Functional groups
59 flashcards covering Functional groups for the MCAT Chem / Phys / Psych / Soc section.
Functional groups are specific arrangements of atoms within a molecule that dictate its chemical behavior and properties. For example, in organic chemistry, a hydroxyl group (-OH) makes a compound an alcohol, influencing how it reacts with other substances. These groups are the building blocks of more complex molecules, helping us predict reactions, solubility, and biological functions, which is essential for understanding everything from drug design to metabolic processes.
On the MCAT, functional groups frequently appear in the Chem/Phys section, often in questions about identifying structures, predicting reaction outcomes, or analyzing biochemical pathways. Common traps include confusing similar groups, like aldehydes and ketones, or overlooking how they affect acidity and reactivity. Focus on memorizing key groups—such as alcohols, carboxylic acids, and amines—and practicing their identification in various contexts to handle passage-based and standalone questions effectively.
A concrete tip: Draw structures regularly to visualize and differentiate functional groups quickly.
Terms (59)
- 01
Alcohol
An organic compound containing a hydroxyl group (-OH) attached to a saturated carbon atom, which makes it polar and capable of hydrogen bonding, affecting its boiling point and solubility.
- 02
Ether
A compound with an oxygen atom connected to two alkyl or aryl groups (R-O-R'), often used as solvents due to their low reactivity and ability to dissolve a wide range of substances.
- 03
Aldehyde
An organic molecule with a carbonyl group (C=O) at the end of a carbon chain, bonded to at least one hydrogen atom, making it more reactive than ketones in nucleophilic addition reactions.
- 04
Ketone
A compound featuring a carbonyl group (C=O) bonded to two carbon atoms, which influences its polarity and participation in reactions like nucleophilic addition, but less so than aldehydes.
- 05
Carboxylic acid
An organic acid with a carboxyl group (-COOH), which is acidic due to resonance stabilization of its conjugate base, and commonly involved in esterification reactions.
- 06
Ester
A derivative of carboxylic acids formed by replacing the -OH with an -OR group, often responsible for pleasant odors in fruits and used in hydrolysis reactions like saponification.
- 07
Amide
A functional group with a carbonyl attached to a nitrogen atom (-CONH2 or similar), which is less reactive than esters and important in proteins and peptide bonds.
- 08
Amine
A derivative of ammonia with one or more hydrogen atoms replaced by organic groups, acting as bases and nucleophiles in reactions like alkylation or acylation.
- 09
Alkane
A hydrocarbon with single bonds between carbon atoms, making it relatively unreactive and serving as a baseline for comparing other functional groups' reactivity.
- 10
Alkene
A hydrocarbon containing at least one carbon-carbon double bond, which allows for electrophilic addition reactions due to the electron-rich pi bond.
- 11
Alkyne
A hydrocarbon with at least one carbon-carbon triple bond, exhibiting acidity at the terminal hydrogen and undergoing addition reactions similar to alkenes.
- 12
Aromatic ring
A stable ring structure, like benzene, with delocalized pi electrons following Hückel's rule, making it resistant to addition reactions and preferring substitution.
- 13
Halide
An organic compound with a halogen atom (F, Cl, Br, I) attached to a carbon, acting as a good leaving group in substitution and elimination reactions.
- 14
Nitro group
A -NO2 group that is electron-withdrawing, increasing the acidity of nearby hydrogens and often used in electrophilic aromatic substitution reactions.
- 15
Thiol
A compound similar to alcohol but with a -SH group, which is more acidic and nucleophilic, playing a role in biochemical molecules like cysteine.
- 16
Sulfide
An ether-like compound but with a sulfur atom (R-S-R'), often involved in oxidation reactions to form sulfoxides or sulfones.
- 17
Imine
A functional group with a carbon-nitrogen double bond (C=NR), formed from aldehydes or ketones and amines, and key in reactions like the Wolff-Kishner reduction.
- 18
Enol
A compound with a hydroxyl group on a double-bonded carbon, existing in equilibrium with its keto form through tautomerism, affecting reactivity in aldol reactions.
- 19
Epoxide
A three-membered ring containing an oxygen atom, highly strained and reactive towards nucleophiles, commonly opened in ring-opening reactions.
- 20
Anhydride
A compound with two acyl groups linked by an oxygen atom, used in acylation reactions and more reactive than esters or amides.
- 21
Acyl halide
A derivative of carboxylic acids with a halogen on the carbonyl (R-COCl), highly reactive as an electrophile in nucleophilic acyl substitution.
- 22
Nitrile
A compound with a -CN group, which can be hydrolyzed to carboxylic acids and acts as a precursor in reactions like the Grignard addition.
- 23
Phenol
An aromatic compound with an -OH group directly on the benzene ring, more acidic than alcohols due to resonance stabilization of the phenoxide ion.
- 24
Enone
A compound with both an alkene and a ketone, allowing for conjugated systems that stabilize charges and enable reactions like Michael addition.
- 25
Alpha carbon
The carbon atom adjacent to a carbonyl group, which is acidic due to the stabilizing effect of the carbonyl on the enolate ion formed upon deprotonation.
- 26
Hydrogen bonding in alcohols
The intermolecular attraction between the -OH group of one alcohol molecule and a hydrogen atom of another, leading to higher boiling points compared to similar hydrocarbons.
