OCHEM 2 Lab Final
What might happen if a low molecular weight carboxylic acid is exposed to a slightly acidic aqueous environment such as one's skin?
it will produce burns
a secondary allylic carbocation forms the kinetic or thermodynamic product?
kinetic product
Cyclic esters containing six or fewer carbons
lactones
carbonyl compounds can be reduced by
lithium aluminum hydride and sodium borohydride
the greater the number of conjugated multiple bonds a compound contains the ____ will be the wavelength at which the compound absorbs the light
longer
the more conjugation present in a molecule the ___ the wavelength of absorbance is
longer
the higher energy carbocation forms the higher or lower energy product?
lower energy product
Cyclic esters containing more than nine carbons
macrolides
what compounds yield positive results for the ceric ammonium nitrate test?
methanol
what compounds yield positive results for the permanganate test?
methanol and ethene
What is true of the ratio of products formed by a reaction under thermodynamic control?
the ratio of products is determined by energies of products and the ratio of products is not determined by relative energies of transition states
When the reaction flask was shaken, it was observed that the magnesium sulfate swirled around freely at the bottom of the flask. What does this observation indicate?
The correct amount of drying agent has been used.
LD-50
The dose found to be lethal in 50 percent of a group of test animals when administered by the specified route
What experimental mistakes will decrease the effectiveness of a Grignard reaction?
The glassware was not dried before use and the magnesium ribbon was not wiped clean before use
what relates the value and magnitude of the delta H to stability of a product?
a large negative value of delta H indicates a stable product
lachrymator
a substance that irritates the eyes and causes tears to flow
In a β-pleated sheet, the side chains extend where?
above and below the sheet
what are the seven basic odor classifications?
camphor, musk, floral, peppermint, ether, pungent, and putrid
health problems associated with UVC light
can be lethal
A strong hugely broad absorbance from ~3500 to 2500 wavenumbers indicates what
carboxylic acid
β-pleated sheet is held together by what?
hydrogen bonds between adjacent segments
reduction can often be achieved with
hydrogen gas, an appropriate catalyst, and some pressure and/or heat
what classification test detects a methyl group attached to the carbonyl carbon?
idodoform test
health problems associated with UVA light
immediate sunburn, premature skin aging; skin cancer and catacracts
why do we need to convert indigo to leucoindigo to dye a fiber?
indigo is not water-soluble
What is true of a-helix secondary structures?
involve hydrogen-bonding interaction between amino acid groups that are 4 residues apart on the same chain
reduction of camphor with excess sodium borohydride followed by acid workup produces what
isoborneol
what was the solvent used in experiment 2 with the UV-VIS lab?
isopropyl alcohol
water-soluble derivative of indigo
leucoindigo
a powerful reducing agent that reduces aldehydes, ketones, carboxylic acids, esters, and amides
lithium aluminum hydride
why do esters, which have higher molecular weights than carboxylic acids, have lower boiling points than the carboxylic acids they were made from?
most carboxylic acids exist as dimers which are held together by two hydrogen bonds
the liquid in the filter flask
mother liquor
order of amino acids describe which protein structure level?
primary
What color of visible light does tetraphenylcyclo-pentadienone transmit?
purple
purification procedure most often favored for high melting points and thermally unstable solids
recrystallization
the process of dissolving a solid material into a suitable solvent or mixture of solvents and allowing the material to crystallize
recrystallization
natural fibers derived from insect sources
silk
Method used to separate a volatile liquid from a soluble nonvolatile impurity
simple distillation
What effect will result if the filtrate solution is cooled too rapidly?
small impure crystals will form
If fire should occur in your distillation apparatus, what is the best course of action?
smother the flames with a watch glass or beaker
a milder reducing agent that can only reduce aldehydes and ketones
sodium borohydride
camphor contains a simple ketone therefore what reducing agent was used in lab?
sodium borohydride
Identify the components of the iodoform test reagent
sodium hydroxide, potassium iodide, and iodine
this technique involves the measurement of the interactions of electromagnetic energy with matter
spectroscopy
what is true about the operation of an automated micropipettor?
