Organic Chemistry Lab FINAL Review

organic solid waste

-hydrocarbons: anthracene, fluorene -ethers: 2-methoxynaphthalene -phenols: phenol -carboxylic acids: trans-cinamic acid -anhydride: maelic anhydride

trash can

NaCl, boiling stones, MgSO4 (anh), not contaminated: paper, cotton towel, and gloves.

Key Features of Interfacial Polymerization

-interfacial polymerization is controlled by the diffusion of the reagents to the interface -monomers diffusing to the interface react only with polymer chain ends -when one of the monomers is used up, the reaction is complete -polymerization occurs at the interface between the organic and aqueous phases -polymerization occurs at low temperatures

Which of the statements are principles of green chemistry?

-prevent waste, rather than cleaning it up after it is created -use less energy when technically and economically sensible -products should degrade into non-toxic products at the end of their usefulness -produce products with the minimum amount of materials

At high concentrations, glacial acid is dangerous because it will ...

-produce hazardous fumes -damage skin as dehydrating agent -damage skin with heat by exothermically reacting with water in tissue

Grignard Reaction Glassware Setup

-use of stirring hot plate

theoretical yield formula

1) balance equation

Grignard Reaction

A carbonyl addition reaction between a Grignard reagent (R-MgX) with an aldehyde or ketone to produce an alcohol after aqueous acidic work-up. (nucleophilic addition) -carbon bonded to the magnesium acts as a strong nucleophile with a negative charge / carbanion -Grignard reagent must be prepared fresh and is easily destroyed by water -In order to remove the biphenyl after aqueous acidic work-up of the reaction mixture, the crude product is dissolved in hot hexane -> when cooled, biohenyl is soluble and remains in solution while triphenylmethanol is insoluble and crystallizes out

Ferric Chloride Test-FeCl3 (stable enols)

Aldehydes and ketones with an α-hydrogen can undergo an equilibrium called tautomerization (isomerization) to form enols. enol form is stabilized by certain structural features, such as hydrogen-bonding and/or resonance effects in which enol form is favored. positive test: FeCl3 is colorless or slightly orange in color. when FeCl3 reacts with stable enols and phenols a colored complex is formed -> color change to red, blue, purple, green

Green Synthesis of Chalcones

Aldol reaction important synthetically as a carbon-carbon bond forming reaction -> chalcones Chalcones: natural occurring compounds and have variety of very important medical applications such as antiifungal, antitumor, anti-inflammatory Claisen-Schmidt reaction: crossed aldol condensation and involves an aldehyde or ketone without alpha-Hs and an aldehyde or ketone with alpha-Hs (mixed aldol condensation reactions usually yield 4 products that are hard to separate and has limited usefulness) Mechanism for Chalcones: E1cB or Unimolecular Elimination of Conjugate Base

refluxing (diers alder)

The solution of reactants is placed in a round-bottom flask fitted with a condenser placed vertically over the flask liquid -> vapor -> liquid (flask remains at constant value ) -the location where condensation occurs is known as the condensate ring

Tollens Silver Mirror Test (aldehydes)

aldehydes oxidized into corresponding carboxylic acids by aqueous soln of silver-ammonia complex in sodium hydroxide. positive test: silver ion reduces to metallic silver which deposits as a mirror on the inside of a warm test tube. hazards: tollens reagent can become explosive if allowed to stand. flush down sink w/ copious amounts of water

Bromination - Br2/CH2Cl2 (alkenes)

alkenes readily undergo electrophilic addition at double bond. the mode of addition of bromine to an alkene is anti. positive test: the bromine solution is a red-brown color. when alkene added to bromine soln, the soln turns colorless.

