Introduction to Organic Chemistry Pt II

The three-dimensional structure of a molecule is its ________. ________ involves the consideration of what can move and what can't in each of the molecules involved in a reaction. ______ bonded atoms are locked in place in three dimensional space relative to one another while _____ bonds are free to rotate.

Isomers are unique molecules that share the same ______ ______. "Iso" is a Greek prefix meaning "the same"or "equal." A lone molecule ____ an isomer by itself. It must be an isomer in relation to another molecule. Two molecules are isomers if they have the same molecular formula but are different compounds. This section will discuss the three major types of isomers tested by the MCAT®: _______ (_______) isomers, ________ isomers, and ________.

The simplest form of isomer is a _____ isomer (define).

_______ isomers or conformers are not true isomers. At room temperature, atoms rotate rapidly about their ___ bonds, resulting in a mix of _______ isomers at any given moment. The eclipsed conformers exist at _____ energy than staggered conformers, as shown in Figure 2.13. This difference in energy levels is due in large part to ____ ____. The simplest way to distinguish between conformers is with _____ _____. Figure 2.13 shows the Newman projections ofthe conformers of butane and their relative energy levels.

Two unique molecules with the same molecular formula and the same bond-to-bond connectivity are called ______. The two major types of stereoisomers are _______ and _______.

Define Enantiomers

Enantiomers must have _______ absolute configurations at each and every chiral carbon

The mirror image of a right hand is a left hand. In chemistry this "handedness" is called ______ ("chiros" is Greek for "hand"). Molecules that have "handedness" are called ______ molecules. Chirality has important ramifications in biology. Many nutrients are chiral, and the human body may not be able to assimilate the _____ _____ of such a nutrient. Many pharmaceutical drugs also have chirality, with the mirror images acting ______ inside the body.

Chirality on the MCAT® is mainly concerned with carbon. Any carbon is chiral when it is bonded to ____ different substituents.

The only one way to describe the physical orientation of atoms about a chiral center such as a chiral carbon is to provide the _____ ______ of the chiral center. Since there are two possible configurations that are mirror images of each other, absolute configuration is given as ___ (_____: the Latin word for right) or ___ (_____: the Latin word for lift).

In order to determine the configuration of a given molecule, the atoms attached to the chiral center are numbered from ______ to ______ priority. 1)The highest priority is given to the atom with the ____ _____ _____. 2)If two of the atoms are the same element, their substituents are sequentially compared in order of decreasing priority until a substituent is found to have a greater priority than the corresponding substituent on the other atom. 3)Substituents on double and triple bonds are counted ____ and ____ times respectively.

In the molecule shown in Figure 2.15 the carbon labeled "2" has a _____ priority than the carbon labeled "3" because _____ has a higher priority than ______. The carbon labeled "3" is considered to have two oxygens for the purposes of assigning priority, due to the double bond.

How do you determine the absolute configuration?

Relative configuration is not related to absolute configuration. Two molecules have the same relative configuration about a chiral carbon if they differ by only ____ substituent and the other substituents are oriented ______ about the carbon.

R and S enantiomers differ in their rotation of _____ ______ light. Knowing the absolute configuration of the molecules ____ indicate the direction in which each configuration rotates the light, though. Determining the direction of rotation for each enantiomer requires ______ measurement.

Light is made up of ______ waves. A single photon can be described by both a changing _____ ____ and a changing _____ _____. Both fields are _______ to each other and to the direction of ________. For simplicity, the _______ field is often ignored and only the direction of the ______ field is considered.

A typical light source releases millions of photons whose fields are oriented in _____ directions. Define polarimeter and plane-polarized light

The orientation of the electric field produced by a photon is _____ when that photon reflects off a molecule. The enantiomer of that molecule _____ the electric field to an ______ degree but in the ______ direction.