store the pipette upright and the point of initial resistance is the level of depression that will fill the pipette with the desired volume of solution
toxicity
sum of adverse effects resulting from exposure to a material, generally by the mouth, skin, or respiratory tract
if light of a particular wavelength (color) is absorbed, the resulting color transmitted through the solution will be
the complementary color
a primary allylic carbocation forms the kinetic or thermodynamic product?
thermodynamic product
this analyzes the vibrations of molecular bonds, providing information about the nature of the bonding and the functional groups in the molecule
(IR) infrared spectroscopy
this detects transitions between energy states of nuclei in a magnetic field and provides information about the electronic and molecular environment of the nuclei
(NMR) nuclear magnetic resonance
a synthetic copolymer that contains at least 35%, but not more than 85%, acrylonitrile units
S.E.F. (modacrylic)
a number that indicated the amount of sun protection a product will offer
SPF
What was the purpose of the saturated sodium chloride solution in the Grignard reaction?
Saturated sodium chloride decreases the solubility of the organic product in water
UV-Visible energies correspond to
electronic transitions
both chemically derived from cellulose
Cellulose diacetate, known as diacetate, and filament acetate
this detects the electronic transitions of conjugated pi-systems and provides information about the length and structure of the conjugated part of the molecule
(UV-Vis) Ultraviolet-Visible Spectroscopy
four rules of recrystallization solvent selection
1. the solvent should not chemically react with the compound 2. the solvent should dissolve the compound while hot 3. this same solvent should not dissolve the compound when cold 4. the solvent should either dissolve the impurities at all temperatures or not dissolve the impurities at all
the wavelength region of UVC
100-290
what classical qualitative test is used to identify aldehydes and ketones while providing a useful derivative?
2,4-DNP
What is the minimum boiling point difference allowed for acceptable separation in simple distillation?
25 degrees C
the wavelength region of UVB
290-315
the wavelength region of UVA
315-400
What is Tollen's reagent?
A solution of silver nitrate in aqueous ammonia
irritant
A substance which, by contact in sufficient concentration for a sufficient period of time, will cause an inflammatory response or reaction of the eye, skin, or respiratory system
derived from natural cellulose
Acetate and diacetate
what functional groups are common to all amino acids?
COOH and NH2
acrylics (polymeric acrylonitriles) manufactured by different companies
Creslan (American Cyanamide) and Orlon 75 (Dupont)
these are polyesters
Dacron 54 and Dacron 64
What defines what a lachrymator is?
Exposure to the chemical vapors make you cry.
what are the steps if concentrated sulfuric acid is spilled
First, rinse the affected area with copious amounts of water Second, treat the area with aqueous sodium bicarbonate solution
an equilibrium process in which the carboxylic acid is mixed with an excess of the alcohol and a trace of mineral acid acts as the catalyst
Fischer esterification
a natural dye originally isolated from the plant, Indigofera tinctoria
Indigo
When performing qualitative tests in glass test tubes, such as Iodoform test or dinitrophenylhydrazine test, why should you avoid rinsing the glassware with acetone prior this experiment?
It will give a false positive for some carbonyl classification tests.
polymer made with a diamine and a dicarboxylic acid, resulting in a polymeric amide of repeating units from the amine and carboxylic acid
Nylon
a polyolefin composed entirely of carbon and hydrogen
Polypropylene
what reagents, which are also mild oxidizers, are used to identify aldehydes?
Tollens' and Schiff's
which identification test is also known as the silver mirror test?
Tollens' test
SPF only refers to product effectiveness against the ___ ray of the sun
UVB
What is likely to be observed for a positive test for the iodoform test?
a bright yellow precipitate
Why is rinsing with acetone not suitable for the Grignard reaction?
acetone is a ketone.. Grignard reagents will react with acetone to make an unwanted byproduct
Rank the carboxylic acid derivatives from most reactive to least reactive
acid chloride, acid anhydrides, esters, then amides
Which groups are typically ortho-, para- directors?
activating, electron donating groups
List the procedural steps, from start to finish, that are required to generate a low molecular mass ester, and to characterize it by smell.
