Organic Chemistry Introduction Functional Groups Alkanes Alkenes Alkynes

Organic Chemistry Introduction Functional Groups Alkanes Alkenes Alkynes Alcohols Acids, Esters and Amides

Introduction n Organic chemistry is the study of carboncontaining compounds n especially compounds containing C-C bonds n The field of organic chemistry is very important for a wide variety of reasons. n A huge number of carbon-containing compounds are known. n More than 16 million known compounds n About 90% of new compounds made each year contain carbon

Introduction n Most of the advances in the pharmaceutical industry are based on a knowledge of organic chemistry. n Many drugs are organic compounds n Life as we know it is based on organic chemistry. n Most biologically important compounds contain carbon: n DNA, RNA n proteins n carbohydrates

Introduction n Learning organic chemistry requires you to integrate and apply many of the concepts you’ve learned in general chemistry: §Electron configuration §Valence bond theory §Lewis structures §Resonance structures §Hybrid orbitals §Molecular geometry §Acid/base reactions §Oxidation/reduction §Kinetics §Equilibrium §Thermodynamics §Stoichiometry

Introduction n Some familiar organic compounds: methane acetylene propane acetone

Introduction n Some familiar organic compounds: Acetic acid “ether” aspirin Ethyl alcohol

Introduction n Most organic compounds have a “skeleton” that is composed of C-C bonds. n The C-C bonds may be single bonds, double bonds, or triple bonds. n The “skeleton” of an organic compound has H’s attached to it. n other “heteroatoms” like O, halogens or N may be present as well

Introduction n The number of bonds formed by C in an organic compound is determined by the electron configuration of C. n Carbon has four valence electrons: 1 s 22 p 2

Introduction n Carbon generally forms 4 equivalent bonds. n The formation of four equivalent bonds is best explained using the concept of hybrid orbitals.

Introduction n The structure of an organic compound can be predicted by drawing a Lewis structure: H H O H C C C H H H acetone

Introduction n In organic molecules, we generally describe the geometry around each carbon atom. n Geometry is predicted using: n VSEPR n hybrid orbitals

Introduction n When C forms four single bonds: n sp 3 hybrid orbitals are involved n tetrahedral geometry n When C forms a double bond: n sp 2 hybrid orbitals are used n trigonal planar geometry n When C forms a triple bond: n sp hybrid orbitals are used n linear geometry

Introduction Example: Identify the electron domain geometry and hybrid orbitals used by each atom (except hydrogen) in the following compound.

Introduction n Organic compounds contain not only C-C bonds but also C-H bonds. n C-C and C-H bonds tend to be non-polar because there is a small difference in electronegativites n Most (but not all) organic compounds are relatively non-polar ngenerally not very soluble in water

Hydrocarbons n The simplest organic compounds are the hydrocarbons: n organic compounds that contain only carbon and hydrogen n four general types: nalkanes nalkenes nalkynes naromatic hydrocarbons

Hydrocarbons n Alkanes: n hydrocarbons that contain only single bonds n Examples: n Methane n ethane CH 4 H H H–C–C–H H H

Hydrocarbons n Alkenes: n hydrocarbons that contain a C = C double bond n H 2 C = CH 2 (ethylene) n Alkynes: n hydrocarbons that contain a C bond n H – C C – H (acetylene) C triple

Hydrocarbons n Aromatic hydrocarbons: n contain a planar ring structure in which the carbon atoms are connected by a combination of both s and p bonds H C H-C C-H C H benzene

Introduction n Organic compounds that are soluble in polar solvents such as water generally have a polar functional group present in the molecule. n An atom or group of atoms that influences the way the molecule functions, reacts or behaves. n an atom or group of atoms in a molecule that undergoes predictable chemical reactions n the center of reactivity in an organic molecule