irritant

alkyl halides: CH2Cl2, 1-chlorobutane, chlorobenzene

dehydration of 2-methylcyclohexanol

an alcohol can be dehydrated to an alkene w/ H3PO4 & heat. the reaction mainly proceeds by an E1 mechanism with 2° and 3° alcohols where the rate of the reaction is determined by the formation of the carbocation. Zaitsev's rule: more substituted alkene is the more favored

aqueous solvent (extractions)

aqueous acid- HCl (aq): in case the compound top extract is basic (ex. amines) aqueous base-NaHCO3 (aq): in case the compound to extract has pKa lower than 6 (carboxylic acids) aqueous base-NaOH (aq): in case compound to extract has pKa lower than 15 (carboxylic acids and phenol)

sat. sodium bicarbonate (extractions)

aqueous solvent appearance: clear liquid

The reaction of isopentyl alcohol with acetic acid to form isopentyl acetate is reversible. The reaction has an equilibrium constant, K, of 4.2 Select the action that will increase the yield of isopentyl acetate

b a. decrease the temperature of the reaction b. use a large excess of acetic acid c. use a weaker acid catalysts such as formic acid d. use a lower concentration of H2SO4

Besides increasing the temperature, how might the rate of an aromatic bromination reaction be increased ?

b a. by adding NaOH b. by adding a Lewis acid catalysts c. by placing the reaction in the dark d. by constantly stirring to keep the reaction well mixed

A student develops their TLC plate and places it under a UV light, but nothing appears What mistake might the student have made?

b. a. used too much sample b. spotted the compound below the level of eluent c. used a sample that was too concentrated d. spotted the compound above the level of eluent

distillation

based on boiling points. A liquid exerts a vapor pressure which depends on temperature. At the boiling point of a liquid, this vapor pressure equals the atmospheric pressure, and the liquid begins to vaporize (turn into a gas).

bromine/dichloromethane test reagent (dehydration)

br2 hazards: corrosive, acute toxic, environmental CH2Cl2 hazards: health hazard appearance: strong odor, brownish-reddish color

Select the two functional groups that can react to form an ester

c a. a ketone and an alcohol b. an alcohol and an aldehyde c. a carboxylic acid and an alcohol d. a ketone and an aldehyde

Reduction of Benzoin

carbonyl containing compounds such as aldehydes and ketones, reduce with sodium borohydride (NaBH4) and ethanol by the gain of hydrogen and the loss of pi bonds to oxygen -Benzoin could be reduced to three possible stereoisomers (a racemic mixture and a meso compound) -(S,S) and (R,R) hydrobenzoins of the racemic mixture will have same physical properties (melting point: 122-123 °C ) and meso compounds (melting point: 137-139 °C) -mechanism of reduction involves front and back attack of the carbonyl carbon by a hydride (H: -)

Jones Oxidation-CrO3/H2SO4 (alcohols)

chromic acid (H2CrO4) which is made in situ by dissolving chromium trioxide in concentrated sulfuric acid -Jones reagent oxidize primary alcohols to carboxylic acids and secondary alcohols to ketones. positive test: orange color of reagent Cr(VI) changes to dark green of Cr3+. hazards: H2SO4 is corrosive poison, Cr (VI) compounds are carcinogenic

Why is a flask never distilled to dryness ?

d a. the flask could crack or break b. the flask could become charred c. the flask could explode because of residue d. all of these choices are correct

the intermolecular force that predominates in the binding of polar organic molecules to silica gel adsorbent in thin‑layer chromatography (TLC).

dipole-dipole forces

Diazonium Coupling (Azo Dye)

electrophilic aromatic substitution

Nitration of Bromobenzene

electrophilic aromatic substitution (EAS) electron donating groups: ortho, para electron withdrawing groups: meta

gas chromatography

form of gas-liquid chromatography where the mobile phase is a gas and the stationary phase is a liquid absorbed on a solid support. Peaks are generated and the peak area is calculated by a computer program. The GC chromatogram shows the peaks obtained for that sample with a chart that shows the resulting retention time on the column of each peak and the percentage of each peak (each compound) in the sample

classification of solvents (tlc)

h-bonding/highly polar: methanol, formic acid dipole-dipole/ intermediate polarity: ethyl acetate, THF (tetrahydrofuran), DCM (CH2Cl2) van der waals: hexane

