ORGO 2 LAB FINAL UF

Can you work alone in the lab?

No, an instructor must be present and strictly during your class period. Only do authorized experiments in the lab.

Can you take off your safety glasses once you're done with your experiment but still in the lab?

No, glasses must be worn at all time when inside the lab, EVEN if you wear prescription glasses.

Can you wear contact lenses in the lab?

Yes, but it is highly recommended to refrain from doing so.

*many compounds in the lab are volatile and cause eye irritation

*let your TA know if you're wearing them, in case you require eye wash

*highly recommended to wear splash goggles over glasses

What is strictly prohibited in the lab?

(hint: 8 things)

*eating

*drinking (including water)

*chewing gum

*eating candy

*using cough drops

*smoking

*chewing tabacco

*applying chapstick

What needs to be tied back while working in the lab?

*billowy clothing

*long hair (shoulder length or longer)

Appropriate protective clothing must be worn AT ALL TIMES while in the lab (or you won't be permitted in the lab) , what is appropriate clothing? What's inappropriate clothing?

ALLOWED:

*long pants (loose fitting jeans, slacks or scrub pants)

*shirt or blouse (must cover entire upper torso including the midriff and chest area, AND must cover 2-3 in of the waist of your pants when your hands are raised above your head)

*cotton t-shirts are fine

*proper shoes a.k.a. flat soled shoes that enclose entire foot (should be able to take a quick glance at your foot and not see any exposed skin or sock on top of foot or around the ankle area) LEATHER offers best protection

NOT ALLOWED:

*tank tops, scoop or boat neck top, leotards, sleeveless shirts and blouses, and tops made of sheer material

*shorts of any kind, tight pants gathered at the ankle, and tights

*thin cotton canvas shoes, ballet flats, sandals, clogs, mules, open toed/heeled shoes

P.S. don't wear good clothes to the lab because it could get stained, bleached or generate holes

Are cellphones and other personal devices allowed in the lab at any given time?

NO

*devices must be silenced and stored in your storage locker in front of lab bay

IF YOU NEED TO MAKE A PHONE CALL go outside and when you enter again store your phone away.

*bring calculator bcs you will need it, but can't use phone calc

Aisles, walkways, drawers, personal items and personal transportation?

Aisles and walkways should be kept clear during the laboratory period.

Drawers must be closed unless you're actively retrieving something.

Personal items must be kept in bay .

Personal transport shouldn't be brought into the lab.

What are the only items you should have at your workstation?

*lab manual

*pen/pencil

*calculator

Can you sit on floors or counters?

NO

When working with chemical reagents...

1) read labels on all chemical and reagent bottles carefully, many of them have similar names, can easily be confused

2) always use a spatula or scoopula when transferring chemicals (DONT pour directly out of jar, increases waste), DON'T USE YOUR FINGER (contaminate)

3) never pipet any liquid by mouth and don't put pipets directly into any reagent, solvent or acid bottle (can contaminate)

4) take only the amount of chemical you need , and don't pour excess in bottle, pour in waste

5) keep lids on reagents unless in use, many chemicals are sensitive to light or the moisture in the air

6) when diluting concentrated acids or bases, always do acid/base into water and not vice versa, water going into concentrated acid/base can cause the solution to splatter

7) clean up spills as soon as they happen , dispose of spilled materials in the proper container

When should you use a fume hood?

-whenever you're working with or generating chemicals that fume or give off vapor

ALL reflux assemblies and extractions should be set up in the fume hood

Should you work with broken or cracked glassware? If not, what should you do?

NO

-replace all broken glass immediately

- contaminated broken glass goes in waste

-clean broken glass goes to stockroom

What should you do when working with hot glassware?

- be careful, hot and cold glass look the same, therefore possibility of burning yourself

- use your tongs when working with hot glassware so you don't get burned

How to dispose wate?

