ORG CHEM LAB - EXP #13: SYNTHESIS OF SOAP AND DETERGENT

SOAP

is the sodium or potassium salt of a fatty acid, produced from the hydrolysis of fats in a chemical reaction called saponification

SOAP

by-product of the reaction between fats (plant-based or animal based) and alkali (NaOH/KOH)

NaOH

produces hard soap (soap in bar soap)

KOH

produces soft soap (soap in liquid form; ex: body wash)

TAIL

• long hydrocarbon chain

• "hydrophobic"; water-hating, non-polar (soluble in non-polar substances)

HEAD

• carboxylic acid

• "hydrophilic"; water-loving; polar (ionic - soluble in water)

AMPHIPHILIC MOLECULES

• contain both polar and non-polar parts

• attract polar and non-polar substances

9-10

pH of soap

Basic

soaps are ______ in nature

ACIDIC CONTAMINANT

• solutions of alkali metal soaps are slightly alkaline due to hydrolysis

• if the pH of a soap solution is lowered by ___________________, insoluble fatty acids precipitate and form a scum

• these divalent cations cause aggregation of micelles, which then deposit as a dirty scum

Dirty scum

layer of dirt that forms at the surface of a liquid

DETERGENTS

• sodium or potassium salts of a long alkyl chain ending with a sulfonate group

• synthetic amphiphiles

SULFONIC ACID

• head of the detergent

• much stronger acid compared to carboxylic acid

less sensitive to pH changes

by using a much stronger acid for the polar head group, water solutions of the amphiphile are __________________

SOAP SCUM

soaps react with metal ions in the water and can form insoluble precipitates; the precipitates can be seen in the soapy water and are referred to as _____________ (turn yellowish/black colored in clothes)

SODIUM CARBONATE

washing soda (washing aid to avoid scum formation)

SODIUM TETRABORATE

borax (washing aid to avoid scum formation)

sodium palmitate; sodium stearate

examples of soaps

deoxycholic acid; sodium lauryl sulfate

examples of detergents

ACROLEIN TEST

detect the presence of glycerol in the sample

POTASSIUM BISULFATE

to the residue containing glycerol, add a pinche of powdered ________________

• dehydrating agent

UNSATURATED ALDEHYDE

if potassium bisulfate is added to residue (glycerol) - it will be converted to ________________

formation of pungent irritating odor

positive result in test for glycerol

SODIUM DODECYL SULFATE; dodecyl alcohol with sulfuric acid

• a synthetic detergent, a sodium alkyl sulfate called _______________, can be prepared by reacting ___________________

DODECYL ALCOHOL (dodecanol - IUPAC)

• colorless, thick liquid with characteristic sweet odor

• produced industrially from kernel oil/coconut oil

LAURLY ALCOHOL

another name for dodecyl alcohol

sodium hydroxide

the resulting dodecyl sulfate is converted to a sodium salt by a reaction with _____________

SOFT WATER

• occurs naturally

• water that is free from dissolved salts of metals such as calcium, magnesium, or iron

• produce good lather with soap

• washing with soap is easy

HARD WATER

• formed when soft water picks up minerals (lime, chalk, calcium, magnesium)

• water that has high mineral content such as magnesium, carbonates, and calciums

• does not produce good lather with soap

• difficult to wash with soap

TEMPORARY HARDNESS

• refers to the calcium and magnesium carbonates and bicarbonates in the water

• boiling the water or reacting it with lime removes this hardness

CARBONATE HARDNESS

temporary hardness is also called ______________

PERMANENT HARDNESS

• due to the presence of calcium or magnesium sulfates, chlorides, and nitrates

• not removed through boiling

• may be removed by using lime with soda ash depending on the chemical composition of the water

NON-BICARBONATE HARDNESS

permanent hardness is also called _______________