karbokatioonit

Karbokatioonit, or carbocations, are reactive intermediates in organic chemistry characterized by a positively charged carbon atom. This positive charge arises from the carbon atom having only three valence electrons and an incomplete octet, making it electron-deficient. They are typically formed when a bond to a leaving group breaks heterolytically, with the leaving group taking both electrons from the bond. The stability of carbocations generally follows the order tertiary > secondary > primary > methyl, due to the inductive effect and hyperconjugation of alkyl groups, which help to stabilize the positive charge.

Karbokatioonit play a crucial role in a variety of organic reactions, including nucleophilic substitution (SN1) and elimination (E1) reactions. In these reactions, the carbocation intermediate is formed, which is then attacked by a nucleophile or loses a proton to form an alkene. Their high reactivity means they are transient species, usually existing for only a very short time before reacting further. Due to their electron-deficient nature, carbocations are strong electrophiles and readily react with nucleophiles. Rearrangements, such as hydride or alkyl shifts, can occur to form more stable carbocations.