NEVER DISPOSE CHEMICAL WASTE DOWN THE DRAIN

-there's a container for solid and liquid waste, use the appropriate one

-NEVER overfill a waste container , notify TA and/or stockroom to replace container

-place all contaminated filter and ph paper in waste container

Don't put your hand into the waste container , place all broken glass, capillary tubes, and pipets in the wasted container

How to report an accident?

- Tell TA, you will both have to fill out an accident report

- if severe injury to you , you will be escorted to infirmary

What are the consequences of not observing laboratory safety rules and procedures resulting in injury to you or your lab mates?

First violation:

you will receive a warning and an opportunity to correct the issue

Second or Third Violation:

will result in suspension for the lab period and a grade of zero for the day (this time isn't excused)

Further Violation:term-20

will result in a grade of E for the course

CHAPTER 1: Greening Organic Chemistry

What is a superfund?

a congressional fund that allocates resources to help clean up the nations uncontrolled hazardous waste , including old factories , landfills , and illegal dumping sites

Green Chemistry

focuses on finding ways to improve chemical products and processes to help reduce or eliminate potential hazards to human health and the environment

The 12 Principles of Green Chemistry

Prevention - It's better to prevent waste than to treat or clean it up after it's formed.

Atom Economy - Design synthetic methods to maximize the incorporation of all materials used in the process into the final product.

Less Hazardous Chemical Syntheses - Design methods that use and generate substances with little or no toxicity to human health and the environment.

Designing Safer Chemicals - Create products that are effective while minimizing toxicity.

Safer Solvents and Auxiliaries - Avoid or minimize the use of auxiliary substances (e.g., solvents), and make them as non-hazardous as possible.

Design for Energy Efficiency - Minimize energy requirements; conduct reactions at ambient temperature and pressure when possible.

Use of Renewable Feedstocks - Prefer raw materials that are renewable rather than depleting.

Reduce Derivatives - Avoid unnecessary derivatization (use of blocking or protecting groups).

Catalysis - Use catalytic reagents (as selective as possible) over stoichiometric ones.

Design for Degradation - Design chemical products that break down into innocuous substances after use.

Real-time Analysis for Pollution Prevention - Develop methods to monitor and control processes to prevent the formation of hazardous substances.

Inherently Safer Chemistry for Accident Prevention - Choose substances and forms that minimize the risk of chemical accidents.

CHAPTER 2: Introduction to Melting Points

What's the melting point of a pure substance?

the temperature at which the solid phase is in equilibrium with the liquid phase (same as freezing point)

What is the melting point range of a compund?

the temperature range from when the first drop of liquid is observed until the last bit of solid has liquified

Melting point range for a pure compound...

- unique property for that compound

- often used to help identify the compound and assess it's purity

- is sharp, meaning that the range is narrow, typically 1-2 degrees at most

Are two samples with different MP different?

Yes, we can be sure of that.

*if two samples have the same MP we can't ensure they're the same sample until further tests have been done

What does the presence of a SOLUBLE impurity in a sample change?

it has the effect of lowering and broadening the the melting point range

(Reasoning: the impurity disrupts the crystalline lattice of the sample so less energy is required to convert the solid phase into a liquid phase. This means the crystals will begin to melt at a lower temperature , and the range will be broader, sometimes 5 degrees or more.)

* soluble was bolded bcs an INSOLUBLE impurity (ex. sand or glass) has no effect on MP range

How do you ensure an accurate determination of MP?

-sample must be finely powdered

-proper amount must be firmly packed into a capillary tube

What are common errors in MP determination?

- sagging or shrinking of crystals is mistaken for melting

-the presence of solvent can cause the crystals to "sweat" before melting occurs

What are the MP for benzoic acid and mandelic acid?

Benzoic acid: 122-123°

Mandelic Acid: 120-122°

For MP how big should the sample in your capillary tube be?

1-2mm tall

How do you use the digital MP instrument?

To use the digital melting point instrument, first set the start and stop temperatures using the buttons on the instrument. After setting the ramp rate, press the start button and the instrument will quickly preheat to the start temperature. During this preheating, the preheat light on the instrument will be illuminated. When the instrument reaches the start temperature, the ready light will be illuminated. At that point you should place your capillary tube into the instrument and begin your measurement by pressing the start button.

