CHE 233 Final

Which is the correct expression for calculating percent yield?

% yield = (experimental yield/theoretical yield) x 100

What is the formula used to calculate % yield?

% yield= (actual yield/theoretical yield) x 100

What are the best practices for safely handling waste in the lab?

-Always wear appropriate Personal Protective Equipment. -Check labels or instructions before any disposal.

How will you characterize your product in this experiment? What specific differences will you be looking for compared to the starting material?

-Appearance of peak due to -OCH3 -1H NMR Spectroscopy -Disappearance of -CH2 peak due to triglyceride

Complete the statements below by matching the following. 1. Unsaturated fatty acids 2. Saturated fatty acids

1. have one (or more) C=C bonds 2. have no C=C bonds

How is the product characterized in this experiment?

1H NMR Spectroscopy

What information does not need to be included a chemical waste label?

A description of the experiment the chemicals were used for

At the end of second day of the experiment (synthesis of 6,13-dihexynylpentacene ), where would you dispose the waste containing tin salts?

Aqueous liquid hazardous chemical waste container

In this experiment, LiHMDS acts as an acid.

False

Which types of signs are posted to convey information about chemical storage?

-Hazard signs such as "Flammable," "Oxidizer," and "Corrosive' -National Fire Protection Association (NFPA) diamond -Gas Cylinder sign

Identify the types of information that are necessary to communicate with emergency responders.

-How the incident happened -Any chemicals involved in an incident -Any other hazards present in the lab

What should you do every time before you leave the lab?

-Remove your gloves -Remove your labcoat, if you are wearing one. -Wash your hands

What information is needed in order to be prepared for an emergency?

-Understanding of where to go should an emergency occur -Contact information for emergency personnel -Location of all exits -Location of lab phone and first aid kit

In general, which characteristics are necessary for a location to be suitable for chemical storage?

-dry -cool -dark

Determine which items of personal protective equipment (PPE) you will likely use in a general chemistry lab.

-gloves -lab coat -goggles

For the previous reaction, how many grams of hexynyl lithium should be produced?

0.0881 grams

Read each statement regarding food and beverages in the lab and determine if each is true or false. 1. Chewing gum is okay in the lab as long as you don't blow bubbles. 2. Tobacco products of all kinds are prohibited in lab 3. Food items should not be brought into the lab. 4. Beverages are allowed in lab as long as they are in containers with lids.

1. False 2. True 3. True 4. False

Why should Bunsen burners not be used when heating organic materials?

Many organic materials are flammable and could cause a fire.

Most laboratory chemical spills are cleaned up in a similar manner, but acid and base spills require an extra step. What is this extra step?

Neutralize the spill before cleaning it up.

Safety Quiz

Safety Quiz

Column chromatography uses a stationary and a mobile phase to separate compounds. What is the stationary phase in the column chromatographic purification of crude pentacene derivative?

Silica gel

Following the procedure for this experiment, various TLCs were taken to monitor the reaction at 5 minute intervals from the beginning and up to the 25 minute reaction time. It was observed that the reaction was completed after 20 minutes. On the TLC schematics below, the corresponding lane labels stand for:

Which TLC is likely to be observed after 0 minutes? C Which TLC is likely to be observed after 10 minutes? F Which TLC is likely to be observed after 20 minutes? A

Biodiesel

Biodiesel

Why is BocPhe used for comparison in TLC?

BocPhe is used for comparison in the TLC because it is aromatic and shows the UV-visible absorption. Also, it is the limiting Reagent.

In the biodiesel experiment, the NaOCH3 serves as a ____

Catalyst

In this experiment, you will be recording IR spectra of 6,13-pentacenequinone and 6,13-dihexynylpentacene. Match the following functional groups with the approximate wavenumbers (cm-1) that you expect to see in the spectra.

C≡C: NOT 1650-1780 C=O: 1650-1780

Hexynide lithium reacts with 6,13-pentacenequinone via:

Nucleophilic addition to carbonyl

After completion of the experiment, where do you dispose of FAMEs?

