soaps and detergents

what are fats?

a name used to describe a number of organic compounds belonging to a larger class of biological molecules called lipids

what are the best known lipids?

fats and oils

where are fats and oils typically obtained by?

from either plant or animal sources

what is the state of animal fats at room temperature?

solid

what is the structure of animal fats?

they are mainly saturated fats (all carbon carbon single bonds)

what is the state of plant oils at room temperature?

they exist as liquids

what is the structure of plant oils?

they are mainly unsaturated fats (they contain one or more double or triple bonds)

what functional group are animal fats and plant oils?

esters (RCOOR)

What are the structure of fats and oils?

fats and oils contain large non-polar molecules triglycerides.

non polar molecules…

have no overal dipole present

do fats and oils have similar chemical structure?

yes, and they are distinguished simply on the basis of their physical state at room temperature

what is the solubility of fats and oils in water?

they are non polar, therefore triglycerides are unable to form hydrogen bonds with water, so fats and oils are insoluble in water.

how are triglycerides synthesised?

by condensation reactions between a glycerol molecule and 3 fatty acids.

fats and oils are known as…

triglycerides or triesters

what is the structure of a fatty acid?

they are carboxylic acids with chain lengths of eight or more carbon atoms (usually 8-20)

what is the common glycerol that is in animal fats and vegetable oils?

the glycerol is propane-1,2,3-triol

why do we have different kinds of fats and oils?

because the fatty acids can vary but the alcohol part does not

what is the reaction which synthesises triglycerides?

it is a condensation reaction between an organic acid that contains a carboxyl group (COOH) and an alcohol that contains a hydroxyl group (OH). an ester (COO-) functional group is formed linking the molecules a molecule of water is also produced for each of the fatty acid (therefore 3 water molecules)

what is the link that is formed during the synthesis of a triglyceride?

an ester link (3 are produced)

what is the formula for the ester link?

OOCR, there is one double bond between one of the oxygen carbon bonds, the other is single.

can a triglyceride be formed from 3 different fatty acids?

yes, if they are differing in length that’s fine, the fatty acid might also contain one or more double bond.

fats are classified according to the…

structural features of the hydrocarbon chains of their fatty acid components.

what are saturated fatty acids?

they have hydrocarbon chains that contain only single carbon - carbon bonds, e.g steric acid CH3(CH2)16COOH

what is a monounsaturated fatty acid?

is a fatty acid that contains one carbon-carbon double bonds in their hydrocarbon chain. e.g oleic acid found in vegetable oils

what are polyunsaturated fatty acids?

they are fatty acids that contain more than one carbon carbon double bond in their hydrocarbon chain.

what are the characteristics of fatty acids?

they contain unbranched chains of carbon atoms, usually even number of carbon atoms (around 8-20), they have one COOH in their chain arranged in cis or trans geometrical distribution.

what are there kinds of fatty acids that can have cis/ trans isomers?

monounsaturated and polyunsaturated fatty acids

is the hydrocarbon chain of a triglyceride polar or non polar?

is non polar, therofre have diapersion forces, longer the chain the greater the dispersion forces, the strength of the intermolecular forces depend on how close the molecules can get to one another

what happens because of the double bod in the hydrocarbon chain of triglycerides?

because of the presence of the double bond, the symmetrical shape and structure is disrupted and therefore the molecules cannot get as close to each other as possible. this decreases the intermolecular forces in the triglycerides formed from unsaturated fatty acids (this is why vegetable oils are liquids)

what makes oils reactive?

the double bonds

what is the name for the production of soaps?

saponification

describe. saponification

esters (triglycerides) can be hydrolysed and that hydrikisus with a strong base will produce a salt pf carboxylic acid and the alcohol that forms the ester. therefore heating up an ester with an alkaline willll return the acid and alcohol from which it was made. the acid will react with the alkaline producing soap.

each triglyceride will produce how many moles of soap?

3 moles

soap molecules contain…

a long hydrocarbon chain attached to a charged end.

to synthesis soap from a triglyceride…

the ester ones must be broken (in theory water can be used in this reaction, a hydrolysis reaction, this would be very slow. therefrore a strong base e.g NaOH. KOH is used.

reaction with water under alkaline conditions is known as…

base hydrolysis (when base hydrolysis is applied specifically to esters, it is called saponification)

what is soap?

it is the fatty acid ion, combined with the metal ion from the base used for hydrolysis. e.g K+O-C=C (and still bonded to the carbon)-R (the carboxylate group and a metal cation)

what is produced in the saponification reaction?

glycerol and soap.

what is a common soap?

potassium stearate. C₁₈H₃₅KO₂

which part of the soap is non polar?