How do you report MP?

As a range, smallest number being when the first droplet forms and higher number being when the last piece of solid turns to liquid

POST LAB QUESTIONS

How well did your data agree for the pure samples measured on different machines? What could be the possible reasons for different readings?

-The amount of the sample in the capillary tube could be why the readings were different.

(maybe) these may be a result of differing temperature ranges or ramp rate, or perhaps one machine heating up quicker than the other as a result.

Describe differences in your observations for the pure sample versus the mixture

The mixture melted quicker than the pure sample

What if you measured the melting point of a sample, allowed the capillary tube to cool, and then remeasured the melting point of that sample? Would you expect the melting point of the sample to change or remain the same? Why?

I would expect the melting point to stay the same because in both cases, the machine must preheat to the same temperature. Furthermore, the melting point value is fixed, meaning the sample should mainly have its melting point be within a certain range.

CHAPTER 3: Identification of Organic Compounds Using Spectroscopy

PRE LAB QUESTIONS

Pre lab:

An unknown compound was determined to be 74.97% carbon, 8.39% hydrogen, and no nitrogen. Calculate the empirical formula.

Carbon : 74.97g x 1mol/12g = 6.2475mol of C

Hydrogen: 8.39g x 1mol/1g = 8.39mol of H

100 - (74.97+8.39) = 16.64

Oxygen: 16.64 x 1mol/16g = 1.04mol of O

6.2475/1.04 = 6.007

8.39/1.04 = 8.067

1.04/1.04 = 1

Formula = C6H8O

Pre lab:

Can IR spectroscopy be used to distinguish 2-pentanone from 2-hexanone? Why or why not

No

IR distinguishes molecules based on functional groups. 2-pentanone and 2-hexanone both have a carbonyl group. NMR would be a better method.

How do you calculate empirical formula?

1) Start with the mass (or %) of each element.

*If given percentages, pretend you have 100 grams total so the % becomes grams.

2) Convert grams to moles

Use:

Moles= (grams)/(atomic mass (from periodic table))

​

3) Divide each mole value by the smallest one

*This gives you a ratio.

4) Round to nearest whole number

If you get something like 1.5, 2.33, etc., multiply all numbers to make them whole (e.g., ×2, ×3)

5) Write the formula using those numbers as subscripts.

How did chemists 75 years ago determine the structure of an organic compound?

chemists relied on qualitative chemistry

- these tests utilized different reactivities of functional groups with reagents that give a color change, a precipitate, or some other visible sign of reaction

ex. to test for alkene/alkyne in an unknown compound, they would use bromine (reddish brown) and if an alkene/ alkyne was present the color would be colorless after the reaction

IMPORTANT:

these tests only identify the presence of specific functional groups not the actual molecule

What does spectroscopic data provide us with?

spectroscopic data provides us with the "fingerprint" for a molecule, and each individual molecule has its own set of data

Infrared Spectroscopy (IR)

provides us information about what functional groups are present in the molecule

Nuclear Magnetic Resonance (NMR) Spectroscopy

gives us information about the structure and bonding in a molecule

-CNMR

-HNMR

Elemental Analysis

-simplest form is for carbon, hydrogen, and nitrogen

involves burning an organic compound in an oxygen atmosphere and measuring the amount of combustion products produced (from this data we can solve for EMPIRICAL FORMULA)

What would you do if you're trying to calculate empirical formula and percentage of nitrogen is 0.02%?

Don't use nitrogen, it's only a trace amount

If your empirical formula is C2H3O, is there other ways of writing it?

Yes, you can write the multiples.

Ex.

C4H6O2

C6H9O3

Chapter 4: Synthesis of Acetophenetidin

PRE LAB QUESTIONS

Pre lab:

Explain the purpose of the hot gravity filtration. Why is it good to use the stemless funnel for this technique?