add 10 drops of liquid carboxylic acid to a clean dry test tube smell the acid by wafting your hand over the open tube add 10 drops of alcohol to the carboxylic acid add 5 drops of concentrated sulfuric acid to the mixxture shake the tube then place it in a warm water bath for 20 minutes allow to cool, and pipet put the organic layer onto a watch glass allow any excess alcohol time to evaporate, then smell the ester by wafting your hand over the watch glass
Grignard reagents are most often used in reactions with
aldehydes, ketones, or esters
Another name for a β-hydroxycarbonyl compound
aldol
how does schiff's test distinguish between aliphatic and aromatic aldehydes?
aliphatic aldehydes produce an almost instantaneous color change to wine-purple whereas ketones and aromatic aldehydes produce the same color change but at a much slower rate
Under what conditions does the hydrolysis of amide bond occur?
amide hydrolysis occurs under basic and acidic conditions and the reactants must be heated for hydrolysis to occur
a peak between 1690 to 1740 and a secondary peak just below 2900 indicate what?
an aldehyde
A strong peak in the 1690 to 1740 wavenumber region indicates the presence of what?
an aldehyde or ketone carbonyl group
what compounds yield positive results for the ninhydrin test?
aspartic acid and phenylalanine
what two amino acids contribute to the structure of aspartame?
aspartic acid and phenylalanine
in the reduction of ketones, an excess of sodium borohydride is usually used:
because borohydride reacts slowly with the solvent
How do activating groups make the benzene ring more reactive and therefore the resulting intermediate more stable and easier to form?
by donating electron density either through resonance (lone pairs of electrons) or through sigma bonds
How are Grignard reagents prepared?
by the reaction of alkyl or aryl halides with magnesium
List the procedural steps that are required for the correct use of an automatic micropipettor.
check that the pipette is set to dispense the correct volume depress the knob until the point of initial resistance is reached immerse the tip of the pipette into the solution slowly release the plunger to draw solution into the tip withdraw the tip from the solution, then place the tip on the internal wall of the container the solution should be dispensed into depress the knob to the initial point of resistance for a second time pause, then depress the knob as far as it will go
why is potassium permanganate a better choice as a classification test reagent than chromic acid to detect the methanol produced by aspartame hydrolysis?
chromic acid also oxidizes amino acids, and will give a false positive color change potassium permanganate loses its purple color as it oxidizes alcohols, so the reaction can be followed visually
which is the general category of compounds that are the common active ingredients in sun screens?
conjugated aromatic compounds
fibrous form of a polysaccharide made up of glucose units attached to one another by covalent bonds
cotton
natural fibers derived from plant
cotton
Which groups are usually meta- directing?
deactivating, electron withdrawing groups
what is the procedure for converting collecting the Grignard reaction alcohol product by microdistillation?
decant dried THF solution into 25 mL round bottom flask add boiling chips to the solution in the round-bottom flask grease all joints and attach the flask to a micro distillation apparatus set apparatus in heating mantle and use heat shield tiles adjust variac to distill THF at 60 degrees C increase variac setting to cause distillation of higher-boiling product stop distillation before the flask becomes dry
when the yield of the ester increases the branching in the alcohol what?
decreases
health problems associated with UVB light
delary, more intense sunburn; skin cancer; skin aging; cataracts; immunosuppression
procedure for salicylamide undergoing iodination by electrophilic aromatic substitution
dissolve salicylamide in ethanol add sodium iodide add sodium hypochlorite to the ice cold solution of salicylamide and sodium iodide add sodium thiosulfate acidify by adding 10% HCl collect the crude product by vacuum filtration recrystallize from hot ethanol
List the procedural steps, from start to finish, that are required to convert benzoic acid into methyl benzoate via a Fischer esterification.
dissolve the benzoic acid in methanol in a round bottom flask add concentrated sulfric acid and heat under reflux on a steam bath pour the reaction mix into ice, and rinse the reaction flask with dichloromethane. collect the combined layers in a test tube wash the DCM layer with sodium carbonate solution, followed by a wash with sodium chloride solution dry the DCM solution over magnesium sulfate remove the DCM by distillation on a steam bath distill the remaining liquid ester in a vial on a heating mantle
What were the steps to convert 2-butanone into 3-methyl-3-hexanol using a Grignard reagent?
