CHM2211L Final Quiz

1 ring or 1 double bond

1 degree of unsaturation means?

2 double bonds, 2 rings, 1 double bond & 1 ring, or 1 triple bond

2 degrees of unsaturation means?

biodiesel & ethanol

2 most common biofuels used for transportation.

liquid-liquid extraction

2 solvents chosen must be immiscible (one polar (typically H2O or aq. solution) & one nonpolar); compounds to be extracted must have different affinities for the 2 solvents.; components are extracted based on "like dissolves like."

condensation, chain addition, & cross-link

3 types of polymerization?

pH-dependent flurorescence

4-methylumbelliferone displays _____ that is easily observed under a standard UV lamp.

blue & green

7-(Diethylamino) coumarins are efficient laser dyes in the _____ & _____ regions of the electromagnetic spectrum, w/ high quantum yields in most organic solvents.

substituion

EAS mechanism: aromaticity will be reestablished thru _____, not thru addition. therefore, it will only undergo _____.

10% aq. sodium thiosulfate

EAS: added to react w/ leftover, unreacted iodine in the soln. - thiosulfate anion is acidified using 1 M HCl to precipitate out the product.

I+

EAS: sodium iodide (NaI) is added to the mixture, which will serve as the source of _____ in soln.

electrophile

EAS: the free I+ is the _____ that reacts w/ salicylamide to produce the EAS product.

6% hypochlorite soln. (bleach, NaOCl)

EAS: the oxidizing agent to react w/ NaI, producing I+ in soln.

before

EAS: you cool the soln. ______ reaction (nothing happens before you add bleach) to slow the rxn rate & avoid unwanted secondary rxns.

flammable

EtOH is _____; handle w/ care.

corrosive

HCl & sodium carbonate solutions are both _____; handle w/ care.

- use IR cell for gas samples. - use salt plates (NaCl) for liquid samples. - use KBr pellet for solid samples.

IR spectroscopy technique?

crystalline lattice

MP is dependent on the stacking arrangement of the _____. because the impurity affects the _____, it's easier to overcome the intermolecular interactions between the molecules.

- use deuterated solvents to keep spectra clean (prevents unwanted H peaks from solvent).

NMR spectroscopy technique?

NMR spectral analysis

Pechmann condensation: _____ of the mother liquor usually reveals only the desired product, though occasionally unreacted resorcinol remains.

organic solvent

Pechmann condensation: avoidance of a(n) ______ eliminates the associated hazards as well as reduces waste.

liquid rxn mixture to a solid product

Pechmann condensation: the conversion from a _____ to a _____ effectively signals when the reaction is complete.

chromatography

Pechmann condensation: the purification method, a simple recrystallization from aqueous EtOH, avoids _____, often a major source of waste generation, in the form of the spent solid support & the elution solvent(s).

beads

Pechmann condensation: use of an acid catalyst in the form of easy-to-handle nonvolatile _____ makes handling this acid catalyst safer.

acid catalyst

Pechmann condensation: waste is minimized by utilizing a mild, reusable _____ that's easy to work with & recover, rather than with a stoichiometric auxiliary reagent.

nonpolar

Rf values for _____ compounds are closer to 1.

small

Rf values for polar compounds are ____.

4-methylumbelliferone (non-toxic, easy to prepare & isolate)

_____ can be rapidly synthesized by simply heating resorcinol & ethyl acetoacetate in the presence of a strong-acid ion exchange resin (Dowex 50WX4), enhancing the green chemical relevance of the experiment & making it more accessible even to those teachers w/ limited budgets.

vegetable oil

_____ is converted to biodiesel in a simple transesterification catalyzed by hydroxide ion, making this process economically viable on an industrial scale.