Organic liquid hazardous chemical waste container

Pentacene

Pentacene

What type of electrons are responsible for the photophysical properties of pentacene?

Pi electrons

Polymer Macrocapsules

Polymer Macrocapsules

Name two other techniques other than TLC used in this experiment.

Two other techniques that are used in the experiment besides TLC are proton NMR spectroscopy and the use of a separatory funnel to extract and purify the solution.

In lab, you may need to evaluate the odor or smell of a chemical. What is the best way to smell a chemical sample?

Use your hand to gently waft the smell toward you.

What is the main precaution to take if a Gas Cylinder sign is present in the lab?

Visually check that the gas cylinder is restrained but keep a safe distance from it.

Determine the best way to deal with each of the following items that may dangle into the way during lab work. 1. Loose bracelets 2. flowy sleeves 3. long hair 4. long earrings 5. long necklaces

1. remove 2. tie back or secure 3. tie back or secure 4. remove 5. remove

Dipeptide

Dipeptide

Determine when you should remove your goggles in the lab room.

When everyone in the room is done handling any chemicals or glassware

What is LeChatelier's Principle? How it is applicable in this experiment?

Le Chatelier's principle states that when a chemical system that is at equilibrium is disturbed, the system will sift In a way that minimizes the disturbance as much as possible. For example, if the concentration of the reactant is increased the reaction will shift towards products. This is applicable to this experiment because a large and excess amount of alcohol will be used to shift the equilibrium to products, and therefore, increase the yield of the product (during transesterfication).

For the following reaction, which is the limiting reagent? Reagents and quantities are provided. (0.22 ml 1-hexyne) + (1 ml of 1 M LiHMDS in THF)---> Hexynyl Lithium

Limiting Reagent: LiHMDS

Determine the limiting reagent and excess reagent in the reaction you will perform in this experiment.

Limiting Reagent: Triglyceride Excess Reagent: Methanol

If unprotected amino acids are used for dipeptide formation, there is a possibility of formation of mixture of products instead of a single product due to cross coupled condensation reactions.

True

What is the first step for response to an emergency situation?

Remain calm and quiet, gather information, and assess the situation.

Was the experiment successful/unsuccessful? Why?

Yes, I would say this experiment was successful. When comparing the standard vegetable oil NMR and my given NMR, there is only one peak that differs from the standard. Also, the aim of this experiment was to use transesterfication to convert cooking oils into FAMEs and then further, determine the FAMEs fatty acid profile. Through this experiment this purpose was achieved because a cooking oil (vegetable oil) went through transesterfication into a FAME and the FAME was determined as coming from vegetable oil, therefore profiling the FAME.

What is the importance of using protected amino acids during dipeptide formation?

A protecting group prevents cross-coupled reactions. This means that only the single desired product is obtained with no other mixture of products.

Identify each component of the liquid waste set-up

A-Funnel B-Primary Container C-Waste Label D-Secondary Container

Select the number indicating the chiral center, if one is present, in each structure below.

A: 2 B: none C: 7 D: 16

Determine when to put on disposable gloves for work in the lab

Before handling any glassware or chemicals for the experiment

When should lab participants look at the Safety Data Sheet (SDS) of a substance?

Before using the substance

Which amino acid does not have a chiral center?

Glycine

Eyewash Station Sign

Identify the sign

Gas Cylinder

Identify the sign

Lab exit sign

Identify the sign

NFPA Diamond

Identify the sign

Safety Shower Sign

Identify the sign

What was the purpose of using thin-layer chromatography in this experiment?

TLC is used to see if the experiment was successful and the reaction was complete. The R.M. column should be absent of the BocPhe Spot and this will tell you that the reaction was complete/successful.

What is the driving force for elimination of water during the reaction to form pentacenequinone?

The driving force for E1cB elimination is the increased conjugation when forming the product.

List all techniques that were used (e.g. NMR sample preparation) and data needed (e.g. amount of reagents, etc.) for the successful completion of this experiment.

