CHM247H1 Lecture Notes - Lecture 1: Infrared Spectroscopy, Green Chemistry, Sulfuric Acid

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5 May 2019

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In this lab, the main reaction involved dehydrating t-amyl alcohol with an acid catalyst (h2so4) to create a mixture of alkene products (2-methyl-2-butene (major) and 2-methyl-1-butene (minor), the products were then isolated through distillation and identified using gc analysis. T-amyl alcohol dehydration is a reversible reaction, and therefore distillation was used to push the reaction to the product side and ensure maximum yield and removing the products from solution as they were produced. To verify that the products were formed gc analysis was done and the two alkene products moved through the gc column at different rates. This helped identify them correctly based on their retention rates. The product was washed twice and then dried to prepare it for gc analysis. Gc analysis was used to identify the percent yield of each alkene product. For unknown analysis, using ir spectroscopy, 1h nmr and deductive reasoning four unknowns, c5h12o;

Related Questions

I want another 600 word discussion on 3-methyl-3-pentanol, here is the attached example if you need an idea. I don't want it to be the same.

"Discussion:

In this experiment, the 3-methyl-3-pentanol solution was being used in the dehydration process. The alcohol was a five carbons aliphatic hydrocarbon which one of the hydrogen atoms, H was substituted by one hydroxyl group, OH^-. Due to the low melting point, the pentanol appear in liquid form at room temperature. The dehydration process of alcohol converted pentanol which the hydroxyl group, OH^-was removed to become pentene. Pantene was a five carbons aliphatic hydrocarbon with a single double bond in the molecule. The solution was added with concentrated phosphoric acid in a 5-ml vial and was mixed together by swirling. The phosphoric acid was added as catalyze as such increased the rate of reaction in dehydration without affected the particular chemical reaction. The spin vain added into the solution in order to prevent over boiling of the solution.

The heating of mixture was carried out in a fractional distillation apparatus. As the mixture was heated, the alkene and water were produced as the products in the reaction. Besides, the side product and impurities of the reaction was being produced at the same time. The temperature of mixture when heating was fluctuated. During the temperature 80Â°C, the temperature of mixture dropped suddenly by 2Â°C and the temperature remained at 78Â°C constantly for few seconds. This was because some impurities or side products were being produced in the mixture which might had the boiling point of 78Â°C. The temperature of mixture dropped suddenly because the heat being was absorbed which used to break down the bonding of the side products. When the boiling point was reached, then temperature of mixture remained constant as the state of the side products are converted from liquid form to gaseous form. The temperature of mixture was increased until 107Â°C after all the side products were being converted.The temperature of mixture was reached to maximum at 107Â°C. This temperature was known as the activation temperature which the pentanol started to be dehydrated. In all the distillation process, some of the product was being lost since it washoled up in the apparatus which reduce the product yield. In order to maximize the yield, the mixture was continued to be heated at higher temperature range which more than the boiling point of pentanol. When the mixture was heated at 90Â°C-100Â°C, the water in the mixture pushed over the products into the receiving vial along the condenser. The products produced were collected in the same receiving vial.

Then, the receiving vial containing pentene, water and small amount of the impurities. Two layers liquid were presented in the receiving vial, one drop of distilled water was added into vial in order to determine the location of aqueous layer. Since the water droplet mixed with the lower layer, so the upper layer was determined as cloudy solution while the lower layer was aqueous layer. The upper cloudy layer was pentene with some impurities and water inside. The lower aqueous layer was removed and discarded. But, that is not easy to remove all the water in the receiving vial. So, anhydrous calcium chloride was being added. The purpose of adding of anhydrous calcium chloride was used to remove residual water in the organic solvent. It is known as drying agent in the organic solvent which are not dissolves in the solvent but drying the solvent. The calcium chloride clumped together with the water droplets as it solidified them. In another word, it reacted with water to form hydrates which was their preferred form when water was available. An excess drying agent should be used to ensure that all the water in solvent was removed. If the water remains in the materials collected, it could interfere with the analysis.Water had been successfully removed from the organic compound mixture, so it was very important to not reintroduce water into the mixture. The final distillation of unpurified 3-methyl-3-pentene must be done very carefully to obtain purified products. "

Hello, I need help answering the questions for this experiment, please.

