Chapter 2: Families of Carbon Compounds and Infrared Spectroscopy (Vocabulary Flashcards)

Vocabulary flashcards covering key terms from Chapter 2: functional groups, hydrocarbon families, naming conventions, representative groups (alkyl, aryl, arenes), common functional groups (alcohols, ethers, amines, amides, nitriles, carbonyls), and infrared spectroscopy concepts (wavenumber, IR spectrum, diagnostic regions, and intermolecular forces).

Functional group

Atom pattern defining a molecule's reactivity and properties.

Alkene

Hydrocarbon with a C=C double bond; ends with -ene; undergoes addition reactions.

Alkyne

Hydrocarbon with a C≡C triple bond; ends with -yne; highly unsaturated.

Alkane

Hydrocarbon with only C–C and C–H single bonds; saturated; ends with -ane.

Cycloalkane

Cyclic alkane; saturated ring; uses cyclo- prefix.

Aromatic (benzene)

Planar cyclic compound with delocalized π electrons (4n+2 rule).

Delocalized electrons

Electrons spread over multiple atoms, equalizing bond character.

Huckel rule

A cyclic π-electron system is aromatic if it has 4n+2 π electrons.

Longest continuous carbon chain

Basis for the parent name in alkane nomenclature.

Prefixes meth-, eth-, prop-, but-, etc.

Indicate carbon atom count in the parent alkane.

Alkyl group

R– group from an alkane by removing H; name ends with -yl.

R group

Represents any substituent or alkyl group.

Arene (Ph) group

Phenyl substituent: C6H5- or Ph–.

Benzyl group

CH2- group attached to a phenyl ring (CH2Ph or Bn–).

Haloalkane

Alkane with a halogen substituent (R–X).

Aryl halide

Halogen directly attached to an aromatic ring (Ar–X).

Alkenyl halide

Halogen attached to an alkene (C=C–X).

Quaternary carbon

A carbon atom bonded to four other carbon atoms.

Alcohol (ROH)

Hydroxyl group (-OH) on an sp^3-hybridized carbon.

Primary alcohol

OH-bearing carbon is attached to one other carbon.

Secondary alcohol

OH-bearing carbon is attached to two other carbons.

Tertiary alcohol

OH-bearing carbon is attached to three other carbons.

Phenol

Hydroxyl group directly bonded to an aromatic ring; more acidic.

Ether

R–O–R' linkage.

Amine

Substituted ammonia (RNH2, R2NH, or R_3N) with a lone pair on N.

Amide

Carbonyl compound attached to an amine (R–CO–NR'R'').

Nitrile

R–C≡N; sp-hybridized carbon; linear.

Aldehyde

R–CHO; carbonyl carbon bonded to at least one hydrogen.

Ketone

R–CO–R'; carbonyl carbon bonded to two carbon substituents.

Carboxylic acid

R–CO_2H; contains carbonyl and hydroxyl; highly acidic.

Ester

R–CO_2-R'; carbonyl adjacent to an alkoxy group.

Fischer esterification

Acid-catalyzed reaction of a carboxylic acid with an alcohol to form an ester.

Hydrogen bonding

Strong dipole-dipole between H–X (X = N, O, F) and an electronegative atom.

Intermolecular forces

Dispersion, dipole-dipole, hydrogen bonding, and ionic interactions affecting MP/BP and solubility.

Solubility (Like dissolves Like)

Polar compounds dissolve in polar solvents; nonpolar in nonpolar.

Water solubility rule

Soluble if up to \sim3 g/100 mL; 1–3 C soluble, 4–5 borderline, 6+ insoluble (exceptions apply).

Micelles

Spherical arrangements of soap molecules around dirt.

IR spectroscopy

Technique to detect functional groups by observing molecular vibrations.

Wavenumber

Position of an absorption band in cm^{-1}; higher wavenumber = higher energy.

IR spectrum

Plot of percent transmittance vs wavenumber; reveals functional groups.

Carbonyl region (IR)

\text{C=O} stretch typically around 1630–1780 cm^{-1}.

C–H stretches in hydrocarbons

Aliphatic C–H \sim2853–2962 cm^{-1}; C=C \sim1620–1680 cm^{-1}; fingerprint region 1400–1600 cm^{-1}.

O–H stretch in alcohols vs carboxylic acids

Alcohols: 3200–3550 cm^{-1} broad; Carboxylic acids: 3600–2500 cm^{-1} broad with a separate carbonyl peak.

N–H stretch

Amine N–H stretch in 3300–3500 cm^{-1} region; primary amines show two bands, secondary one, tertiary none.

Diagnostic IR region

Regions above \sim1500 cm^{-1} used to identify functional groups.

Triple bond regions in IR

Alkyne C≡C \sim2100–2260 cm^{-1}; Nitrile C≡N \sim2220–2260 cm^{-1}.