Organic Chemistry Lab Final

solubility tests

H2O 5% NaOH 5% NaHCO3 5% HCl conc. H2SO4

order of solubility tests

H2O 5% NaOH - soluble --> 5% NaHCO3 - insoluble --> 5% HCl 5% HCl -- insoluble --> conc. H2SO4

what tests can you use to determine if the functional group is an amine?

SOLUBILITY: if H2O insoluble, NaOH insoluble, HCl soluble (litmus test to make sure) LITMUS TEST: H2O soluble, litmus test for basicity (red to blue)

compound(s) that is/are H2O insoluble, NaOH insoluble, and HCl soluble

1, 2, 3 amines

compound(s) that is/are H2O soluble and basic

1, 2, 3 amines

what two achiral molecules did we generate in lab 4?

1-(diisopropoxymethyl)-4-nitrobenzene -- O,O-acetal 1,3-diisopropyl-2,4-(nitrophenyl)-imidazolidine -- N,N'-acetal

what tests can you use to determine if the functional group is a ketone?

1. 2,4-DNP test 2. iodoform test for 2-alkanones

what tests can you use to determine if the functional group is an aldehyde?

1. jones (chromic acid) oxidation 2. 2,4-DNP test

what tests can you use to determine if the functional group is an alcohol?

1. jones (chromic acid) oxidation 2. cerium(IV) nitrate (ceric ammonium nitrate) test 3. lucas test (for water-soluble alcohols only) 4. iodoform test for 2-alkanols (secondary alcohols)

what are the 11 possible functional groups?

1. primary alcohol 2. secondary alcohol 3. tertiary alcohol 4. ketone 5. carboxylic acid 6. aldehyde 7. amine (1, 2, or 3) 8. phenol 9. ester 10. 2-alkanone 11. 2-alkanol

what tests can you use to determine if the functional group is a phenol?

1. solubility in sodium hydroxide (soluble in 5% NaOH and insoluble in 5% NaHCO3) 2. cerium(IV) nitrate (ceric ammonium nitrate) test 3. iron(III) chloride test 4. decolorization of Br2/CH2Cl2 solution

compound that generates blue precipitate during jones oxidation, shows cloudy solution within 5-10 minutes of addition of HCl:ZnCl2, and shows a yellow precipitate when treated with NaOH, and potassium idiode?

2-alkanol

iodoform test

20% NaOH, 10% iodine in potassium iodide solution for 2-alkanols (secondary alcohols) and 2-alkanones (ketones) positive test = precipitate of iodoform (bright yellow solid)

compound that does not generate blue precipitate during jones oxidation, changes the cerium(IV) nitrate reagent to an orange-red color when treated with acetone, and shows cloudy solution immediately with addition of HCl:ZnCl2?

3 alcohol

how to synthesize O,O-acetal

4-nitrobenzaldehyde anhydrous 2-propanol triisopropyl orthoformate tetrabutylammonium tribromide -- stir mixture for 1 hr -- then liquid-liquid extraction (interested in upper organic layer) --- upper organic layer = product + ether --- lower aqueous layer = water + NaHCO3 - dry with anhydrous Na2SO4 - rotary evaporate the ether out to obtain product

how to synthesize N,N-acetal

4-nitrobenzaldehyde N,N'-diisopropylethylene diamine use heating mantle with sand voltage regulator; heat until 140 degrees perform mini-extraction - interested in upper organic layers = product + cyclohexene - lower aqeous layer = water dry with anhydrous Na2SO4 - rotary evaporate the cyclohexene solution to obtain product

compound that generates blue precipitate during jones oxidation and remains yellow-orange during 2,4-DNP?

alcohol - use lucas test to see if 1,2,3 alcohol - if 2 alcohol, use iodoform test to see if 2-alkanol

compound(s) that is/are H2O insoluble, NaOH insoluble, HCl insoluble, and H2SO4 reactive

alcohols, aldehydes, ketones, esters

compound(s) that is/are H2O soluble and neutral

alcohols, aldehydes, ketones, esters

compound that generates blue precipitate during jones oxidation and generates a vibrant red, orange, or yellow precipitate during 2,4-DNP?

aldehyde

what tests can you use to determine if the functional group is an ester?

alkaline iron(III) hydroxyamate test

goal of lab 4

an NMR investigation of diasteriotopicity/nonequivalence of methyl groups in achiral and non-stereogenic-bearing O,O-N,N-acetals generating two achiral (superimposable on their mirror image) molecules with no pre-existing stereogenic centers - determine whether pre-existance of stereogenic center(s) is a required structural precondition for diastereotopicity/nonequivalence of CH3 groups in these molecules obtain the NMR spectra to see if the methyl groups are diastereotopic/nonequivalent (of the isopropyl groups) -- they are not equivalent -- therefore, diastereotopic

electrophilic aromatic substitution

an electrophile replaces a proton (H) on the aromatic ring (a benzene ring i.e.)

