- Experiment 8 Substitution Or Elimination Instructions Each Team Must Submit One Copy Of The Lab Data Sheet Experimen 1 (116.11 KiB) Viewed 45 times
major product. It is a physical property of compounds that is
useful in this experiment as it is relatively easy to get, and
because we already know what the melting point of the possible
products are. Experimentally, we found a melting point range of
34.8°C to 36.5°C, which is VERY close to the melting point of one
of the possible products, 2-ethoxynaphthalene, which has a melting
point of 37.5°C. The range found in the lab may be lower because of
possible impurities present with the product made, which will
weaken the intermolecular forces between the molecules of
2-ethoxynaphthalene by disrupting attraction between them.
2-methoxynaphthalene
2-ethoxynaphthalene
Melting point : 72 °C
Melting point : 37.5 °C
2-naphthol
Melting point : 123.0 °C
Reference:
“2-Naphthol.” Pubchem,
pubchem.ncbi.nlm.nih.gov/compound/2-Naphthol#section=MeSH-Entry-Terms.
Accessed 27 Apr. 2022.
“2-Ethoxynaphthalene.” Pubchem,
pubchem.ncbi.nlm.nih.gov/compound/2-Ethoxynaphthalene. Accessed 27
Apr. 2022.
“2-Methoxynaphthalene.” Pubchem,
pubchem.ncbi.nlm.nih.gov/compound/2-methoxynaphthalene. Accessed 27
Apr. 2022.
3. a) The major product of this reaction is formed from a
substitution reaction.
b) The reaction kinetics is of second order (Sn2 reaction) and will
have a rate determined by the concentration of both the nucleophile
(2-naphthol) and the substrate (ethyl iodide).
c) We know that the substitution reaction forming the major product
of 2-ethoxynaphthalene is an Sn2 reaction. Multiple factors like
the structure of the substrate, the nature of the leaving group and
the solvent as well as the reactivity of the nucleophile explain
the latter.
First, the substrate is a 1st order alkyl halide which therefore
has a really low steric hindrance when the nucleophile wants to
attack the alpha carbon. In other words, it’s easier for the
nucleophile to bond to the carbon as there is not much
obstruction.
Secondly, because the nucleophile is negatively charged, it makes
it more reactive and stronger than if it would be neutral,
therefore more fitted for the Sn2 reaction.
Then, the solvent in this experiment is polar aprotic. The
nucleophile is much more available to react than the cation metal,
K, because of the attraction of the solvent by the cation leaving
the nucleophile more “naked” to react, thus increasing reactivity
for Sn2. The I- leaving group is stabilized really well by the
aprotic solvent making it less reactive thus more likely to
occur.
4. We can rule out the 3rd reaction as a possible minor reaction
because the hydroxyl group is a very weak leaving group as it is
not particularly stable when isolated from its parent molecule
(instead of a good leaving group, which will be a weak base). In
other words, elimination may produce a minor product including
2-naphthol and ethene. In our process, we might have used heat,
which may have facilitated the elimination process.
As a result of the primary alkyl carbon in the alkyl halide, the
most likely mechanism for elimination is an E2 mechanism, as the
development of a carbocation is less likely due to the lack of
hyperconjugation and inductive action. The mechanism appears to be
bimolecular. Thus, both the reagent concentration and the base
concentration should be considered in determining the rate.
5.
I answered everything apart for 5 can someone look over my answers
and answer 5
EXPERIMENT 8: SUBSTITUTION OR ELIMINATION? Instructions: Each team must submit one copy of the lab data sheet (Experiment #8 data sheet posted), calculations, and post lab questions as hard copy. No lab data will be accepted by mio or by electronic submission. Lab data sheet (Experiment #8 data sheet posted) for this lab should be submitted according to the following criteria: • Fill all Tables with the observation, correct values,correct number of significant figures and units, do not leave any sections empty. • Show sample calculation for each of the following calculations, use dimensional analysis for mark: • Amount of 2-Naphthol (amount means number of moles) • Mass of Potassium Hydroxide (use % by mass and density of the solution provided in the procedure) • Amount of Potassium Hydroxide • Mass of Ethyl lodide (use density = 1.930 g/mL) • Amount of Ethyl Iodide • Find limiting reactant (Sodium Hydroxide or 2-Naphthol or Ethyl lodide, show all steps for full mark) • Theoretical yield of reaction (ing) • Percent yield using the below equation: % Yield Mass of dry recrystallized product x 100 Theoretical Yield x 10 Percent mass recovery using the below equation: Mass of dry recrystallized product % Mass Recovery = Mass of crude product • Answer the following post lab questions and hand in along with your completed lab data sheet and calculations: Post Lab Questions: 1. Using the curved arrows draw plausible mechanism for formation cach of three possible products, three mechanisms are required. Read in the Introduction of the experiment about three possible reactions. 2. Explain how you have decided about the identity of the major product, include any data used to identify the major product 3. a) Is the major product of this reaction formed from an elimination or a substitution reaction? b) Specify the kinetics of the reaction for the formation of the major product. b) Justify the formation of major product considering the factors such as solvent effect, type of alkyl halide, type of nucleophile/base..... Continue next page 1
4. a) Propose a product that can be the minor product for this reaction. Draw its bond line structure. b) Is the minor product of this reaction formed from an elimination or a substitution reaction? Explain based on the reaction conditions why you have decided this to be the minor product. c) Specify the kinetics of the reaction for the formation of the minor product proposed. Explain your reasons. Read in the Introduction of the experiment about three possible reactions, 5. Propose a practical method to identify the minor product of this reaction. Explain by providing details for the practical steps in the lab, how you would use this method to identify the minor product. At least one paragraph required to give all the required details. Note: 1) You can submit your lab data handwritten or typed 2) When references such as a web page or textbook used to prepare the data/post lab questions, make sure to cite them 3) Do not use Wikipedia or Britannica.... or similar websites as a reference. 4) Late submission mark deduction is applied if you fail to submit labs on the due date and time The due for the Experiment #8 is Wednesday April 27th at the beginning of the class time.