Recitation Problems for Group Project- Overcoming Experimental Difficulties Sect
ID: 1034618 • Letter: R
Question
Recitation Problems for Group Project- Overcoming Experimental Difficulties Section Name Recitation problems may be collected randomly for a grade. These questions are designed to help your group think critically toward solving issues that might have been faced on your first day of experimentation, in order to make the rest of your lab time as efficient as possible. h) of researchers focusing on each reaction 1-3, but make sure these groups sit Form two groups (3-4 people eac next to each other. Answer the following questions in these new groups: 1. If you were unsuccessful in completing your synthesis on the first attempt, or if you achieved impure product, was the major obstacle to your success? What steps could you take during reaction preparation or reflux to improve this result? 2. Encountering problems during separation/purification is a very common issue in are crucial to isolate your desired product. Use your testbook or other sources to get an idea of the relative polarity/solubility of all possible compounds in compounds are listed with a relative polarity to water. b. What issues could arise during extraction if you had a significant amount of starting material present within your product mixture? e Which of the following would be less lkely to dissolve organie compounds, water or an aq, salt solution? Why? Reform your research groups. Share what you've learned then answer the following questions: 3. When analyzing your product by IR, what are a few reasons that you could receive false information based on the methods you used to prepare your sample for analysis? 4. Should your product elute before or after your starting material by gas chromatography (GC)? What is your reasoning? Remember, GC separates compounds by boiling point and polarity.Explanation / Answer
1. Since the product was not made successfully, so there could be a possibility of presence of some impurity in the product. So the major obstacle was the impurity present in the product which could be arrived due to following reasons:
(i) The reactants taken may contain some impurity. (ii) The reagents used may be impure. (iii) The impurities may be transferred from outer atmosphere.
To avoid this situation, I would try to carry out reaction with precautions. The reagents and reactants should be measured and weighed in clean beaker to avoid the entry of any impurity and reaction is carried out in a clean and in a proper state container with all safety equipments, such as fuming chamber to avoid entry of gases in reaction mixture. Mini work-up should be done to check the progress of reaction. Gloves should be worn by the person who is doing experiment to avoid any contamination and also for the safety purpose.
2. a) The compounds need to be separated depends upon the reaction which is carried out. Now these waste products are separated by dissolving them in the residual liquid so that the major required product is separated from residual liquid which will have then all the soluble impurities. The major principle of solubility is "like dissolves like". So if residual liquid is polar, then polar impurities will dissolve in it.
b) If there is presence of significant amount of starting material in the product mixture, then it will become difficult to extract product from it. There is possibility that the starting compound may go the ether layer which has the product also, and when product is extracted, then starting material will also get extracted with it. So now the actual product will be a mixture of starting material and desired product. In this case, starting material will be impurity for desired product.
c) Aqueous salt solution will not dissolve organic compounds in any case. This is because aqueous salt solution contains ions in it which will not dissolve organic compounds but water may dissolve some organic compounds containing O, N, Cl by forming hydrogen bonds, or with hydrocarbon with lesser number of carbon atoms (<4).
3. IR will give false information if the compound has impurities in it. So there could be the possibility that starting material is not completely utilized in a chemical reaction giving wrong IR. Or if there is formation of some other side products which are not separated from product mixture giving wrong IR. Other reason could be the impurity in solvent used for dissolving sample before taking IR.
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