Fragrance Chemistry AKA Perfume Chemistry V1.0



Fragrance Chemistry AKA Perfume Chemistry V1.0Key words: Intermolecular forces, functional groups, estersAs well as being sold as perfumes, fragrance chemicals are added to hundreds of products including household products (cleaners, laundry, air fresheners) and cosmetics (makeup, shampoo, moisturisers). Fragrance chemistry is big business.In most countries fragrances are comprised of ‘essential oils’ dissolved in denatured alcohol (table 1). In other countries the essential oils may be dissolved in an oil, The various fragrance types are names for the concentrations in the solvent. Denatured alcohol used is ethanol containing denatonium benzoate (figure 1). Denaturing agents make the alcohol unfit to drink and so do not have the tax applied as whiskey would.Table SEQ Table \* ARABIC 1 Fragrance type and their concentrationsFragrance TypePercentage of Essential OilsPerfume22Eau de Parfum15-22Eau de Toilette8 to 15 Eau de Cologne4The essential oils (essences) can be obtained from natural products (plants and animal) or may be synthesised in a laboratory. When natural occurring compounds are made in a lab they are usually referred to as nature identical compounds. The oils are organic compounds with a mixture of functional groups including alkene, alcohols, aldehydes, ketones, carboxylic acids and esters. They may be aromatic or aliphatic. Some examples may be found in figure 1.Figure 1 Denatonium benzoateNatural compound s can be extracted from source via steam distillation, solvent extraction and expression. The latter is used the materials like citrus peel where the oils in the pith are extracted into cloth by passing through a roller and then extracting the oils using a solvent. Some oils used in fragrance are totally synthetic as nature cannot provide them.Various fragrances are then blended from several different starting essences. The more oils the more complex the mixture. Table SEQ Table \* ARABIC 2 Some examples of common fragrance molecules.With the oils, the stronger the intermolecular bonding the longer most molecules stay on the skin and vice versa. This does mean that the smell profile of the fragrance will change from the time it was applied.As the fragrances are mixtures of dozens of chemicals with different functional groups (figures 1 and 3) they are still capable of reacting with each the in the bottle changing the components and therefore changing the smell profile-seldom for the better! Applying basic chemistry principles can slow the reactions down.Table SEQ Table \* ARABIC 3 Structure of polyfunctional molecules.vanillinvanillaeugenolclovesvanillinvanillaeugenolcloves0444500Tim Harrison is the Director of Outreach and Sciecne Communicato in Residence at the School of Chemistry, University of Bristol. He has a passion for the promotion of chemistry through writing, performing lecture demonstrations and facilitating hands =on practical chemistry with students and teachers of all ages.Fragrance Chemistry AKA Perfume ChemistryQuestionsWhat is the elemental formula (simple formula) of euginol? [1 mark].Using figure 1 what is the formula for the benzoate ion? [1 mark].Instead of using ethanol as a solvent for a fragrance petrol could be used. Why isn’t it? [1 mark]If the only intermolecular bonding is van der Walls (instantaneous dipole-dipole interactions) which molecules would evaporate first small molecular mass or large molecular mass? [1 mark]Methylated spirits is an example if a denatured alcohol. What compound is used to denature the ethanol in meths? [1 mark]Which functional group is present in all the molecules in figure 2? [1 mark]Which fragrance is an isomer of banana? [1 mark]Name the 3 functional groups in vanillin in figure 3. Note, one of them may be outside of your specification. [3 marks]To reduce side reactions in a fragrance bottle, several techniques may be employed, Name two of them. [2 marks]Coconut is a cyclic ester (a lactone). Suggest a single molecule that can be converted to the ester. [2 marks]ExtensionConsider vanillin and eugenol. (a) Suggest 2 chemical tests to tell apart the two molecules, giving details (b) explain how infra-red spectroscopy can b used to tell the two molecules apart.You may wish to use a data book.Fragrance Chemistry AKA Perfume ChemistryQuestionsWhat is the elemental formula (simple formula) of euginol? [1 mark].Using figure 1 what is the formula for the benzoate ion? [1 mark].Instead of using ethanol as a solvent for a fragrance petrol could be used. Why isn’t it? [1 mark]If the only intermolecular bonding is van der Walls (instantaneous dipole-dipole interactions) which molecules would evaporate first small molecular mass or large molecular mass? [1 mark]Methylated spirits is an example if a denatured alcohol. What compound is used to denature the ethanol in meths? [1 mark]Which functional group is present in all the molecules in figure 2? [1 mark]Which fragrance is an isomer of banana? [1 mark]Name the 3 functional groups in vanillin in figure 3. Note, one of them may be outside of your specification. [3 marks]To reduce side reactions in a fragrance bottle, several techniques may be employed, Name two of them. [2 marks]Coconut is a cyclic ester (a lactone). Suggest /draw a single molecule that can be converted to the ester. [2 marks]ExtensionConsider vanillin and eugenol. (a) Suggest 2 chemical tests to tell apart the two molecules, giving details (b) explain how infra-red spectroscopy can b used to tell the two molecules apart. You may wish to use a data book.Fragrance Chemistry AKA Perfume ChemistryAnswers ................
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