Organic Chemistry n Introduction n Functional Groups n

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

Introduction n Organic chemistry is the study of carbon- containing compounds 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 Most of the advances in the pharmaceutical industry are based on a knowledge of organic chemistry. n Life as we know it is based on organic chemistry.

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 Carbon forms a total of 4 bonds. n The “skeleton” of an organic compound has H’s attached to it. n other “heteroatoms” like O, halogens, N, S, and P may be present as well

Introduction n Some familiar organic compounds: methane acetylene propane acetone

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

Introduction n Organic compounds are commonly classified and named based on the type of functional group present. n An atom or group of atoms that influences the way the molecule functions, reacts or behaves. n The center of reactivity in an organic compound

Functional Groups n On your exam, you will be responsible for recognizing and naming the various common functional groups that are found in organic compounds: n Use Table 25. 4 and the following slides to help you study

Functional Groups Class of Compound Functional Group Alkane None Cycloalkane None Alkyl halide Alkene Alkyne Alcohol Ether

Functional Groups Class of Compound Aldehyde Ketone Carboxylic Acid Ester Functional Group

Functional Groups Class of Compound Amine Amide Nitrile Aromatic ring Functional Group

Alkanes n Contain C-C single bonds n no functional group n Tetrahedral electron domain geometry n sp 3 hybridized carbons n Free rotation around single bonds propane

Cycloalkanes n Contain C – C with at least 3 of the carbons arranged in a cyclic (ring) structure n No functional group n Tetrahedral n sp 3 hybrid orbitals

Alkyl Halides n Contain C-halogen bond n F, Cl, Br, or I

Alkenes n Contain C=C (carbon-carbon double bonds) n 1 sigma bond & 1 pi bond n Trigonal planar geometry Which atoms must be coplanar in an alkene? 1 -propene n sp 2 hybridized carbons

Alkenes n The C=C present in an alkene is composed of 1 sigma (s) bond and 1 pi (p) bond. ethylene n Double bonds are rigid and cannot rotate freely. n Rotation would cause loss of overlap of the p orbitals, destroying the p bond.

Alkynes n Contain C C triple bonds n 1 sigma bond n 2 pi bonds n Linear electron domain geometry n sp hybridized carbons Which atoms must be co-linear in an alkyne?

Aromatic Ring n Planar ring system with alternating single and double bonds n does not react like an alkene benzene n Trigonal planar n sp 2 hybridized carbons n Benzene ring is a very common aromatic ring. pyridine

Functional Groups n Alkanes are often called saturated hydrocarbons n Organic compounds composed of carbon and hydrogen that contain the largest possible number of hydrogen atoms per carbon atom. n Alkenes, alkynes, and aromatic hydrocarbons are called unsaturated hydrocarbons n Organic compounds composed of carbon and hydrogen that contain less hydrogen than an alkane having the same number of carbon atoms

Alcohols n Contain C-O-H bond n hydroxyl group n Alcohols form hydrogen bonds. n How does hydrogen bonding affect boiling point? ? ? n Amphoteric

Ethers n Contain C-O-C bond n tetrahedral e. d. geometry n bent molecular geo.

Amines n Contain C-N-R R’ n R and R’ can be H or C n Primary and secondary amines form hydrogen bonds. n Common organic bases n lone pair of e- on N primary secondary tertiary

Aldehydes O n Contain C - H (-CHO) n Carbonyl (C=O) n always on the 1 st or last carbon in a chain n trigonal planar geometry n sp 2 hybrid orbitals

Ketones O n Contain C-C-C n Carbonyl attached to middle of chain n Trigonal planar e. d. geo. n sp 2 hybridized C

Carboxylic Acids n Contain carboxyl group n Form hydrogen bonds n trigonal planar n sp 2 hybridized carbon

Esters n Contain n trigonal planar n sp 2 hybridized

Amides n Contain n where R and R’ = H or C n C=O is trigonal planar & sp 2 hybridized

Nitriles n Contain n Linear n sp hybridized C

Functional Groups Example: Identify the functional groups present in the following compounds. thyroxine testosterone

Functional Groups Example: Identify the functional groups in the following compounds. Lisinopril Vanillin

Depicting Structures of Organic Compounds n Organic compounds can be depicted using a variety of formulas: n n n n Empirical formula Molecular formula Lewis structure Full structural formula Three dimensional drawings Condensed structural formula Line angle drawings

Depicting Structures of Organic Compounds n Ethyl acetate is an organic molecule with: n empirical formula = C 2 H 4 O n molecular formula = C 4 H 8 O 2

Depicting Structures of Organic Compounds n Ethyl acetate is an organic molecule with: n Lewis structure: n depicts all covalent bonds using a straight line and shows all nonbonding pairs of electrons n Full structural formula: n a Lewis structure without the nonbonding electrons

Depicting Structures of Organic Compounds n Ethyl acetate is an organic molecule with: n 3 -d drawing: n Condensed structural formula n Line angle drawing

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 straight- chain 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 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: n longest chain may not always be written in a straight line 1 CH 3 -2 CH - 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 n groups 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 propyl butyl Know these! 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 n. F fluoro

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 n Tri = three Know these. 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 n designate 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 n cis isomer n trans isomer

Alkenes n Alkene Nomenclature n Cis isomer: n two identical groups (on adjacent carbons) on the same side of the C = C double bond n Trans isomer: n two 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 CH 3 CH 2 CH 3 CHCH 2 CH 3 H H C = C H 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 n number from the end of the chain closest to the triple bond n just 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 3 Cl. CH 2 C CH

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