Alkanes and alkenes

What is the reaction mechanism for the addition of bromine to an alkene? Does the mechanism change if the solvent is changed? Do the products of the reaction depend on the solvent used? Can isomeric products be formed in the addition of bromine to an alkene?

Alkanes and alkenes

Free radical thermal cracking to give shorter alkanes and ionic catalytic cracking to give shorter alkanes and alkenes.

Revision notes include full diagrams and explanation of the mechanisms of alkanes and the 'molecular' equation and reaction conditions and other con-current reaction pathways and products are also explained. Most reactions require some energy input to initiate a reaction e.

A combination of two main reasons account for this lack of reactivity compared to most other homologous groups of organic molecules. The single covalent C-C bond enthalpy kJ mol-1 and C-H bond enthalpy kJ mol-1 bonds are very strong so bond fission does not readily happen.

The carbon atom radius is small, giving a short and strong bond with other small atoms. This is an important organic synthesis process to manufacture organochlorine and organobromine compounds.

What is the reaction mechanism of chlorine reacting with alkanes like methane and ethane etc. Under the influence of high temperature heat or uv light, alkanes will react with chlorine or bromine via a free radical substitution reaction mechanism.

The basic reaction is: The reaction is initiated by higher temperatures e. If other hydrogen atoms are available on the original hydrocarbon then polysubstituted chloroalkanes will be formed e. Homolytic bond fission means the original pair of Cl-Cl bonding electrons is split between the two radicals formed.

Step 1 illustrates how to use half-arrows to show a homolytic bond fission step Not all exam boards demand half-arrows, so the 'style' is deliberately varied in the diagram.

The red dots represent the unpaired electron on the free radical and the half-arrows show the individual electron 'shifts'. The breaking of the Cl-Cl bond in the chlorine molecules begins the reaction because it is the weakest of the bonds of any reactant molecule involved.

Free radicals are highly reactive species with an unpaired electron and tend to form a new bond as soon as is possible by e. Steps 2 and 3 are chain propagation steps, because as well as producing one of the reaction products, a new free radical is also produced to continue the reaction, which is why such reactions are sometimes referred to as 'chain reactions'.

Step 2 Illustrates how to use half-arrows in a chain propagation step where an attacking radical abstracts an atom from a stable and complete molecule and another radical is formed in the process. Steps 4 to 6 are three possible chain termination steps which remove the highly reactive free radicals as two unpaired electrons form a new bond, in this case single C-C covalent bonds.

Step 5 illustrates how to use half-arrows to indicate a termination step where the unpaired electrons of the two radicals pair up to form a new bond, in this case a C-Cl bond. When the alkane is methane, traces of ethane are found in the final mixture of products.

This provides evidence for a mechanism involving a methyl radical. It would be formed from combining two methyl radicals:The electrophilic addition of bromine to alkene (non-aqueous media) Alkenes are reactive molecules, particularly when compared to alkanes.; They are reactive towards electron pair accepting electrophiles because of the high density of negative electron charge associated with the ∏ pi electrons of the double bond.

Tweet. This site has many resources that are useful for students and teachers of Chemistry 11 in BC as well as any introductory high school chemistry course in the US or anywhere else in the world. n = 2 & 4 butter **unsaturated fats (alkenes- hydrogen can add on C==C) n = 18 peanut oil.

n = 10 coconut oil. IV. Nucleic Acids DNA deoxyribonucleic acid (molecular masses = several billion g/mol). Alkenes and alkynes can be transformed into almost any other functional group you can name! We will review their nomenclature, and also learn about the vast possibility of reactions using alkenes and alkynes as starting materials.

Chemistry of Natural Substances – Organic Chemistry Worksheets 1 Worksheets for Organic Chemistry Worksheet 1 Alkanes Question 1. Provide IUPAC names for the following structures. The physical properties of alkenes and alkanes are similar.

They are colourless, nonpolar, combustable, and almost odorless. Reduction of alkynes is a useful method for the stereoselective synthesis of disubstituted alkenes.

Alkanes and alkenes

If the cis-alkene is desired.

Alkenes and alkynes | Organic chemistry | Science | Khan Academy