Chapter 4 Flashcards
Hydrocarbons having only single (σ) bonds between carbon atoms
Alkanes
Hydrocarbons having at least one double bond between carbon atoms
Alkenes
Hydrocarbons having at least one triple bond between carbon atoms
Alkynes
Alkanes in which some or all of the carbon atoms are arranged in a ring
Cycloalkanes
A process used in the petroleum industry for breaking down the molecules of larger alkanes into smaller ones; may be accomplished with heat, or with a catalyst
Cracking
Each carbon atom within the chain is bonded to no more than two other carbon atoms
Unbranched
Compounds that have the same molecular formula but that differ in their connectivity
Constitutional isomers
A set of nomenclature rules overseen by the Internal Union of Pure and Applied Chemistry (IUPAC) that allows every compound to be assigned an unambiguous name
IUPAC system (“systematic nomenclature”)
The designation given to a fragment of a molecule hypothetically derived from an alkane by removing a hydrogen atom
Allyl group
A system for naming compounds that uses two or more words for naming compounds that uses two or more words to describe the compound
Functional class nomenclature
A system for naming compounds in which each atom or group, called a substituent, is cited as a prefix or suffix to a parent compound
Substitutive nomenclature
Alcohols containing two hydroxyl groups
Glycol
The carbon atoms common to both rings
Bridgeheads
Each chain of atoms connecting the bridgehead atoms
Bridge
Compounds with two fused or bridged rings
Bicyclic compounds
The H2C=CH- group
Vinyl group
The -CH2CH=CH2 group
Allyl group
Substitutes on the same side
Cis compound
Substitutents on opposite sides
Trans compound
Monosubstituted acetylenes or 1-alkynes
Terminal alkynes
A hydrogen atom attached to a carbon atom that is bonded to another carbon atom by a triple bond
Acetylenic hydrogen atom
The anion obtained when the acetylenic hydrogen is removed
Alkynide ion or an acetylide ion
A series of compounds in which each member differs from the next member by a constant unit
Homologous series
A particular temporary orientation of a molecule that results from rotations about its single bonds
Conformation
A particular staggered confirmation of a molecule
Conformer
An analysis of the energy changes that a molecule undergoes as its groups undergo rotation (sometimes only partial) about the single bonds that join them
Conformational analysis
A means of representing the spatial relationships of groups attached to two atoms of a molecule; imagine viewing the molecule from one end directly along the bond axis joining the atoms
Newman projection formula
A temporary orientation of groups around two atoms joined by a single bond such that the bonds of the back atom exactly bisect the angles formed by the bonds of the front atom when shown in a Newman projection formula
Staggered conformation
The angle between two atoms (or groups) bonded to adjacent atoms, when viewed as a projection down the bond between the adjacent atoms
Dihedral angle
A temporary orientation of groups around two atoms joined by a single bond such that the groups directly oppose each other
Eclipsed conformation
Electron delocalization (via orbital overlap) from a filled bonding orbital to an adjacent unfilled orbital; generally has a stabilizing effect
Hyperconjugation
A graphical plot of the potential energy changes that occurs as molecules (or atoms) react (or interact). Potential energy is on the y-axis and the progress of the reaction on the x-axis
Potential energy diagram
The barrier to rotation of groups joined by a single bond caused by repulsion’s between the aligned electron pairs in the eclipsed form
Torsional barrier
The strain associated with an eclipsed confirmation of a molecule; it is caused by repulsions between the aligned electron pairs of the eclipsed bonds
Torsional strain
An effect on relative reaction rates caused when the spatial arrangement of atoms or groups at or near the reacting site hinders or retards a reaction
Steric hinderance
Doesn’t have torsional strain from steric hinderance because the groups are staggered and the methyl groups are far apart
Anticonformation
The methyl groups are close enough to each other that the dispersion forces between them are repulsive
Gauche conformation
Compounds with the same molecular formula that differ only in the arrangement of their atoms in space; they have the same connectivity
Stereoisomers
Stereoisomers differing in space only due to rotations about single (σ) bonds
Conformational stereoisomers
An analysis of the energy changes that a molecule undergoes as its groups undergo rotation (sometimes only partial) about the single bonds that join them
Conformational analysis
The increased potential energy of the cyclic form of a molecule (usually measured by heats of combustion) when compared to its acyclic form
Ring strain
The increased potential energy of a molecule (usually a cyclic one) caused by deformation of a bond angle away from its lowest energy value
Angle strain
The strain associated with an eclipsed confirmation of a molecule; it is caused by repulsions between the aligned electron pairs of the eclipsed bonds
Torsional strain
Rotations about the carbon-carbon single bonds of cyclohexane can produce different conformations which are interconvertible. The most important are the chair conformation, the boat conformation, and the twist conformation
Conformations of cyclohexane
The all-staggered conformation of cyclohexane that has no angle strain or torsional strain and is, therefore, the lowest energy conformation
Chair conformation
A conformation of cyclohexane that resembles a boat and that has eclipsed bonds along its two sides: it is of higher energy than the chair conformation
Boat conformation
Molecules that are synthesized that have large rings threaded on chains and that have large rings threaded on chains and that have large rings that are interlocked like links in a chain
Catenanes
The six bonds of a cyxlohexane ring that are perpendicular to the general plane of the ring, and that alternate up and down around the ring
Axial bond
The six bonds of a cyclohexane ring that lie generally around the “equator” of the molecule
Equatorial bond
The change in a cyclohexane ring (resulting from partial bond rotations) that converts one ring conformation to another; converts any equatorial substituent to an axial substituent and vice versa
Ring flip
The interaction between two axial groups that are on adjacent carbon atoms
1,3-diaxial interaction
Diastereomers that differ in their stereochemistry at adjacent atoms of a double bond or on different atoms of a ring
Cis-trans isomers
An old name for an alkane
Paraffin
A reaction in which hydrogen adds to a double or triple bond; often completed through the use of a catalyst such as platinum, palladium, rhodium, or ruthenium
Hydrogenation
Equals the number of pairs of hydrogen atoms that must be subtracted from the molecular formula of the corresponding alkane to give the molecular formula of the compound under consideration
Index of hydrogen deficiency (IHD)