NMR spectra of para-disubstituted benzene

benzene ring ~6.5-8 (4 hydrogens) 2 doublets (from benzene ring in 6.5-8 area- four hydrogens on ring, but two are equivalent) plus peak of the pre-existing G group

NMR spectra of ortho-disubstituted benzene

benzene ring ~6.5-8 (4 hydrogens) 2 doublets, 2 triplets (in 6.5-8 area) plus peak of the pre-existing G group

NMR spectra of meta-disubstituted benzene

benzene ring ~6.5-8 (4 hydrogens) two doublets, a singlet, and a triplet (in 6.5-8 area) plus peak of the pre-existing G group

decolorization of Br2/CH2Cl2 solution

bromine in CH2Cl2 tests for phenols positive test = if more than 5 drops of bromine solution are needed to make the Br2 color (change from red to clear, precipitate of product, or HBr gas released) remain for at least 1 minute

compound(s) that is/are H2O insoluble, NaOH soluble, and NaHCO3 soluble

carboxylic acid

compound(s) that is/are H2O soluble and acidic

carboxylic acid

compound that generates blue precipitate during jones oxidation, shows cloudy solution within 5-10 minutes of addition of HCl:ZnCl2, and does not react with addition of NaOH, and potassium idiode?

compound = 2 alcohol

compound that generates blue precipitate during jones oxidation, shows cloudy solution within 5 minutes of addition of HCl:ZnCl2, and generates a yellow precipitate with addition of NaOH, and potassium idiode?

compound = 2-alkanol

how do diastereotopic molecules look on NMR?

due to their nonequivalence, diastereotopic groups often display different chemical shifts and hence are represented by different NMR signals

what are meta directors?

electron withdrawing groups double bonds (C or N) triple bonds (C or N) charge carboxylic acids aldehydes nitro group (NO2)

Goal of experiment 3

electrophilic aromatic nitration of an unknown monosubstituted benzene goal: use stereoscopic methods to identify the G groups in unknown monosubstituted benzene and determine its directive effect

compound that does not generate precipitate during jones oxidation and remains yellow-orange during 2,4-DNP but turns magenta when treated with hydroxylamine hydrochloride and sodium hydroxide?

ester

lucas test

for water-soluble alcohols only lucas reagent - conc. HCl:Zn2Cl2 1:1 distinguishes between primary, secondary, and tertiary alcohols based on the rate of formation of the insoluble alkyl chloride primary = do not react secondary = react within 5-10 minutes tertiary = react within seconds, immediate emulsion CLOUDY SOLUTION = POSITIVE

alkaline iron(III) hydroxylamate test

hydroxylamine hydrochloride, 20% NaOH, heat to boiling point, add HCl and solid iron(III) chloride tests for esters (sometimes phenols) positive test = red-blue magenta color some phenols react to give similar colors; if you have a (+) test, perform all steps except addition of hydroxylamine; if you still have color, your unknown is a phenol

how to tell if molecule is diastereoptic

if the molecule already has a stereogenic center, and by replacing an R group with Cl makes creates a new stereogenic center, then the molecule is diastereotopic

jones oxidation (chromic acid) test

jones oxidation reagent = chromic acid in sulfuric acid, and reagent grade acetone positive tests for aldehydes, primary and secondary alcohols positive test = complete/incomplete disappearance of orange color and the formation of a green (blue green) precipitate negative test = no disappearance of orange color, no precipitate formation

compound that does not generate precipitate during jones oxidation and remains orange, but generates a vibrant red, orange, or yellow precipitate during 2,4-DNP?

ketone further check for 2-alkanone via iodoform test

what are ortho/para directors?

lone pairs halogens (Cl, I, Br, etc) R, Ar, Ph (neutral compounds) NH2

purpose of NaCl-ice bath

makes the temperature go below 0 degrees

purpose of methanol (expt 3)

must be ice-cold, product soluble within, quickly rinse to remove excess impurities (same with water - removes excess remaining acid)

tollens test

only performed if it has already been shown that the unknown compound is either an aldehyde or a ketone and the 2,4-DNP test is inconclusive after several attempts

compound(s) that is/are H2O insoluble, NaOH soluble, and NaHCO3 insoluble

phenol

preliminary examination

physical state (solid or liquid) color (most are colorless, highly colored compounds usually contain conjugated multiple bonds) odor

goal of experiment 5

qualitative organic analysis: establishing the principle functional group (FG) of unknown organic compounds to determine the FG of each compound by subjecting them to the solubility and classification tests

purpose of the mini-extraction

removes excess N,N'-diisopropylethylene diamine

mass spectra

reveals the molar mass of a compound molecules with an odd number of atoms have odd molar masses but those with even number of N's (including zero) have even molar masses the molar mass of a compound combined with combustion analysis can reveal the molecular formular of a compound

what tests can you use to determine if the functional group is a carboxylic acid?

soluble in both 5% NaHCO3 (with CO2 gas evolution) and 5% NaOH

2,4-DNP test

tests for aldehydes and ketones positive test = formation of vibrant yellow, orange, or red precipitate esters and alcohols DO NOT react: the yellow-orange color of reagent will persist and no precipitate

what happens if the temperature rises

the nitronium ion will be very reactive and will add ortho, para, and meta -- selectivity is diminished

why do you pour organic product over ice

the organic product is insoluble in water, so when added over ice, it precipitates out

what happens if the reaction is stirred to quickly

the solid reagents will go to the walls, where they will stick and not react

iron(III) chloride

water or water-ethanol (for water-insoluble phenols), 10% iron(III) chloride solution tests for phenols positive test = red, blue, green, or purple color sterically hindered phenols will have negative result

what is combustion

when an organic compound containing C, H, and O is burned, it produces CO2 and H2O

nitration

when the electrophile is the nitronium ion (NO2+)

cerium (IV) nitrate (ceric ammonium nitrate) test

acetone, cerium(IV) nitrate reagent tests for alcohols and phenols (distinguishes alcohols from esters and other neutral compounds) positive test = change in color of the reagent from yellow to orange-red negative test = esters, ketones, carboxylic acids, and simple aldehydes DO NOT change the color of the reagent

how is the nitronium ion generated

acid-base reaction between concentrated H2SO4 and concentrated HNO3 HNO3 acts as the base H2SO4 acts as the acid