A key reaction of aromatic compounds is electrophilic aromatic substitution, where a C-H bond is broken and a new C-E bond (E being an electrophilic atom such as Cl, Br, N...) is formed. When we covered the reactions of alkenes a while back - a lot of reactions! - we saw that the vast … [Read more...]
More On 1,2 and 1,4 Additions To Dienes
In the last post we covered 1,2 and 1,4 additions to dienes, specifically the addition of strong acid (e.g. HCl or HBr) to dienes. To recap: In Org 1 we learned that addition of HCl and HBr to normal, isolated alkenes (such as 1-butene) just gives one product - the Markvonikoff product … [Read more...]
Synthesis (2) – Reactions of Alkanes
In this post we're going to begin building our reaction map, starting with the simplest organic compounds of all: alkanes.*We've only learned one synthetically important class of alkane reaction: free-radical halogenation. [Combustion is also technically a reaction of alkanes, but producing CO2 and … [Read more...]
Halogenation At Tiffany’s
As we discussed in the last post on radicals, bromine radicals are considerably more selective than chlorine radicals in the halogenation of alkanes. For example, a hydrocarbon exposed to Br2 in the presence of heat or light (for initiation) can selectively be brominated at the tertiary C–H bond, … [Read more...]
Selectivity In Free Radical Reactions
In the last post we showed some examples of how different isomers might be formed in free-radical halogenation of alkanes. And I left off with a question. If we performed a free-radical chlorination on propane with 1 equiv Cl2 under normal conditions (25°C, initiated with light), what be the … [Read more...]
Isomers From Free Radical Reactions
Last time we covered a comparatively simple reaction: free-radical chlorination of methane to (CH4) to give chloromethane (CH3Cl) and saw that the reaction proceeds through three stages - initiation (where free radicals are created), propagation (the main "product-forming" step of the chain … [Read more...]
Free Radical Reactions
With rare exceptions, until now every reaction we've discussed (acid-base, substitution, elimination, addition) has involved the formation of bonds between an electron pair donor (Lewis base) and an electron pair acceptor (Lewis acid) or the breakage of bonds to generate the same [this is called … [Read more...]
Alkyne Addition Reactions: The 3-Membered Ring Pathway
Last time we discussed the similarities (and differences) between the carbocation pathway for alkenes and alkynes. In this post, we'll do the same for the "3-membered ring pathway". If you'll recall from the series of posts on alkenes, alkenes react with certain electrophiles (such as halogens, … [Read more...]