Introduction n Functional groups that contain O or N atoms often lead to a polar organic molecule n large difference in electronegativity n. C vs. O n. C vs. N n Examples of familiar polar organic compounds: Functional groups n glucose contain C-O bonds n acetic acid n Vitamin C Functional groups contain n amino acids C-O and C-N bonds

Functional Groups n Since functional groups are responsible for the many of the chemical and physical properties of organic compounds, we often classify and study organic compounds by the type of functional group present. n On your exam, you will be responsible for recognizing and naming the various common functional groups that are found in organic compounds:

Functional Groups

Functional Groups

Functional Groups

Functional Groups

Functional Groups Example: Name the functional groups that are present in the following compounds: CH 3 CH 2 OH O H 2 C = CHCOH CH 3 CH 2 NCH 3

Functional Groups Example: Name the functional group(s) that is (are) present in the following compounds: O H 2 C CH 2 CH 3 NHCH 2 OCH 3

Hydrocarbons n Alkanes are often called saturated hydrocarbons n they contain the largest possible number of hydrogen atoms per carbon atom. n Alkenes, alkynes, and aromatic hydrocarbons are called unsaturated hydrocarbons n they contain less hydrogen than an alkane having the same number of carbon atoms

Alkanes n Organic compounds can be represented in many different ways: n molecular formula: C 4 H 10 (butane) n Lewis structure: n Condensed structural formula n CH 3 CH 2 CH 3 n Line angle drawings

Alkanes Some of the simplest alkanes: You must know these!!!

Alkanes Some of the simplest alkanes: You must know these!!!

Alkanes n The previous alkanes are also called straightchain hydrocarbons: n all of the carbon atoms are joined in a continuous chain n Alkanes containing 4 or more carbons can also form branched-chain hydrocarbons (branched hydrocarbons) n some of the carbon atoms form a “branch” or side-chain off of the main chain

Alkanes n An example of a straight chain hydrocarbon: n C 5 H 12 CH 3 CH 2 CH 2 CH 3 pentane n Examples of a branched hydrocarbon: n C 5 H 12 CH 3 CHCH 2 CH 3 2 -methylbutane CH 3 CCH 3 2, 2 -dimethylpropane

Alkanes n The three structures shown previously for C 5 H 12 are structural isomers: n compounds with the same molecular formula but different bonding arrangements n Structural isomers generally have different properties: n different melting points n different boiling points n often different chemical reactivity

Alkanes n Alkanes with three or more carbons can also form rings or cycles. n Cycloalkanes: n Alkanes containing a ring structure that is held together by C – C single bonds n Examples: H 2 C CH 2 cyclopropane

Alkanes n Examples of cycloalkanes: CH 2 H 2 C CH 2 cyclopentane H 2 C CH 2 CH 2 cyclohexane

Alkanes n Organic compounds can be named either using common names or IUPAC names. n You must be able to name alkanes, alkenes, alkynes, and alcohols with 10 or fewer carbons in the main chain using the IUPAC naming system.

Alkanes n Alkane Nomenclature: n Find the longest continuous chain of carbon atoms and use the name of the chain for the base name of the compound: nlongest chain may not always be written in a straight line 1 2 CH 3 - CH 3 3 CH 2 - CH 3 4 5 6 Base name: hexane

Alkanes n Alkane Nomenclature: n Number the carbon atoms in the longest chain beginning with the end of the chain closest to a substituent ngroups attached to the main chain that have taken the place of a hydrogen atom on the main chain 1 A substituent CH 3 -2 CH - CH 3 3 CH 2 - CH 3 4 5 6

Alkanes n Alkane Nomenclature: n Name and give the location of each substituent group n. A substituent group that is formed by removing an H atom from an alkane is called an alkyl group: n Name alkyl groups by dropping the “ane” ending of the parent alkane and adding “yl”

Alkanes n Alkane Nomenclature: n Common alkyl groups (substituents): CH 3 CH 2 CH 2 1 methyl Know ethyl propyl these! butyl CH 3 -2 CH - CH 3 3 CH 2 - CH 3 4 5 6 2 -methylhexane

