{"id":2181,"date":"2018-11-30T16:24:33","date_gmt":"2018-11-30T16:24:33","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry2\/?post_type=chapter&p=2181"},"modified":"2019-01-09T12:59:26","modified_gmt":"2019-01-09T12:59:26","slug":"23-1-properties-of-amines","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry2\/chapter\/23-1-properties-of-amines\/","title":{"raw":"23.1. Properties of amines","rendered":"23.1. Properties of amines"},"content":{"raw":"
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\r\n\r\n[caption id=\"attachment_2490\" align=\"aligncenter\" width=\"100\"]\"\" Ammonia[\/caption]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nAmines<\/b> are organic compounds which contain an\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nAmines<\/b> are organic compounds which contain and are often actually based on one or more atoms of nitrogen. Structurally amines resemble ammonia in that the nitrogen can bond up to three hydrogens, but amines also have additional properties based on their carbon connectivity. In an amine, one or more of the hydrogen atoms from ammonia are replaced by organic substituents like alkyl (alkane chain) and aryl (aromatic ring) groups.\r\n\r\nAnother type of organic molecule contains nitrogen without being, strictly speaking, an amine<\/i>: carboxylic acid derivatives containing a trivalent (three-bond) ammonia in ground state are actually amides<\/i> instead of amines. Amides and amines have different structures and properties, so the distinction is actually very important. Organic-nitrogen compounds containing metals are also called amides<\/i>, so if you see a molecule that has a nitrogen and either a carbonyl group or a metal next to that nitrogen, then you know that molecule should be an amide instead of an amine.\r\n
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Properties<\/span><\/h1>\r\n

Types of amines<\/span><\/h2>\r\nAmines can be either primary<\/i>, secondary<\/i> or tertiary<\/i>, depending on the number of carbon-containing groups that are attached to them. If there is only one carbon-containing group (such as in the molecule CH3<\/sub>NH2<\/sub>) then that amine is considered primary. Two carbon-containing groups makes an amine secondary, and three groups makes it tertiary. Utilizing the lone electron pair of nitrogen, it is sometimes energetically favored to use the nitrogen as a nucleophile and thus bind a fourth carbon-containing group to the amine. In this case, it could be called a quaternary ammonium ion<\/i>.\r\n\r\n[caption id=\"attachment_2500\" align=\"aligncenter\" width=\"75\"]\"\" Primary Amine[\/caption]\r\n\r\n[caption id=\"attachment_2498\" align=\"aligncenter\" width=\"75\"]\"\" SecondaryAmine[\/caption]\r\n\r\n[caption id=\"attachment_2497\" align=\"aligncenter\" width=\"75\"]\"\" Tertiary Amine[\/caption]\r\n\r\nAn organic compound with multiple amine groups is called a diamine<\/b>, triamine<\/b>, tetraamine<\/b> and so forth, based on the number of amine groups (also called amino groups<\/i>) attached to the molecule. The chemical formula for methylene diamine (also called diaminomethane), for example, would be as follows: H2<\/sub>N-CH2<\/sub>-NH2<\/sub>\r\n

Aromatic amines<\/span><\/h2>\r\nAromatic amines have the nitrogen atom directly connected to an aromatic ring structure. Due to its electron withdrawing<\/i> properties, the aromatic ring greatly decreases the basicity of the amine - and this effect can be either strengthened or offset depending on what substituents are on the ring and on the nitrogen. The presence of the lone electron pair from the nitrogen has the opposite effect on the aromatic ring itself; because the nitrogen atom can \"loan\" electron density to the ring, the ring itself becomes much more reactive to other types of chemistry.\r\n

Naming conventions<\/span><\/h2>\r\nFor primary amines, where the amine is not the principal characteristic group, the prefix \"amino-\" is used. For example: 4-aminobenzoic acid where the carboxylic acid is the principal characteristic. Otherwise, the suffix \"-amine\" is used with with either the parent hybride or the R group substituent name. Example: ethanamine or ethylamine. Alternatively, the suffix \"-azane\" can be appended to the R group substituent name: Example: propylazane.\r\n\r\nFor secondary, tertiary, and quarternary amines, the naming convention is a bit different, but the suffixes are the same. For symmetrical amines, the \"di\" or \"tri\" prefix is used depending on whether there are 2 or 3 substituents. For example, dipropylamine is a secondary amine, and triphenylamine is a tertiary amine. For asymmetric amines, the parent chain gets the \"-amine\" suffix. This name is then prefixed with \"N-\" (indicating the nitrogen bond) and the substituent group name, for each substituent, using alphabetic order for tertiary amides. For example, N-ethyl-N-methyl-propylamine, not N-methyl-N-ethyl-propylamine.\r\n\r\nTo sum up:\r\n