Chemistry Chapter 12
ALKANE
"SATURATED": single bonds only
cis and trans isomers
--ARE DIFFERENT COMPOUNDS WITH DIFFERENT PHYSICAL PROPERTIES AND CHEMICAL PROPERTIES.
In identifying if a pair of formulas are structural isomers or the same molecule:
--Add up number of C atoms and H atoms to make sure they give the same molecular formula. --How long is the longest chain? --Are the substituents/branches or drawn up/bent ends all part of the same chain of carbons? If so, they are NOT structural isomers. They are the same molecule. --If there is a DIFFERENT ORDER TO THE BONDING or the length of the longest chain is different, then they are structural isomers.
Methylene
--CH2==>condensed formula
methyl
--CH3=>condensed formula
4-methyl-2-pentene
--pent indicates 5 carbons in longest chain --"ene" indicates the presence of at least one double C-C bond. --2 represents the PLACEMENT of the first DOUBLE CARBON BOND (necessary since there are more than 3 bonds) --methyl indicates the substituent and its location.
trans-2-butene
-CH3 groups attached on opposite sides of the double bond.
cis-2-butene
-CH3 groups attached on the same side of the double bond
Naming cycloalkenes
1. IF NO SUBSTITUENT, DOUBLE BOND DOES NOT NEED A NUMBER 2. If SUBSTITUENT: --CARBONS in the double bond are numbered as 1 and 2. --Ring is numbered in the direction that will give the lower number to the substituent.
EXAMPLE OF NAMING ALKENE CH3 CH3-CH-CH=CH-CH3 5 4 3 2 1 4-methyl-2-pentene
1. Longest chain that contains DOUBLE BOND (5 C in the chain and has double bond so replace 'ane" with 'ene'--pentene) 2. Number Cs starting from nearest double bond. 3. PLACE THE NUMBER OF THE FIRST CARBON BOND in the double bond in FRONT OF THE ALKENE NAME so long as there are more than THREE Cs) 4. Give location and name for each substituent (alphabetical) as a prefix to the alkene name.
Example of NAMING ALKYNE CH3-CH2-C=_C-CH2-CH3 1 2 3 4 5 6 3-hexYNE
1. NAME THE LONGEST CARBON CHAIN THAT CONTAINS THE TRIPLE BOND. 2. Number the carbon chain starting from the end nearer the triple bond. Place the NUMBER OF THE FIRST CARBON IN THE TRIPLE BOND IN FRONT OF THE ALKYNE NAME. 3. Give the location and name for each substituent (ALPHABETICAL ORDER) as a PREFIX to the alkyne name.
5 or more Carbon atom alkanes prefixes:
5--Pent 6--Hex 7--Hep 8--Oct 9--Non 10--Dec
TRANS isomer
ATOMS BONDED TO DOUBLE CARBON ATOMS (in alkene) are on OPPOSITE SIDES of the double bond. GENERALLY ARE MORE STABLE than CIS counterparts because the groups that are bigger than hydrogen atoms on the double bond are FARTHER APART. trans="across"
CIS isomers
ATOMS BONDED TO DOUBLE CARBON ATOMS (in alkene) are on the SOME SIDE of the double bond. GENERALLY ARE LESS STABLE than TRANS counterparts because the groups that are bigger than hydrogen atoms on the double bond are CLOSER TOGETHER. cis="on this side"
BRANCHED ALKANE
Alkane with at least one branch
SUBSTITUENT/BRANCH
Atoms arranged in a side group attached to a carbon chain when an alkane has four or more carbon atoms.
EXAMPLES OF BUTANE CONFORMATIONS
CH3-CH2-CH2-CH3 CH3 ! CH2--CH2 CH2 ! ! ! CH3 CH3 CH2 ! CH3
ALKENE
Contains ONE OR MORE CARBON-CARBON double bond. Double bond forms when adjacent carbon atoms SHARE TWO PAIRS OF VALENCE ELECTRONs.
CYCLOALKENES
Cyclic alkenes names as cycloalkanes. Have double bond within a ring structure.
CONFORMATIONS of ALKANES
DIFFERENT ARRANGEMENTS of alkanes that occur during the rotation about a single bond. Because alkanes have only single carbon-carbon bonds, groups attached to each C are NOT in fixed positions and can rotate freely about the bond connecting the carbon atoms (like toy car wheels) As groups turn around the single bond, the carbon chain in the condensed structural formulas may appear at different angles but each represents the same compound with four carbon atoms.