Hot gravity filtration is used in the process of recrystallization. Specifically, it is used to remove any insoluble impurities from the sample while keeping the acetophenetidin dissolved.

-It is good to use the stemless funnel for this technique because it prevents crystallization from occurring on the stem of the funnel (since stemless).

(To elaborate, if hot solution were to become stuck on the stem of the funnel, it may cool and therefore crystallize and obstruct/block the funnel stem.)

Pre Lab:

The density of acetic anhydride is 1.08g/ml. How many moles of acetic anhydride are used in this experiment.

Given: 1.8ml used in experiment

MW: 102.09g

Density: 1.08g/ml

Use density to find mass:

Mass= volume * density

Mass= 1.8ml* 1.08g/ml

Mass= 1.944g

Use molar mass to find moles:

Moles= mass/molar mass

Moles= 1.944g/ 102.09g

Moles= 0.019 mol

Pre Lab:

Consider the solvents that will be used as potential recrystallization solvents: water, hexane, and ethanol. Which is most polar? Least polar? Which are miscible?

(miscible: forming a homogenous structure when mixed)

Most polar = water

Middle= ethanol

Least polar = hexane

Miscible = water and ethanol

PS molecular weight and molar mass are the same thing, different units

molar mass ( g/mol)

molecular weight (amu)

Pre Lab:

Calculate the amounts of p-acetamidophenol (in grams) and bromoethane (in milliliters) that are used in this reaction.

Given:

10mmol of p-acetamidophenol

15mmol of bromoethane

MW of p-acetamidophenol is 151.17 g/mol

MW of bromoethane is 108.97 g/mol

Density of bromoethane is 1.46 g/mL

P- acetamidophenol

10mmol--> 0.01 mol

0.01 mol* (151.17 g/ 1 mol) =1.5117 g

Bromoethane

15mmol--> 0.015 mol

0.015mol * (108.97 g/ 1 mol)= 1.6346 g

volume= mass/ density

Volume= 1.6346g / (1.46g/mL)= 1.1195 mL

Pre Lab:

What is activated carbon? What is it used for, either in the lab or other application? Is activated carbon known by any other names? If so, what are they?

In this experiment, activated carbon is used to remove the colored impurities from the sample; in general, activated carbon is used to purify and decolorize samples (because it's absorbent).

Activated carbon is also known as "decolorizing carbon" or "activated charcoal."

This is the question:

Is the acetophenetidin formed through a Williamson ether synthesis identical to that formed from acetylation of p-phenetidine?

Whats the Goal?

determine if the products formed from these two routes are identical, and to determine if one of the synthetic pathways has any considerable advantage over the other

williamson ether: forms ether linkage

amide synthesis: forms amide bond

what is recrystallization used for?

a common technique that's used to purify organic solids

How do impurities affect crystal lattices? How should they normally be?

Most pure organic solids have normal crystal lattices. The more well ordered the crystal lattice is , the better the packing is within the crystal. This allows the organic molecules to self assemble into a very pure crystal with a narrow melting point.

Impurities in a sample will cause a disruption in the order of the crystal lattice, which causes imperfections in the crystals that in turn lead to lower melting points.

What type of solvent so scientists prefer when conducting recrystallizations?

- completely dissolves both the compound and any other organic impurities when the solvent is hot (usually boiling )

- the desired compound must be insoluble at cold temperatures and the organic impurities must remain soluble

simpler way:

you want the solvent to make sure everything is liquid when boiling BUTT you want impurities only to be liquid when cold so that they can drain out when vacuum filtering , and then you're only left with the pure material as a solid

How does recrystallization work?

- an impure sample is dissolved in a min amount of solvent at boiling point

-any impurities are normally removed by hot gravity filtration

-the hot saturated solution is then allowed to cool slowly to room temp

-during the cooling process , small crystals form of the desired compound

-these seed crystals serve as nucleation sites where more molecules of the desired compound deposit themselves (various shapes form i.e. plates, needles and snowflakes)

- after cooled at room temp, solution is put in an ice bath to maximize crystal formation

- crystals are collected by vacuum filtration and are usually rinsed with a small amount of ice cold solvent to rinse any traces of impurities from the crystal surface

What is the "mother liquor"? What purpose does it serve?