There were many techniques used in this experiment. These included weighing and measuring specific masses of compounds, using a stir bar with the hot plate "stir" function, using an ice bath, Thin Layer Chromatography (TLC), liquid-liquid solvent extraction using a separatory funnel and various washes, extracting the bottom layer out of the separatory funnel, venting the pressure in separatory funnel during washes, filtering solution through filter paper and sodium sulfate, evaporating the solution, and preparing a proton NMR analysis. There were also many measurements that needed to be taken during this experiment. These included the mass of BocPhe, AlaOMe, DMAP, EDCI, the empty scintillation vial, and the scintillation vial with product. Additionally, various volumes were measured including chloroform, methanol, DCM, HCl, distilled water, NaHCO3, and brine.

During the FAMEs synthesis, a mixture will be added to a vial and two layers will form. Identify the components of each layer.

Top: FAMEs with methanol Bottom: Glycerol

Which is NOT a good source of information about the hazards that affect waste disposal in a chemistry lab?

Your lab partner

Using your NMR spectrum that you obtained, identify the oil given to you for the experiment. Compare the observations with the standard NMR spectrum for the oil.

Based on the NMR spectrum, the oil I was given was vegetable oil. I came to this conclusion based on the ratio of integrals of methoxy protons and bis-allylic protons being 2:1. From the lecture slides, it could be determined that with this ratio the oil can be identified as vegetable oil. When comparing my given NMR spectrum to the standard NMR spectrum for vegetable oil FAME, both spectrums have 8 prominent peaks with the tallest 2 peaks at 3.6 and 1.3 ppm. Overall, the standard spectrum and my given spectrum closely resembled each other and this confirmed to me that my given oil was vegetable oil.

How should students prepare to use chemicals in the lab?

-Locate the spill kits and understand how they are used -Become familiar with the chemicals to be used, including exposure or spill hazards.

Match each lab incident to the item of PPE that will protect you from it. Each item of PPE will only be used once. 1. While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench. 2. While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor. 3. While checking on a stirring solution, the solution splashes up towards your face 4. While picking up a buret, an unknown solution left by a previous solution drips onto your hand.

1. Lab Coat 2. Closed-toe shoes 3. Goggles 4. Gloves

Given the list of waste generated in this experiment, select the appropriate container where the waste was disposed of. 1. FAMEs 2. Glycerol 3. Deuterated chloroform 4. Methanol 5. Pipets

1. Organic liquid hazardous chemical waste container 2. Organic liquid hazardous chemical waste container 3. Organic liquid hazardous chemical waste container(??) 4. Organic liquid hazardous chemical waste container 5. Broken glass waste container

It is often helpful to remember the acronym PASS when using a fire extinguisher. Fill in the word that corresponds with each letter to complete the steps needed for operation of this device. 1. P ___ the pin 2. A ___ the nozzle at the base of the fire 3. S ____ the lever slowly 4. S ____ the spray from side to side over the fire

1. Pull 2. Aim 3. Squeeze 4. Sweep

Given the list of waste generated in this experiment, select the appropriate container where the waste was disposed of. 1. TLC plates 2. Brine solution 3. HCl 4. Capillary tubes 5. CHCl3

1. Solid hazardous chemical waste 2. Aqueous liquid hazardous chemical waste container 3. Aqueous liquid hazardous chemical waste container 4. Broken glass waste container 5. Organic liquid hazardous chemical waste container

Identify the section in which each type of information can be found on a Safety Data Sheet. 1. recommended personal protective equipment (PPE) 2. chemical name and formula 3. incompatibility or reactivity with other chemicals 4. possible dangers and health effects 5.recommendations in case of accidental contact with the chemical

1. exposure controls/personal protection 2. identification 3. handling and storage 4. hazards identification 5. First Aid Measures

Review the Safety Data Sheet (SDS) (click the SDS icon below) for hydrogen peroxide, then identify the best course of action for each type of chemical exposure. 1. If inhaled... 2. In case of skin contact... 3. If swallowed... 4. In case of eye contact...

