Background

Plants have throughout human history been used for medicinal purposes. The Chinese used tea from sweet wormwood leaves to cure chills and fevers, Egyptians used a brew from a plant called Khella to help pass kidney stones. Bundjalung Aboriginal people from the coast of New South Wales crushed tea-tree (Melaleuca alternifolia) leaves and applied the paste to wounds as well as brewing it to a kind of tea for throat ailments.

Throughout the ages people have relied on medicinal compounds derived from plants. In medieval times people utilised a tea brewed from Willow bark to relive aches and pains. In 1763 the active ingredient of Willow bark was identified as Salicylic Acid. As an analgesic, salicylic acid is highly effective, however its tendency to cause stomach bleeding seriously limited in its usage. Felix Hoffmann, a chemist at Bayer, has been credited with the synthesis of aspirin in 1897. Aspirin (acetyl salicylic acid) tends to be less harmful than salicylic acid taken directly. Another derivative of Salicylic acid is its methyl ester, which is commonly called Oil of Wintergreen or simply Wintergreen.

Methyl salicylate is used as a liniment and is the active ingredient in products such as Deep Heat. Methyl salicylate and salicylic acid were originally derived from plants however in today’s world they are produced through chemical reactions utilizing base chemicals such as phenol, methanol and acetic anhydride.

Prior Knowledge

This program will best suit students who understand basic organic chemistry, in particular functional groups and IUPAC nomenclature.

Learning Intentions

Students will:

• Consolidate their understanding of functional groups and organic reactions.
• Practice identifying key peaks in IR spectra
• Analyse data they produce using HPLC and a calibration curve to quantify active ingredients in analgesic tablets
• Develop their laboratory skills and identify common sources of experimental error

Activities

Students will:

• Improve their wet lab skills by performing an organic reaction.
• Use Ecolinc’s infrared spectrometer to identify functional groups from IR spectra
• Use Ecolinc’s HPLC to determine the amounts of aspirin and paracetamol in several commercial analgesics

Learn Online

Ecolinc Learn Online is a virtual outreach learning management system (LMS) offering interactive online courses for students and teachers. These courses can be undertaken either as a pre-visit, post-visit or stand-alone.

Students are encouraged to do the pre-learning course on Ecolinc Learn Online called Safe Labs prior to coming to Ecolinc. In this course students will cover all the necessary aspects of laboratory safety during their time at Ecolinc. When planning any work in a laboratory the risk of exposure to laboratory hazards is an important consideration. This course is part of Ecolinc’s risk minimisation for student safety.

VCE links

Area of Study 1: How are organic compounds categorised and synthesised?

Structure, nomenclature and properties of organic compounds

• Characteristics of the carbon atom that contribute to the diversity of organic compounds formed, with reference to valence electron number, relative bond strength, relative stability of carbon bonds with other elements, degree of unsaturation, and the formation of structural isomers
• Molecular, structural and semi-structural (condensed) formulas and skeletal structures of alkanes (including cyclohexane), alkenes, benzene, haloalkanes, primary amines, alcochols (primary, secondary, and tertiary), aldehydes, ketones, carboxylic acids and non-branched esters
• The International Union of Pure and Applied Chemistry (IUPAC) systematic naming of organic compounds up to C8, with no more than two functional groups for a molecule, limited to non-cyclic hydrocarbons, haloalkanes, primary amines, alcohols (primary, secondary, tertiary), aldehydes, ketones, carboxylic acids and non-branched esters.

Reactions of organic compounds

• Organic reactions and pathways, including equations, reactants, products, reaction conditions and catalysts (specific enzymes not required):
  • synthesis of primary haloalkanes and alcohols by substitution
  • addition reactions of alkenes
  • the esterification between and alcohol and carboxylic acid
  • hydrolysis of esters
  • pathways for the synthesis of primary amines and carboxylic acids

Area of Study 2: How are organic compounds analysed and used?

Instrumental analysis of organic compounds

• Identification of bond types by qualitative infrared spectroscopy (IR) data analysis using characteristic absorption bands
• The principles of chromatography, including high performance liquid chromatography (HPLC) and the use of retention times and the construction and use of a calibration curve to determine the concentration of an organic compound in a solution (excluding features of instrumentation and operation)