dry all glassware and reagents prior to starting the experiment add 1-bromopropane to clean Mg wait for reaction to turn cloudy. sonicate if needed add 2-butanone dropwise to the Grignard reagent, allowing a gentle reflux add aqueous ammonium chloride to quench the reaction wash the reaction mixture with sodium bicarbonate and sodium chloride solutions in a separatory funnel dry over magnesium sulfate and distill product from THF
what are the two uses of a vacuum filtration setup?
drying a filtered solid and separation of a solution and a precipitate
the energy needed to excite an electron from one molecular orbital to another
electronic transitions
ultraviolet frequencies correspond to shorter wavelengths causes them to have much larger what
energy
high-molecular weight globular proteins that catalyze biological reactions
enzymes
the reduction of camphor by sodium borohydride produces two isomeric alcohol products with the major product having the oh in the what position
equatorial
List the procedural steps that are required to convert dibenzyl ketone and benzil into tetraphenylcyclopentadienone.
equip a round bottomed flask with a condenser add a solution of dibenzyl ketone and benzil in ethanol to the flask/condenser assembly warm the flask on a steam bath add a pre-prepared solution of ethanolic KOH into the reaction mix, slowly down the condenser heat the purple reaction mix under reflux for 15 minutes cool the reaction flask in an ice bath collect the purple crystals by vacuum filtration
what is the only primary alcohol and the only aldehyde that produce positive iodoform tests?
ethanol and acetaldehyde
What color of visible light does tetraphenylcyclo-pentadienone absorb?
green
ortho, para-directing, group that also deactivates in electrophilic aromatic substitution reactions
halogens
the lower energy carbocation forms the higher or lower energy product?
higher energy product
what is true about semi-empirical methods?
it is faster to calculate than ab initio methods and it combines a theoretically sound model of bonding with some experimentally determined parameters
what actions should you follow if you spill bleach on your arms?
immediately flush the affected area with running water and notify the TA
List the procedural steps, from start to finish, that are required to prepare indigo from nitrobenzaldehyde and acetone in base, and then test its ability as a dye.
mix 2-nitrobenaldehyde and acetone in a test tube, then slowly add sodium hydroxide collect the purple precipitate by filtration and wash with water followed by ethanol fit a silt pipette bulb over the side arm of a filter flask place solid indigo into the pre-prepared filter flask and heat vigorously with sodium hydroxide solution inthe stoppered flask add sodium dithionate until the solution is a clear yellow place a fabric strip into the hot solution and heat for ten minutes remove the strip, rinse with water, and record the color when dry
Aldol condensations between different carbonyl compounds
mixed aldol condensations
is a measure of how strongly the sample absorbs light at that wavelength
molar extinction coefficient
simplification that combines a theoretically sound model of bonding with some empirically determined parameters
semiempirical method
the four most common methods for the separation and purification of organic compounds
recrystallization, extraction, distillation, and chromatography
coil, B-pleated sheet, and a-helix all describe which level of protein structure?
secondary
protects best against long UVA exposure
sunscreen containing avobenzone
overall shape of a single polypeptide unit describes which level of protein structure?
tertiary
reduction
the addition of hydrogen to an organic molecule
what allows for the highly colored TPCP product?
the highly conjugated structure of the molecule
Why are ethers commonly used as a solvent for Grignard reagent preparations?
the lone-pairs of electrons on the ether solvate the magnesium ion Ether's high vapor pressure helps to prevent moisture from entering the reaction vessel
What is likely to be observed for a positive test for the Schiff's test?
the solution becomes red
The secondary level of protein structure refers to what?
the spatial arrangements of short segments of the protein
why are qualitative tests nice to use for identification purposes?
they yield an obvious color change and/or they form a precipitate
what is the purpose of the initial hot vacuum filtration in the recrystallization process?
to remove insoluble solid impurities
The use of what is key requirement for the successful synthesis of Grignard reagents?
use of an ether solvent
manufactured from regenerated cellulose fiber
viscose (rayon)
When is recrystallization not a suitable method to purify an organic material?
when the organic material is a liquid instead of a solid
how to choose which purification procedure to use?
which is the easiest to use; which will be the fastest; which will give the best results for the given situation
natural fibers derived from animal
wool
naturally occurring polymers made up of amino acid repeating units
wool and silk