Preview

Alkenes from Alcohols: Analysis of a Mixture by Gas Chromatography

Good Essays
Open Document
Open Document
774 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Alkenes from Alcohols: Analysis of a Mixture by Gas Chromatography
Alkenes from Alcohols: Analysis of a Mixture by Gas Chromatography

Aim: To analyze a mixture of alkenes by gas chromatography.

Introduction: In this lab, we specifically used elimination reaction; however we only used the E1 reaction. In the presence of strong acids, alcohols protonate to form a good leaving group, namely water. Upon loss of a proton to a good leaving group, an introduction of unsaturation (a double bond) can be preformed. According to Wikipedia, an E2 reaction is typically of secondary and tertiary substituted alkyl halides. An E2 reaction results in formation of a Pi bond. The reason we only used an E1 reaction is because the alcohol functional group was attached to a tertiary carbon, which makes it very compatible to have the compound go through an E1 reaction. In addition, we were using sulphuric acid with heat, it is considered as a weak base making the reactivity for an E1 reaction strong. The reaction also would favor a protic solvent in order for it to be an E1 reaction. When the compound goes through the E1 reaction, it forms a carbocation, and in some cases it could be formed on a secondary carbon. This is when you will see rearrangement of hydrogen to put the compound in more stable alkenes. The stability of the carbocation plays an important role in the amount of alkenes formed. In an E2 reaction, we use a compound that is attached to a secondary or primary carbon. The reactivity is better in those conditions and also when heat is used. When the product is formed, you want it to follow Zaitsev’s Rule. When the more stable product of an elimination reaction predominates the reaction is said to obey Zaitsev’s Rule. An E1 m reaction will obey Zaisev’s Rule. In this experiment two forms of alkenes are produced, disubstituted and trisubstituted alkene is more stable than the disubstituted. The di- and tri- are very important to understand. They refer to double bond and how it is attached to whatever number

You May Also Find These Documents Helpful

  • Powerful Essays

    9-Fluorenone Lab Report

    • 1496 Words
    • 6 Pages

    In this experiment a ketone, 9-fluorenone is reduced to and alcohol. The are two possible ways by which this reduction can occur. One is by a catalytic hydrogenation, this uses a catalyst such as palladium or nickel, hydrogen gas, and heat/pressure. This can reduced an alkane to alkene. This catalytic process is preferred in industrial practices because the cost is low in the long run and more importantly there is little to no waste expense. However, hydrogen gas is dangerous due to being very flammable/combustible. Therefore, a reducing agent will be used in this experiment instead. There are multiple types of reducing agents that reduce different types of functional groups and thus selection of the proper reducing agent is crucial.…

    • 1496 Words
    • 6 Pages
    Powerful Essays
  • Good Essays

    Sn1 Lab

    • 759 Words
    • 4 Pages

    An SN1 reaction is a nucleophilic substitution reaction where the rate determining step of the reaction is unimolecular, thus, the rate equation is often shown as having first-order dependence on electrophile and zero-order dependence on nucleophile. This relationship holds for situations where the amount of nucleophile is much greater than that of the carbocation intermediate. The reaction (which involves a carbocation intermediate) is commonly seen in reactions of secondary or tertiary alkyl halides under strongly basic conditions or, under strongly acidic conditions (in this case strongly acidic conditions), with secondary or tertiary alcohols. In this reaction, the alcohol will be protonated by the hydrochloric acid. H2O will then “leave” the molecule in the rate-determining step, forming a relatively stable tertiary carbocation (which is highly substituted). The chloride ion, acting as a Lewis base will donate a pair of electrons to the carbocation (acting as a Lewis acid) forming the…

    • 759 Words
    • 4 Pages
    Good Essays
  • Satisfactory Essays

    This experiment was a study of protonating a cyclo-alcohol to become a cyclo-ene. In this case 4-methylcyclohexanol was protonated using phosphoric acid to become 4-methylcyclohexene. This demonstrates the loss of an alcohol group by protonation, the loss of a proton from the cyclohexane to form an alkene through elimination. This also demonstrates Le Chatelier's principle, by using distillation to remove the product as it is formed the equilibrium of the reaction will constantly be in favor of the product.…