- 27
Nucleophilic addition to carbonyls
A reaction where a nucleophile attacks the electrophilic carbon of a carbonyl group, resulting in addition products like alcohols from aldehydes.
- 28
Electrophilic addition to alkenes
A reaction mechanism where an electrophile adds to the double bond of an alkene, often followed by a nucleophile, leading to saturated products.
- 29
Saponification
The base-catalyzed hydrolysis of an ester to produce a carboxylate salt and an alcohol, commonly used in soap making from fats.
- 30
Fischer esterification
An acid-catalyzed reaction between a carboxylic acid and an alcohol to form an ester and water, reversible and equilibrium-driven.
- 31
Hofmann rearrangement
A reaction converting an amide to an amine with one fewer carbon atom, involving migration and loss of CO2, useful for shortening chains.
- 32
Gabriel synthesis
A method to prepare primary amines from alkyl halides using potassium phthalimide, avoiding over-alkylation common in other amine syntheses.
- 33
Priority order for functional groups
In IUPAC naming, functional groups are ranked by seniority, such as carboxylic acids over alcohols, to determine the main chain and suffixes.
- 34
Common naming for ethers
Ethers are often named as alkoxy alkanes in IUPAC, but commonly as alkyl alkyl ethers, like diethyl ether, which is more familiar in lab contexts.
- 35
Resonance in carboxylate ions
The delocalization of electrons in a carboxylate ion (-COO-) stabilizes the negative charge over two oxygen atoms, enhancing the acidity of carboxylic acids.
- 36
Acidity of terminal alkynes
Terminal alkynes (RC≡CH) are weakly acidic due to the sp hybridization of carbon, allowing deprotonation by strong bases to form alkynylides.
- 37
Basicity of amines
Amines act as bases by donating their lone pair on nitrogen, with basicity decreasing as the amine becomes more substituted due to steric and electronic effects.
- 38
Steric hindrance in SN2 reactions
Bulky groups around the reaction site in halides slow down SN2 substitution by blocking nucleophile access, favoring SN1 or elimination.
- 39
Tautomerism in keto-enol
The interconversion between keto and enol forms, catalyzed by acids or bases, which is crucial for reactions like the aldol condensation.
- 40
Diels-Alder reaction
A cycloaddition between a diene and a dienophile, often involving functional groups like alkenes, to form cyclic structures in a stereospecific manner.
- 41
General formula for alcohol
Represented as R-OH, where R is an alkyl group, indicating the presence of a hydroxyl group on a carbon chain.
- 42
General formula for aldehyde
Denoted as R-CHO, showing a carbonyl at the end of the chain with a hydrogen attached, which defines its reactivity.
- 43
General formula for ketone
Written as R-COR', where both R and R' are alkyl groups, distinguishing it from aldehydes by the carbonyl's position.
- 44
Difference between aldehyde and ketone
Aldehydes have the carbonyl at the chain end, making them more reactive to oxidants, while ketones are internal and more resistant.
- 45
Why carboxylic acids are acidic
Carboxylic acids donate a proton due to the resonance-stabilized carboxylate anion, which disperses the negative charge effectively.
- 46
Ethanol as a primary alcohol
Ethanol (CH3CH2OH) is a primary alcohol because the -OH is on a carbon attached to only one other carbon, affecting its oxidation products.
- 47
Nomenclature of 2-propanol
Propanol is named as such in IUPAC because the -OH group is on the second carbon of a three-carbon chain, indicating its position.
- 48
Oxidation of primary alcohols
Primary alcohols can be oxidized to aldehydes and further to carboxylic acids, depending on the conditions and reagents used.
- 49
Reduction of esters
Esters can be reduced to alcohols using agents like LiAlH4, breaking the carbonyl and producing two alcohol groups from the ester.
- 50
Markovnikov's rule
In addition reactions to alkenes, the hydrogen adds to the carbon with more hydrogens, and the other group to the carbon with fewer, due to carbocation stability.
- 51
Anti-Markovnikov addition
Occurs with peroxides in HBr addition to alkenes, where bromine adds to the carbon with more hydrogens, opposite to Markovnikov's rule.
- 52
Wolff-Kishner reduction
A reaction that converts carbonyls in aldehydes or ketones to methylene groups via hydrazone intermediates, useful for deoxygenation.
- 53
Clemmensen reduction
Similar to Wolff-Kishner, it reduces ketones or aldehydes to alkanes using zinc and HCl, preserving other functional groups.
- 54
Aldol condensation
A reaction between two carbonyl compounds, at least one with alpha hydrogens, forming beta-hydroxy aldehydes or ketones that can dehydrate.
- 55
Claisen condensation
The reaction of two esters to form a beta-keto ester, requiring a base and occurring via enolate formation and nucleophilic attack.
- 56
Grignard reagent with carbonyls
Grignard reagents react with carbonyls to form alcohols after hydrolysis, with aldehydes giving secondary alcohols and ketones giving tertiary.
- 57
Hydrolysis of amides
Amides can be hydrolyzed under acidic or basic conditions to carboxylic acids and amines, though it requires harsh conditions due to stability.
- 58
Esterification equilibrium
Fischer esterification reaches equilibrium, so removing water drives the reaction forward to favor ester product formation.
- 59
Resonance in phenols
Phenols exhibit resonance where the oxygen's lone pairs delocalize into the ring, stabilizing the molecule and increasing its acidity.