Organic Chemistry Functional Groups Practice Exam

Question 1 Organic Chemistry Functional Groups

What product results from aldehyde oxidation?

A carboxylic acid (or carboxylate salt), via an amide intermediate. Cysteine residues in proteins form disulfide bridges that stabilize tertiary/quaternary protein structure. A carboxylic acid (aldehydes oxidize easily because they retain an H on the carbonyl carbon). C_nH_2n.

Question 2 Organic Chemistry Functional Groups

How are alcohols classified by substitution?

Primary (1°), secondary (2°), or tertiary (3°) based on the number of carbons attached to the carbinol carbon. Ring strain in the three-membered ring makes them susceptible to ring-opening by nucleophiles. Tollens' test: aldehydes reduce Ag(NH3)2+ to metallic silver, forming a 'silver mirror'; ketones do not react. E2 (concerted, anti-periplanar, requires strong base) and E1 (stepwise via carbocation, competes with SN1).

Question 3 Organic Chemistry Functional Groups

What reaction converts a carboxylic acid + alcohol into an ester?

Fischer esterification, acid-catalyzed, releasing water. Around 6.5-8.5 ppm, due to ring-current deshielding from the aromatic pi system. Homolytic cleavage splits a bond evenly, forming two radicals; heterolytic cleavage splits a bond unevenly, forming a cation and an anion. Primary (1°), secondary (2°), or tertiary (3°) based on the number of carbons attached to the carbinol carbon.

Question 4 Organic Chemistry Functional Groups

What type of bonds do alkanes contain?

Acid chlorides and anhydrides (roughly 1750-1820 cm^-1), due to strong electron withdrawal, followed by esters, then aldehydes/ketones, then amides (lowest, due to resonance donation from N). A primary alcohol (from the acyl portion) plus the alcohol corresponding to the -OR leaving group. Protonation of the epoxide oxygen activates it; the nucleophile attacks the more substituted carbon (via partial carbocation character). Only sigma (single) bonds between carbon and carbon, and carbon and hydrogen.

Question 5 Organic Chemistry Functional Groups

How can 1H NMR distinguish an aldehyde proton from other protons?

Aldol condensation, forming an alpha,beta-unsaturated carbonyl compound. Aryl halides (Cl, Br, or CN) using CuX catalysts, replacing the diazonium group. The terminal C-H (pKa ~25) is acidic enough to be deprotonated by strong bases like NaNH2, forming an acetylide ion. The aldehyde C-H proton appears far downfield, typically 9-10 ppm, due to the deshielding carbonyl group.

Question 6 Organic Chemistry Functional Groups

What distinguishes electrophilic addition from electrophilic aromatic substitution?

Polar aprotic solvents (e.g., DMSO, acetone), which do not hydrogen-bond to and hinder the nucleophile. Formation of a planar carbocation intermediate allows nucleophilic attack from either face, giving a mixture of both enantiomers (often not perfectly 50:50 due to ion pairing). Around 6.5-8.5 ppm, due to ring-current deshielding from the aromatic pi system. Alkenes undergo addition (breaking the pi bond permanently); aromatics undergo substitution (regenerating the aromatic pi system after loss of H+).

Question 7 Organic Chemistry Functional Groups

What functional group defines an anhydride?

A strong C=O stretch around 1705-1725 cm^-1, with no aldehyde C-H peaks. Two acyl groups joined by an oxygen, R-CO-O-CO-R', formally derived by loss of water from two carboxylic acids. Hydroboration-oxidation, using BH3 then H2O2/NaOH, giving the less substituted alcohol. Cleaving the C=C bond with O3 followed by reductive (Zn/H2O) or oxidative workup to give aldehydes/ketones or carboxylic acids.

Question 8 Organic Chemistry Functional Groups

What numbers are used and how are locants assigned in IUPAC names?

A base-mediated disproportionation of a non-enolizable aldehyde (no alpha-H) into one molecule of carboxylate and one molecule of alcohol. Medium-intensity absorption around 1620-1680 cm^-1; =C-H stretch above 3000 cm^-1. An imine (C=N-R) forms from a primary amine + carbonyl; an enamine (C=C-NR2) forms from a secondary amine + carbonyl, with loss of water in both cases. The parent chain is numbered to give the principal functional group (or substituents overall) the lowest possible locant(s).