85% phosphoric acid (dehydration)

hazards: corrosive appearance: clear, thick liquid

sebacoyl chloride (polymers)

hazards: corrosive appearance: clear liquid

glacial acetic acid (Lidocaine)

hazards: corrosive appearance: —

1,6-hexanediamine (polymers)

hazards: corrosive, irritant appearance: clear liquid/ slight odor

Salicylic acid (Azo Dye)

hazards: corrosive, irritant, health hazards appearance: white powdery solid

9,10- Dihydroanthracene- 9,10- a,B-succinic acid anhydride

hazards: environmental hazards appearance: white crystal-like solid *bridged adducts are formed ONLY when using a cyclic diene

xylenes (diers alder)

hazards: flammable appearance: clear liquid

Magnesium (Grignard)

hazards: flammable appearance: silver, shiny

sodium borohydride (reduction of benzoin)

hazards: flammable, corrosive, irritant appearance: white solid

2-methylcyclohexanol (dehydration)

hazards: flammable, irritant appearance: strong odor, clear

Toulene

hazards: flammable, irritant, and health hazard appearance: transparent and yellow-tinted liquid

1-methylcyclohexene (dehydration product)

hazards: flammable, irritant, health hazard

tetrahydrofuran (THF)

hazards: flammable, irritant, health hazard appearance: clear liquid, slight odor

2,6-dimethylaniline (Lidocaine)

hazards: highly toxic, carcinogenic, irritant appearance: transparent liquid

Metanilic acid (Azo Dyes)

hazards: irritant appearance: beige, clustered solid *anilines and naphthols are toxic irritants

methyl benzoate (Grignard)

hazards: irritant appearance: clear liquid

octyl acetate (Fischer ester)

hazards: irritant appearance: clear liquid with citric smell

Lidocaine (Xylocaine)

hazards: irritant appearance: clear, brittle solid

TPO (polymers)

hazards: irritant appearance: slightly yellow liquid

para-bromonitrobenzene (skin irritant)

hazards: irritant appearance: white clumpy solid

benzoin (reduction of benzoin)

hazards: irritant appearance: white solid

4-chlorobenzaldehyde (para-sub benzaldehyde; Chalcones)

hazards: irritant appearance: white, crystal-like solid

triphenylmethanol (Grignard)

hazards: irritant appearance: yellow, curdy solid

4'-bromo-4-chlorochalcone (Chalcone)

hazards: irritant, environmental hazard appearance: bright yellow, clumpy solid

octanol (Fischer alcohol)

hazards: irritant, environmental hazard appearance: clear liquid

Iodine (Grignard)

hazards: irritant, environmental hazard appearance: dark crystals

anthracene (diers alder)

hazards: irritant, health hazard appearance: white crystal-like solid

bromobenzene (nitration)

hazards: skin irritant, flammable, and environmental hazard appearance: yellow liquid / slight odor

TMPTA polymer

hazards: — appearance: transparent and shiny solid

meso-hydrobenzoin or racemic-hydrobenzoin (reduction of hydrobenzoin)

hazards: — appearance: white, crystal-like solid

nylon [6,10] (polymers)

hazards: —- appearance: white and stretchy solid

silica gel (TLC)

highly polar absorbent compounds w/ H-bonding will be highly attracted to silica gel nonpolar compounds will have low attraction to silica gel

flammable

hydrocarbons: 1-methylcyclohexene, xylenes, anthracene alcohols: methanol, ethanol, 1-butyl alcohols: benzyl alcohol ethers: 2-methoxynaphthalene aldehydes: benzaldehyde ketones: acetone, fluorenone, cyclohexanone esters: ethyl acetate

