What is the hybridization of propene


Relevance for chemistry lessons

For chemistry lessons, propene is only really important for discussing the Markovnikov rule. In contrast to ethene, the propene molecule has two primary and one secondary carbon atom. When an electrophile such as a proton is attached, two different carbenium ions can form, a primary and a secondary. Since the secondary is more stable than the primary, this also forms preferentially. Otherwise, propene does not play a special role in chemistry lessons, except perhaps when handling certain plastics.

In the petrochemical industry, however, propene is very important. After ethene, propene is the most important starting material for syntheses, at least that's what the English Wikipedia claims. The German Wikipedia entry is relatively short, so you can hardly do anything with it.

Structure and structural data

Structural data of the propene molecule

The two carbon atoms of the double bond are sp2-hybridized, while the carbon atom not involved in the double bond is sp3-hybridized. For the C = C double bond, see the entries "Ethene" and "C = C double bond".

Physical Properties

The physical properties of propene are comparable to those of ethene and are also not particularly relevant for chemistry lessons.

Chemical properties

Much more important for chemistry classes are the chemical properties of propene and alkenes in general. The most important reaction for everyday life is perhaps the combustion with oxygen, but more important for teaching is the addition of electrophilic substances to the C = C double bond. This topic is discussed in detail on the pages on electrophilic addition. In addition to the electrophilic addition, the radical addition to the C = C double bond also plays a certain role, and even plays an important role in the production of plastics (see polymerisation).

Propene is particularly interesting for the treatment of electrophilic addition because two different carbenium ions can be formed when a proton is taken up, a more stable secondary carbenium ion and a less stable primary carbenium ion. The hydrobromination (addition of HBr) therefore mainly produces 1-bromopropane and almost no 2-bromopropane. According to Markovnikov's rule, the more stable carbenium ion is always formed, i.e. if possible a secondary or even a tertiary ion. This is where radical addition comes into play because this mechanism enables the synthesis of anti-Markovnikov products.