Question 9 Organic Chemistry Functional Groups

What is the characteristic reaction type of benzene and other aromatics?

Electrophilic aromatic substitution (EAS), which preserves the aromatic ring. Homolytic cleavage splits a bond evenly, forming two radicals; heterolytic cleavage splits a bond unevenly, forming a cation and an anion. Combustion (with O2 to give CO2 + H2O) and free-radical halogenation. -yne (e.g., ethyne, propyne).

Question 10 Organic Chemistry Functional Groups

What is a lactone?

A cyclic ester, formed by intramolecular esterification of a hydroxy acid. They possess a leaving group on the carbonyl carbon, allowing the tetrahedral intermediate to collapse and expel it, regenerating the C=O. Acyl halide > anhydride > ester > amide (based on leaving group ability). By naming the two alkyl groups alphabetically followed by 'ether' (common) or using 'alkoxy' as a substituent prefix (IUPAC).

Question 11 Organic Chemistry Functional Groups

What functional group results from double dehydration of a diol?

Aldol condensation, forming an alpha,beta-unsaturated carbonyl compound. -al (e.g., methanal, ethanal). Le Chatelier's principle — using excess alcohol or removing water shifts the equilibrium toward ester formation. An ether (intramolecular) or diene, depending on conditions.

Question 12 Organic Chemistry Functional Groups

What reaction do two aldehyde/ketone molecules undergo with a base to form a beta-hydroxy carbonyl?

Nucleophilic acyl substitution, forming an amide. Carboxylic acid > ester > amide > nitrile > aldehyde > ketone > alcohol > amine > alkene/alkyne (roughly, per oxidation-state based seniority rules). The aldol addition reaction. sp3 hybridized, giving tetrahedral geometry (~109.5° bond angles).

Question 13 Organic Chemistry Functional Groups

What product forms when two thiols are oxidized together?

Aldehydes have an H on the carbonyl carbon (less steric hindrance, easily oxidized further); ketones have two carbon substituents (more hindered, resistant to oxidation). A carbonyl carbon bonded to a nitrogen, R-CO-NR'2. A disulfide, R-S-S-R, linked by a new S-S bond. The aldol addition reaction.

Question 14 Organic Chemistry Functional Groups

What is the key structural difference between an aldehyde and a ketone that affects their oxidation and nucleophilic addition reactivity?

A secondary alcohol after aqueous workup. The halogen is attached to an sp2 carbon; the C-X bond is shorter/stronger and the leaving group departure would disrupt pi conjugation, and backside attack is blocked by the pi system. -nitrile (e.g., ethanenitrile/acetonitrile), retaining the carbon of the nitrile in the parent chain count. Aldehydes have an H on the carbonyl carbon (less steric hindrance, easily oxidized further); ketones have two carbon substituents (more hindered, resistant to oxidation).

Question 15 Organic Chemistry Functional Groups

What test uses Tollens' reagent to detect aldehydes?

Electron-donating groups like -OH, -NH2, -OR, and alkyl groups (via resonance or induction donation into the ring). Tollens' test: aldehydes reduce Ag(NH3)2+ to metallic silver, forming a 'silver mirror'; ketones do not react. A strong C=O stretch around 1720-1740 cm^-1, plus two weak aldehyde C-H stretches near 2720 and 2820 cm^-1. Medium-intensity absorption around 1620-1680 cm^-1; =C-H stretch above 3000 cm^-1.

Question 16 Organic Chemistry Functional Groups

What is a Fischer esterification's equilibrium driven by?

No, ethers are relatively unreactive — they lack an acidic O-H and resist oxidation/reduction, but they are cleaved by strong acids like HI or HBr. Ring strain in the three-membered ring makes them susceptible to ring-opening by nucleophiles. Le Chatelier's principle — using excess alcohol or removing water shifts the equilibrium toward ester formation. Sulfur is larger and more polarizable, and the S-H bond is weaker, making the conjugate base (thiolate) more stable.

