Intro to organics Flashcards
what is organic chemistry
study of compounds containing carbon
what is molecular formula
actual number of atoms in each element in one molecule
empirical formula
simplest ratio of atoms of each element in a compound
general formula
number of atoms of each element when carbon is n
alkane = CnH2n+2
alkene = CnH2n
structural formula
shows how atoms are joined together in a molecule
displayed formula
shows all the bonds in a molecule
skeletal formula
uses lines to represent bonds
the peaks are the carbon atoms
H-H bonds not usually shown
functional group
atom/group of atoms responsible for chemical reactions of a molecule
homologous series
family of compounds that have the same general formula and chemical properties
rules of nomenclature
Systematic nomenclature can be used to name organic compounds and therefore make it easier to refer to them
The alkanes provide the basis of the naming system and the stem of each name indicates how many carbon atoms are in the longest chain in one molecule of the compound
If there are any side-chains or functional groups present, then the position of these groups is indicated by numbering the carbon atoms in the longest chain starting at the end that gives the lowest possible numbers in the name
The hydrocarbon side-chain is shown in brackets in the structural formula
CH3CH(CH3)CH2CH3
The side-chain is named by adding ‘-yl’ to the normal alkane stem
This type of group is called an alkyl group
If there are more than one of the same alkyl side-chain or functional groups, di- (for two), tri- (for three) or tetra- (for four) is added in front of its name
The adjacent numbers have a comma between them
Numbers are separated from words by a hyphen
If there is more than one type of alkyl side-chain, they are listed in alphabetic order eg 3-bromo-2-fluoro-2-methlypentane
what rule to watch out for in alkene nomenclature
the bond position comes before the added molecules
so start naming from the double bond- class double bond as one
rules of skeletal formula
carbon represented by end points of lines
dont draw hydrogen UNLESS they are in a separate functional group eg OH
double bonds represented by a double line adjacent to the position of carbon that it is on
if halogen present then write the actual symbol alongside the line
what are some of the functional groups
alkenes- c=c-ene
alkane c-c -ane
alcohol c-OH -suffix -ol
-prefix hydroxy-
haloalkanes c-halogen prefix chloro,bromo,iodo
alehydes c=o-h suffix al
ketones c=o suffix -one
prefix oxo-
carboxylic acid c=o-oh -oic acid
nitriles c triple bond n nitrile
amines c-NH2 suffix -amine
prefix amino-
what is isomerism
Isomerism is when more than one compounds have the same chemical formula but different chemical structures.
what are the 3 types of organic molecules
Straight, branched and cyclic organic molecules are also called aliphatic compounds as long as they do not contain a benzene ring
Straight-chain
Straight-chain organic molecules are those in which the carbon atoms are connected to each other in one continuous chain
Branched
Branched organic molecules have side groups attached to the main chain of carbon atoms
Cyclic
Cyclic organic molecules are those in which the carbon atoms are connected to each other in a ring shape
what are structural isomers
Structural isomers are compounds that have the same molecular formula but different structural formulae
what are the 3 types of structural isomer
There are three different types of structural isomerism:
Chain isomerism
Positional isomerism
Functional group isomerism
what is chain isomerism
Chain isomerism
Chain isomerism is when compounds have the same molecular formula, but their longest hydrocarbon chain is not the same
This is caused by branching
E.g. pentane and 2,2-dimethylpropane
what is positional isomerism
Positional isomerism
Positional isomers arise from differences in the position of a functional group in each isomer
The functional group can be located on different carbons
For example, butan-1-ol and butan-2-ol
what is functional isomerism
Functional group isomerism
When different functional groups result in the same molecular formula, functional group isomers arise
The isomers have very different chemical properties as they have different functional groups
For example, butanol and ethoxyethane
how do you deduce a structural isomer
Step 1: Draw the structural formula of the compound
Step 2: Determine whether it is a stereo or structural isomer
Step 3: Determine whether it is a functional group, chain or positional isomerism
Draw the longest chain described in the name of the compound. Refer back to chapter 72 if you do not remember the different stems used to name carbon compounds of different chain lengths.
Number the carbons. The main chain will be numbered in such a way the substituents are given the lowest number as possible.
Add the functional groups to the carbons described in the name. The carbon to which the functional group is bonded to will be indicated with a number in the name.
How many isomers are there of the compound with molecular formula C4H10?
Step 1: Draw the structural formula of the compound
Step 2: Determine whether it is a stereo or structural isomer.
There is no restricted bond rotation around the C-C bond so it is structural isomerism
Step 3: Determine whether it is a functional group, chain or positional isomerism
Functional group? No, as there are no functional groups
Positional? No, as there are no functional groups which can be positioned on different carbon atoms
Chain? Yes!
How many isomers are there of dibromopropane, C3H6Br2?
Step 1: Draw the structural formula of the compound
Step 2: Determine whether it is a stereo or structural isomer
There is no restricted bond rotation around the C-C bond, so it is structural isomerism
Step 3: Determine whether it is a functional group, chain or positional isomerism
Functional group? No, as Br is the only functional group possible
Chain? No, as the longest chain can only be 3
Positional? Yes, as the two bromine atoms can be bonded to different carbon atom
that means move the functional group to all its possible positions