organic liquid waste

hydrocarbons: cyclohexene, xylenes, 1-methylcyclohexene alkyl halides: 1-chlorobutane, 2-chlorobutane, chlorobenzene alcohols: 1-butanol, cyclohexanol, tert-butyl alcohol, isoamyl alcohol, benzyl alcohol, 2-methylcyclohexanol aldehydes: benzaldehyde ketone: acteone, cyclohexanone esters: ethyl acetate

soluble in water

ionic compounds: sulfonates, carboxylates, and aminium salts H-bonding: alcohols, carboxylic acids (4C or less), phenol, amides (5C or less), primary amines (4C or less), secondary amines (6C or less) dipole-dipole: tertiary amines (6C or less), aldehydes/ketones (4C or less), esters/nitriles (3C or less) dimethyl ether, nitromethane, chloromethane

fluorene (TLC)

less polar -> will be higher up on TLC plate hazards: irritant, environmental hazard appearance: white, shiny, clumpy

Lucas Test-HCl/ZnCl2 (alcohols)

limited to lower molecular weight alcohols (up to 5 or 6 carbons) that are soluble in aqueous solution. PhOH, CH3OH, RCH2OH DO NOT react. positive test: turbid suspension

flush down the drain with plenty of water

methanol, ethanol, 1-propanol, NaCl (aq), NaHCO3 (aq), NaOH (s), NaOH (aq)

corrosive

mineral acids: HCl, H2SO4, HNO3, H3PO4, H2CrO4 organic acids: acetic acid, phenol strong base: NaOH (s), NaOH (aq)

fluorenone (TLC)

more polar -> will be lower on the TLC plate hazards: irritant, environmental hazard appearance: crystal-like yellow

organic solvent (extractions)

must be water insoluble + low boiling point -CH2Cl, Dichloromethane (DCM): denser than water -CH3CO2CH2CH3, Ethyl Acetate (EtOAc): less dense than water

insoluble in water

nonpolar compounds (ex. hexane, benzene, carbon tetrachloride) alkyl halides, nitrocompounds, and ethers are insoluble minus the exceptions)

SN2 Test - NaI/Acetone (alkyl halides)

one-step, concerted mechanism. reacts fasted w/ least sterically hindered alkyl halides methyl > primary > secondary positive test: appearance of a precipitate or turbidity due to formation of NaCl which is insoluble in the acetone stereochemistry: inversion in configuration

2,4-DNP (aldehydes and ketones)

only reacts with aldehydes and ketones. positive test: 2,4-DNP soln is red and a positive test is indicated by a yellow-orange or red ppt. hazards: suspected carcinogen, corrosive

ethyl acetate (extractions)

organic solvent hazards: irritant, flammable appearance: strong odor, clear liquid

extraction technique

pear-shaped separatory funnel w/ stopcock that is attached with washer, gasket, and nut -swirl two layers together while occasionally venting by opening stopcock or glass stopper (organic solvents are volatile) drying agent: is added to react with water and form a solid hydrate that is easily removed by suction filtration

neutralize with NaHCO3 and flush down the drain with plenty of water

phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid

Polymerization Reactions

polycondensation: technique where polymer is formed only at the interface between two immiscible liquids, one containing the diamine and one containing the acid chloride -the abbreviation nylon [6, 10] first number refers to the number of carbon atoms in the DIAMINE; second number refers to the number of carbon atoms in the DIACID CHLORIDE -nylon is a strong versatile plastic due to hydrogen bonding between polymer chains

The absorption of energy by nuclei in NMR spectroscopy occurs in a specific part of the electromagnetic spectrum. Select the correct type of electromagnetic radiation that is used.

