Alkanes The most significant reaction of alkanes is combustion. This is because alkanes do not have any functional groups. Functional groups are where reactions occur. CH 3 (CH 2 ) 8 CH 3 + 15.5 O 2 (g) 10CO 2 (g) + 11H 2 O(l)
Showing the Structure of an Organic Molecule You must be able to read and interpret drawings of molecules from the start! structural formula = Lewis structure condensed (structural) formula line-angle formula 3-dimensional formula (The molecular formula does not show structure. It just gives numbers and types of atoms.)
Molecular Formula, Lewis Structure, and Condensed Structural Formula These are all the same compound: cis-hex-3-en-2-one The Lewis structure shows all bonds and unbonded valence electrons. Please view the Lewis structures PowerPoint on the 2114 web page if you need a refresher.
Condensed Structural Formula The atoms following the C are bonded to the C: CHCl 2 CH 3 Sometimes the atoms bonded to the leading C are shown on the left: H 3 CCH 2 CH 3 or CH 3 CH 2 CH 3 The C is bonded to the C immediately before it and the C atom immediately after it…all C atoms in molecules have 4 bonds.
Condensed Structural Formula A group bonded to a C is shown in parentheses, except on the last C. Typically, C=C and C ≡ C are shown, but C=O is not. CH 3 CH 2 CH=CHCOCH 3 CH 3 CH 2 CH 2 OH is 1-propanol CH 3 CH(OH)CH 3 is 2-propanol
Line-Angle Structure There is a C at the end of every line segment and enough H atoms to give each neutral C four bonds.
3-D Structure Solid lines are bonds in the plane of the board or paper. Wedges show bonds to atoms in front of the plane. Dashed lines show bonds to atoms behind the plane.
Showing the Structure of an Organic Molecule START NOW practicing drawing these different types of structures!
Functional Groups Is this compound an alkane? Is it a hydrocarbon? It contains two functional groups: an alkene and a ketone. Functional groups are sites of reactivity in an organic compound.
Functional Groups In hydrocarbons alkanes (no functional groups) alkenes (contain C=C) alkynes (contain C ≡ C) aromatics (contain an aromatic ring, the most common of which is the benzene ring) Two representations of a benzene ring…it is NOT classified as an alkene!
Functional Groups In compounds containing N amines (RNH 2, RNHR’, RNR’R”) amides (RCONH 2, RCONHR’, RCONR’R”) nitriles (R-C ≡ N) In compounds containing X alkyl halides or haloalkanes X=halogen
Functional Groups-Alcohols (R- OH) and Ethers (R-O-R’)
Functional Groups-Aldehydes (HC=O) and Ketones (RC=OR’) C=O is a carbonyl group. C=O on the end of the carbon chain is an aldehyde. C=O elswhere in the carbon chain is a ketone.
Functional Groups-Carboxylic Acids and Their Derivatives COOH is a carboxylic acid group. COOR is an ester. COCl is an acid chloride.
Functional Groups-Amines, Amides, and Nitriles Amides are like amines, but with an adjacent C=O. Be careful! Both amines and amides have different forms: primary (1°), secondary (2°), and tertiary (3°). Nitriles are R-CN.
Primary (1°) Amines and Amides A primary (1°) amine has one C atom (one alkyl group R) and two H atoms bonded to the N. The general formula is RNH 2. A 1° amide has one acyl group and two H atoms bonded to the N. The general formula is RCONH 2.
Secondary (2°) Amines and Amides A secondary (2°) amine has two C atoms (two alkyl groups) and one H atom bonded to the N. The general formula is RNHR’. A 2° amide has two C atoms (one in the acyl group) and one H atom bonded to the N. The general formula is RCONHR’.
Tertiary (3°) Amines and Amides A tertiary (3°) amine has three C atoms (three alkyl groups) and no H atoms bonded to the N. The general formula is RNR’R”. A 3° amide has three C atoms (one in the acyl group) and no H atoms bonded to the N. The general formula is RCONR’R”.