Because of its double bond, an alkene has fewer hydrogens than an alkane with the same number of carbons—CnH2n for an alkene versus CnH2n+2 for an alkane—and is therefore referred to as unsaturated. Ethylene, for example, has the formula C2H4, whereas ethane has…
Ethylene and propylene, the simplest alkenes, are the two most important organic chemicals produced industrially. Approximately 220 million tons of ethylene and 138 million tons of propylene are produced worldwide each year for use in the synthesis of polyethylene, polypropylene,…
Figure 7.1 Tomatoes are good for you. Their red color is due to lycopene, which has 13 double bonds. (credit: modification of work “Tomatoes” by Jeremy Keith/Flickr, CC BY 2.0) Chapter Contents 7.1 Industrial Preparation and Use of Alkenes 7.2 Calculating the Degree of…
All chemical reactions, whether in the laboratory or in living organisms, follow the same chemical rules. To understand both organic and biological chemistry, it’s necessary to know not just what occurs but also why and how chemical reactions take place. In this chapter, we’ve taken a…
It has been estimated that major pharmaceutical companies in the United States spent some $200 billion on drug research and development in 2020, while government agencies and private foundations spent another $28 billion. What does this money buy? From 1983…
Beginning in the next chapter, we’ll be seeing a lot of reactions, some that are important in laboratory chemistry yet don’t occur in nature and others that have counterparts in biological pathways. In comparing laboratory reactions with biological reactions, several…
How can we describe the carbocation formed in the first step of the reaction of ethylene with HBr? The carbocation is clearly different from the reactants, yet it isn’t a transition state and it isn’t a final product. We call…
For a reaction to take place, reactant molecules must collide and reorganization of atoms and bonds must occur. Let’s again look at the addition reaction of HBr and ethylene. As the reaction proceeds, ethylene and HBr approach each other, the…
We’ve just seen that heat is released (negative ΔH) when a bond is formed because the products are more stable and have stronger bonds than the reactants. Conversely, heat is absorbed (positive ΔH) when a bond is broken because the…
Every chemical reaction can go in either a forward or reverse direction. Reactants can go forward to products, and products can revert to reactants. As you may remember from your general chemistry course, the position of the resulting chemical equilibrium…