L-lactide

_____ is the monomer end block in the synthesis of triblock copolymer.

impure; pure

_____ substances are easier to break/melt. thus, less heat is needed to melt a(n) _____ mixture than is required to melt the _____ structure.

covalent bonds

_____ vibrate at only certain allowable frequencies, depending on the strength of the bond & the atoms connected by that bond.

polar components

_____ will move more slowly, because they're attracted to the polar stationary phase.

nonpolar componets

______ will more more quickly, because they're less attracted to the stationary phase (TLC plate).

reactive species

a chain addition polymerization involves the use of an initiator that forms a _____.

warfarin

a coumarin derivative that operates as an effective blood thinner and rat poison by antagonism of vitamin K 2,3-epoxide, preventing thrombin synthesis required for clotting.

slime

a cross-linked polymer that's formed from the reaction of poly(vinyl) alcohol (PVA) w/ borax (sodium borate decahydrate) under aqueous conditions. this polymerization gives an elastic gel.

lower; broaden

a small amount of impurity will _____ s compounds' MP by a few degrees (sometimes 5 or more) & _____ the MP temperature range.

monomer

a small molecule.

~ 1/3

a solvent system that moves the target compound about _____ of the total solvent path (Rf value of 0.25-0.35) is considered good.

higher temperature

a substance cannot be observed to melt @ a _____ than its MP.

reflux

a technique that prevents organic solvent from evaporating from the reaction vessel; this allows a reaction to be heated, increasing the rate of the reaction; allows chemists to run reactions in less time.

acetic anhydride & 85% phosphoric acid

acylium ion is made of _____ & _____.

while heating, hot H2O added until soln. becomes slightly cloudy & then flask is removed from hot plate, & mixture is allowed to cool slowly to room temp.

after adding hot EtOH (95%) to dissolve the tan solid & rinse Dowex beads, what is the next step in the Pechmann condensation experiment?

you must break the test tube by screwing it in a clamp & tightening it to break the tube; shield tube w/ paper or towel to avoid being cut. - check solubility of polystyrene in acetone, toluene, & ethanol by placing small pieces of polystyrene sample in 3 small test tubes & adding about 5 mL of each solvent.

after allowing the test tube w/ styrene & benzoyl peroxide to cool to room temp., how do you get the sample of polystyrene out?

use match to ignite end of cotton string soaked in gasoline & set timer to see how long it takes to burn. then, repeat the burn test w/ the same length of string soaked in the biodiesel you made. record times & observations for both strings.

after decanting the biodiesel from the drying agent, what should you do next?

pour the potassium methoxide solution into the oil (don't turn the heat off) and stir for 15 minutes.

after forming the potassium methoxide for biodiesel synthesis, what should you do next?

obtain 20 mL of anhydrous methanol in a clean, dry graduated cylinder; weigh 0.5 g of KOH into a clean, dry 50 mL Erlenmeyer flask (make sure you close the lid on the KOH bottle quickly since KOH is quite hygroscopic).

after heating the vegetable oil to 65°C for biodiesel synthesis, what's the next step?

nucleation sites

after insoluble impurities are removed by hot gravity filtration, the hot saturated soln. slowly cools to room temperature & forms seed crystals which serve as _____.

1 hour or more (until mixture has solidified/become very viscous). - allow test tube to cool to room temp. & test consistency again.

after mixing to dissolve the benzoyl peroxide in styrene, how long should you heat the mixture in boiling water?

transfer the warm rxn mixture to a separatory funnel; shake the mixture vigorously for about 5 min. (venting periodically to release the pressure); let the separatory funnel stand until the next lab period to allow the rxn mixture to separate.

after pouring the potassium methoxide soln. into the oil during biodiesel synthesis, what should you do?

do one final wash w/ brine to remove as much H2O as possible from biodiesel; dry biodiesel over anhydrous magnesium sulfate for approx. 10 min. (swirling periodically), then decant the biodiesel from the drying agent.

after washing the biodiesel & getting a clear separation of layers, what should you do?

broken-glass container

all broken glass goes where?

initiation (chain addition)

an initiator will form a reactive species (radicals). initiators will have a weak bond that'll easily break w/ appropriate heating to form these radical species (O-O bond is weak).

thermoplastics

annealing of copolymer: the triblock copolymers formed are _____, which means they readily soften when heated, allowing them to be molded & recycled.