    • 894 Words
    • 4 Pages
    Satisfactory Essays
  • Good Essays

    The goal of this experiment was to separate Toluene and Hexane by distillation and gas chromatography based on their difference in boiling points. The boiling point of hexane is 69 degrees Celsius and the boiling point of toluene is 110 degrees Celsius. Three fractions were collected for both simple and fractional distillation. The first fraction was hexane since it had the lower boiling point. The second fraction was a mixture of toluene and hexane. The third fraction was toluene since it had the high boiling point of 110 degrees Celsius. Gas chromatography was also preformed on each of the fractions from simple and fractional distillation. In the gas chromatography process, the compounds are carried through a stationary phase, and pushed…

    • 395 Words
    • 2 Pages
    Good Essays
  • Satisfactory Essays

    Orgo Lab 5

    • 539 Words
    • 3 Pages

    The objective of this experiment was to carry out an elimination reaction on 2-methylalcohol with an acid to produce alkenes as a product. The product formed is separated through distillation. Because more than one alkene product can result from the reaction, Gas Chromatography is used to analyze the composition of the product mixture. IR spectrometry is also carried out to confirm the product.…

    • 539 Words
    • 3 Pages
    Satisfactory Essays
  • Powerful Essays

    The 2-methylcyclohexanol alcohol used in this experiment was a mixture of both cis and trans isomers. The way this reaction occurs is as follows. Through protonation, the acid-catalyst converts the already present, poor leaving group (-OH) to a much better leaving group (H2O+). Then once the H2O and the H+ are eliminated the reaction yields an alkene in which the un-protonated alcohol serves as the reaction solvent. This experiment then called for the distillation of this mixture, using a distillation apparatus. As this distillation took place the products, alkenes and water continuously distilled from the reaction mixture into a Hickman still as they were formed. The removal of these elements shifted the equilibrium to the right, ultimately increasing the yield of alkene, this is also known as Le Chatelier’s Principle. Then both fractions were washed with 1.5mL of 5% aqueous sodium bicarbonate, the reason or this is that the sodium bicarbonate gets rid of the excess acid present. In order to analyze the fractions, both were put through gas…

    • 969 Words
    • 4 Pages
    Powerful Essays
  • Satisfactory Essays

    Ochem Lab

    • 394 Words
    • 2 Pages

    The purpose of this experiment was to determine which of the 3 compounds was formed from the starting material. The third compound was the oxidation of both alcohols. This could not have been my product because of the results of my IR. I had a broad large absorption is the range of 3200 to 3500 wavenumbers. This indicates the presence of an alcohol. If my compound had been fully oxidized then there would be no such alcohol present. Also, because of my IR, I know that my compound was one of the other 2 compounds because of the strong sharp absorption at 1705 wavenumbers. This indicates the presence of a carbonyl. Therefore I had to prove which of the two compounds my final product was. The first was the oxidation of the primary alcohol, forming an aldehyde and a secondary alcohol. The textbook states that aldehydes show 2 characteristic absorption’s in the range of 2720-2820 wavenumbers. No such absorption’s were present in my sample. Therefore my final product was the oxidation of the secondary alcohol. My final product had a primary alcohol and a secondary ketone.…

    • 394 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Gas Chromatography Lab

    • 648 Words
    • 3 Pages

    E1 reactions are two-step unimolecular reactions. The first step of an E1 reaction occurs when a leaving group, which consists of a weak base, leaves an organic compound, leaving an intermediate carbocation. In the second step, a carbon on the organic compound is deprotonated by a Lewis base, resulting in the formation of an alkene. The dehydration reactions of 1- and 2-Butanol with sulfuric acid occur through an E1 mechanism, so they follow the steps previously…

