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