simple hydrocarbon backbone

another difference between chain addition and condensation polymerization is that polymers formed by chain addition from vinyl-type monomers have a _____, & any functional group is pendant to the polymer chain.

polarity

as the eluent moves up the TLC plate by capillary action, the sample components are carried w/ it & are separated on the stationary phase based on _____.

borate ion

borax forms the _____ in solution & has the following structure:

yes

can a SB & a SA form a rxn?

vinyl-type monomer

chain addition differs from condensation polymerization in many ways, one of them being the fact that chain addition usually involves a _____.

decrease

chain addition: increasing amount of initiator will _____ the MW of polymer, because more chains will be made, but they will be shorter overall.

increase

chain addition: increasing amount of monomer will _____ the MW of polymer because longer chains can be made.

vacuum filtration

crystals are collected by _____ & rinsed w/ ice cold solvent. - the filtrate (mother liquor) can be reheated to bP, evaporated slightly, & cooled again to yield a second crop of crystals.

~2-3 mL hot EtOH (95%) added to dissolve solid & pipet is used to transfer hot soln. from Dowex beads to clean flask (if desired, beads may be rinsed w/ additional portion of hot 95% EtOH).

during Pechmann condensation, after the rxn mixture has solidified to a tan solid (~20-30 min.), what should you do next?

potassium methoxide (the reagent needed for this reaction)

during biodiesel synthesis (after closing the lid on KOH bottle quickly), carefully pour the 20 mL of methanol SLOWLY into flask containing KOH (make sure to cork the flask to prevent methanol from evaporating); swirl the flask to dissolve the KOH. this step forms?

to maximize crystal formation.

during recrystallization, after the saturated solution has cooled to room temp, why do we put it in an ice bath for further cooling?

lactones

during synthesis of a homopolymer, _____ undergo ring-opening transesterification polymerization.

ortho & para

electron donating groups (EDG) direct ______.

-NR2, -NHR, -NH2, -OR, -OH

electron donating groups include? - these groups have a lone pair that they're able to donate to electron density to the pi system. - ring activating by increasing electron density, more nucleophilic.

meta

electron withdrawing groups direct ______.

-CF3, -CN, -SO3H, -NH3(+), -NO2, -COOH

electron withdrawing groups include? - these groups are e- deficient & remove electron density from pi system. - ring-deactivating by decreasing electron density, less nucleophilic.

irritants

ethyl acetoacetate, Dowex 50WX4 (acid form), & 4-methylumbelliferone can all act as _____. - use gloves & eyewear.

formation of Nylon-10,6 (a polyamide)

example of condensation polymerization?

polyamides & polyesters

examples of condensation polymers?

cotton, silk, & wool

examples of natural polymers in our everyday lives?

polystyrene, polyethylene, & PVC

examples of synthetic polymers in our everyday lives?

solid-liquid extraction

extract D-limonene from orange rind using liquid CO2. liquid CO@ was obtained from dry ice under pressure. solid CO2 sublimes & builds up pressure in the tube, causein the CO2 (g) to liquify. dipping the vessel in warm H2O speeds up sublimation.

back extraction

extraction: if precipitation of a neutral compound doesn't occur from aq. phase, you should perform _____: - neutralize the carboxylate &/or phenolate ions by adding 10% HCl soln. until the soln. registers as acidic w/ pH paper. - of there's no precipitation, extract the compound from the H2O using fresh portion of organic solvent (_____).

50 mL Erlenmeyer flask w/ ethyl acetoacetate (1 mL), resorcinol (800 mg), & Dowex 50WX4 beads (1 g); flask placed on a hot plate, set to lowest setting; rxn proceeds @ reasonable rate @ temps. low as 80°C, & commencement of rxn is indicated by gentle bubbling; mixture occasionally stirred w/ glass rod until bubbling stops, & mixture solidifies to a tan solid (~20-30 min).

first step of Pechmann condensation in synthesizing 4-methylumbelliferone?

heat 75 mL of vegetable oil to 65°C in a 250 mL beaker, stirring periodically to prevent steam pockets.

first step of biodiesel synthesis?

a crude (impure) sample is dissolved in a minimum amount of solvent at the BP.

first step of recrystallization?