Part A: Microscale Hydration of 2-Ethyl-1-butene Add 2.5 mL of water to a 10-mL round-bottom flask containing a stir bar. Place the flask in a heat block or sand bath at room temperature and carefully add 0.64 g of mercuric acetate with stirring. Stir the mixture until the solid has dissolved. Add 1.0 mL of diethyl ether. Attach a reflux condenser to the flask and adjust the flow of cold water through the condenser. Using a calibrated pipet, measure out 290 Î¼L of 2-ethyl-1- butene in a conical vial and add 1.0 mL of diethyl ether. Use a Pasteur pipet to transfer this solution in small portions to the stirred aqueous solution down through the con- denser. Stir vigorously for 45 minutes. Remove the condenser. Add 1.0 mL of 6 M NaOH to the mixture using a Pasteur pipet, followed by a solution of 0.50 g of sodium borohydride in 2.0 mL of 3 M NaOH. Stir the mixture vigorously for 15 minutes. A mercury precipitate should form at the bottom of the flask. Remove the apparatus from the heat block or sand bath and remove the condenser. Allow the precipitate to settle. Use a Pasteur filter pipet to transfer the supernatant liquid (both layers) to a centrifuge tube. Set aside the mercury and mercuric salts for proper disposal. Transfer the lower aque- ous layer to a second centrifuge tube. Place the diethyl ether layer in a 5-mL conical vial. Add 1 mL of diethyl ether to the aqueous solution in the centrifuge tube. Cap and swirl gen- tly. Carefully remove most of the ether layer and add it to the ether solution in the conical vial. Repeat the extraction with a second portion of 1 mL of diethyl ether. Add the ether layer to the ether solution in the conical vial and add a small portion of anhydrous sodium sulfate. After a few minutes use a Pasteur filter pipet to transfer the solution to a tared 5-mL conical vial containing a boiling chip. If doing IR characterization (below), put a few drops on a salt plate and run the IR spectrum now. Evaporate the diethyl ether using a heat block, a sand bath, or water bath (40â45Â°C). Weigh the vial to determine the weight of the prod-uct. Keep the vial capped during analysis because the product is volatile.

Characterization for Part A Gas-liquid Chromatography: Using a 10-Î¼L syringe, remove a 1-Î¼L aliquot and inject it onto a moderately polar or polar GC column. One or more peaks may be recorded on the chromatogram including a peak for any remaining solvent and peaks for any remaining starting material and product(s). Authentic samples of potential products (if available) and starting material should be used as standards. Refractive Index: Use a few drops of product to determine the refractive index and apply the appropriate temperature correction. 3-Methyl-3-pentanol has an RI (nD) of 1.419020, and 2-ethyl-1-butanol has an RI (nD) of 1.422020. Infrared Spectroscopy (optional): Transfer 2â3 drops of the diethyl ether solution con- taining the product(s) to a salt plate, and press a second plate against the first to spread out the liquid. Remove the plates from one another briefly and press together a second time. The liquid remaining should now be free or nearly free of diethyl ether. Obtain the IR spec- trum. Compare the spectrum to authentic 3-methyl-3-propanol (a tertiary alcohol) and 2- ethyl-1-butanol (a primary alcohol). 3-Methyl-3-pentanol shows strong C O absorption at 1380, 970, and 900 cmâ1; these bands are not present in 2-ethyl-1-butanol.

Results and Conclusions for Part A

1. Identify each of the peaks by comparison of GC retention times of observed peaks with standards.

2. Measure the areas of the peaks in the chromatogram to calculate the mass percent. The correction factors for the alcohol and the starting alkene are approximately equal.

