Question

You have just gone into the cosmetic and bath products industry. You see the massive profit in combining simple chemicals and substances to create wonderful scented lotions and soaps. a) Describe to me how you would go about creating a lotion and a soap (two things) and why you choose that substance. b) Mention materials and apparatus you would need. c) Mention any scents or textures you would put in why you would add a certain item (ie. lanolin is a great moisturizer) For example, soaps can be clear or not, heavily scented or not; lotions can be for degreasing a mechanic’s hands or an after bath skin softener for women or a baby’s butt. d) Mention any product tests you might run on it to insure its safety.

Answer 1

1) Soaps are usually salts of long chain fatty acids (carboxylic acids) which have the general formula (RCO₂⁻)_nMⁿ⁺ where, R = alkyl groups, M = usually alkali metal in its cationic forms (such as Na and K, used in Toilet soaps) example: Sodium Stearate, They are produced by a process of Soaponification of fats (triglycerides) by introduction of alkaline solution such as sodium hydroxide. Non-toilet soaps can be achieved by changing the cations which changes the properties (e.g Li in the case of Metallic Soaps). Soaps clean the dirt/grime particles by the phenomenon called micelle formation. Soap bubbles forms micellar aggregates, i.e, it has polar hydrophylic group outside (the cationic metal part) in contact with water and hydrophobic group (long alkyl chain) inside. The inside part of the confinement engulfs the oil or dirt by the principle of 'like attracts like' and therefore the dirt is lossened from either the fabric or hands when you wash. A lotion on the other hand is an emulsyfying mixture of oil and water which is kept together in one phase by an emulgent. Most oil-in-water lotions are prepared for example with the help of cetearyl alcohol to keep the constituents together. To make a lotion, you will need an appropriate oil and water, emulgent, a glass vessel such as conical flask to heat them upto certain degrees (45 to 85 degrees C) to get the uniform consistency. Depending on the nature of utility one can add aromatic substance for scenting purpose, sun screen compounds etc. both in soaps and lotions. For exmple, Triclosan and anti-bacterial compound is generally added in the case of antibacterial soaps. The content of glycerin can be adjusted to make the soap softer or transparent. For removing tough grease, metallic soaps usually containing calcium, lithum and aluminium cations are used. Depending on the purpose of utility the safety tests need to be carried out. For example: Detergents should be ensured that it is not too strong to decolurize the fabric. Toilet soaps need to be tested for Total Fatty Matter (TFM) percentage such that it should not above or below certain limit such that it is does not harm the skin or make it extremely dry after use. Typical analytical instruments such as HPLC and NMR can be used to determine the constituents of a soap/lotion.