H2SO4 & POCl3

for Pechmann condensation, high temperatures & extreme reagents such as _____ & _____ were originally used to effect the transformation, the reaction has been improved upon by the development of protocols involving recyclable, solid acid catalysts (acidic ion exchange resin Amberlyst-15). - has made this experiment a greener chemical process.

formed 2 separate layers.

for the biodiesel synthesis: while the rxn mixture was allowed to stand in the lab, what should it have done?

mass spectrometry (MS)

fragments the molecule and measures the masses, giving information about the molecular formula.

polystyrene

generated from chain addition of polymerization of styrene.

nuclear magnetic resonance (NMR) spectroscopy

gives info about structure & bonding in a molecule using H & C NMR spectra of a molecule; detects signals from hydrogen atoms and can be used to distinguish between isomers.

block copolymer

has 2 different monomer units that alternate & make up the polymer chain.

homopolymer

has same monomer unit making up the polymer chain.

umbelliferones

have recently found applications in fluorometric enzyme assays & as blood-brain barrier probes, anti-inflammatory agents, dyes, & fluorescent pH indicators.

diesel

heavier, oilier than gasoline; has a higher BP than gasoline; less refined & has higher energy density than gasoline. _____ engines are also more efficient at burning fuel & also work better for bigger engines.

higher energy

higher frequency means _____.

poly(δ-decalactone)

homopolymer (_____) is a viscous, amorphous liquid because of the flexibility of the alkyl backbone & side chains. - it's the "soft" midblock. - if there's more of this midblock in the final triblock copolymer, then the properties of the copolymer will be more flexible, clear, tacky.

- used to remove insoluble impurities (like charcoal) from solns. - use stemless funnel, because it allows for quick filtration, while keeping soln. hot - soln. needs to be kept hot to keep desired compound in soln.

hot gravity filtration technique?

after the crude sample is dissolved in minimal amount of solvent @ BP, any insoluble impurities (e.g., de-colorizing carbon) are removed by hot gravity filtration).

how are insoluble impurities removed from the crude sample during recrystallization?

wash the biodiesel w/ several portions of deionized water. GENTLY shake funnel to mix layers (vigorous shaking will cause excessive foaming) & vent periodically to release the pressure.

how can the soap byproduct of biodiesel be removed?

through addition of 10% HCl soln. to the H2O layer containing the ionic species, you can protonate the species, converting it back to neutral CA.

how can you isolate the compound by converting it back to its natural form?

perform a mixed MP (grind roughly equal portions of the 2 samples together to mix well & take MP of the mixture). - if 2 substances are identical, the MP range will be sharp. - if they're different, the MP range will be lowered & broadened.

how do you differentiate between 2 compounds using MP?

- cotton prevents silica from falling out of column. - then, sand which acts as the foundation for stationary phase & allows for even elution. - add silica gel slurry. - even out packing & remove air bubbles by tapping column. - after column sufficiently packed w/ silica, add layer of sand to protect stationary phase. - load concentrated solution of crude product into column as a small, narrow band. - run column w/ eluent & collect fraction as they elute.

how do you pack the column for column chromatography?

white to off-white crystal-line precipitate is isolated by vacuum filtration & is washed w/ H2O; product is allowed to dry before determining MP & carrying out spectral analysis.

how is the product isolated after allowing the mixture to cool slowly to room temp. after adding hot H2O & making the soln. cloudy during Pechmann condensation experiment?

do as many as you need until you get a distinct line between the 2 layers (should be about 4-6 washes).

how many washes of the biodiesel should you perform?

distinct, not tailing

how should to marks on the TLC plate be made?

do not pour any solid pieces of polystyrene into funnel of liquid waste bottle. just decant liquid & put solid polystyrene leftover into solid waste.

how should you get rid of the waste from the preparation of polystyrene?

no, there will be no separation.