Question 17 Organic Chemistry Functional Groups

What does 'racemization' mean in the context of SN1 reactions at a stereocenter?

The halogen is attached to an sp2 carbon; the C-X bond is shorter/stronger and the leaving group departure would disrupt pi conjugation, and backside attack is blocked by the pi system. Formation of a planar carbocation intermediate allows nucleophilic attack from either face, giving a mixture of both enantiomers (often not perfectly 50:50 due to ion pairing). Carboxylic acid > ester > amide > nitrile > aldehyde > ketone > alcohol > amine > alkene/alkyne (roughly, per oxidation-state based seniority rules). Sulfur is larger and more polarizable, and the S-H bond is weaker, making the conjugate base (thiolate) more stable.

Question 18 Organic Chemistry Functional Groups

What reagent and conditions convert a vicinal dihalide back to an alkyne?

A Grignard reagent (R'MgX) adds once to the nitrile carbon, and acidic aqueous workup hydrolyzes the imine intermediate to a ketone. Two equivalents, since the triple bond can undergo two successive addition reactions. A strong, often unpleasant odor, exploited in adding trace thiols to natural gas for leak detection. Strong base (e.g., excess NaNH2) via double E2 elimination.

Question 19 Organic Chemistry Functional Groups

What catalyst is used for alkene hydrogenation?

A tertiary alcohol, via an intermediate ketone that reacts with a second equivalent of Grignard. They withdraw electron density inductively (deactivating) but donate lone pair electron density by resonance at ortho/para positions (directing). Primary (1°), secondary (2°), tertiary (3°) based on the number of carbon groups attached to nitrogen (different from alcohol classification, which is based on the carbon). A metal catalyst such as Pd, Pt, or Ni, converting C=C to C-C with H2.

Question 20 Organic Chemistry Functional Groups

What common oxidizing agent is used to oxidize a primary alcohol directly to a carboxylic acid in one pot?

They form stable hydrogen-bonded dimers through their -COOH groups. A cyclic amide, formed by intramolecular amide bond formation within an amino-acid-like molecule. Jones reagent (CrO3/H2SO4) or hot, excess KMnO4. -al (e.g., methanal, ethanal).

Question 21 Organic Chemistry Functional Groups

What is a carbocation and how does its stability trend by substitution?

A carbon triple-bonded to nitrogen, -C≡N. Ring strain in the three-membered ring makes them susceptible to ring-opening by nucleophiles. A positively charged trivalent carbon; stability order is tertiary > secondary > primary > methyl, due to hyperconjugation and inductive electron donation from alkyl groups. Friedel-Crafts alkylation.

Question 22 Organic Chemistry Functional Groups

What is the Baeyer-Villiger oxidation used to convert ketones into?

Esters (or lactones from cyclic ketones), via peracid-mediated insertion of an oxygen atom next to the carbonyl. Only sigma (single) bonds between carbon and carbon, and carbon and hydrogen. A cyclic ester, formed by intramolecular esterification of a hydroxy acid. A carbon-carbon triple bond, C≡C.

Question 23 Organic Chemistry Functional Groups

What type of isomerism is common in alkenes?

-ane (e.g., methane, ethane, propane). Two N-H stretch bands near 3300-3500 cm^-1 (secondary amines show one band; tertiary amines show none). Cis-trans (E/Z) geometric isomerism due to restricted rotation around the double bond. Only sigma (single) bonds between carbon and carbon, and carbon and hydrogen.

Question 24 Organic Chemistry Functional Groups

What suffix pattern names anhydrides?

'...oic anhydride' (e.g., ethanoic anhydride/acetic anhydride). A C=O stretch ('amide I band') near 1630-1700 cm^-1 (lower than esters/ketones) and N-H stretch(es) near 3300 cm^-1 if N-H present. The terminal C-H (pKa ~25) is acidic enough to be deprotonated by strong bases like NaNH2, forming an acetylide ion. -oyl chloride (e.g., ethanoyl chloride/acetyl chloride).

