Organic Chemistry Lab final

what are two ways that the extraction efficiency could be maximized to get the most trimyristin out of the nutmeg?

-repeat extraction more times -use more ether -stir longer

IR spectroscopy enables us to determine functional groups based on

bond stretching and bending energies

how can purification be obtained through distillation?

by collecting multiple fractions as the distillation temperature approached the boiling point of the substance

IR range of 2500-3100, sharp

carboxylic acid

alkyl halides are not soluble in water even though they are somewhat polar because they cannot participate in what?

hydrogen bonding

Which test provides the most information about functional groups?

infrared spectroscopy

What does two spots on a TLC plate indicate?

Either that a reaction is taking place, or impurity in the product

Why was N-Phenylmalemide used as the dienophile in our Diels-Alder reaction?

-it has electron withdrawing groups and is therefore more reactive -it will add a UV-chromophore to the product so that the reaction can be followed by TLC

indication of aromatic compounds on IRs

1600, 1580, 1500, and 1450 cm-1. have sharp bands and variable intensity

o-disubstitution of aromatic compounds IR

770-735 cm-1

p-disubstituion of aromatic compounds IR

800-860 cm-1

m-disubstitution of aromatic compound IR

860-900, 760-810, 670-710

what is the chemical formula of the heavy white precipitate that forms when ethanoic solver nitrate is added to a solution of 1-bromoethylbenzene?

AgBr

What would happen if the rate of the addition of alkyl bromide to the reaction medium got out of control?

Another side reaction could have occurred. This reaction is the coupling reaction between the organomagnesium halide and the alkyl halide. (R-R, MgX2)

Which compound is more polar? Something that dissolves in... A. ether, but not water B. water, but not ether C. both ether and water

B

In the Grignard reaction, what was used to help initiate the reaction and activate the magnesium surface?

Iodine

what type of extraction was done to isolate trimyristin from nutmeg?

solid-liquid

how are Mw and Mn different?

Mw is the "average" Mn is the average assuming that each individual is weighted equally

what indicates that a compound is polydispersed?

Mw/Mn= more than 1

extraction separates compounds on the basis of their

solubility

Reactivity of organic halides with magnesium order

R-I > R-Br > R-Cl

What was the silver nitrate test?

Tested to see if 1-bromoethylbenzene was formed. If it was, a white precipitate was formed.

What role did Quinnoline play in the styrene formation?

Was the solvent. Drove the dehydrohalogenation of 1-bromoethylbenzene.

What functional group is in myristic acid and is protonated with the addition of HCl?

acid

What kind of reaction is the grignard reaction?

addition. Grignard reagents undergo rapid nucleophillic addition to the carbonyl group go aldehydes, ketones, carbon dioxide, and carboxylic acid derivatives.

IR frequency range of 3100-3650, wide

alcohol

IR range of 1000-1300

alcohol, ether, ester

IR range of 2850-3000

alkane, sp3

IR range of 1620-1680

alkene C=C

IR range of 3000-3100

alkene, sp2

what class of compounds will NOT dissolve/react with H2SO4? amines alcohols aldehydes alkenes alkyl halides ketones

alkyl halides

IR range of 2100-2260

alkyne, C---C

IR range of 3270-3320

alkyne, sp

if you were to mistakenly run your TLC plate with hexane as 100% eluent, rather than the ethyl acetate/ hexane mixture,

all of your compounds would move much less or not at all on the TLC plate

What role did AIBN play in that allowed the polymerization of sytrene to occur?

allows radical polymerization to occur

What is the significance of GPC?

also called size exclusion chromatography. is a type of liquid chromatography that separates polymers of different sizes. -larger compound eluted first -smaller compounds eluted second

IR range of 3300-3500, sharp

amine (N-H)

During the second step of the grignard reaction, why was it necessary to add the aldehyde solution to the grignard solution slowly?

because it's an exothermic reaction

why was n-phenylmalemide used as the dieneophile in the dies-alder reaction?

conjugated, and electron withdrawing groups

which has the lowest boiling point? nutmeg trimyristin diethyl ether methanol

diethyl ether

How is styrene made from 1-bromoethylbenzene?

elimination (E2) and dehydrohalogenation

IR spectroscopy allows us to determine the functional groups baed on

energies of bond stretching and bending vibrations

What functional group is present in trimyristin and is hydrolyzed with NaOH?

ester

Was Trimyristin more soluble in ether or methanol, and why?

ether, because it has lower polarity

What substance would be more likely to float on water, 1-bromoethylbenzene or ethylbenzene?

ethylbenzene, because it has a lower molecular weight.

