and corrosive! Do not breath the vapors! Use in a hood! When heating a reaction apparatus, be sure that it is open to the air so that pressure build up and subsequent rupture of the apparatus does not occur. When heating liquids, make sure the liquid is stirred (or a boiling chip is added) to prevent â€Å"bumping†. When performing an extraction, make sure to vent the separatory funnel often to prevent pressure build-up. The apparatus shown in Figure 1 was assembled. The 10-mL reaction flask was charged with 0. 275 g of m-toluic acid (0. 0020 mol) and 0. 30 mL of thionyl chloride (0. 492 g, 0. 0041 mol). The condenser water was started, and the mixture was gently heated with stirring on an aluminum block (block temp ~ 90 oC) until boiling started. The reaction mixture was then gently boiled for about 15 minutes. After the boiling period was finished, the reaction mixture was cooled to room temperature. 4. 0 mL of anhydrous ether were added, and the mixture was stirred at room temperature until a homogeneous mixture was obtained. To this solution was added (dropwise over a 15 minute period) a solution of 0. 6 mL of cold (0 oC) diethylamine (0. 462 g, 0. 0063 mol) in 1. 33 mL of anhydrous ether. During the addition, a thick white cloud of diethylamine hydrochloride was formed. After complete addition, the reaction mixture was stirred at room temperature for about 10 minutes. 10% aqueous sodium hydroxide (2 mL) was then added, and the reaction mixture was stirred for an additional 15 minutes at room temperature, then poured into a separatory funnel and allowed to separate. The aqueous layer was discarded, and the organic layer was washed with an additional portion of 10% aqueous sodium hydroxide (2 mL), followed by a portion of 10% hydrochloric acid (2 mL). The organic layer was washed with water (2 mL), dried (Na2SO4) and evaporated to yield crude N,N-diethyl-m-toluamide as dark brown liquid. The crude product was filtered through a short alumina column using hexane as the eluent (~ 5 mL). The hexane solution was evaporated to give 0. 340 g of pure N,N-diethyl-m-toluamide as a yellow liquid. Reaction of m-toluic acid with thionyl chloride, followed by diethylamine produced 0. 340 g of a yellow liquid the IR spectrum of which unequivocally showed the presence of the amide carbonyl functional group at 1633 cm-1. In addition, absorptions due to aliphatic C-H (2980 – 2880 cm-1), and aromatic C=C (at 1585 cm-1). The IR spectrum is attached to this report. These data are consistent with the structure of N,N-diethyl-m-toluamide (DEET), shown in Figure 2 below: [pic] Figure 2: N,N-Diethyl-m-toluamide (DEET) In addition, the IR of the product closely corresponds with that of an authentic sample of N,N-diethyl-m-toluamide (DEET) shown in the lab text. 9 Also, the 1H-NMR shows the presence of four (4) aromatic protons in the region 7. 3 – 7. 1 ppm, as well as a three (3) proton singlet at 2. 35 ppm, which corresponds to the benzylic methyl group. The presence of two ethyl groups is clearly shown by the presence of two quartets which integrate to 2 protons each at 3. 53 and 3. 24 ppm, and two triplets which integrate to 3 protons each at 1. 23 and 1. 09 ppm.

What You Need To Know About Writing A Background Essay Sample

What You Need To Know About Writing A Background Essay SampleStudents in the US are expected to write a college essay, as part of their admission process. It is a part of the application to the college for which they are expected to write a speech or essay, in a short period of time. Nowadays, students have a variety of options when it comes to writing college essays.There are many topics that recent college students can write about, as well as issues that are really important to them. One such topic is why they choose to attend college in the first place. Some students who may not have been very good at academics, still find the subject interesting enough to write about. They might even get their teacher to suggest that they include a comment on the topic.Students can also write an essay on the subjects that are truly important to them. This could be about the money they need to get, or how much they want to do with the future of their children. Or, there are those students who like to write about the fashion of the year, as long as it reflects their taste and preferences. They will do well in doing so, as long as they understand that there are a wide range of ways in which they can express themselves, and the best way to do so is through a speech.In terms of writing a more personal essay, a background essay sample can be used. Background essays are often used by instructors as part of a portfolio. Most students will likely have a story about a bad experience that they had in school, or perhaps a time in their life when they were made fun of. They will also most likely share a hobby or interest, or a funny incident that happened while they were in school.These essays usually help students, when they are choosing how they will express themselves during their essay. It is an opportunity for them to talk about what they think are important things, to avoid the fear of what other people will think. By writing about something that has happened, students will not fe el too self-conscious about how their essay is written.The essay sample can also be used as an aide for choosing a topic. It is easy to find a topic that has been made popular by a certain television show, or a movie, or a book. A good student will pick a subject that they feel has something to say about themselves, and something that they have learned from other students, or the teachers.Background essays can be as complex or simple as the student would like it to be. By writing a college essay, students are given a chance to write about things that they have learned, or that have been told to them by someone else. It is usually the student's task to explain how this relates to the topic at hand. With today's technology, it is easier than ever to write a background essay sample, and students can even use it to show their professor how interesting their essay will be.