radiofrequency radiation

SN1 Test - AgNO3/Ethanol (alkyl halides)

rate-determining step is formation of carbocation. reagent used for alkyl halides soluble in alcohol -primary, vinylic, and phenyl halides DO NOT react -secondary halides react slowly -tertiary, primary, tertiary benzylic and allylic halides react rapidly positive test: formation of AgCl (white solid) stereochemistry: racemic mixture of R and S

recrystalizaiton

recrystallization solvent should dissolve the solid to be purified at high temp. and not dissolve it at room temp. -minimum amount of hot solvent (dropwise) is added to dissolve solid in small flask or beaker until solid dissolves -cool to room temperature -> place into ice bath to complete precipitation -collect by suction filtration

suction filtration

ring stand with clamp attached to filtration flask; rubber hose connected to flask; neoprene adapter to help with proper filtration; Buchner funnel on top with slightly wet filter paper so that it sticks

thin layer chromatography (tlc)

separation technique based on the partition of a mixture of compounds (solutes) between two phases, a solid (stationary phase), which consists of a thin layer of absorbent material immobilized onto a flat, inert carrier (silica gel deposited on a plastic, metal or glass plate) and a liquid solvent or mixture of solvents (mobile phase).

2-methoxynapthalene (extractions)

solubility: H2O soluble hazards: irritant, environmental hazard appearance: white, shiny, crystal-like solid

trans-cinnamic acid (extractions)

solubility: soluble in organic compounds hazards: irritant appearance: beige, clustered solid

95/5 hexane/ethyl acetate (TLC)

solvent that will help solutes move up through capillary action hazards: flammable

stability of alkenes

tetra > tri > trans di > cis di > mono

In a Grignard reagent, the bond between carbon and magnesium atoms is covalent, but highly polarized. Select the appropriate word or phrase that completes the sentences about the character of this carbon atom.

the magnesium-bond carbon of a Grignard reagent reacts as if it is a -carbanion This carbon atom is a STRONG BASE and also an excellent NUCLEOPHILE

An organic compound was extracted into dichloromethane and then the aqueous layer is shaken with saturated sodium chloride solution. What is the purpose of the sodium chloride?

to decrease solubility of organic product in water

rotary evaporator

used to remove solvent from a reaction mixture or reaction work-up by distilling off the solvent under vacuum. Often heat is applied through the use of a water bath to speed up this process.

carcinogenic

Cr (VI): CrO3, H2CrO4 (Jones Reagent) Hydrazine: H2NNH2 (aq), 2,4-DNP (s), 2,4-DNP/H2SO4

Rf value (TLC)

Distance travelled by substance / distance travelled by solvent

What is the difference between green chemistry and environmental chemistry ?

Environment chemistry is a broad term, whereas green chemistry specifies industrial processes.

chloro-acetoxylidide (Lidocaine)

hazards: corrosive, irritant appearance: white solid structure: 2,6-dimethylaniline connected to choloacteyl chloride through the amine

maelic anhydride (diers alder)

hazards: corrosive, irritant, health hazards appearance: large white solid crystals

chloroacetyl chloride (Lidocaine)

hazards: corrosive, lachrymator appearance: clear liquid

acetic acid (Fischer carboxylic acid)

hazards: flammable, corrosive appearance: clear liquid

diethylanimine (Lidocaine)

hazards: flammable, corrosive appearance: clear liquid

4-bromoacetophenone (para-sub acetophenone ; Chalcones)

hazards: irritant, health hazard appearance: white powdery solid

Azo Dye (D4)

hazards: irritant, health hazard appearance; dark orange colored liquid *Diazonium salts can be explosive if allowed to dry (keep in solution below 5°C)

TMPTA monomer (polymers)

hazards: irritant, sensitizer appearance: clear liquid

Sodium Nitrite/ NaNO2 (Azo Dye)

hazards: toxic oxidizer appearance: —

explosive

tollens reagent: Ag(NH3)2OH (aq)

Dying Mechanisms (Azo Dye)