3. Determine the extent of conversion of 2-ethyl-1-butene to alcohol.

4. Write a detailed mechanism for the formation of the observed product(s). 5. Using your mechanism from above, explain the predominance of the observed product.

Please help me with the following problem. It has many parts to it, but it is one question. Thank you in advance

Synthesis of 1-Bromobutane

Reaction Scheme

NaBr, H2SO4

CH3CH2CH2CH2OH---------------------> CH3CH2CH2CH2Br + NaHSO4 + H2O

H2O

Possible by-products:

1-butene (bp â6.3 ^oC), di-n-butyl ether, C₄H₉OC₄H₉, (bp 141 ^oC)

Properties of reagents and product:

Substance	Mol Wt. (g/mol)	Density (g/ml)	bp, ^oC	Solubility	Hazards
1-butanol	74.12	.81	117-118	Sol water, Miscible alc, ether, and more	Flammable, irritant
H₂SO₄ (con)	98.07	1.84	280	X	corrosive material
sodium bromide	102.89	X	X	X	X
1-bromobutane	137.03	1.27	101.6	Insol in water; sol in alcohol, ether	Flammable, irritant

Quantities used in the reaction and yield data:

Substance	g or mL	Calculated moles	Theoretical Yield moles grams		Actual Yield, grams
1-butanol	mLs		x	x	x
H₂SO₄ (con)	11.5 mL		x	x	x
sodium bromide	13.3 g		x	x	x
Water	15.0 mL	x	x	x	x
1-bromobutane	x	x			Want 7.5 g

A. Assume the above synthesis of 1-bromobutane is known to proceed in 75% yield and you would like to prepare 7.5 g of material. Back calculate how many mLs of 1-butanol you will need for the reaction to synthesize the 7.5 g of product, assuming that the 1-butanol is the limiting reagent. Place this number in the table. Also, calculate all the remaining missing data to fill the table.

Experimental Procedure: The NaBr, 1-butanol, and water are combined in a round-bottomed flask containing a stir bar and cooled to 0 ^oC. Concentrated sulfuric acid is slowly added with stirring. The reaction flask is then prepared for a 50-minute âbriskâ reflux using a heating mantle. After reflux, two layers will be present. The condenser is removed and replaced with a distillation apparatus. Distill the mixture, recording the temperature range, until no more water- insoluble droplets are collected and the temperatures reaches around 115 ^oC. (The boiling point is elevated due to azeotropic distillation of the water with the 1-bromobutane and increasing amounts of sulfuric acid).

B. Propose a way that you could test if the droplets coming over are âwater-insolubleâ.

Be specific with the manipulations, glassware, and what observation you would see.

The collected liquid is transferred to a separatory funnel and 10 mL of water is added. Two layers form, the bottom being the 1-bromobutane layer. The layers are separated, one through the bottom and one through the top, and the separatory funnel is cleaned and dried. The bromobutane layer is returned to the separatory funnel and washed with ice-cold sulfuric acid to remove traces of the starting material, butene and ethereal by-products.

C. Will the top or bottom layer be the bromobutane layer when washing with concentrated sulfuric acid? Why?

The sulfuric acid layer is removed and the 1-bromobutane is washed with 10 mL 3 M NaOH followed by 10 mL aqueous sodium chloride (brine).

D. What is the purpose of each of these washes?

NaOH â

Brine -

Care should be taken to save the correct layer. The 1-bromobutane is then dried over anhydrous CaCl₂.

E. How will you decide how much drying agent to use? How will you know that the 1-bromobutane is dry.

The product is distilled to obtain a clear, colorless liquid.

F. TLC â Suppose you wanted to follow the above reaction by TLC.

a. Describe how you would go about finding a good solvent or solvent pair to use.

b. Suggest a specific solvent system you would try.

c. Draw below what you would want the TLC plate to look like and show the expected relative R_f values for the 1-butanol and 1-bromobutane. Label the spots, baseline, and solvent front.

CHM247H1 Lecture Notes - Lecture 1: Infrared Spectroscopy, Green Chemistry, Sulfuric Acid

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