the hydrocarbon chain (this is saturated)

what is considered the head of the soap?

the carboxylate ion (COO-), these ions are the conjugate bases of the carboxylic acid. with a metal ion usually Na+ or K+ (this head is polar)

what does it mean if the head of the soap is polar and the tail is non polar?

that means there is an uneven distribution of charge in the soap molecule

how do we represent different fatty acids in the tryglycerides?

we use R, R’, R”

soap can be made using…

a mixture of suitable fat or oil with concentrated NaOH and heating it up. the product is rinsed with water which removes most of the glycerol and any residual NaOH

is soap a batch or continuous process?

it is a batch process, this is where reactants are placed in a vessel, the reaction takes place over a period of time, then products are removed.

what conditions is soap made in?

it is performed in enormous vats at high temperatures and uses a continuous process. This is where the products are removed as reactants are being added to continue the reaction process.

why is soap production done at a high temperature?

the high temperatures ensure that the hydrolysis of all the oil present, meaning all the oil added will be converted into soap.

soap is precipitated trough…

the addition of NaCl and is removed by filtration. the remaining solution from the reaction is also removed and the glycerol is separated from the basic solution. while the soap and glycerol are being removed, more oil and hydroxide are being added to the vat so the saponification reaction continues

what is the by product of saponification?

is glycerol (however some soaps keep it in for moisturising properties)

glycerol is found in…

gums, resins, explosives, laxatives

what are the limitations in soap

it is a significant disadvantage especially in WA, as it has limited effectiveness because water supply in these regions contains high levels of metal ions such as Ca2+ and Mg2+ and Fe2+ (hardwater contains a high concentration of these ions)

what happens when a typical soap such as sodium stearate is added to hard water?

the stearate ions mix with the calcium nd magnesium ions. but because sodium stearate is soluble , calcium and magnesium stearate is not (this forms a precipitate called soap scum)

what is the chemical reaction of formation of soap scum?

2CH3(CH2)16COO-(aq) +Ca2+ —> (CH3(CH2)16 COO)2 Ca (s)

what is the net effect of using soap in hard water?

an insoluble scum is formed by the soap and the Ca2+ ions is difficult to remove from household areas such as bathrooms and from clothes. more soap needs to be used for washing in hard water than in ‘soft’ water to obtain results. this results in poorly washes clothes, blocked drains from soap scum, grey scum in wash tubs, unsightly stains around basins and taps

to obtain a satisfactory result from soap…

extra soap needs to be used to create an excess of fatty acid ions or some go the metal ions need to be removed

what is an indication of hard water?

the failure of the soap to produce a lather

how are the metal ions removed so that scum is not produced?

by adding other negative ions such as carbonate to the soap. these ions soften the water by precipitating the Mg2+ ions to the magnesium carbonate with the equation

Mg2+ + CO3 2- —> MgCO3 (s)

What happens to soap in water?

in water the anions in the soap tend to come together to form clumps (this clump arrangement is called a micelle). the hydrophilic ends are on the outer perimeter of these clumps where. they will be in contact. with the water. these hydrophilic ends of the soaps produce ions dipole forces between the ionic end of the soap which carries charge and the highly polarised O-H bond in water. the hydrophobic non polar sections of the soap are in the centre of the clump where they are in contact with each other.

what is a micelle

a stable arrangement made by the anions of the soap tend to come together to form clumps

what are hydrophilic molecules?

they are polar water loving molecules or ions that can form strong forces. of attraction with water, in case of soaps these forces of attraction are ion dipole forces

describe the bonds between the hydrophilic parts of soap molecules and water.

ion dipole forces are produced between the ionic end of the soap which carries charge (-ve charge from the COO- group) and the highly polarised O-H bond in water.

what are the specator ions in cleaning solutions?

the sodium or potassium that were from the base which was used to make the soap.

is dirt polar or non polar?

polar (but sometimes dirt molecules can be non polar and therefore the dirt will not dissolve and the dirt becomes difficult to wash off)

describe the cleaning action of dirt if no soap is used?

if the dirt is polar it is soluble in water. therefore the polar ends of the water attack the respective ends of the dirt and rip off the dirt engulfing it. when the water washes away it takes the soluble dirt molecules with it

describe the cleaning action of dirt molecules with soap.

since soap is a salt is dissociated in water into its respective ions soap is made of the bond non polar carbon chain originating from the acid (hydrophobic) and the polar end which is (hydrophilic). the soap works by stabilising the insoluble non polar particles, the hydrophilic end attaches to water while the hydrophobic attaches to the insoluble molecule e.g grease. this forms micelles which compromises of non polar molecules on the inside and the hydrophobic tails and the hydrophilic ends on the inside. this enables the non polar molecules to be easily washed away by the water

what happens when a soap is added to water?

