MCAT Organic Chemistry 2012

Nam this substituent isopropyl Name this substituent neopentyl Name this substituent t-butyl Name this substituent sec-butyl Name this substituent isobutyl Which organic molecules have this formula? Alkanes NOMENCLATURE (Alkanes)1. Find the longest chain.2. Number the chain.3. Name subtituents4. Prefixes such as di, tri, tert, sec..etc are ignored in alphabetizing; cyclo, iso and neo are included in alphabetization. Review Which organic molecules have this formula? Alkenes Nomenclature (Alkenes) In naming alkenes, the double bond receives the lowest possible number; note any isomers cis/trans and Z/E. Multiple double bonds must be names using prefixes di-, tri-, etc. Review Nomenclature (Alkenes)CH2 groups are referred to as methylene Methylene cyclohexane Nomenclature (Alkenes)Monosubstituted ethylenes (2 carbons) are referred to as vinyl groups. Review Nomenclature (Alkenes)Allyl groups are propylene's substituted at the C-3 position. allyl chloride Which organic molecules have this formula? Alkyne NomenclatureSubstituted Alkanes: Haloalkanes Haloalkanes are compounds that contain a halogen substituent. These compounds may be named as alkyl halides. ex: ethyl (2 carbons) chloride Substituted Alkanes: AlcoholsAlcohols are named by replacing the -e of the corresponding alkane with -ol. Priority is given to the carbon with the -OH group. Molecules with two hydroxyl groups are termed diols or ____ and have the suffix -diol. When two hydroxyl groups are on adjacent carbons the groups are called _____; when they are on the same carbon they are called ____. Geminal diols are called _____ and are less common than vicinal diols due to their tendency to spontaneously lose water to produce a C=O compound. glycols; vicinal; geminal hydrates What type of compound is this? Alkyl halide What type of compound is this? Alcohol What type of compound is this? Glycol or diol Geminal or vicinal? Vicinal Geminal or vicinal? Geminal NomenclatureSubstituted Alkanes: Ethers1. Larger alkyl group is the backbone2. Smaller alkyl group has oxy attached to it Ex: alkoxy alkane3. 3 member cyclic ethers are called ____.*IUPA suffix is ether ROR Epoxides Methoxyethane (image) NomenclatureAldehydes 1. Longest chain containing aldehyde functional group 2. The suffix ____ replaces the -e on the corresponding alkane. Ex: Alkanal 3. The ____ carbon receives the number 1 since by definition an aldeyhde group is terminal. *IUPAC prefix is oxo-RCOH -al carbonyl butanal NomenclatureKetones 1. The carbonyl group in a ketone should receive the lowest possible number (if there is no other priority group) 2. Suffix is is _____. Ex: Alkanone IUPAC prefix is oxo (like aldehyde) RCOR -one NomenclatureCarboxylic Acids 1. Like aldehydes carboxyl groups are ____ groups and are numbered one. 2. The suffix ____ acid replaces the -e on the corresponding alkane. Ex: Alkanoic Acid*IUPAC prefix is "carboxy" RCOOH terminal -oic NomenclatureAmines 1. The backbone is the longest chain containing _____. 2. The suffix ____ replaces the -e in the corresponding alkane. Ex: Alkanamine *When additional alkyl groups are attached to the nitrogen use the prefix "N" RNH2 nitrogen amine ESTER suffix is "-oate" RCOOR IsomersIsomers are chemical compounds that have the same ____ formula but different structure. This can be a difference in atomic _____, 3-D orientation, and ____ orientation. Structural IsomersStructural/ constitutional isomers are compounds that only share their molecular _____. Their atomic connectivity is different, thus they have different _____ and chemical properties. molecularconnectivityrotational formulaphysical IsomersSteroisomerismStereoisomers are compounds that differ from each other only in the way that their atoms are oriented in space. Geometric isomers; enantiomers, diastereomers and meso compounds; and conformational isomers all fall under this heading. Review IsomersStereoisomerism--Differ in atomic orientationGeometric Isomers Geometric Isomers (Diasteromers) are configurational compounds that differ in the ____of substituents on the double bond------cis/trans isomers. Z= same (cis) E = opposite (trans) position IsomersStereoisomerismChirality Chiral = Not superimposable; Achiral = superimposable (identical to mirror image) An enantiomer is a chral and _________ molecule. An asymetric carbon is a carbon atom with 4 _____ substituents. (chirality) nonsuperimposable different IsomersStereoisomersChiralityTo Find the Absolute Configuration: 1. Assign priority: Priority is given to the molecule with the _____ atomic #. 