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2. once the two pure melting points have been determined find a partner and together prepare 3 samples: one of 1:9 urea : cinnamic acid, one of 1:1 urea : cinnamic acid, and one of 9:1 urea : cinnamic acid. take the melting point of each of these mixtures. plot the graph of melting point vs. the composition of the sample. note: you can prepare a large batch of sample and share the materials among yourselves (take 10mg urea and 90 mg cinnamic acid for 1st sample and mix it together, ratio should be same).

Part ii. determination of an unknown substance

In this portion of the lab you cannot determine the identity of an unknown by comparing its melting point with the melting point of the three possible compounds. Mixing characteristics will be used instead to determine the identity.

1. Prepare three capillary tubes in the following manner. Take a piece of weighing paper and mix a small amount of the unknown with a small amount of the sample of diphenylacetic acid (1:1). Place this in a capillary tube. Then on a new piece of weighing paper, weigh a small amount of the unknown and mix it with a small amount of adipic acid. Place this in a capillary tube.

2.Place these three capillary tubes in the melting point apparatus and record in detail what occurs to each tube and at what temperature. Using this knowledge determine the identity of the unknown.

Experimental procedure for diels-alder

Cyclopentadiene dimerizes at ambient conditions. Because of this cyclopentadiene is purchased as the stable dimer dicyclopentadiene. In order to be of any use, the dimer must be cracked and distilled. Due to time constraints you will be given the cyclopentadiene that has been prepared by your TA.

Part iii. diels alder reaction

1.       Dissolve 0.20 g of powdered maleic anhydride in 1 mL of ethyl acetate in a test tube and then add 1 mL of petroleum ether. This combination of solvents is used because the product is too soluble in pure ethyl acetate and not soluble enough in pure petroleum ether.

2.To the solution of maleic anhydride add 200 mL (0.160 g) of cyclopentadiene and mix the reactants. Mixing can be accomplished by tapping the bottom of the test tube back and forth with your finger.

Safety: Be careful when injecting the cyclopentadiene into the test tube and make sure the test tube points away from you.

3.Crystals should begin to form, if no crystals begin to form scratch the inside of the tube with a pipette to initiate growth. The scratch marks on the inside of the tube often form the nuclei on which crystallization starts.

4.Should crystallization occur too rapidly at room temperature the crystals will be very small. If so, save a seed crystal, heat the mixture until the product dissolves, seed it and allow it to cool slowly to room temperature. You will be rewarded with large plate-like crystals.

5.Remove the solvent from the crystals with a pipette forced to the bottom of the tube. Wash the crystals with one portion of cold petroleum ether then again remove the solvent. Scrape the product onto a piece of filter paper, allow the crystals to dry in air, determine their weight, and calculate the yield of the product.

6.Take the melting point of the product.

7.Take and analyze an IR and NMR spectrum of your compound.

 Waste disposal

All capillary tubes are to be disposed of in the GLASS CONTAINER and NOT in the trash can!! Dispose organic substances in their proper containers.

Approximate lab time 2-2.5 hours

Report1: Diels-Alder and Melting Point(Total 30 points)

Here for the Report

Note: In preparing this report you are free to use references and consult with others. However, you may not copy from other students’work or misrepresent your own data (see honor code).

Name(Print then sign): ___________________________________________________

Lab Day: ___________________Section: ________TA__________________________

1. Draw the reaction and mechanism of maleic anhydride and cyclopentadiene. (4 points)

 

 

 

2. Show theoretical and percent yield calculations of the reaction between maleic anhydride and cyclopentadiene. (2 points)

 

 

3. What are the important IR frequencies and the functional group they correspond to? (2 points)

 

4. Analyze the NMR spectrum of the product. Draw the structure and assign each peak to the correct proton on the NMR spectrum. Are there any impurities? If yes, what are they? (4 points)

5. Write the major product of the following reactions with proper stereochemistry if required. (8 points)

Part 2: melting point (total 10 points)

1. Fill in the blanks: (5 points)

Melting Points of: Temperature in°C
Urea _________________________
Cinnamic acid _________________________
1:9 mixture _________________________
1:1 mixture _________________________
9:1 mixture _________________________

2. Draw a Plot of melting point versus composition of the mixture. (2 points)

 

