Organic Chemistry 2

Abstract

A brief but important discussion on the concept of aromaticity.The discussion is centred around the Kekulé model of the structure of benzene in which benzene is considered a hybrid of two structures with alternating single and double bonds. The article gives in a summary form the characteristics of aromatic compounds. Rationale: The article will help you to study the major characteristics of aromatic compounds and prepare you better to attempt questions on aromaticity. African Virtual University 0 Reading #2 Complete reference: Benzene: From Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/benzene 6th September 2006 SubstitutionReactions of benzene and other Aromatic compounds(see screen capture below Abstract : The article mostly deals with the structure of benzene from Kekulé’s point of view that it is aresonance stabilized structure whose bonds are neither fully single nor double but intermediate between the two, and that all bonds lengths in benzene are equalent. The typical reactions of benzene are also highlighted in the article. Rationale: Although the article does not provide a comprehensive coverage of benzene and its reactions, it t is enough to stimulate further reading for a more detailed understanding of arenes and aromaticity. The article mostly deals with the structure of benzene from Kekulé’s point of view that it is aresonance stabilized structure whose bonds are neither fully single nor double but intermediate between the two, and that all bonds lengths in benzene are equalent. The typical reactions of benzene are also highlighted in the article. Rationale: Although the article does not provide a comprehensive coverage of benzene and its reactions, it t is enough to stimulate further reading for a more detailed understanding of arenes and aromaticity. African Virtual University Reading #3 Complete reference : From Wikipedia, the free encyclopedia Pyrrole: http://en.wikipedia.org/wiki/pyrrole Furan: http://en.wikipedia.org/wiki/furan Thiophene: http://en.wikipedia.org/wiki/thiophene Pyridine : http://en.wikipedia.org/wiki/pyridine Abstract :The links above give free wikipedia articles on pyrrole, furan, thiophene and pyridine, discussing their chemistry, physical properties, and uses. There are a number of search engines that will lead you to many other important topics on these heterocyclic molecules. You are advised to follow these links to read more on the chemistry of these important heterocyclics Rationale: Pyrole, furan and thiophene are three important aromatic heterocyclics that are found in a number of natural products. These are aromatic systems that have reactions similar to benzene in that they undergo substitution reactions. It is therefore important that you learn of their chemistry. You will realize that furan is more reactive than benzene in that it even undergoes Diels-Alder reaction. Going throug these articles you will learn quite a good amount of chemistry of other heterocyclic compounds and also follow other suggested web links..The links above give free wikipedia articles on pyrrole, furan, thiophene and pyridine, discussing their chemistry, physical properties, and uses. There are a number of search engines that will lead you to many other important topics on these heterocyclic molecules. You are advised to follow these links to read more on the chemistry of these important heterocyclics Rationale: Pyrole, furan and thiophene are three important aromatic heterocyclics that are found in a number of natural products. These are aromatic systems that have reactions similar to benzene in that they undergo substitution reactions. It is therefore important that you learn of their chemistry. You will realize that furan is more reactive than benzene in that it even undergoes Diels-Alder reaction. Going throug these articles you will learn quite a good amount of chemistry of other heterocyclic compounds and also follow other suggested web links.. African Virtual University XII. Compulsory Resources Resource #1 Benzene: movie file Abstract : The film shows the benzene molecular structure and tries to answer the important question: what is it about benzene that makes it behave so much differently from other unsaturated compounds. We will see from the film that the answer is a simple one-the low reactivity of benzene and its derivatives reflects their special stability. Kekulé was wrong. It remained for 20 century electronic theories of bonding to provide insight into why benzene is so stable Rationale: It is important that you see this movie because it demonstrates concepts in more intuitable forms which are rather abstract and normally difficult to understand. Without the movie you would find it difficult to visualize the p-orbitals with their electrons being delocalized within the six carbon atoms. Resource #2 Benzene 3d: movie file Abstract : This interesting movie shows the structure of benzene in three dimensions. The movie depicts the fully symmetrical benzene molecule. It rotates the molecule to show its three dimensions and its planar structure as well.l. At one point two of the six carbons are shown in colour, this does not in any way signify that the two are different, it just shows that all the six carbons are equally bonded to the two other carbons and to hydrogen. Probably the two carbons are shown in colour so that one can realize that there has been a rotation of the molecule otherwise it would be difficult to make any distinction. Rationale: The movie depicts the three dimensional nature of benzene, and so it assist you to get a better understanding of the structure of benzene, its bonding and its planar nature as well as its symmetry. African Virtual University