Question 25 Organic Chemistry Functional Groups

What suffix names nitriles?

Alkenes and alkynes (which decolorize bromine via addition) from alkanes and aromatics (which do not react without a catalyst). Fischer esterification, acid-catalyzed, releasing water. They can hydrogen bond via the -OH group, unlike ethers or alkanes of similar mass. -nitrile (e.g., ethanenitrile/acetonitrile), retaining the carbon of the nitrile in the parent chain count.

Question 26 Organic Chemistry Functional Groups

What functional group defines an alcohol?

A diol with -OH groups on adjacent carbons, typically made by syn dihydroxylation of an alkene with cold dilute KMnO4 or OsO4/NMO. An amine (the C=O is fully reduced to CH2). It is reduced all the way to a primary alcohol. A hydroxyl group, -OH, bonded to an sp3 carbon.

Question 27 Organic Chemistry Functional Groups

What is keto-enol tautomerism?

-yne (e.g., ethyne, propyne). A nitrogen atom bonded to one or more carbon (alkyl/aryl) groups, with a lone pair, R-NH2. The equilibrium between a ketone/aldehyde (keto form) and its enol form (C=C with adjacent -OH), interconverted via an alpha-hydrogen shift. Primary (1°), secondary (2°), or tertiary (3°) based on the number of carbons attached to the carbinol carbon.

Question 28 Organic Chemistry Functional Groups

What reaction occurs between a primary amine and an acid chloride?

The aldol addition reaction. Nucleophilic acyl substitution, forming an amide. A carboxylic acid (over-oxidation past the aldehyde). The halogen is attached to an sp2 carbon; the C-X bond is shorter/stronger and the leaving group departure would disrupt pi conjugation, and backside attack is blocked by the pi system.

Question 29 Organic Chemistry Functional Groups

What forms when a nitrile is reduced with LiAlH4?

SN2 (bimolecular, backside attack, inversion) and SN1 (unimolecular, via carbocation, racemization). A primary amine (the triple bond is fully reduced). Fehling's/Benedict's test: Cu2+ (blue) is reduced to Cu2O (brick-red precipitate) by aldehydes. A strong C=O stretch around 1705-1725 cm^-1, with no aldehyde C-H peaks.

Question 30 Organic Chemistry Functional Groups

Why are carboxylic acids acidic?

Fischer esterification, acid-catalyzed, releasing water. Nonpolar; they are largely unreactive except toward combustion and halogenation (free radical). The carboxylate anion formed after deprotonation is resonance-stabilized, delocalizing the negative charge over both oxygens. Around 4.5-6.5 ppm.

Question 31 Organic Chemistry Functional Groups

What is the general order of reactivity of carboxylic acid derivatives toward nucleophilic acyl substitution?

An oxygen atom bonded to two carbon groups, R-O-R'. Acyl halide > anhydride > ester > amide (based on leaving group ability). An aldehyde (PCC is a mild oxidant that stops at the aldehyde stage). 'Alkyl alkanoate' (e.g., ethyl acetate) — the alkyl group from the alcohol, then the acid-derived name ending in -oate.

Question 32 Organic Chemistry Functional Groups

What is a hemiacetal?

Protonation of the epoxide oxygen activates it; the nucleophile attacks the more substituted carbon (via partial carbocation character). The product of one alcohol adding to an aldehyde or ketone carbonyl, containing both -OH and -OR on the same carbon. Grignard reagents are strong bases and react immediately with water (or any acidic proton source) to form the corresponding alkane. Substitution of the -OH by -Cl, producing an alkyl chloride, SO2, and HCl.

Question 33 Organic Chemistry Functional Groups

What reaction installs an acyl group onto a benzene ring using AlCl3?

Friedel-Crafts acylation, which is not prone to carbocation rearrangement or polysubstitution issues like alkylation. Electron-donating groups like -OH, -NH2, -OR, and alkyl groups (via resonance or induction donation into the ring). An ester group (the acetate ester of the phenolic -OH on salicylic acid). Grignard and organolithium reagents favor 1,2-addition; softer nucleophiles like cuprates (R2CuLi) favor 1,4-(conjugate) addition.