1. move person to fresh air 2. take off any contaminated clothing and rinse thoroughly 3. rinse mouth with water 4. rinse with water for 15 minutes

Identify the term that matches each definition. 1. Fatty acid molecules with single bonds between all carbons ____ 2. A type of fuel synthesized by breaking down lipids from natural sources ____ 3. Fatty acid molecules with single bonds between some carbons and double bonds between some carbons _____ 4. A molecule made up of glycerol connected to three fatty acid chains ____ 5. A chemical reaction in which an ester is converted into a new type of ester ____

1. saturated fatty acid 2. biodiesel 3. unsaturated fatty acid 4. triglyceride 5. transesterfication

Determine where to dispose of each type of waste. 1. unused solid Reagent 2. Titrant solution 3. Broken flask 4. Syringe tips

1. solid waste container 2. nalgene bottle with cap 3. box lined with puncture resistant bag 4. sharps container

Match the following reagents with their role during the work-up of the reaction mixture. 1. Aqueous sodium bicarbonate _______ 2. Aqueous hydrochloric acid ______ 3. Water ______ 4. Sodium sulfate ______

1. to remove unreacted acid 2. to remove unreacted amine, DMAP 3. to remove urea, any other salts (byproducts after the reaction) 4. to remove water from the organic layer

Identify the equipment best suited for extinguishing each type of fire. 1. small benchtop fire 2.large fire on floor 3.clothing fire

1.overturned beaker 2.fire extinguisher 3.fire blanket

Calculate molecular weight for 6,13-pentacenequinone in appropriate units.

308 g/mol

What would be a possible source of error in this experiment?

A possible source of error could occur during the washing and separating step of the experiment (day 2). This error could be from not completely separating out the layers when opening the stopcock of the funnel. If some of the top layer was collected with the organic layer, this could lead to a less pure collected solution. The goal of the washes is to purify the organic layer and if the aqueous layer was collected with it, even a little bit, this would defeat the point of the various washes that were used. In the end, this would lead to a sample that is not a purified and could affect the yield of product at the end of the experiment.

Fill in the words to complete each step in liquid spill cleanup. 1. Surround the area with ___(A)___, then cover the spill. 2. Scoop up the material and place in a __(B)__. 3. Place the bagged waste in a ___(C)___. 4. Wipe down the area with __(D)__.

A. Absorbent Material B. Plastic Bag C. Solid waste container D. Detergent and Water

Move to the safety shower if you spill hazardous chemicals on your ___(A)___ .Stand under the shower and ___(B)___the lever. Remove clothing and continue flushing the area for __(C)__.

A. Skin or clothing B. Pull C. 15 minutes

If you drop glassware in lab, first ___(A)___. Then, ___(B)__. Finally, place all that material into the ___(C)__.

A. get thick gloves or a dustpan B. carefully collect all broken glassware C. broken glass container

Changing gloves often will minimize the spread of chemicals. To properly remove gloves, first, __(A)__, and then, __(B)__. Then insert __(C)__ between the interior edge of the second glove and the skin, and remove the second glove.

A. grasp the exterior of one glove with a gloved hand B. peel off the first glove C. a bare finger

A typical TLC schematic, following the procedure for this experiment, is shown below for the co-spot. Identify the labels A-E.

A: Origin B: N,N dimethyl 4-aminopyridine C: Bocages Phenylalanine D: Dipeptide E: Solvent Front

What are allylic and vinylic hydrogens? Explain briefly using examples. Insert image (.jpeg, .png or .heic) of your lab notebook page to show the examples.

Allylic hydrogens are hydrogens bonded to an sp3 hybridized carbon that is adjacent to a carbon-carbon double bond. Vinylic hydrogens are hydrogens bonded to an sp2 hybridized carbon (or the carbon involved in the carbon-carbon double bond).

What is an amino acid? Explain zwitter ions.

An amino acid is a certain type of molecule that contains a carboxylic acid, an amine group, and one of a variety of different side chains. Amino acids are also the foundation for building proteins. There are 20 amino acids that occur in nature, and all but one (glycine) are chiral. A zwitter ion contains both acidic and basic functional groups and has a pH that is close to neutral. This pH is called a pI, or an isoelectric point. At the isoelectric point the net charge on the zwitter ion is zero.