Direct dye: dye attaches to fibers by the formation of ionic bonds Mordant dye: dye complexes with metal ions, which in turn complex with functional groups on fiber molecules, thus bonding the dye to the fiber Fiber-reactive dye: dye forms a covalent bond with the functional groups on the fiber Vat dye: dye is introduced into fibers as a soluble, colorless form by a chemical reaction into an insoluble, colored form Ingrain dye: dye is trapped inside the fiber structure when small molecules react to form larger dye molecules react to form larger dye molecules, which cannot escape. AZO DYES can be used as ingrain dye

diethylammonium chloride (Lidocaine)

Et2NH2Cl hazards: irritant appearance: clear crystal-like solid

Use information from the SDS of magnesium sulfate to fill in the information on the safety of this substance

Methods for cleaning up: sweep up no shovel Materials to avoid: strong oxidizing agents MgSO4 is NOT a flammable substance

Synthesis of Lidocaine

Local anesthetics are agents which prevent transmission of nerve impulses without causing unconsciousness (can be either ester or amine based) -nucleophilic acyl substitution and bimolecular nucleophilic substitution are performed + use of buffer and use of 2 moles of diethylamine

Fischer Esterification

The acid-catalyzed condensation reaction of a carboxylic acid with an alcohol to form an ester. -reversible; one way to drive the reaction to completion is to remove the water formed by azeotropic distillation. Products can also be favored by addition of more of the acid or alcohol - esters can be hydrolyzed under acidic or basic conditions. hydrolysis is endothermic and requires heating -suitable acid catalysts include: H2SO4, p-toluenesulfonic acid, and strongly acidic resins which are easily removed by filtration at the end of the reaction

Please select the given statement that is not true about Diazonium salts

a a. Diazotization and coupling reagents must be performed at least 100°C to suppress the hydrolysis of the Diazonium salt b. Alkyldiazonium salts are likely to decompose and give a variety of products because N2 is far more stable than R-N2 + c. Arlydiazonium salts are moderately stable in water at 0 °C because the pi system of the aromatic ring stabilizes the pi system of the N2+ (the Diazonium ion) d. Arlydiazonium salts are used in the synthesis of commercially available dyes through coupling reagents between activated aromatic compounds

Select the action that will not help increase the yield of a Grignard reagent.

a a. Rinse the glassware with acetone immediately prior to use b. Use only anhydrous ethers as solvents c. Scrape or grind the magnesium pieces prior to use d. dry the glassware in an oven prior to use

Diers-Alder Reaction

a [4+2] cycloaddition between a conjugated diene and a dienophile. conjugated diene must be able to adopt a s-cis (sigma cis) conformation so that ends of conjugated diene are close enough to react w/ alkene (trans dienes will not react) -dienophiles have electron withdrawing groups (reaction where the diene has electron donating and dienophile has electron withdrawing groups react faster) -cyclic dienes react w/ certain alkene-dienophiles in such a way that the endo product is formed rather than the exo one in bridged adduct

acid-based extraction

a liquid-liquid extraction that is based on the neutral/acidic/basic properties of compounds. The extraction is performed by using two immiscible solvents: one is aqueous (water) and the other one organic (usually DCM or ethyl acetate because of their safer properties with regards to flammability and toxicity).

melting point determination

a means of determination of the purity of a sample after subjecting it to separation or extraction procedures -the presence of impurities causes depression in melting point; pure substance has sharp melting range w/ difference of 1 degrees -powdered product placed into melting point capillary tube and gently tapped to bottom end -place into RD-MP -> temp reading must be 20 degrees lower than melting point -for a sample that should melt around 200 degrees, turn knob on Mel-Temp to 7 as determined by heat curve

Consider the Diers-Alder reaction between cyclopentadiene and para-benzoquinone and select the statement that is not true about the reaction

a. a. para-Benzoquinone is the heterophile b. the reaction is pericylcic c. the reaction is concerted d. cyclopentadiene is the diene

percent yield formula

actual yield/theoretical yield x 100

which one of the following is the best choice for neutralizing a spilled acid on the lab bench?

add sodium bicarbonate to the spill