if both species are ionic (polar), then both will go into the (polar) water phase; is there a separation?

use UV light, because it activates flurorescent indicator on the plate.

if compounds are not colored on TLC plate, you should?

add 10-15 mL of brine to the mixture.

if significant foaming occurs during the washing step of the biodiesel, what can you do to break up the foam?

flatten out

if you leave a ball of slime on a flat surface, it will slowly _____ as the molecular chains slide over each other, rearrange themselves, & reconnect. however, if you pull suddenly on the material, it will snap apart.

lower & broader

impure solid melts at a _____ temperature & over a _____ temperature range.

soluble

impurities must be _____ to afect the MP range.

dialkylamino groups

in 7-(Diethylamino) coumarins, electron-donating _____ enhance fluorescence, while shifting the lasing region to longer wavelengths.

magnetic field

in NMR, the spinning charged nucleus generates a _____.

condensation polymerization

in _____, the functional groups are part of the polymer backbone and are formed as the monomer units link together.

gasoline engine

in a _____, fuel is mixed w/ air, compressed by pistons & ignited by sparks from spark plugs.

diesel engine

in a _____, however, the air is compressed first, & then the fuel is injected. because air heats up when it's compressed, the fuel ignites.

rapidly

in chain addition, long polymer chains are generated quite _____.

different

in condensation polymerization, a small molecule is produced as 2 monomer units link together. thus, the empirical formulas of the monomer & polymer are _____.

polymer backbone

in condensation polymerization, the functional groups are part of the _____ & are formed as the monomer units link together.

ester

in organic reactions, an alcohol reacts w/ carboxylic acid to make a(n) _____. - in this case, there's only one reactive site on both the CA & the alcohol.

polyester

in polymer reactions, a diol & a diacid react to make a _____. - in this case, there are 2 reactive sites on both monomers, allowing for the formation of a polymer.

benzoyl peroxide

in polystyrene synthesis, our initiator was _____, a compound that generates radicals when heated to an appropriate temperature (~80-95 degrees Celsius).

acid halide & amine

in the rxn to form Nylon-10,6 (condensation polymerization), an amide linkage forms between a(n) _____ & a(n) _____, w/ the elimination of HCl.

poly(L-lactide)

in the synthesis of triblock copolymer, the end block is added to the homopolymer. - _____ is the "hard" end block. - if there's more of this end block in the final triblock copolymer, then the properties of the copolymer will be more tough, opaque, & rigid.

ferrocene

is the aromatic component of the EAS reaction.

acylium ion

is the electrophile in the ferrocene column chromatography experiment.

monomer

it's important to note that the initiator is not a big part of the polymer chain, because the repeat units of the monomer, n, are very large relative to the single molecule of initiator. thus, the properties/characteristics of the polymer are from the _____, not the initiator.

washing

leaves the desired compound in the organic phase, while it removes other impurities to the aqueous phase.

mobile phase (eluent)

liquid phase (the solvent in the chamber). - can vary from very polar (e.g., water, methanol) to much less polar (e.g., ligroin).

- keep fingers on stopper to prevent it from falling off when mixing. - point funnel away from you when venting. - remove stopper before draining. - multiple small extractions are better than one large extraction. - if you forget identity of your phases, add water & see which phase it adds to.

liquid-liquid extraction using separatory funnel for extraction experiment?

polymer

long-chain molecule made of a repeated pattern of monomers; formed thru synthetic process called polymerization.

glucose

many large biological molecules are polymers. for example, the plant material cellulose is a polymer of _____.

polymer

means "many units."

poly

means "many."

mer

means "units."

infrared (IR) spectroscopy

measures the bond vibration frequencies in a molecule & is used to determine the functional group (best for seeing polar functional groups like alcohols, amines (1 & 2 degree), & carbonyl compounds). - uses infrared light to excite molecules. - signals arise from changes in dipole moments (when bonds vibrate). - gives info about what functional groups are present. - only worry about the 4000-1500 cm region. *NOTE: cannot be used for atoms & homonuclear diatomic molecules (ex. H2, O2, N2, & all halogens); they don't possess IR spectra. also, complex mixtures & aqueous solns. are difficult to analyse due to the large OH stretch from H2O.

molecular weight

monomer & initiator amount influences MW of polymer.