Question 34 Organic Chemistry Functional Groups

Why do carboxylic acids have unusually high boiling points?

Fischer esterification, acid-catalyzed, releasing water. Carboxylic acid > ester > amide > nitrile > aldehyde > ketone > alcohol > amine > alkene/alkyne (roughly, per oxidation-state based seniority rules). They form stable hydrogen-bonded dimers through their -COOH groups. A new, longer alkyne via SN2 alkylation of the acetylide.

Question 35 Organic Chemistry Functional Groups

What functional group defines an alkyl halide?

A carbon-carbon triple bond, C≡C. A nitrogen atom bonded to one or more carbon (alkyl/aryl) groups, with a lone pair, R-NH2. A halogen atom (F, Cl, Br, I) bonded to an sp3 carbon, R-X. The equilibrium between a ketone/aldehyde (keto form) and its enol form (C=C with adjacent -OH), interconverted via an alpha-hydrogen shift.

Question 36 Organic Chemistry Functional Groups

How many equivalents of HX or H2 fully react with an alkyne?

Primary, secondary, and tertiary amines, based on their differing reactivity with benzenesulfonyl chloride. Loss of CO2 from a carboxylic acid, often facilitated by a beta-keto or beta-carboxyl group. Alkenes, by reacting an aldehyde or ketone with a phosphorus ylide (Wittig reagent), forming C=C and triphenylphosphine oxide as byproduct. Two equivalents, since the triple bond can undergo two successive addition reactions.

Question 37 Organic Chemistry Functional Groups

What is the typical IR signature of a carboxylic acid?

Polar aprotic solvents (e.g., DMSO, acetone), which do not hydrogen-bond to and hinder the nucleophile. They are good aprotic polar solvents for reactions like Grignard formation because they solvate cations without acting as proton donors. A very broad O-H stretch from 2500-3300 cm^-1 overlapping C-H stretches, plus a strong C=O stretch near 1710 cm^-1. No — there is no H on the carbinol carbon to remove, so tertiary alcohols resist oxidation.

Question 38 Organic Chemistry Functional Groups

What is a Michael addition?

A four-membered cyclic amide, found in antibiotics such as penicillin, notable for high ring strain that increases its reactivity toward hydrolysis. A primary amine with one fewer carbon, via degradation of a primary amide with Br2/NaOH. 1,4-conjugate addition of a nucleophile (often an enolate) to an alpha,beta-unsaturated carbonyl compound. Cis-trans (E/Z) geometric isomerism due to restricted rotation around the double bond.

Question 39 Organic Chemistry Functional Groups

What reagent converts a carboxylic acid into an acid chloride?

SN2 (bimolecular, backside attack, inversion) and SN1 (unimolecular, via carbocation, racemization). No — there is no H on the carbinol carbon to remove, so tertiary alcohols resist oxidation. A carboxylic acid (over-oxidation past the aldehyde). Thionyl chloride (SOCl2) or phosphorus pentachloride (PCl5).

Question 40 Organic Chemistry Functional Groups

What reagent reacts with a nitrile to add a Grignard R group, giving a ketone after hydrolysis?

No — ketones lack the removable H needed for oxidation to a carboxylic acid, so they do not reduce Tollens' reagent. C_nH_2n+2 — saturated hydrocarbons with only single bonds. A primary amine (the triple bond is fully reduced). A Grignard reagent (R'MgX) adds once to the nitrile carbon, and acidic aqueous workup hydrolyzes the imine intermediate to a ketone.

Question 41 Organic Chemistry Functional Groups

Why do alcohols have relatively high boiling points?

The phenoxide anion is resonance-stabilized by the aromatic ring, delocalizing the negative charge. They can hydrogen bond via the -OH group, unlike ethers or alkanes of similar mass. Geminal: both halogens on the same carbon; vicinal: halogens on adjacent carbons. Generally upfield, around 0.5-2.5 ppm, depending on neighboring groups.

Question 42 Organic Chemistry Functional Groups

What functional group defines a thiol?