3. Your explanation as to why your measured melting points do not match those in literature. (1 point)

4. Identity the unknown (Part II) product. (1 point)

5. Melting point of the DA product is: ____ (1 point)

Questions & Answers

What is price elasticity of demand and its degrees. also explain factors determing price elasticity of demand?
Yutansh Reply
Price elasticity of demand (PED) is use to measure the degree of responsiveness of Quantity demanded for a given change on price of the good itself, certis paribus. The formula for PED = percentage change in quantity demanded/ percentage change in price of good A
GOH
its is necessarily negative due to the inverse relationship between price and Quantity demanded. since PED carries a negative sign most of the time, we will usually the absolute value of PED by dropping the negative sign.
GOH
PED > 1 means that the demand of the good is price elasticity and for a given increase in price there will be a more then proportionate decrease in quantity demanded.
GOH
PED < 1 means that the demand of the good is price inelasticity and for a given increase in price there will be a less then proportionate decrease in quantity demanded.
GOH
The factors that affects PES are: Avaliablilty of close substitutes, proportion of income spent on the good, Degree of necessity, Addiction and Time.
GOH
Calculate price elasticity of demand and comment on the shape of the demand curve of a good ,when its price rises by 20 percentage, quantity demanded falls from 150 units to 120 units.
Helen Reply
5 %fall in price of good x leads to a 10 % rise in its quantity demanded. A 20 % rise in price of good y leads to do a 10 % fall in its quantity demanded. calculate price elasticity of demand of good x and good y. Out of the two goods which one is more elastic.
Helen
what is labor
Grace Reply
labor is any physical or mental effort that helps in the production of goods and services
Kwabena
what is profit maximizing level of out put for above hypothetical firm TC = Q3 - 21Q2 + 600 + 1800 P = 600 MC = 3Q2 - 42Q + 600
Sosna Reply
consider two goods X and Y. When the price of Y changes from 10 to 20. The quantity demanded of X changes from 40 to 35. Calculate cross elasticity of demand for X.
Sosna
sorry it the mistake answer it is question
Sosna
consider two goods X and Y. When the price of Y changes from 10 to 20. The quantity demanded of X changes from 40 to 35. Calculate cross elasticity of demand for X.
Sosna
The formula for calculation income elasticity of demand is the percent change in quantity demanded divided by the percent change in income.
Sosna
what is labor productivity
Lizzy Reply
if the demand function is q=25-4p+p² 1.find elasticity of demand at the point p=5?
Puja Reply
what are some of the difference between monopoly and perfect competition market
Obeng Reply
n a perfectly competitive market, price equals marginal cost and firms earn an economic profit of zero. In a monopoly, the price is set above marginal cost and the firm earns a positive economic profit. Perfect competition produces an equilibrium in which the price and quantity of a good is economic
Naima
what are some characteristics of monopoly market
Obeng Reply
explicit cost is seen as a total experiences in the business or the salary (wages) that a firm pay to employee.
Idagu Reply
what is price elasticity
Fosua
...
krishna
it is the degree of responsiveness to a percentage change in the price of the commodity
Obeng
economics is known to be the field
John Reply
what is monopoly
Peter Reply
what is taxation
Peter
is the compulsory transfer of wealth from the private sector to the public sector
Jonna
why do monopoly make excess profit in both long run and short run
Adeola Reply
because monopoly have no competitor on the market and they are price makers,therefore,they can easily increase the princes and produce small quantity of goods but still consumers will still buy....
Kennedy
how to identify a perfect market graph
Adeola Reply
what is the investment
jimmy
investment is a money u used to the business
Mohamed
investment is the purchase of good that are not consumed today but are used in the future to create wealth.
Amina
investment is the good that are not consumed
Fosua
What is supply
Fosua
 Supply represents how much the market can offer.
Yusif
it is the quantity of commodity producers produces at the market
Obeng
what is the effect of scarce resources on producers
Phindu Reply
explain how government taxes and government producer subsidies affect supply
Chanda
what is economic
Charles Reply
what are the type of economic
Charles
macroeconomics,microeconomics,positive economics and negative economics
Gladys
what are the factors of production
Gladys
process of production
Mutia
Basically factors of production are four (4) namely: 1. Entrepreneur 2. Capital 3. Labour and; 4. Land but there has been a new argument to include an addition one to the the numbers to 5 which is "Technology"
Elisha
what is land as a factor of production
Gladys
what is Economic
Abu
economics is how individuals bussiness and governments make the best decisions to get what they want and how these choices interact in the market
Nandisha
Economics as a social science, which studies human behaviour as a relationship between ends and scarce means, which have alternative uses.
Yhaar
Economics is a science which study human behaviour as a relationship between ends and scarce means
John
Economics is a social sciences which studies human behavior as a relationship between ends and scarce mean, which have alternative uses.....
Pintu
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Source:  OpenStax, Chem217labsfall07. OpenStax CNX. Oct 16, 2007 Download for free at http://cnx.org/content/col10463/1.4
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