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5.4.2 Organic nitrogen compounds: amines, amides, amino acids and proteins Diazo formation • 1o, 2o and 3o aromatic based amines. Video 1o amine undergoing decomposition T>10oC Methyl orange via diazo coupling http://www.science.cmu.ac.th/educate/ couresware_chem/203204/Arputtinan6.htm The colours of Methyl Orange • Other Azocompounds (salters chem) Polymers • Video of polymer – ‘bubblegum’ a.k.a. Plastics, rubber, food colouring, sucrose and dextrose – yum huh? Nylons… • Video 1 – intro to polymers • Video 2 – nylon – brave? no glasses guy • Video 3 – specific chemicals used nylon • Product name : SAP-Super Absorbent Polymer • Chemical name : Sodium polyacrylate • Monomer Molecular formula : C3H4O2 monomer Many COOH (or COONa) groups allow for widespread large amount of interaction with water molecules ? = addition polymer repeating unit of sodium poly(acrylate) Super Absorbent Polymers for Diaper http://www.made-in-china.com Video Other water interacting polymers • Propeneamide Dissolving Plastics Poly(ethanol) Propeneamide •Webpage: DissolvingPolymers.mht ? = addition polymer repeating unit of poly(propeneamide) Polyurethane formation (isocyanate with polyol) PU video http://ec.gc.ca/substances/nsb/images/Polyurethane_S1.gif Condensation polymers • Terylene is used to make fishing nets clothes (quick-dry, non-iron) cassette and video tapes Condensation polymers: There are two main types of condensation polymer made from carboxylic acid derivatives: polyesters and polyamides. i) Polyesters: A well-known polyester, Terylene, is made by heating ethane-1,2-diol with dimethylbenzene-1,4-dicarboxylate (dimethyl terepthalate): The dimethlybenzene-1,4-dicarboxylate is obtained via the following reaction pathway: The manufacture of ethane-1,2-diol has already been described in section 26.4.2. Or simpler rxn (more edexcel friendly) not using the diester as previously, but the dicarbox acid… Kevlar Poly(N-substituted amide) Kevlar again. Synthesis of Kevlar Should be familiar with monomers and polymer requirments now. Poly(N-substituted) amide – similar to Nylon Amino acids. • Naturally occurring ones are L acids (laevorotatory) • Strecker synthesis give L and R (next slide) The Strecker synthesis. - Synthesis of amino acids (1) (2) O R . O. (1) .. NH3 C R H C H H + (3) (2) N H R H H (1) . O. H H (2) C .. N H H H R O water C .. N H H an imine (1) C N H H H H (2) R The nitrogen version of a carbonyl. C=N can replace C=O (recall 2,4-DNP reaction !!) (2) .. CN CN R O C .. .N. H H CN R Like C=O's, C=N's are susceptable to nucleophilic attack - addition - by -CN R Acid hydrolysis of niriles. OH C *C .. N H H H ( +OH - ions) H H The N equivalent of the alpha-hydroxy nitriles. An alpha-amine nitrile (1) The imine O C .. N H An alpha-amino acid The amino acids vary in their side chains (indicated in blue in the diagram). The eight amino acids in the orange area are nonpolar and hydrophobic. The other amino acids are polar and hydrophilic ("water loving"). The two amino acids in the magenta box are acidic ("carboxy" group in the side chain). The three amino acids in the light blue box are basic ("amine" group in the side chain). Amino acids – Ninhydrin rxn and test Ninhydrin rxn with amino acids. Procedure Add about 2 mg of the sample to 1 mL of a solution of 0.2 g of ninhydrin (1,2,3indanetrione monohydrate) in 50 mL of water. The test mixture is heated to boiling for 15-20 sec; This reaction is important not only because it is a qualitative test, but also because it is the source of the absorbing material that can be measured quantitatively by an automatic amino acid analyzer. This color reaction is also used to detect the presence and position of amino acids after paper chromatographic separation. Positive Test A blue to blue-violet color is given by a-amino acids and constitutes a positive test. Other colors (yellow, orange, red) are negative. Complications Proline, hydroxyproline, and 2-, 3-, and 4-aminobenzoic acids fail to give a blue color but produce a yellow color instead. Ammonium salts give a positive test. Some amines, such as aniline, yield orange to red colors, which is a negative test. Amino acids – analysis with ninhydrin chromatography Protein synthesis (biological) • Video (real time) • Video 2 • Salters Organic Toolbox • Salters Organic Reactions.mht