Cyclobutene
Doesn't need a number because doesn't have substituents. "ENE" indicated it has a double bond Cyclo indicates cycloalkene cyclo indicates it has 2 FEWER H atoms. "but" indicates FOUR carbons so SQUARE.
2-Methylcyclopentene
Double bond so counting started at 1st carbon of double bond. Methyl is at the 2nd Carbon in double bond.
CONDENSED STRUCTURAL FORMULAS ALKANES
Each Carbon atom and its attached hydrogen atoms are written as a group. A subscript indicates the NUMBER OF HYDROGEN atoms bonded to each CARBON ATOM.
Carbon atom ALWAYS FORMS ________ covalent bonds.
FOUR
CYCLOALKANES
Hydrocarbon cyclic or ring structures TWO FEWER HYDROGEN ATOMS than the corresponding alkanes. -CnH2n --SIMPLEST cycloalkane=CYCLOPROPANE (C3H6) has a ring of THREE CARBON ATOMS bonded to SIX HYDROGEN ATOMS. --Most often drawn using their LINE-ANGLE STRUCTURAL FORMULAS.
SATURATED HYDROCARBON
Hydrocarbon in which ALL THE BONDS IN THE MOLECULE ARE SINGLE BONDS.
IUPAC system
International Union of Pure and Applied Chemistry's system to name ORGANIC COMPOUNDS.
SIMPLEST HYDROCARBON
METHANE (CH4) --Carbon atom forms an OCTET by sharing its four valence electrons with FOUR HYDROGEN ATOMS.
chlorobenzene
ONLY ONE SUBSTITUENT so the RING IS NOT NUMBERED.
PREFIXES USED TO SHOW POSITION OF SUBSTITUENTS IN NAMING AROMATICS/BENZENES
ORTHO (o)--indicates a 1,2-arrangement META (m)--indicates 1,3 arrangement PARA (p)--indicates 1,4 arrangement
ALKENE DOUBLE BONDS
Rigid NO ROTATION around the double bond. Atoms or groups are attached to the carbon atoms in the double bond on one side the the other.
ALKYNE
TRIBPLE BOND forms when TWO CARBON ATOMS share THREE PAIRS of valence electrons. Two carbon atoms of the triple bond are each attached to ONE hydrogen atom.
p-dichlorobenzene
TWO SUBSITUENTS; RING NUMBERED. Chloros are in 1,4 arrangement-PARA (p)
o-dichlorobenzene
TWO SUBSTITUENTS SO RING IS NUMBERED. Chloros are in a 1,2 arrangement so that is an ORTHO (0) arrangement.
m=dichlorobenzene
TWO SUBSTITUENTS SO RING NUMBERED. Chloros are in 1,3 arrangements=META (m)
PENTANE (C5H12) STRUCTURAL ISOMER
Three different structural isomers for pentane.
NAMING ALKENES and ALKYNES
Use ALKANE name with same number of CARBON ATOMS/prefix, replacing "ANE" with "ENE" for an ALKENE and "YNE" for ALKYNE. 1. Name the longest carbon chain that contains the double or triple bond. 2. Number the carbon chain starting from the end nearer the double or triple bond. 3. Give the location and name of reach substituent (alphabetical order) as the prefix to the alkene or alkyne name.
CIS-TRANS ISOMERS WITH SAME AND DIFFERENT ATOMS ex. 1,1-dichloropropene NO cis or trans
When the carbon atoms in the double bond of an alkene are attached to two DIFFERENT atoms or groups of atoms, an alkene can have CIS-TRANS isomers. Take this into consideration when drawing. When alkene has identical groups on the SAME carbon atom of the double bond, Cis and TRANS ISOMERS canNOT be drawn. ex. 1,1-Dichloropropene (has TWO Cl on one C...no trans or cis.)
STRUCTURAL ISOMER
When two compounds have the SAME MOLECULAR FORMULA BUT DIFFERENT ARRANGEMENTS OF ATOMS. Have the same NUMBER and TYPE of ATOMS but are BONDED in a DIFFERENT ORDER. --SAME MOLECULAR FORMULA --DIFFERENT ARRANGEMENTS OF ATOMS
3-hexYNE
YNE indicates there is at least one triple bond. "hex" indicates there are 6 Carbons in the longest chain that contains the triple bond. 3 indicates the POSITION of the FIRST CARBON in the triple bond.
HYDROCARBONS: alkANE: alkENE: alkYNE:
all Single C-C bond (propane...) at least 1 Double C-C bond (propene, ) at least 1 Triple C-C bond (propyne,)
cyclobutane
cyclo=has 2 less H atoms BUTANE=C4H10 cyclobutane=C4H8