Alkanes n Alkane Nomenclature: n Halogen atoms are another common class of substituents. n. Name halogen substituents as “halo”: n. Cl chloro n. Br bromo n. I iodo

Alkanes n Alkane Nomenclature: n When two or more substituents are present, list them in alphabetical order: n Butyl vs. ethyl vs. methyl vs. propyl n When more than one of the same substituent is present (i. e. two methyl groups), use prefixes to indicate the number: n Di = two Know these. n Tri = three n Tetra = four n Penta = five

Alkanes Example: Name the following compounds: CH 3 CH 2 CH 3 CH 3 CHCHCH 3

Alkanes Example: Name the following compounds: CH 3 CH 2 CHCH 3 CH 2 Br CH 2 CH 3 CHCHCH 3 Cl

Alkanes n You must also be able to write the structure of an alkane when given the IUPAC name. n To do so: n Identify the main chain and draw the carbons in it n Identify the substituents (type and #) and attach them to the appropriate carbon atoms on the main chain. n Add hydrogen atoms to the carbons to make a total of 4 bonds to each carbon

Alkanes Example: Write the condensed structure for the following compounds: 3, 3 -dimethylpentane 3 -ethyl-2 -methylhexane 2 -methyl-4 -propyloctane 1, 2 -dichloro-3 -methylheptane

Alkenes n Alkenes: n unsaturated hydrocarbons that contain a C=C double bond n Alkene Nomenclature: n Names of alkenes are based on the longest continuous chain of carbon atoms that contains the double bond.

Alkenes n Alkene Nomenclature n Find the longest continuous carbon chain containing the double bond. n Change the “ane” ending from the corresponding alkane to “ene” n butane butene n propane propene n octane octene

Alkenes n Alkene Nomenclature n Indicate the location of the double bond using a prefix number ndesignate the carbon atom that is part of the double bond AND nearest to the end of the chain n Name all other substituents in a manner similar to the alkanes. n Use a prefix to indicate the geometric isomer present, if necessary.

Alkenes n Alkene Nomenclature n Different geometric isomers are possible for many alkenes. n Compounds that have the same molecular formula and the same groups bonded to each other, but different spatial arrangements of the groups ncis isomer ntrans isomer

Alkenes n Alkene Nomenclature n Cis isomer: ntwo identical groups (on adjacent carbons) on the same side of the C = C double bond n Trans isomer: ntwo identical groups (on adjacent carbons) on opposite sides of the C = C double bond

Alkene CH 3 C=C H H C=C H cis-2 -butene H CH 3 trans-2 -butene

Alkene For an alkene with the general formula A P C=C B Q cis and trans isomers are possible only if A = B and P=Q

Alkene Example: Name the following alkenes: CH 3 CH 2 H C=C H CH 3 CH 2 CH 3 CHCH 2 CH 3 H H C=C CH 2 CH 3

Alkenes Example: Draw the structures for the following compounds: 2 -chloro-3 -methyl-2 -butene trans-3, 4 -dimethyl-2 -pentene cis-6 -methyl-3 -heptene

Alkynes n Alkynes: n unsaturated hydrocarbons that contain a C C triple bond n Alkyne Nomenclature: n Identify the longest continuous chain containing the triple bond n To find the base name, change the ending of the corresponding alkane from “ane” to “yne”

Alkynes n Alkyne Nomenclature: n Use a number to designate the position of the triple bond nnumber from the end of the chain closest to the triple bond njust like with alkenes n Name substituents like you do with alkanes and alkenes

Alkynes Example: Name the following compounds: CH 3 CH 2 C CCHCH 3 CH 2 CH 2 C Cl CH

Alkynes Example: Draw the following alkynes. 4 -chloro-2 -pentyne 3 -propyl-1 -hexyne