functionalization

Examples of functionalization in the following topics:

• Functional Groups

  • Functional groups are atoms or small groups of atoms (two to four) that exhibit a characteristic reactivity when treated with certain reagents.
  • A particular functional group will almost always display its characteristic chemical behavior when it is present in a compound.
  • Because of their importance in understanding organic chemistry, functional groups have characteristic names that often carry over in the naming of individual compounds incorporating specific groups.
  • In the following table the atoms of each functional group are colored red and the characteristic IUPAC nomenclature suffix that denotes some (but not all) functional groups is also colored.

• Functional Groups

  • Functional groups also play an important part in organic compound nomenclature; combining the names of the functional groups with the names of the parent alkanes provides a way to distinguish compounds.
  • Functionalization refers to the addition of functional groups to a compound by chemical synthesis.
  • In materials science, functionalization is employed to achieve desired surface properties; functional groups can also be used to covalently link functional molecules to the surfaces of chemical devices.
  • Alcohols are a common functional group (-OH).
  • Define the term "functional group" as it applies to organic molecules

• By Functional Group

  • Functional groups are atoms or small groups of atoms (usually two to four) that exhibit a characteristic reactivity when treated with certain reagents.
  • A particular functional group will almost always display its characteristic chemical behavior when it is present in a compound.
  • Because of this, the discussion of organic reactions is often organized according to functional groups.
  • The following table summarizes the general chemical behavior of the common functional groups.
  • For reference, the alkanes provide a background of behavior in the absence of more localized functional groups.

• Related Carbonyl Derivatives

  • Other functional group combinations with the carbonyl group can be prepared from carboxylic acids, and are usually treated as related derivatives.
  • Functional groups of this kind are found in many kinds of natural products.
  • Some examples are shown below with the functional group colored red.
  • Most of the functions are amides or esters, cantharidin being a rare example of a natural anhydride.
  • Penicillin G has two amide functions, one of which is a β-lactam.

• Group Frequencies

  • The following table provides a collection of such data for the most common functional groups.
  • Infrared absorption data for some functional groups not listed in the preceding table are given below.

• Alcohol Nomenclature

  • In the IUPAC system of nomenclature, functional groups are normally designated in one of two ways.
  • The presence of the function may be indicated by a characteristic suffix and a location number.
  • For the mono-functional alcohols, this common system consists of naming the alkyl group followed by the word alcohol.
  • When the hydroxyl functional group is present together with a function of higher nomenclature priority, it must be cited and located by the prefix hydroxy and an appropriate number.
  • Compounds incorporating a C–S–H functional group are named thiols or mercaptans.

• Background and Properties

  • If these same functional groups are attached to an acyl group (RCO–) their properties are substantially changed, and they are designated as carboxylic acid derivatives.
  • Carboxylic acids have a hydroxyl group bonded to an acyl group, and their functional derivatives are prepared by replacement of the hydroxyl group with substituents, such as halo, alkoxyl, amino and acyloxy.
  • Some examples of these functional derivatives were displayed earlier.
  • The last nine entries in the above table cannot function as hydrogen bond donors, so hydrogen bonded dimers and aggregates are not possible.
  • The relatively high boiling points of equivalent 3º-amides and nitriles are probably due to the high polarity of these functions.

• Functionalized Organometallic Reagents

  • However, the reactivity of these powerful nucleophiles limits the functional groups that are tolerated in their preparation and use.
  • Thus the presence of hydroxyl, amino, carbonyl, nitro or nitrile functions in the halide precursor of a desired lithium or magnesium reagent presents a serious compatibility problem, as noted earlier for 5-bromo-1-pentanol.
  • The resulting dialkylzinc reagent tolerates some functional substituents (e.g. esters and nitriles), and undergoes carbonyl addition reactions with aldehydes and ketones provided a titanium(IV) catalyst is present.
  • In all the examples functional groups are present in one or both of the reactants.
  • This brief discussion of functionalized organometallic reagents would not be complete without illustrating the synthetic utility of low temperature magnesium-halogen exchange reactions involving simple Grignard reagents.

• Directed ortho-Metalation

  • Among the most useful reactions for the synthesis of complex molecules are those that achieve direct selective functionalization of a hydrocarbon moiety.
  • Since organometallic reagents function as powerful nucleophiles, selective metal hydrogen exchange, Metalation, would represent a powerful first step to that end.
  • Snieckus (University of Waterloo, Ontario, Canada) the ortho-lithiation of functionally substituted aromatic rings has proven to be a powerful technique for regioselective synthesis.
  • Many derivatives of common functional groups may serve as DMGs.
  • Two examples of this function are drawn below.

• Nomenclature of Aldehydes and Ketones

  • Aldehydes and ketones are organic compounds which incorporate a carbonyl functional group, C=O.
  • A ketone carbonyl function may be located anywhere within a chain or ring, and its position is given by a locator number.
  • The atom adjacent to the function is alpha, the next removed is beta and so on.
  • In all cases the aldehyde function has a higher status than either an alcohol, alkene or ketone and provides the nomenclature suffix.
  • The other functional groups are treated as substituents.