Why Your Perfume Smells Like Bananas: Organic Chem Secrets for WA

1. Identify functional groups — Recall that esters have the general formula RCOOR' where R and R' are alkyl or aryl groups. The functional group contains a carbonyl group (C=O) adjacent to an ether-like oxygen (C-O-C).
   $$R-C(=O)-O-R^{\prime }$$
2. Analyze each compound — Compound A is ethanoic acid (acetic acid) with formula CH₃COOH - it has a carboxyl group (-COOH), not an ester group. Compound C is ethanol (CH₃CH₂OH), an alcohol with hydroxyl group (-OH). Compound B has the characteristic -COO- group between two carbon chains.
3. Name the ester — For ester naming, identify the alcohol part (alkyl group attached to oxygen) and acid part (alkyl group attached to carbonyl). The alcohol part here is 3-methylbutyl (from isoamyl alcohol), and the acid part is ethanoate (from ethanoic acid).
   $$\text{3-methylbutyl ethanoate}$$

$$C{H}_3-C(=O)-O-C{H}_2-C{H}_2-CH(C{H}_3)-C{H}_3$$

→ Compound B is the ester. Its IUPAC name is 3-methylbutyl ethanoate. Structural formula: CH₃-C(=O)-O-CH₂-CH₂-CH(CH₃)-CH₃

1. Word equation — Alcohol + carboxylic acid → ester + water. This is the general pattern for esterification.
2. Molecular formulas — Isoamyl alcohol is C₅H₁₂O, acetic acid is C₂H₄O₂. The ester isoamyl acetate is C₇H₁₄O₂. Water is H₂O.
   $$C_5{H}_{12}O+C_2{H}_4{O}_2\to C_7{H}_{14}{O}_2+H_{2}O$$
3. Name products — The ester is isoamyl acetate (3-methylbutyl ethanoate). Water is obviously water.
4. Reaction type — This is a condensation reaction because two molecules combine to form one larger molecule while releasing a smaller molecule (water). Each esterification removes one H₂O molecule.

$$C_5{H}_{11}OH+C{H}_{3}COOH\to C_7{H}_{14}{O}_2+H_{2}O$$

→ C₅H₁₁OH + CH₃COOH → C₇H₁₄O₂ + H₂O. The ester is isoamyl acetate (3-methylbutyl ethanoate). It's a condensation reaction because water is eliminated during the formation of the ester bond.

1. Calculate mass of alcohol — Use density to convert volume to mass: mass = volume × density.
   $$m=150\text{ mL}\times 0.81\text{ g/mL}=121.5\text{ g}$$
2. Convert to moles — Use molar mass to find moles: moles = mass / molar mass.
   $$n=\frac{121.5\text{ g}}{88\text{ g/mol}}=1.38\text{ mol}$$
3. Stoichiometric ratio — From the balanced equation, 1 mole of alcohol produces 1 mole of ester. So moles of ester = moles of alcohol = 1.38 mol.
   $$n_{ester}=1.38\text{ mol}$$
4. Calculate ester mass — Convert moles of ester to mass using its molar mass.
   $$m_{ester}=1.38\text{ mol}\times 130\text{ g/mol}=179.4\text{ g}$$

$$179.4\text{ g}$$

→ The theoretical yield is 179.4 grams of isoamyl acetate.

1. Advantages of synthetic — Synthetic isoamyl acetate is cheaper to produce at scale, has consistent quality, doesn't depend on banana harvest seasons, and can be precisely controlled for strength and purity. Natural extracts vary in composition and are more expensive.
2. Chemical evidence — Look for 'isoamyl acetate' or '3-methylbutyl ethanoate' on the ingredient list. Natural banana extract would list 'banana fruit extract' or similar. Synthetic versions are often labeled as 'flavouring' or 'aroma compound'.
3. School lab test — Perform a simple esterification test: react an alcohol with a carboxylic acid in presence of concentrated sulfuric acid catalyst. If the banana scent appears, it confirms ester formation. Compare with authentic samples.
4. Economic benefit — Local production creates jobs in Sierra Leone, reduces import costs (no foreign exchange spent on importing extracts), and supports local chemical industry development near Fourah Bay College or industrial areas like Wellington Industrial Estate.

→ Synthetic isoamyl acetate is cheaper, more consistent, and locally producible. Look for 'isoamyl acetate' on labels. Test via simple esterification reaction. Local production saves foreign exchange and creates jobs.