For compound s without an _______ or for an equal mixture of _______, there are so many millions of molecules colliding with photons that on average, photons leave the compound with the same electric field orientation with which they went in. Since no single molecular orientation is favored, what is the net result? Such compounds are _____ _____. These compounds may be compounds without _____ _____ or molecules with _____ _____ planes

Enantiomers can be separated by ______ (or in rare cases, physical) means. The result of such a separation is a ____ "right-handed" or "left-handed" sample. When plane-polarized light is projected through such a chiral compound, the orientation of its electromagnetic field is _____. Such a compound is ______ _____. If the compound rotates plane polarized light clockwise, it is designated with a '+' or' d' for ________. If it rotates plane-polarized light counterclockwise, it is designated with a '-' or' I' for _______ (Latin: dexter; right: laevus; left).

The direction and number of degrees that the electromagnetic field is rotated when it passes through a compound is called the compound's _____ rotation. _____ rotation is a standardized form of observed rotation that is calculated from the observed rotation and experimental parameters. The equation takes into account the _____ of the polarimeter, the ________ of the solution, the ________, and the type of ______ of light used.

When placed separately into a polarimeter, enantiomers rotate plane-polarized light in ______ directions to an _____ degree. The specific rotation of (R)-2-Butanol is -13.52° while its enantiomer, (S)-2-Butanol, has a specific rotation of _____.

Except for interactions with plane-polarized light and reactions with other chiral compounds, enantiomers have the same _____ and ______ properties. When enantiomers are mixed together in equal concentrations, the resulting mixture is called a racemic mixture. A racemic mixture does not rotate plane-polarized light (why?)

When enantiomers are mixed in unequal concentrations, light is rotated in the same direction as it would be in a _____ sample of the enantiomer in _____, but only to a ______ of the degree. The ratio of actual rotation to the rotation of pure sample is called _____ _____.

The other major type of stereoisomer is a diastereomer (define). Unlike enantiomers, diastereomers with multiple chiral centers have the same ______  configuration at one or more of those chiral centers.

Diastereomer pairs ____ in their physical properties (rotation of plane-polarized light, melting points, boiling points, solubilities, etc.) and in their chemical properties. The maximum number of optically active isomers that a single compound can have is related to the number of its chiral centers by the following formula: maximum number of optically active isomers = 2", where n is the number of _____ _____

A meso compound is one that has multiple ____ ____, but is _____ _____. Meso compounds have a plane of symmetry through their center, which divides the molecule into two halves that are _____ ____ of each other. Because of their ______, the chiral centers offset each other and the overall compound _____ rotate plane-polarized light. Meso compounds are considered to be _____.

Define Epimers and Anomers
The chiral carbon of an anomer is called the ______ carbon. As will be described in the next lecture, carbohydrates are classified according to their configuration at the _____ carbon.

Cis/trans isomers or ______ isomers are a special type of _______ that exist due to hindered rotation created by _____ bonds or a _____ structure. Cis/ trans isomers are disubstituted (explain)

Cis/ trans isomers have _____ physical properties. Cis molecules have a dipole moment while trans molecules do not. Because they have dipole moments, cis molecules have _____ intermolecular forces than trans molecules, leading to _____ boiling points (it takes _____ energy to make them boil, since they're "stuck" together by _____ intermolecular forces). Since their substituents are concentrated on the same side, however, cis molecules do not form _____ as readily, and thus have _____ melting points than their respective trans isomers.

The substituent groups in the cis position may "crowd" each other, a phenomenon known as ____ _____. Steric hindrance in cis molecules _____ their energy levels, ______ stability.

For tri- and tetrasubstituted alkenes or ring structures, the terms cis and trans may be ambiguous or simply ______. The MCAT® requires knowledge of a system that is used to describe such isomers unambiguously. First, the two substituents on each carbon are prioritized using _____ _____, similar to the system used for absolute configuration. When the higher priority substituents are on opposite sides of the "_____" bond, the molecule is labeled E for entgegen; if on the same side, then Z for zusammen.

In branched diagram form, break down the different types of isomers