-the liquid at the bottom after filtering

-can be reheated to boiling, evaporated slightly , and cooled again to yield a second crop of crystals

what color is p-phenetidin? As what color can it appear to be when impurities are present?

- pure p-phenetidin is colorless

- when impurities are present it can appear to be a reddish-brown color , caused by air oxidation of the amino functional group in the compound

how do you remove the colored impurities?

using activated (or decolorizing) carbon

What happens if you add the activated carbon to the hot solution too quickly ?

the solution will foam up and out of the beaker

What color should your solution be after its been gravity filtered with the decolorizing carbon?

colorless or very slightly pink

- if your solution is dark pink, brown, or black and cloudy , you will need to repeat the decolorizing step

When collecting crystals by vacuum filtration using the buchner funnel, what should you resist doing?

resist the urge to stir the crystals in the funnel , this makes the filtration less efficient and does not adequately remove the solvent from the crystals

How to determine the best solvent in this lab?

1) take the same amount of acetophenetidin and place in three different test tubes

2) add 2-3 mL of solvent to each tube (water, ethanol, and hexane)

3) check solubility at boiling point , room temperature, and when cooled in ice

What determines a good solvent for recrystallization? What was the best solvent in this lab?

best solvent:

cold: stays solid

hot: dissolves

the best solvent in this lab was water

What does a wooden applicator stick and boiling chips do?

helps with gentle boiling

Should you use filter paper as a substitute for weighing paper?

no, filter paper is very porous and some of your solid chemicals will be trapped in the pores and won't make it into your reaction

Is it normal to have droplets of liquid on the bottom tip of the condenser that will begin dripping down to the round bottom flask?

YES it's normal, don't worry your condenser isn't leaking

-this is condensing solvent, and the boiling , condensing , and dripping cycle is "reflux"

In a good reflux, where should the vapor line be?

the vapor line should be between 1/4 and 1/2 of the way up the condenser

What is the perfect ice bath?

a little slushy , maybe 3/4 ice and 1/4 water

theoretical yield (in grams)

moles of limiting reagent x molecular weight of product

percent yield

actual yield (grams) /theoretical yield (grams) x 100

OR

actual yield (moles) /theoretical yield (moles) x 100

percent recovery

(mass of recovered recrystallized product/ mass of crude product) x 100

POST LAB QUESTIONS

Discuss your experimental results with your lab mates. How do your yields and melting points compare? Devise a simple experiment that you could use to determine if the samples made through the two synthetic routes are identical.

My lab mates and I have varying melting points and yields. In order to test if the samples are identical , you could mix them together and test their mp. If the range is broad and low the 2 products aren't identical.

Why is HCl used instead of plain deionized water in p-phenetidine in amide synthesis of acetophenetidin?

HCl is used for the acid-base reaction rather than water because HCl's polarity contributes to a reaction driven to the right. It protonates the amine group, making it easy to dissolve.

What is the purpose of the sodium acetate solution in the amide synthesis of acetophenetidin?

It is used to buffer the reaction mixture because control of acidity is important in maximizing yield. Protonation activates acetic anhydride toward nucleophilic attack, but if the pH is too low the starting amine will will be converted to its conjugate acid.

Chapter 5 Extraction

PRE LAB QUESTIONS

Pre lab:

Consider the following solvent pairs when mixed in equal volumes: Which are immiscible/miscible? If the solvents are immiscible, which solvent would be in the top layer?

a. hexane and water

b. dichloromethane and water

c. ethanol and water

d. ether and water

a. immiscible

Hexane would be on top because the density of hexane is smaller than water.

b. immiscible

Water would be on top because the density of water is smaller than dichloromethane.

c. miscible

d. immiscible

Ether would be on top because the density is smaller than water.