From the above derived equation, as the absorption maximum (λmax) for a molecule increases to a longer wavelength (for example from 300 to 700 nm), how does this affect the energy for the electronic transition?

As the wavelength (λ) increases the energy of electronic transition decreases. This is because the wavelength is the denominator of the equation and as it increases, the value on top is divided by a larger number, therefore, making the final answer smaller.

What are common impurities that you might see in your NMR spectrum? What are the chemical shifts for those impurities in your NMR spectrum?

Common impurities that might be seen in the NMR spectrum are Acetone at 2.17 ppm, Water at 1.56 ppm, dichloromethane at 5.30 ppm, methanol at 3.49 and 1.09 ppm, and chloroform at 7.26 ppm.;include triglyceride peak as impurity

What is the purpose of adding base in the aldol condensation reaction? Choose the best answer.

Deprotonate α-carbon to generate nucleophile

Which organic solvent is used to extract the product during the work-up of the reaction?

Dichloromethane

How are dipeptides formed?

Dipeptides are formed when two amino acids (peptides) condense and are linked with a peptide bond. This process happens through a condensation reaction, and water can seen as a product. A mixture of products is possible from this reaction.

What major differences would you be looking for in the IR spectra of 6,13-pentacenequinone and 6,13-dihexynylpentacene?

Disappearance of peak due to C=O in 6,13-pentacenequinone and appearance of peak due to C≡C from 6,13-dihexynylpentacene.

The elimination step of the aldol condensation reaction is an example of:

E1cB

The elimination of water during the aldol condensation is named a(n) __________________ type elimination.

E1cB type elimination. This stands for elimination, unimolecular, and conjugate base

The tin(II)chloride in the synthesis of pentacene derivative works as an oxidizing agent.

False

What are fatty acids? What are FAMEs?

Fatty acids are molecules containing a carboxylic acid group and an R group that is a nonpolar and unbranched hydrocarbon chain that is 8-18 carbon atoms long. Unsaturated fatty acids have at least one carbon-carbon double bond in the hydrocarbon chain, while saturated fatty acids do not have any carbon-carbon double bonds in its hydrocarbon chain. FAMEs are fatty acid methyl esters. In this experiment, the FAMEs will be the top layer in the scintillation vial after day 1.

List all techniques that were used (e.g. recording IR) and data needed (e.g. amount of reagents, etc.) for successful completion of this experiment.

For successful completion of this experiment there are many techniques that are required. Some of these techniques include weighing out various chemicals on a scale, measuring the volume of various liquid chemicals, gently swirling a test tube, and adding a chemical drop-by-drop to a test tube. Vacuum filtration is another technique used in this experiment which includes setting up the vacuum filtration apparatus, pouring and rinsing the solution into the funnel, and using methanol to rinse the product of color impurities. Collecting the filter paper with the product on it is another tedious technique also used in this experiment. Additionally, techniques for using a centrifuge tube and separatory funnel were used in this experiment. Column chromatography is used in day 2 of this experiment. When analyzing the product, IR spectroscopy is used to look at the functional group composition of the product. In this experiment there was certain data that needed to be recorded. In day one this includes the mass of pthalaldehyde, cyclohexanedione, the empty Petri dish, the empty filter paper, and the Petri dish, filter paper, and product together. In day two this includes, the mass of pentacenequinone, the empty scintillation vial and the scintillation vial and product. Also, the volume of LiHMDS and 1-hexyne; include units of mass of reagents used

What might happen if the pentacenequinone was not dried completely of methanol and/or any residual water it might have absorbed, before reacting it with hexynyl lithium? What would the result be?

If the pentacenequinone was not completely dried then the residual water and methanol could react with the strong bases used (i.e. hexynyllithium). This would affect step two in this experiment (synthesis) and the reaction may or may not take place.

Briefly explain why is LiHMDS such a strong base relative to hydroxide ion.

LIHMDS is a stronger base than the hydroxide ion because the nitrogen atom in LiHMDS is less electronegative than the oxygen atom in the hydroxide ion. This makes LiHMDS more basic because when deprotonated, the lone pair is much more unstable than when the lone pair on the hydroxide ion when it is deprotonated. The instability of the lone pair on the nitrogen makes it more reactive, and therefore, is more basic.

