Secondary alcohols can be shown in text as: R2CHOH Secondary alcohols can be oxidised to ketones.
Secondary alcohols have an -OH function attached to a R2CH- group. (It can be difficult to stop the oxidation at the aldehyde stage.) Primary alcohols can be shown in text as: RCH2OH Primary alcohols can be oxidised to aldehydes and on to carboxylic acids.
Primary alcohols have an -OH function attached to an R-CH2- group. Chloro, bromo and iodo alkyl halides are often susceptible to elimination and/or nucleophilic substitution reactions. The functional group approach is 100% empirical in that it is determined by experiment and experience, and not by theory (unlike VSEPR, for example.)Ī multifunctional entity like the drug molecule morphine may have several functional groups and chiral centers:Īlkyl, and occasionally aryl (aromatic) functions are represented by the R- Methyl: CH3–Īlkyl halides consist of an alkyl group attached to a halogen: F, Cl, Br, I. Thus, the carbonyl, C=O, and hydroxy, OH, of a carboxylic acid, RCOOH, are part of a single function and are NOT "alcohol-plus-ketone":Ī Couple of Words About The Functional Group Approach The rule is that functions assume their distinct identity when separated by –CH 2– groups. Organic molecules are also named using the functional group approach: Therefore, it is only necessary to know about the chemistry of a few generic functions in order to predict the chemical behaviour of thousands of real organic chemicals. The functional group approach " works" because the properties and reaction chemistry of a particular functional group (FG) can be remarkably independent of environment. An inert hydrocarbon skeleton onto which functional groups (FGs) are attached or superimposed.Organic chemistry is dominated by the "functional group approach", where organic molecules are deemed to be constructed from: Briefly, the sequence rules rank the substituents in order of decreasing atomic number and if two or more atoms connected to the C atom are the same the second atom determines the order. The other isomer is E (for e ntgegen meaning opposite). If the two with the higher rankings are on the same side of the double bond, that isomer is Z (for the German word zusammen, which means together). The newer method ranks the substituents for each C atom according to the Cahn-Ingold-Prelog sequence rules. But it won’t work well if there were four different atoms involved. The older method uses cis- and trans- which works well for the example given above because there are two H atoms and two Cl atoms. The isomers are diasteromers according to the definition given here. These isomers are superimposable on their mirror images if no chiral centers are present. Geometric isomers are generally not optical isomers unless they also happen to have chiral centers. Geometric isomers are stereoisomers that are distinct and separate because they cannot freely rotate due to a multiple bond or a ring structure. Stereoisomers (briefly and non-optical only!)
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