REACTIVITY OF CARBON SERIES

It is also sp 2 hybridized, but there is a single electron in the unhybridized p orbital. (b) The methyl radical (♼H 3) is a radical that, like the carbocation, is trigonal planar and an electrophile. Its structure is trigonal planar, with an sp 2 hybridized carbon and a vacant p orbital. (a) The simplest carbocation is the methyl cation (CH 3 +), which has six valence electrons and is an electrophile. Thus a tertiary carbocation (R 3C +) is more stable than a primary carbocation (RCH 2 +).įigure 24.11 Transient Intermediates in Organic Reactions In contrast, alkyl groups and other species stabilize the positive charge by increasing electron density at the carbocation. (Recall that electron-deficient compounds, such as those of the group 13 elements, act as Lewis acids in inorganic reactions.) In general, when a highly electronegative atom, such as Cl, is bonded to a carbocation, it draws electrons away from the carbon and destabilizes the positive charge. (from “electron” and the Greek suffix phile, meaning “loving”), which is a species that needs electrons to complete its octet. It is an electrophile An electron-deficient species that needs electrons to complete its octet. A carbocation has only six valence electrons and is therefore electron deficient. (part (a) in Figure 24.11 'Transient Intermediates in Organic Reactions'). The most common species formed is –C +, which is called a carbocation A highly reactive species that can form when a C–H bond is cleaved, carbocations have only six valence electrons and are electrophiles. or −C − and H +, all of which are unstable and therefore highly reactive.A primary carbon is bonded to only one other carbon and a functional group, a secondary carbon is bonded to two other carbons and a functional group, and a tertiary carbon is bonded to three other carbons and a functional group.Ĭleaving a C–H bond can generate either –C + and H −, −C These carbons are designated as primary, secondary, or tertiary. Thus when a bond in a hydrocarbon is cleaved during a reaction, identifying the transient species formed, some of which are charged, allows chemists to determine the mechanism and predict the products of a reaction.Ĭhemists often find that the reactivity of a molecule is affected by the degree of substitution of a carbon that is bonded to a functional group. Nearly all chemical reactions, whether organic or inorganic, proceed because atoms or groups of atoms having a positive charge or a partial positive charge interact with atoms or groups of atoms having a negative charge or a partial negative charge. Moreover, by recognizing the common reaction mechanisms of simple organic molecules, we can understand how more complex systems react, including the much larger molecules encountered in biochemistry. In designing the synthesis of a molecule, such as a new drug, for example, chemists must be able to understand the mechanisms of intermediate reactions to maximize the yield of the desired product and minimize the occurrence of unwanted reactions.

Identifying transient intermediates enables chemists to elucidate reaction mechanisms, which often allows them to control the products of a reaction. Understanding why organic molecules react as they do requires knowing something about the structure and properties of the transient species that are generated during chemical reactions.

REACTIVITY OF CARBON SERIES

To understand the relationship between structure and reactivity for a series of related organic compounds.

Reactivity of carbon