1,1'-diacetylferrocene

most likely Diacetylferrocene product is _____, because acetyl group is EWG, which is ring-deactivating. in other words, once an acetyl group adds to the first ring, that ring will no longer want to react again, but the second ring will react.

because drying out silica gel can form channels in the packing material which will cause poor separation.

never allow the volume of the solvent to go below adsorbent while packing column in column chromatography, why?

nonpolar solvents

nonpolar compounds are more soluble in _____ (e.g., diethyl ether).

it will remove all organic compounds

only use a small amount of de-colorizing carbon, because too much will do what?

ionized

organic compounds contain functional grops that can be _____, so that the compounds becomes water soluble.

H-bond interaction

polar components are capable of _____ w/ silica & hence, get retained toward bottom of TLC plate.

polar solvents

polar compounds are more soluble in _____ (e.g., H2O).

polymer chain

polymers formed by chain addition from vinyl-type monomers have a simple hydrocarbon backbone & functional groups stem from the _____.

sweat

presence of solvent can cause crystals to "_____" before melting. this can be mistaken for actual melting.

Pechmann condensation

produces coumarins via the acid-catalyzed rxn of a phenol with a β-keto ester.

biodiesel

provides a non-toxic, biodegradable, lower pollution alternative to petroleum-based diesel fuel; made from vegetable oils and fats, can be used in diesel engines directly, w/o any need for modification of the engine.

reccrystallization

purification technique for organic solids; allows organic molecules to self-assemble into a crystal lattice that forms pure crystals.

column chromatography

purification technique that uses same concepts as TLC; there is a mobile phase, stationary phase (either silica gel or alumina w/ sites for H-bonding), & adsorbent.

propagation (chain addition)

radicals react w/ monomer to begin chain addition process. the monomer will be a vinyl type. the active species continues to add individual monomer units to the end until all of the monomer is used up & a polymer chains are generated.

transesterification, intramolecular electrophilicaromatic substitution, & alcohol dehydration

reaction types involved in the Pechmann condensation process? - hint: each of these steps is acid-catalyzed.

- use minimal solvent. - cool hot soln. slowly - you'll get bigger, purer crystals. - do not disturb flask while cooling. - mix solvents to optimize recrystallization.

recrystallization technique?

- don't cover top of condenser. - make sure H2O goes in @ bottom & out @ top.

reflux tehcnique?

extraction

removing desired compound from a mixture such that the desired compound ends up in the aq. phase (typically as an ion that will subsequently be neutralized).

concentrated

sample for column chromatography must be _____, not dilute, to obtain optimal separation of compounds. do not introduce water into column. - the more water the less polar sites that are available for organic compounds to bind to, so it becomes ineffective or deactivated.

thin layer chromatography (TLC)

separation technqieu that utilizes the concept of "like dissolves like" to separate the different parts of a mixture.

stationary phase

solid support (e.g., glass, aluminum, plastic sheet) that's coated w/ an adsorbent (e.g., silica gel or alumina - both are inorganic solids w/ sites for H-bonding). - this is the most polar component. - polar compounds more readily adsorb to the ______ than nonpolar. the _____ is the TLC plate.

- don't use same tube more than 5 times. - don't use glass, bc pressure would cause it to shatter. - use gloves to handle dry ice.

solid-liquid extraction

weak acids

strong bases are needed to extract _____.

odor

styrene has a very strong _____. carry out this reaction (preparation of polystyrene) in the hood.

hygroscopic

tending to absorb moisture from the air; relating to humidity or its measurement.

safe

the "slime" you made in the lab is safe/unsafe to take home.

long-range proton-proton coupling

the NMR spectrum for the isomeric coumarin that has the alcohol & ester on the same side provides an example of _____; both four-bond allylic coupling & five-bond aromatic para-coupling are observable.