    • 648 Words
    • 3 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Experiment E Post Lab

    • 321 Words
    • 2 Pages

    1. This experiment followed GCP number 8 which is reduce derivatives. This experiment did not use unnecessary derivation since the reaction was not modified in any way. No additional reagents were required so it did not generate a lot of waste.…

    • 321 Words
    • 2 Pages
    Satisfactory Essays
  • Better Essays

    A common Sophomore Organic Chemistry laboratory experiment that has great potential for further research is the acid catalyzed dehydration of simple alcohols. The classic dehydration of 2-methylcyclohexanol experiment that was introduced in Journal of Chemical Education in 1967 Taber(1967)JCE:44,p620. The rather simple procedure of distilling an alcohol with an aqueous acid has spawned several investigations that have resulted in formal journal articles. At the same time, the experiment has retained its popularity in the Sophomore Organic Chemistry laboratory curriculum. In one line of inquiry it has been observed that a mixture of 2-methylcyclohexanol diastereomers gives rise to a mixture of three isomeric alkenes Todd(1994)JCE:71,p440; Feigenbaum(1987) JCE:64, p273; Cawley (1997) JCE:74l, p102. Explaining the presence of the three alkene products requires an intense synthesis of information communicated in a typical SOC textbook. The continued popularity of this experiment is corroborated by the observation that Googling the phrase “Dehydration of 2-Methylcyclohexanol” on January 13th, 2008 returned no less than 20 hits for online student handouts and/or guides for this SOC laboratory experiment. Moreover, this experiment provides fertile ground for experimentation and innovation that has not yet been fully explored. At Dominican University, the SOC students performed this experiment during the Fall 2007 semester with not only the dehydration of 2-methylcyclohexanol (Aldrich 153087) but also the 4-methyl (Aldrich 153095) and 3-methyl (Aldrich 139734) positional isomers. The reaction products were submitted to GC-FID analysis.…

    • 1627 Words
    • 7 Pages
    Better Essays
  • Better Essays

    To drive the equilibrium forward Le Chatelier's principle is used, in this case there are two ways to adjust reagent concentrations to force isopentyl alcohol to become isopentyl acetate. One way is to remove product as it forms. The other way is to use a large excess of acetic acid. This experiment is based on the latter approach, but it raises two issues. We can use excess acetic acid only if acetic acid is cheap, and if unreacted acetic acid can be removed easily from the…

    • 1671 Words
    • 7 Pages
    Better Essays
  • Good Essays

    Aldehydes and Ketones

    • 868 Words
    • 4 Pages

    Aldehydes and Ketones have certain characteristics in common. However, both couldn’t exist in the same compound. Some test for the presence of aldehyde was made for this experiment. These tests includes Tollen’s test, Benedict’s Test, 2-4-dinitrophenylhydrazine and Schiff’s test.…

    • 868 Words
    • 4 Pages
    Good Essays
  • Better Essays

    The proponents have done several tests for identifying alcohols, aldehydes and ketones. These tests are Dichromate test, Tollens test, Lucas test, DNPH test and Iodoform test. Three samples got positive result in dichromate test and one in Tollens test. Lucas test got one sample that has a positive result, DNPH test got two positive results and Iodoform test also got two. All unknowns are identified from which of the samples are they. Alcohols, aldehydes and ketones are excellently recognized after the experiment.…

    • 2579 Words
    • 10 Pages
    Better Essays
  • Good Essays

    Photochemistry

    • 8395 Words
    • 34 Pages

    The aldehydes and ketones are reduced to give the corresponding alcohols when treated with LAH (Scheme 3). For the reduction of aldehydes and ketones, the reaction is generally performed in ether solvents at low temperature.…

    • 8395 Words
    • 34 Pages
    Good Essays
  • Good Essays

    5. A long splint was lit and used to light the cyclohexane. The front of the fume cupboard was lowered to a 10cm opening.…

    • 3543 Words
    • 15 Pages
    Good Essays