Organic Chemistry Concepts PDF

Organic chemistry: key concepts Understand the importance of carbon compounds. Appreciate some natural products. Understand the bonding and structure of carbon. Name and draw simple organic compounds. Identify functional groups. 1 Today...

Organic chemistry: key concepts Understand the importance of carbon compounds. Appreciate some natural products. Understand the bonding and structure of carbon. Name and draw simple organic compounds. Identify functional groups. 1 Today we will learn about: What organic chemistry is. Bonding in organic molecules. Drawing organic molecules. 2 What is organic chemistry? Organic chemistry is the study of ______________________. These molecules are all around us: Estimate of ~20,000,000 organic compounds are known – billions possible – being discovered constantly. For information only 3  For information only Your body is already an adept organic chemist! Just moving around your body does organic chemistry – reactions in your muscles turn _____ and ______ into _______: Average ATP concentration is about 0.1 mol/L in humans and lasts generally no more than about 60 s. We turn over 50-70 kg of it per day. Your retina in your eye uses an organic molecule to convert _____________ into nerve impulses: 4  Your body is already an adept organic chemist! As you understand this, your brain cells are being bridged by _______________, passing nerve impulses around your brain: Many roles, including Involved in controlling with memory, attention, mood (and many other and learning. things!). To make our minds as good at organic chemistry as our bodies we need to build a good understanding of the basics! For information only 5 Organic chemistry – the beginning Organic chemistry started as the ______________, which was thought to be different from chemistry in the laboratory. Freidrich Wöhler (1800–1882) completed the first synthesis of a naturally-occurring organic compound in 1828. This showed that naturally occurring compounds can be accessed from inorganic precursors, and started modern organic chemistry. For information only 6 Organic molecules can be synthesised Organic chemists _________ molecules containing carbon and look at their properties. Here is a laboratory preparation you have done: The product of this reaction is ……………… For information only 7 Organic compounds are prepared by chemical synthesis Naturally-occurring compounds of astonishing complexity have been prepared in the laboratory by synthetic organic chemists: For information only 8 Bonding in carbon-based molecules Carbon has __________________ and can _______________ ______. The bonds are _________ – electrons shared between atoms. Compare to: Nitrogen: ____ bonds. Oxygen: ____ bonds. Fluorine: ____ bond. … allows structural diversity – many millions of organic compounds! 9 What makes carbon special? Stability: carbon forms strong bonds to other carbon atoms. E.g. in diamond: Oxidation of carbon is slow… (need high temperature to start) 10 Revision from previous lectures: molecular shapes You must be able to draw carbon compounds/organic molecules correctly! 11 How do carbon atoms bond together? Recall prior lectures… Carbon likes to bond to four atoms (has four ______________). The bonds will be _________ – electrons shared between atoms. From Valence Shell Electron Pair Repulsion (VSEPR), carbon will have a tetrahedral geometry. 12 Drawing carbon-based molecules to show their shapes 13 Carbon-carbon bonding: a summary These compounds contain only carbon and hydrogen atoms. They are called hydrocarbons. 14 Carbon-carbon single bonds give alkanes Alkanes are the simplest organic molecules. Alkanes have a formula CnH(2n+2) The carbon atoms of alkanes all have a ___________________. 15 Name alkanes based on the number of carbons Names are less meaningful – memorise prefix Named after Greek numbers – easy to learn 16 Alkane examples 17 Ethane – two-carbon alkane Structural formula: Extended formula: Condensed formula: Line bond drawing: 18 Can carbon atoms bond to each other twice? Yes! When this happens, the compound is called an ________. Each carbon still forms ___________. H Alkanes Alkenes C CH3 H 3C C From VSEPR, the geometry is now trigonal planar. H All bond angles ≈120°. More on this in CHEM112. 19 Can there be more than one carbon-carbon double bond? Yes! These are e.g. ______ and ______. E.g. butadiene and butatriene: 20 Can carbon atoms bond to each other three times? Yes! These are ________. Ethyne (acetylene) is a gas that burns at 3200 °C. H C C H Used in combination with oxygen gas for oxy- acetylene welding. From VSEPR, there are two sets of repelling H C C H electrons, giving a ______________: the bond angles are 180°. 21 How do we draw these things then? Organic chemists are busy and have worked out a way to keep writing to a minimum: We use pictures to show molecules. These are all the same molecule: The last diagram is the easiest to read and fastest to write! 22 How do we draw these things then? Line-bond drawings show the carbon skeleton. Other atoms are represented with their elemental symbol. Drawn like a zig-zag, carbon atoms are at the end of each straight line. There is a carbon at each end and each bend! Double bonds are shown as two parallel lines and triple bonds are three parallel lines. 23 How do we draw these things then? Note that we leave the hydrogen atoms off. We know that carbon always forms four bonds, so any spare bonds will be connected to hydrogen. We leave the hydrogens on atoms other than carbon. Here is the structure of ethanol. 24 How do we draw these things then? Some hints…. 1. Don’t forget atoms in a straight chain are drawn in a zig-zag 2. Draw double bonds as far away from other atoms are possible. 3. Doesn’t matter which direction you start. 25 Carbon compounds can exist as isomers These are structures with the same formula, but different ways of being put together. We will come back to this later on, but… How many molecules are there with five carbons and only single bonds? 26 Today we have learnt… Why we study organic chemistry. Why carbon is special. How carbon atoms bond together. What alkanes, alkenes, and alkynes are. How to draw organic molecules. Isomers are molecules which have the same chemical formulae but different structural arrangements of their atoms. 27