radicals

the _____ generated by benzoyl peroxide react w/ the styrene monomer to begin the chain addition process of styrene polymerization.

weak (they can form/break easily, especially under the weight of the gel or w/ handling).

the bonds in the cross-link are weak/strong?

cross-linking

the borate ion can have weak, non-covalent interaction (H-bonding) with the OH groups of PVA to link the chains together, AKA?

identical

the empirical formula of a chain addition polymer is identical to that of the monomer.

long-wave UV lamp

the fluorescence in soln. of the isomeric coumarin (that has the alcohol & ester on same side) & the pH dependence of this fluorescence is easily observable using a simple _____.

initiator

the homopolymer, poly(δ-decalactone), is the _____ in the synthesis of the triblock copolymer. L-lactide is the monomer end block in the triblock copolymer.

ortho

the intramolecular electrophilic aromatic substitution rxn could conceivably occur @ the _____ position between the 2 aromatic substituents, a rxn that would lead to the formation of the isomeric coumarin that has the alcohol and ester group on opposite sides of each other.

unsafe to take home.

the nylon you made in the lab is safe/unsafe to take home.

- rinse w/ brine (saturated sodium chloride soln.) to draw dissolved H2O out of ether phase. - remove water from ether phase using magnesium sulfate.

the organic layer during extraction has traces of H2O in it, how do you remove it?

above

the origin line should always be _____ the solvent level in the chamber.

sebacoyl chlroide, the 10-carbon diacid chloride, & hexamethylene diamine

the polyamide Nylon-10,6 is produced by a condensation polymerization between _____, _____, & _____ (the 6-carbon diamine).

ethylene

the simplest vinyl-type monomer is _____.

ethanol

the solvent used to dissolve salicylamide to get it in solutino during EAS experiement.

95% ethanol

to observe fluorescence of the product from the Pechmann condensation experiment, a small quantity (~20 mg) of product is dissolved in 2-3 mL of _____ in each of 3 test tubes or scintillation vials. - pH of 2 of the samples is adjusted by adding 2 mL of 10% HCl to one & 2 mL of a 10% Na2CO3 soln. to the other; colors of the 3 solns. are compared under ambient light & under a long-wave UV lamp.

condensation

type of polymerization where 2 monomers react to form a larger unit, while a small molecule (H2O or HCl) is eliminated/lost during polymerization.

resorcinol

used in Pechmann condensation experiment; can be harmful if ingested or exposed to open wounds, though symptoms tend to arise only due to chronic exposure.

elemental analysis

used to determine molecular formula of compound; burn organic compound in oxygen atmosphere & measure amount of combustion produced (CO2, H2O, & nitrogen oxides); any leftover mass is assumed to be oxygen.

spectroscopy

used to identify unknown organic compounds; each molecule has a "fingerprint" that gives a different set of spectroscopic data.

extraction

used to separate a mixture into its respective components; there are 2 types: solid-liquid 7 liquid-liquid.

ultraviolet (UV) spectroscopy

uses electron transitions to determine bonding patterns & amounts of π conjugation in a molecule.

3 M sodium hydroxide

was added to neutralize the solution in the ferrocene column chromatography experiment.

proportional

wavenumbers are _____ to frequency & energy.

no reaction

weak acid + weak base = ?

strong acids

weak bases will extract _____.

sand, glass, decolorizing carbon these are not soluble.

what are some examples of impurities that will not affect the MP range? why won't they affect it?

initiation, propagation, & termination

what are the 3 stages of chain addition polymerization?

deprotonation at the α-carbon in ethyl acetoacetate, aldol-like condensation, dehydration, & transesterification

what are the typical steps in a Knoevenagel con-densation mechanism?

they're monomers & simply ethylene units w/ various substituents (a benzene ring, a chlorine atom, & a cyano group.

what do styrene, vinyl chloride, & acrylonitrile have in common?

polyvinyl alcohol

what does PVA stand for?

sagging/shrinking of crystals

what is an observation when performing MP that is commonly mistaken for melting?

glycerin by-product; drain thru the stopcock of the funnel into a waste beaker.

what is the bottom layer that formed while the rxn mixture sat in the lab after the first day of biodiesel synthesis? what should you do w/ it?

