Draw the first 4 member of alkane serie. Are saturated aliphatic hydrocarbons

Transcription

1 Draw the first 4 member of alkane serie Are saturated aliphatic hydrocarbons

2 Each molecule differs from the next by the structural unit CH 2 This is a homologous series when each member increases by the same structural unit The general formula for an alkane is C n H 2n+2

3 Using the general formula for an alkane, derive the following for specific alkanes. A) number of H atoms present when 8 carbon atoms are present. B) Number of C atoms present when 10 hydrogen atoms are present. C) Number of C atoms present when 41 total atoms are present. D) The total number of covalent bonds present in the molecule when 7 carbon atoms are present.

4 Further practice problems Worksheet 1 problems number 13-16

5 Non-polar Thus are soluble in non-polar solvents and not soluble in polar solvents Remember: Like Dissolves Like Have relatively low boiling points Boiling points, melting points and densities of straight-chain alkanes increase with increasing chain length

6 The strength of London dispersion forces between molecules increase with increasing length of carbon chain Review: your notes or click on the following link: due.edu/gchelp/liquid s/disperse.html

7 Carbons bonded together in long, continuous, chain-like structures Also called unbranched alkanes Ex.

8 All alkanes end with the suffix ane Root of the name is based on the number of carbons in the chain Examples: Methane 1 Carbon Ethane 2 Carbons

9 # of C Atoms Root IUPAC name Condensed Structural Formula 1 Meth- Methane CH 4 2 Eth- Ethane CH 3 CH 3 3 Prop- Prapane CH 3 CH 2 CH 3 4 But- Butane 5 Pent- 6 Hex- 7 Hept- 8 Oct- 9 Non- 10 Dec-

10 # of C Atoms Root IUPAC name Condensed Structural Formula 1 Meth- Methane CH 4 2 Eth- Ethane CH 3 CH 3 3 Prop- Prapane CH 3 CH 2 CH 3 4 But- Butane CH 3 CH 2 CH 2 CH 3 5 Pent- Pentane CH 3 CH 2 CH 2 CH 2 CH 3 6 Hex- Hexane CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 7 Hept- Heptane CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 8 Oct- Octane CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 9 Non- Nonane CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 10 Dec- Decane CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3

11 What is the name of this compound? CH 3 CH 2 CH 2 CH 2 CH 3

12 Ex. Branches are sometimes called side chains. The side chains originating in alkanes are called alkyl groups. What is the general formula for branched-chain alkanes?

13 We name these based on their parent chain (longest chain) and side chains Naming follows the general formula: Prefix + Root + Suffix

14 Root: the longest continuous chain in the hydrocarbon (the parent chain) Suffix: for all alkanes, the suffix is ane Prefix: the branches attached to the parent chain

15 Alkyl groups are alkanes with one less hydrogen Naming: Root (# of C in a side chain) + suffix - yl Eg. Alkane: Propane CH 3 CH 2 CH 3 Alkyl Group: Propyl CH 3 CH 2 CH 2

16 Numbers of Carbon IUPAC Root IUPAC name of the alkyl group Condensed structural formula 1 Meth- Methyl CH 3 2 Eth- Ethyl 3 Prop- 4

17 Numbers of Carbon IUPAC Root IUPAC name of the alkyl group Condensed structural formula 1 Meth- Methyl CH 3 2 Eth- Ethyl CH 3 CH 2 3 Prop- Propyl CH 3 CH 2 CH 2 4 But- Butyl CH 3 CH 2 CH 2 CH 2

18 Prefixes are numbered based on their position along the parent chain these numbers are always given so that the branch has the lowest possible number! When putting prefixes together in the name: Prefixes are put in alphabetical order If there are two or more of the same type of branch, use multiplying prefixes (di, tri etc) Position numbers are put in ascending order Hyphens separate numbers from words Commas separate numbers

19 1. Locate the parent alkane (this is the longest chain) and name it (root and suffix -ane) 2. Assign position numbers: number the parent chain starting with the end closest to the branch 3. Identify prefixes: name the branches 4. Put it together! Prefix + Root + Suffix

20 CH 3 CH 2 CH 2 CH CH 3 І CH 3 CH 3 CH CH 2 CH 2 CH 3 І CH 2 CH 3

21 CH 3 CH CH 2 CH CH 3 І І CH 3 CH 3 CH 3 І CH 3 CH 2 C CH 2 CH 3 І CH 3

22 CH 3 CH 2 CH CH CH 3 І І CH 2 CH 3 І CH 3 CH 3 CH 2 CH CH CH CH 2 CH 2 CH 3 І І І CH 2 CH 2 CH 2 І І І CH 3 CH 2 CH 2 І І CH 3 CH 3

23 Naming alkanes Worksheet 1 problems number Worksheet 2 problem number 1

24 Draw a condensed structural formula for 2,3-dimethylhexane Step 1: Identify the root and the suffix of the name. Hexane. The name tells you that this hydrocarbon contains 6 carbon atoms (root: hex-) and it contains only single carbon-carbon bonds (suffix: -ane).

25 Step 2: Draw the skeletal structure for hexane (only carbons, no hydrogens). Leave spaces beside each carbon on the main chain to write the number of hydrogen atoms later.

26 Step 3: Number the carbons in the main chain. Step 4: Complete the carbon skeleton by attaching alkyl groups as they are specified in the name. Add one methyl group to carbon 2 and second to carbon 3.

27 Step 5: Add hydrogen atoms to the carbon skeleton so that each carbon atom has four bonds. CH 3 CH CH CH 2 CH 3 І І CH 3 CH 3

28 Draw a condensed structural formula for: a) 3-ethyl-2-methylheptane b) 4,5-diethyl-3,4,5-trimethyloctane.

29 3-ethyl-2-methylheptane CH 2 CH 3 І CH 3 CH CH CH 2 CH 2 CH 2 CH 3 І CH 3 4,5-diethyl-3,4,5-trimethyloctane CH 3 CH 3 І І CH 2 CH 2 І І CH 3 CH 2 CH C C CH 2 CH 2 CH 3 І І І CH 3 CH 3 CH 3

30 Drawing alkanes: Worksheet 1 problem 20 Worksheet 2 problems 2-7

31 Worksheet 1 problems number Worksheet 1 problems number Worksheet 2 problem number 1 Worksheet 1 problem 20 Worksheet 2 problems 2-7