Was the Grignard Reaction endothermic or exothermic?

exothermic

true or false, materials that do not contain covalent bonds are absorbed in IR

false

When compounds of similar structure have infrared spectra similar in the diagnostic region, what should be examined to tell the difference between the two?

fingerprint region

Which test provides the most information about substance purity?

gas chromatography

Organomagnesium halide that is formed in the presence of water

is consumed ina rapid acid-base reaction with water to form the corresponding hydrocarbon.

What about a melting point would indicate that a substance is impure?

it broadens and lowers

Why did all the water need to be isolated from the grignard product? How is this accomplished?

it interferes with distillation of the product. -A drying agent combines with water to form a hydrated inorganic compound

IR range of 1620-1800

ketone, aldehyde, carboxylic acid

AlCl3 is a bronsted acid bronsted base lewis acid lewis base

lewis acid

what is the advantage of using a cyclic diene rather than an acyclic one int he dies-alder reaction?

locked in the s-cis conformation

In GC, list how compounds will elute based on their boiling point starting from the shortest retention time going to the longest

lowest BP to highest BP

why was it not useful to recrystallize polystyrene?

many polymers are not crystalline materials

what IR frequencies might you see in 1-bromoethylbenzne?

medium and sharp at 3020 cm-1 medium and sharp at 2970 cm-1

Why weren't there any reactions listed for part I of the Trimyristin lab?

no chemical reactions took place. the trimyristin originally in the nutmeg was isolated and purified, but does not change chemical structure.

why won't a 100% yield of trimyristin be obtained?

nutmeg has many more elements than just trimyristin

thin layer chromatography separates compounds primarily on the basis of

polarity

What are the pros and cons of using magnesium sulfate as a drying agent?

pros: magnesium sulfate is generally more efficient at removing water than sodium sulfate is con: magnesium sulfate is sometimes hard to filter because it is a fine powder

When 1-bromoethylbenzene was made from ethylbenzene, what kind of a reaction was this?

radical substitution

fingerprint region

region below 1400 cm-1

after the second step in the grignard reaction, why is it necessary to workup the reaction with aqueous sodium bicarbonate?

so that alkenes are not formed during distillation

Why are ethers good solvents for the formation of Grignard reaction products?

strongly coordinate to the magnesium in organomegnesium halides

Friedel-Crafs alkylation is what type of a reaction?

substitution

Ceric Ammonium Nitrate test

tests for alcohols. positive test is indicated by a change in color of the reagent from yellow to orange-red when a few drops of the unknown are added.

2,4-Dinitrophenylhydrazine test

tests for aldehydes and ketones. (confirms presence of carbonyl groups) a positive test is the formation of a significant amount of the yellow to orange-red precipitate

Potassium Permanganate test (KMnO4)

tests for alkenes. A positive test is when the purple color fades, and a brown insoluble precipitate forms

what is the advantage of the reactants being less volatile than the solvent used for a chemical reaction?

the boiling point of the solvent restricts the temperature range that can be used when heating a reaction solution

How does one tell the polarity of a substance based on a TLC plate?

the closer it is to the bottom, the more polar it is

why are non-nucleophilic bases such as quinoline useful?

they prevent the corresponding substitution reaction from occurring where the base would substitute for the halogen

Why was the final ether solution treated with solid magnesium sulfate?

to dry the solution

What does it mean to reflux a solution

to heat a solution at a constant temperature

why did we add methanol to our concentrated ether solution of trimyristin?

to precipitate the trimyristin

True or false, at lower concentrations of the alkyl halide in the grignard reaction, the reaction of the alkyl halide with the magnesium metal is favored over the coupling reaction with the ether-soluble organomagnesium halide?

true

What would more rapid heating of the liquid rising in the condenser cause?

vapor to potentially escape out of the condenser, resulting in a partial loss of product, because those vapors would originally condense back to water if they flowed through the condenser with cold water

distillation separates compounds on the basis of their

volatility (bp)