3-acetyl-7-(diethylamino)-2H-1-benzopyran-2-one

what is the final product of the Knoevenagel condensation reaction (we did not actually perform this experiment)?

- place 5 mL styrene in test tube w/ 0.25g benzoyl peroxide. - mix to dissolve solid.

what is the first step in the preparation of polystyrene when making polymers?

4-methylumbelliferone

what is the name of the coumarin derivative that we synthesized thru Pechmann condensation?

to remove impurities caused by air oxidation of the amino functional group in the compound; the impurity is what causes the sample to appear reddish-brown.

what is the purpose of adding de-colorizing carbon?

to dilute HCl & to increase the solubility of p-phenetidine in H2O by making the amine salt, which is H2O-soluble.

what is the purpose of adding p-phenetidine?

to melt the polymer, reducing stress, while also removing excess solvent.

what is the purpose of annealing the copolymer?

used to deprotonate the aminium ion & acetic anhydride is added immediately to react w/ the reformed free amine to give the acetophenetidin product.

what is the purpose of sodium acetate & acetic anhydride?

biodiesel; it's a clear, yellowish liquid.

what is the top layer that formed while the rxn mixture sat in the lab after the first day of biodiesel synthesis? what does it look like?

- scratch inside of flask w/ glass stir rod. - if that doesn't work, take small amount of soln. & spread on watch glass. after solvent evaporates crystals left can serve as seed crystals. put them in flask. - if neither of the above work, there's too much solvent. heat soln. for a period of time to evaporate some solvent, cool, & try to recrystallize again.

what should you do if crystals are not forming during the recrystallization process?

mark solvent front w/ pencil ~1 cm from top of TLC plate

what should you once the solvent front is about 1 cm from top of plate?

- sample must be finely powdered. - proper amount (~1-2 mm in height) must be firmly packed into capillary tube. - sample must be completely dry.

what technique will give you the most accurate/reliable MP by ensuring proper heat transfer to the sample?

soap

what's a common byproduct of biodiesel formation?

termination (chain addition)

when 2 individual chains react together in which no new radical is made (termination because w/o a radical, it can no longer propagate).

vibrate

when a molecule is exposed to infrared light, the bonds in the molecule begin to _____.

because acid halide is more reactive.

when making Nylon-10,6 thru interfacial polymerization, why do you use diacid chloride (sebacoyl chloride) instead of dicarboxylic acid?

insoluble; soluble

when performing recrystallization, the desired compound must be _____ when the solvent is cold, but the impurities must remain _____ after cooling. - if not, there will be no purification.

both the desired compound & the impurities

when performing recrystallization, the solvent choice must dissolved _____ when the solvent is boiling.

yes, this indicates separation

when the nonpolar species dissolves in the organic layer, is there separation?

liquid waste bottle

where does liquid waste go?

~1 cm from the bottom of TLC plate

where should you mark the starting point (origin) on the TLC plate?

because many compounds have MP ranges that differ by less than 1/10th of a degree; you must conduct further analysis/experimentation

why can't you definitively say that 2 samples w/ the same MP range are the same compound?

w/o heat, the rxn proceeded very slowly & we couldn't see product in our lab time. however, it's important to note that both the amide synthesis & Williamson-Ether synthesis would have yielded the same acetophenetidin product.

why didn't the Williamson-Ether synthesis work?

to increase surface area for evaporation, which increases the solvent vapor in the chamber. also, it keeps the stationary phase from drying out before process is finished. if the stationary phase dries out prematurely, the components won't separate properly.

why is a piece of folded filter paper placed in the chamber?

ink will dissolve in solvent

why must you use a pencil to mark the TLC plate?

to neutralize the HCl byproduct (released each time a new amide bond is formed) that formed during polymerization.

why was NaOH added to the polymer reaction in making Nylon-10,6?