How would you prepare 10 mL of the required solvent system to run TLC for this experiment?

Mixing 1 mL of methanol with 9 mL of chloroform

Match the number of atoms of each element present in 6,13-pentacenequinone.

Nitrogen: 0 Iron: 0 Carbon: 22 Oxygen: 2 Hydrogen: 12

Identify the colors of the NFPA Diamond

Red: Flammability Yellow: Reactivity White: Special Hazards Blue: Health

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids do not have any carbon-carbon double bonds in the hydrocarbon chain, while unsaturated fatty acids have one or more carbon-carbon double bonds in the hydrocarbon chain.

What are some possible sources of errors in this experiment?

Some possible sources of error could include: some NaOMe being stuck/left on the weigh paper and not put I the scintillation vial, the presence of air bubbles in the syringes used to measure the methanol and oil therefore, making measurements inaccurate. Also, the temperature of the hot plate going outside of the allowed range and the vial not being removed if/when this happened. Additionally, a small amount of oil being trapped in the tip of the syringe, making measurements inaccurate. When pipetting out the top layer of the scintillation vial, some glycerol could have been drawn into the pipette which could contaminate the product. Lastly, when evaporating off methanol, this could have been done for too short a time and the methanol could be present in the product.

What is the aim of the experiment? Which are the three oils that were used in this experiment?

The aim of this experiment is to perform transesterfication to convert cooking oils into FAMEs. Then, use NMR spectroscopy to figure out the FAMEs fatty acid profile. Transesterfication is the conversion of glycerol esters and methanol to to methyl esters and glycerol. The three oils in this experiment are canola oil, vegetable oil, and olive oil.

List all possible fatty acid methyl esters in your unknown oil.

The possible FAMEs in vegetable oil are methyl oleate, methyl linoleate, methyl palmitate, methyl α-linoleate and methyl stearate.

What type of reaction is the conversion of vegetable oils to FAMEs? Which base was used for this experiment?

The reaction used to convert vegetable oils to FAMEs is called transesterfication. For this experiment specifically, transesterfication is the conversion of glycerol esters and methanol into methyl esters and glycerol. Transesterfication is used for base-catalyzed biodiesel production. In this experiment, sodium-methoxide will be used as the base catalyst.

Name the solutions that were used to wash the reaction mixture during the work up and explain their roles.

The solutions that were used to wash the reaction mixture were HCl, Sodium Bicarbonate (NaHCO3), water, and brine. The HCl was was used to remove any amine or DMAP in the solution that may have been unreacted. The NaHCO3 wash was used to remove an unreacted acid that may have remained in the solution. The water wash was used to remove urea and any other salts that may have been present in the solution. The brine wash was used to remove any water that may have been left in the solution.

List all techniques that were used (e.g. NMR sample preparation) and data needed for this experiment (e.g. amount of reagents, etc.) for the successful completion of this experiment.

The techniques used in this experiment include, carefully weighing out chemicals, carefully measuring liquid chemicals, using a hot plate with stirrer to heat mixture for extended amounts of time, carefully pipetting out a certain layer of scintillation vial, preparing NMR tube for analysis, and analyzing a proton NMR spectrum. The data necessary to collect for this experiment is the mass of NaOMe, volume of oil, volume of MeOH, mass of empty scintillation vial (w/boiling chip), and mass of scintillation vial (w/boiling chip) with product after evaporation of MeOH.

Increasing the conjugation will decrease the energy of absorption.

True

The excess reagent in this reaction is required to shift the equilibrium to the right.

True

Determine the safest option in the lab if you need your vision to be corrected.

Wear corrective glasses or lenses under your safety goggles for the whole experiment, but always check with your TA or Instructor for your school's policy

When should you start a new chemical waste container in the lab?

When the contents of the current container are a couple inches below the brim of the container

What is the full name of LiHMDS?

lithium hexamethyldisilazide

The addition of water to sodium methoxide produces ____ & ____

sodium hydroxide & methanol