Amines
Amines are organic compounds derived from ammonia in which one or more hydrogen atoms are replaced by alkyl or aryl groups. They are characterized by a nitrogen atom bonded to one or more carbon atoms. Amines play a crucial role in biological processes and are widely used in the production of pharmaceuticals, dyes, and other chemicals.
4 Key excerpts on "Amines"
eBook - ePub- Katarzyna Staszak, Karolina Wieszczycka, Bartosz Tylkowski, Katarzyna Staszak, Karolina Wieszczycka, Bartosz Tylkowski(Authors)
- 2020(Publication Date)
- De Gruyter(Publisher)
...Aniline is also necessary in manufacturing of pharmaceuticals and rubber-processing chemicals. This compound is also used as an anti-knock additive and solvent in the improvement of reformat gasoline. Figure 6.1: Industrially relevant nitrogen derivatives. The variety of applications associated with the Amines structures results in a variety of synthesis method. In the case of aliphatic Amines, there are many approaches for the synthesis of primary, secondary, and tertiary Amines; however, methods such as (I) halogenated hydrocarbon ammonolysis, (II) hydroamination of unsaturated carbon–carbon bonds, (III) aldehyde amination hydrogenation, (IV) hydroaminometylation (V) nitrile and nitro compounds reduction, (VI) alcohol amination, and (VI) nitroarene N -alkylation with alcohol have been developed in the last century. Most of these methods are also recommended to produce Amines with benzyl moiety, various alkyl chains, and also having a complexed unsaturated structures. In the case of aromatic Amines the most important is nitrile and nitro compounds hydrogenation. The main types of the methods are listed in Table 6.1. Table 6.1: The most important synthesis of Amines. I. halogenated hydrocarbon ammonolysis II. hydroamination of alkene, alkyne III. aldehyde amination hydrogenation IV. hydroaminomethylation V. nitrile and nitro compounds reduction VI. alcohol amination VII. nitroarene N -alkylation with alcohol 6.1.1 Amination of alcohols Today more than 1 million tons of methylAmines are produced according to this method. Various modifications of the reaction of an alcohol with ammonia provide the most common commercial routes to alkylAmines...
eBook - ePub- Graham Patrick(Author)
- 2004(Publication Date)
- Taylor & Francis(Publisher)
...If the substituents are all alkyl groups, the amine is defined as being an alkylamine. If there is at least one aryl group directly attached to the nitrogen, then the amine is defined as an arylamine. The nitrogen atom has four sp 3 hybridized orbitals pointing to the corners of a tetrahedron in the same way as an sp 3 hybridized carbon atom. However, one of the sp 3 orbitals is occupied by the nitrogen's lone pair of electrons. This means that the atoms in an amine functional group are pyramidal in shape. The C–N–C bond angles are approximately 109° which is consistent with a tetrahedral nitrogen. However, the bond angle is slightly less than 109° since the lone pair of electrons demands a slightly greater amount of space than a σ bond. Pyramidal inversion Since Amines are tetrahedral, they are chiral if they have three different substituents. However, it is not possible to separate the enantiomers of a chiral amine since Amines can easily undergo pyramidal inversion — a process which interconverts the enantiomers (Figure 1). The inversion involves a change of hybridization where the nitrogen becomes sp 2 hybridized (Section A4) rather than sp 3 hybridized. As a result, the molecule becomes planar and the lone pair of electrons occupy a p orbital. Once the hybridization reverts back to sp 3, the molecule can either revert back to its original shape or invert. Although the enantiomers of chiral Amines cannot be separated, such Amines can be alkylated to form quaternary ammonium salts where the enantiomers can be separated. Figure 1. Pyramidal inversion. Once the lone pair of electrons is locked up in a σ bond, pyramidal inversion becomes impossible and the enantiomers can no longer interconvert. Physical properties Amines are polar compounds and intermolecular hydrogen bonding is possible for primary and secondary Amines. Therefore, primary and secondary Amines have higher boiling points than alkanes of similar molecular weight...
eBook - ePubSynthetic Analgesics
Diphenylpropylamines
- Paul A. J. Janssen, D. H. R. Barton, W. Doering(Authors)
- 2014(Publication Date)
- Pergamon(Publisher)
...CHAPTER VIII DiAmines and Derivatives (I : R Contains Amino Group or Derivative) Publisher Summary This chapter discusses the methods for the synthesis of diAmines and their derivatives. Simple diAmines are prepared by Hofmann degradation of the corresponding primary amides. There are compounds available also from aminochlorides and ammonia. They react with alkyl halides, acid chlorides, and anhydrides to yield the derivatives of diAmines. The chapter discusses the analgesic or antihistaminic activity of diAmines and their derivatives. Relatively weak parasympatholytic and local anesthetic properties are detected among the reversed amides. DiAmines are also obtained in high yields by the reduction of the corresponding nitriles with a double molar excess of LiAlH 4. The Raney nickel hydrogenation of nitriles leads to diAmines in low yields. A few tertiary diAmines of structure were prepared by the reduction of the corresponding basic tertiary amides using a molar excess of LiAlH 4. A few ketimines related to methadone were reduced with an equimolar amount of LiAlH 4 in ether. The available data on diAmines are insufficient to allow for theoretically valuable conclusions concerning structure–activity relationships. Further study in this promising field is desirable. The simplest diAmines of this series [8.1a] were prepared in this laboratory (236–240, unpublished results) by Hofmann degradation of the corresponding primary amides (I: R = CONH 2). Compounds [8.1a] are also available from aminochlorides (I: R = Cl) and ammonia (236–240). They react with alkyl halides, acid chlorides and anhydrides to yield derivatives of types [8.1b, c and d] in normal yields (Table IV). None of the compounds of type [8.1] listed in Table V were found to be active as analgesics or antihistaminics...
eBook - ePubBiochemistry Explained
A Practical Guide to Learning Biochemistry
- Thomas Millar(Author)
- 2018(Publication Date)
- CRC Press(Publisher)
...4 Amino Acids and their Functions In this chapter you will learn: the functional groups: an amine and carboxyl groups to understand the general structure of amino acid the structures, names and single letter symbols for the 20 amino acids found in proteins how 2 cysteines may be oxidised to form the bridging amino acid cystine how the carbons of amino acids are named or numbered the terms ampholyte and zwitterion and how these relate to amino acids the structure of an amide bond and the special case a peptide bond special functions of amino acids (e.g. neurotransmitters) and structural relationships between amino acids how ketones are formed from amino acids by removing ammonia from the αC the synthesis of the bioactive Amines dopamine, noradrenaline, adrenaline and serotonin. to understand the basis for Parkinson’s disease and phenylketonuria that tyrosine, serine and threonine are phosphorylation sites in proteins the importance of decarboxylation in the formation of some active Amines such as histamine how sugars may attach to the amino acids serine, threonine and asparagine Basic structure and nomencalture of amino acids The name amino acid suggests that these structures have an amine and an acid group. Indeed this is true; amino acids have an amino group and a carboxylic acid. The structure of a typical L-amino acid is illustrated below. This type of amino acid is the basis of proteins. Q&A 1 : Draw the chemical structures of a carboxylic acid, and an amine group. There is a central carbon that has bonds to an amine group, a carboxylic acid, an hydrogen and a variable R group. Since this central carbon has 4 different groups attached to it, it is a chiral carbon and hence there are 2 possible isomers, L and D. Nearly all amino acids in biochemistry are of the L-form (L for life). Note that this is the opposite of sugars, which nearly always occur as the D isomer. You need to learn their structure in this orientation...