1. Alcohol cost calculation — From Exercice 3, we used 150 mL alcohol for theoretical yield. For 1,000 sachets requiring 500 g total ester (1,000 × 0.5 g). Scale factor = 500/179.4 = 2.79. Alcohol needed = 150 mL × 2.79 = 418.5 mL. Cost = (25,000/500) × 418.5 = 20,925 Leones.
   $$V_{alcohol}=150\text{ mL}\times \frac{500\text{ g}}{179.4\text{ g}}=418.5\text{ mL}{C}_{alcohol}=\frac{\mathrm{25,000}}{500}\times 418.5=\mathrm{20,925}\text{ Leones}$$
2. Acetic acid cost — Acetic acid price per mL = 12,000/500 = 24 Leones/mL. Assuming same volume needed as alcohol (1:1 mole ratio, similar density), cost = 418.5 × 24 = 10,044 Leones.
   $$C_{acid}=418.5\text{ mL}\times 24\text{ Leones/mL}=\mathrm{10,044}\text{ Leones}$$
3. Total production cost — Sum of alcohol and acid costs.
   $$C_{total}=\mathrm{20,925}+\mathrm{10,044}=\mathrm{30,969}\text{ Leones}$$
4. Total revenue — 1,000 sachets × 5,000 Leones each.
   $$R=\mathrm{1,000}\times \mathrm{5,000}=\mathrm{5,000,000}\text{ Leones}$$
5. Profit per sachet — Total profit divided by number of sachets. Profit = Revenue - Cost = 5,000,000 - 30,969 = 4,969,031 Leones. Per sachet = 4,969,031 / 1,000 = 4,969 Leones.
   $$P_{sachet}=\frac{\mathrm{5,000,000}-\mathrm{30,969}}{\mathrm{1,000}}=\mathrm{4,969}\text{ Leones}$$

$$\mathrm{4,969}\text{ Leones}$$

→ Profit per sachet is 4,969 Leones. Total profit for 1,000 sachets is 4,969,031 Leones.

1. Structural formulas — Isoamyl acetate has a branched 5-carbon chain attached to oxygen and a 2-carbon chain attached to carbonyl. Ethyl butanoate has a straight 4-carbon chain on acid side and 2-carbon chain on alcohol side.
   $$\text{Isoamyl acetate: }C{H}_3-C(=O)-O-C{H}_2-C{H}_2-CH(C{H}_3)-C{H}_3\text{Ethyl butanoate: }C{H}_{3}C{H}_{2}C{H}_2-C(=O)-O-C{H}_{2}C{H}_3$$
2. Chain length comparison — Isoamyl acetate has a total of 7 carbons with branching, creating a specific molecular shape. Ethyl butanoate has 6 carbons in a more linear arrangement. The shape determines how the molecule fits into olfactory receptors.
3. Receptor interaction — Olfactory receptors in your nose have specific shapes. Molecules with shapes matching receptor sites trigger nerve signals interpreted as specific smells. The banana-shaped receptor fits isoamyl acetate better than ethyl butanoate, hence banana scent.

→ Isoamyl acetate's branched structure fits banana receptors; ethyl butanoate's linear structure fits pineapple receptors. Molecular shape determines smell through receptor specificity.

1. Theoretical yield — From stoichiometry, 0.2 mol alcohol produces 0.2 mol ester. Mass = moles × molar mass.
   $$m_{theoretical}=0.2\text{ mol}\times 130\text{ g/mol}=26\text{ g}$$
2. Percentage yield formula — Percentage yield = (actual yield / theoretical yield) × 100%.
   $$\text{Percentage yield}=\frac{\text{actual yield}}{\text{theoretical yield}}\times 100\%$$
3. Calculate percentage — Substitute values into the formula.
   $$\text{Percentage yield}=\frac{18}{26}\times 100\%=69.23\%$$

69.2\%

→ The percentage yield is 69.2%.

1. Suspicion reasons — Natural banana extract would require large quantities of bananas, be expensive to produce, and have variable composition. A low price suggests synthetic production which is cheaper and more consistent. Also, '100% natural' is often used as a marketing term without strict regulation.
2. Lab tests — Perform gas chromatography to identify specific ester compounds. Natural extracts contain many compounds while synthetic isoamyl acetate is pure. Test for presence of other banana volatiles like amyl alcohol.
3. Practical tests — Compare smell intensity over time - synthetic esters last longer. Check for oily residue (natural extracts may leave more residue). Perform simple solubility test - esters are less soluble in water than natural extracts might be.
4. Consumer advice — Ask for ingredient lists, request certificates of analysis, compare prices with known synthetic products, and be wary of exaggerated 'natural' claims without proof. Support local industries but demand transparency.

→ The '100% natural' claim is suspicious due to cost and consistency issues. Verify via chemical analysis for pure isoamyl acetate. Practical tests include smell longevity and solubility. Advise buyers to demand ingredient lists and certificates.