Pre lab:

Phenols do not exhibit the same pKa values as other alcohols; they are generally more acidic. Using the knowledge that hydrogen acidity is directly related to the stability of the anion formed (the conjugate base), explain why phenol is much more acidic than cyclohexanol.

Phenol dissociates to the phenoxide anion, which is resonance stabilized. The cyclohexanol anion is not resonance stabilized, and the negative charge is on the oxygen atom.

ps.

phenol- benzene ring connected to an OH

cyclohexanol- OH connected to a six membered ring

Pre lab:

The pKa of 2,4-dinitrophenol is 3.96. Could you separate it from benzoic acid using the extraction procedures in this experiment?

Because the pKa's are so close together, 2,4-dinitrophenol and benzoic acid would not be able to experience selective extraction.

What's extraction?

a technique that chemists use to remove selected components from a mixture, usually based on solubility differences or chemical reactivity

Why are solid liquid extractions often performed using liquid CO2 as a solvent?

offers greener alternative to traditional organic solvents because it is readily available , nontoxic , and safe for the environment

Orange oil is particularly rich in D-limonene, how are we able to extract this orange oil?

- liquid CO2

1) place rind in centrifuge tube , packing the tube with dry ice (solid CO2)

2) seal the tube with a plastic cap

3) as the CO2 sublimes, pressure builds up in the tube and causes the gaseous CO2 to liquefy

4) CO2 percolates through the orange rind and extracts the limonene

5) As the tube warms the liquid CO2 becomes a gas and escapes from the tube

6) at the end of reaction you will be left with a drop of nearly pure orange oil at the bottom

What 2 conditions must be met to in order for a liquid-liquid extraction to be successful?

1) the two solvents that are chosen must be IMMISCIBLE (they must not be soluble in each other), for most extractions one solvent is usually a nonpolar organic liquid and the other is polar (generally water or an aqueous solution)

2)the compounds extracted must have DIFFERENT AFFINITIES for the two solvents

*"like dissolves like", polar compounds are usually more soluble in polar solvents than in nonpolar ones

What occurs if a compound like benzoic acid is placed in a separatory funnel?

*due to benzoic acid having nonpolar (benzene ring) and polar regions (carboxylic acid) you would expect it to be soluble in water and organic solvents

for compounds like benzoic acid , when they're placed in a separatory funnel with water and extracted with an organic solvent (like ether ) an equilibrium distribution will be achieved

Kd= C1/C2= (grams of compound per mL organic solvent)/(grams compound per mL of water)

Once the Kd is known, how do you determine the amount of solute remaining in the original water layer after a series of extractions?

(final mass of solute)water / (initial mass of solute)water

or

((V water)/ (V water + (Vorg* Kd)))^n

Vorg= volume of organic solvent used in each extraction

Vwater= original volume of water

n= number of extractions

Kd= distribution coefficient

Carboxylic acids and phenols are...

- two classes of organic molecules that are considered to be acidic

-act as bronsted lowry acids and easily donate (or lose) a proton when in contact with aqueous base

Substituted amines (including anilines)

- considered basic

-act as bronsted lowry bases and easily accept a proton when in contact with aqueous acid

general rule for acids

weak bases extract strong acids

and

strong bases extract weak acids

How is neutralization, in the context of pH control, achieved?

-use HCL on aqueous layer and check with PH paper until it's acidic

Do the organic solvents used for extractions absorb water?

yes, even though they're immiscible with water, they still tend to absorb some water during the mixing that occurs during extractions

How do we dry the solution (remove the water) before the organic solvent is evaporated?

-wash the organic layer with a portion of brine to remove the majority of the dissolved water

-organic solvent is dried further with a anhydrous inorganic salt, usually anhydrous magnesium or sodium sulfate (will absorb the water that is dissolved in the organic solvent

-add drying agent until it doesn't clump tg (snow globe effect)

How is the drying agent removed?

decanting or gravity fitration