It must be cyclic, planar, fully conjugated, and have 4n+2 pi electrons. Succinic anhydride, formed by intramolecular dehydration of succinic (butanedioic) acid, favored by 5- or 6-membered ring formation. A sulfhydryl group, -SH, the sulfur analog of an alcohol. Protonation of the epoxide oxygen activates it; the nucleophile attacks the more substituted carbon (via partial carbocation character).

Question 43 Organic Chemistry Functional Groups

Why are phenols more acidic than typical alcohols?

A tertiary alcohol, via an intermediate ketone that reacts with a second equivalent of Grignard. The phenoxide anion is resonance-stabilized by the aromatic ring, delocalizing the negative charge. Polar aprotic solvents (e.g., DMSO, acetone), which do not hydrogen-bond to and hinder the nucleophile. A carbon-carbon double bond, C=C.

Question 44 Organic Chemistry Functional Groups

What is nucleophilic acyl substitution?

Nonpolar; they are largely unreactive except toward combustion and halogenation (free radical). Roughly 160-220 ppm (esters/amides/acids lower around 160-180 ppm; ketones/aldehydes higher around 190-220 ppm). A two-step addition-elimination mechanism at a carbonyl carbon: nucleophile adds to form a tetrahedral intermediate, then the leaving group departs to restore the C=O. It must be cyclic, planar, fully conjugated, and have 4n+2 pi electrons.

Question 45 Organic Chemistry Functional Groups

What makes a good leaving group?

A cyclic amide, formed by intramolecular amide bond formation within an amino-acid-like molecule. A nitrogen atom bonded to one or more carbon (alkyl/aryl) groups, with a lone pair, R-NH2. sp, linear geometry (180° bond angles). A weak base that can stabilize negative charge, such as halides (especially I-, Br-) or tosylate/sulfonate esters.

Question 46 Organic Chemistry Functional Groups

Why does an amide nitrogen have reduced nucleophilicity/basicity compared to an amine nitrogen?

A cyclic amide, formed by intramolecular amide bond formation within an amino-acid-like molecule. Resonance delocalizes the amide nitrogen lone pair into the carbonyl pi system, reducing its availability for protonation or nucleophilic attack. A positively charged trivalent carbon; stability order is tertiary > secondary > primary > methyl, due to hyperconjugation and inductive electron donation from alkyl groups. A strong, often unpleasant odor, exploited in adding trace thiols to natural gas for leak detection.

Question 47 Organic Chemistry Functional Groups

What is transesterification?

They can hydrogen bond via the -OH group, unlike ethers or alkanes of similar mass. Exchange of the -OR group of an ester with a different alcohol, typically acid- or base-catalyzed, forming a new ester. A primary amine (the triple bond is fully reduced). Only sigma (single) bonds between carbon and carbon, and carbon and hydrogen.

Question 48 Organic Chemistry Functional Groups

What happens when a carboxylic acid reacts with LiAlH4?

Cysteine residues in proteins form disulfide bridges that stabilize tertiary/quaternary protein structure. A primary amine with one fewer carbon, via degradation of a primary amide with Br2/NaOH. It is reduced all the way to a primary alcohol. No — there is no H on the carbinol carbon to remove, so tertiary alcohols resist oxidation.

Question 49 Organic Chemistry Functional Groups

What biologically important structural motif involves disulfide bonds from thiols?

Fischer esterification, acid-catalyzed, releasing water. sp, linear geometry (180° bond angles). Cysteine residues in proteins form disulfide bridges that stabilize tertiary/quaternary protein structure. Formation of a planar carbocation intermediate allows nucleophilic attack from either face, giving a mixture of both enantiomers (often not perfectly 50:50 due to ion pairing).

Question 50 Organic Chemistry Functional Groups

What is saponification?

A carbonyl group bonded to two carbon groups, R-CO-R'. Base-catalyzed hydrolysis of an ester (often a fat/triglyceride) to give a carboxylate salt (soap) and an alcohol. It is reduced all the way to a primary alcohol. A metal catalyst such as Pd, Pt, or Ni, converting C=C to C-C with H2.