2. Orient the molecule with the lowest priority molecule positioned ____ the page. 3. Determine the order of substituents (highest to lowest): Clockwise is ____ and counterclockwise is _____. highest into R; S IsomersStereoisomersChirality: Fischer ProjectionsA Fischer projection represents a 3-D molecule in 2-D (planar). Horizontal lines = ____ of the page and vertical lines = _____ the page. The mirror image of a fischer projection can be obtained by _____ one pair of substituents or by rotating the molecule 90 degrees. Determining R/S configuration for Fischer Projections: 1. When the lowest priority group is positioned vertically, simply move in the direction from lowest to highest priority group. Clockwise= R and Counterclockwise = S. 2. When the lowest priority group is positioned horizontally, determine R/S as normal, and the true designation will be opposite of that. out of; behind (into) interchanging IsomersStereoisomerismOptical ActivityEnantiomers have all the same chemical and physical properties except for _____ activity. A molecule is considered optically active if it can _____ plane polarized light. An optically active compound will rotate the plane of a light by _____. The enantiomer of this compound will rotate this plane by the same amount but in the _____ direction. Rotation to the right is _____ (dextrorotatory) and rotation to the left is _____ (levorotatory). This is determined experimentally! The amount of rotation is dependent upon the number of _____ that a light wave encounters. The number of molecules a light wave encounters is dependent upon the _____ of the optically active compound and the length of tube through which the light passes. Specific rotation = _________observed rotation concentration (g/mL) x length (dm) A racemic mixture is a mixture of _____ concentrations of (+) and (-). enantiomers; these rotations _____ each other out. optical rotate alpha; opposite positive; negative molecules; concentration; equal; cancel EnantiomersStereoisomersOther Chiral Compoundsn chiral centers have 2n stereoisomers and 2n-2 diastereomers. Enantiomers: opposite R/S designationsex: R, R and S, S Diasteriomers: only one opposite R/S designation.ex: R, R and S, R-----have different physical/chemical properties Ex: Enantiomer: R, R and S, S Diasteriomer: R, R and S, R Meso CompoundsA molecule with a chiral/asymmetric carbon and a line of symmetry is called a mess compound and is not _____ active. Review optically IsomersConformational IsomerismThe anti isomer has the lowest energy (most stable) and the totally eclipsed configuration has the highest energy Review IsomersConformational IsomersCyclohexaneOn the chair conformation, Perpendicular substituents are called _____ and parallel substituents are called _____. Large/bulky groups prefer the _____ position because this avoids steric repulsion. axial; equatorial; equatorial IsomersConformational IsomersTypes of strain: 1. Angle strain is caused when bond angles deviate from their _____ value. 2. Torsional strain is caused when cyclic molecules assume _____ conformations. 3. Non-bonded strain is caused when atoms/groups _____ for the same space. * To avoid strain cyclic molecules adopt nonplanar conformations such as the boat and chair (most stable). ideal eclipsed compete NomenclatureFunctional Groups Carboxylic Acid>Anhydride>Esters>Acyl Halide> Amide> Nitrile> Aldehyde> Ketone> Alcohols>Thiols>Amines> Ethers>Sulfides>Alkenes> Alkynes>Alkyl halides>Nitri>Alkanes Review What functional group is this? Nitrile What functional group is this? Amide What functional group is this? Thiol What functional group is this? Sulfide