since soap is a salt, the dissolved in water it dissociates into its respective ions

what happens when clothes get washed?

the vigorous agitation is used to break up the micelles formed by the soap. the non polar ends of the soap particles are able to position themesbles in the drops of oil or grease, leaving the hydrophilic ends exposed to water. as agitation continues, the water molecules attach to the polar ends of the soap and the oil particles are lifted from the fabric

what happens once the oil is lifted from the fabric

the non polar sections if the soap embedded themselves around the oil. The charged end of the pol protrudes into the water. the oil surrounded by soap molecules is a stable arrangement that prevents the stain from reattaching from the fabric. when water is drained from the wash, the oil stains are drained away as well.

what enables soap to function?

the non polar chain and the charged ends of the soap particles.

with the addition of soap, a …. solvent can successfully remove a …. stain

with the addition of soap, a poor solvent can successfully remove a non polar stain.

what is the general term for substances such as soaps and detergents?

surfactant, shorthand for surface active agents.

what are detergents?

they are cleaning agents that do not suffer from the draw back of soaps. the cleaning mechanism is the same to that of soap because they have same features. Detergetns have the same non polar hydrophobic tail just as soaps

what are the differences between soaps and detergents?

detergents do not form insoluble salts with Ca2+ ions or Mg2+ ions (forming scum). and the polar head is SO3- not COO-

what is an example of a anionic detergent?

alkylbenzenesufoate

what is an anionic detergent?

are those whose active constituent is a negatively charged species. This can be composed of a sultanate group attached to a long carbon chains often via a benzene ring within the. structure

deconstruct the name alkydodecyllbenzenesullfonate.

alkyl refers to the non polar hydrocarbon chain. dodecyl means the hydrocarbon cain contains 12 carbon atoms. benzene is the aromatic hydrocarbon (sometimes called phenyl group

how is alkylbenzenesulfonate produced?

dodecylbenze is reacted with concentrated H2SO4. then the hydrocarbon chain w benzene and SO3H and water is reacted with a solution of NaOH to form alkylbenzenesulfonate (a detergent) and water

how do detergents work?

just like soap does. the non polar hydrocarbon end attaches itsellf to the oil or grease. the polar sultanate end has ion dipole interactions with the water molecules in an aqueous medium. only difference is that detergents do not produce scum. modern detergents may also contain enzymes that break down stains including biollogical stains, e.g the protien in blood. brightener are also added. these fluoresce in ultraviollet light to make clothes appear whiter . some detergents iinicluide substances that brake down in warm water to produce hydrogen peroxide, mild bleach

what are the benefits of using biodiesel compared to petrodiesl

improved engine wear and therfore lifespan of the engine. and petrodiesel is non-renewable and therefore is not replenished and the worldwide amounts are depleted.

what is a biodiesel?

a hydrocarbon fuel derived from vegetable oil and is a mixture of esters, produced by chemical reaction between vegetable oils or animal fats and an alcohol (most commonly methanol CH3OH)

what is transesterfication?

this is when a triglyceride is converted into biodiesel by warming it with alcohol (usually methanol). this requires a catalyst (substance that requires an alternative reaction pathway that speeds up the rate of reaction and os not consumed by the reaction). in a transesterfication reaction, the triglyceride is converted. into glycerin and 3 ester molecules with long hydrocarbon chains.

what are the different kinds of catalysts for a transesterfication reaction?

reaction can be carried out using a base, typically KOH solution, or lipase, which is an enzyme, both of which catalyse the reaction

what is an enzyme?

it is a protein produced by a living organism and fucntions as a catalyst.

the molecules of a typical biodiesel are called?

fatty acid esters because the carboxylic acids with relatively long hydrocarbon chains are referred to as fatty acids

what is a fatty acid ester?

an ester made from a fatty acid and a simple alcohol

is biodiesel a pure substance?

no

what is an example of a triglyceride produced by animals

beef tallow (produces saturated esters (therfore no. double carbon bond)

how is biodiesel manufactured?

triglycerides (usually an oil), methanol and a catalyst are added to a reactor in a batch proces. initial mixture is heated gently and left for 30 mins. (time depends on catalyst and conditions selected)

what are the products in a transesterfication reaction

glycerol, a long hydrocarbon chained methyl ester

what is glycerol?

is a relatively small molecule with three hydroxyl functional groups, thherofre is quite polar.

why is the seperation of glycerol and biodiesel easy?

because they do not dissolve in each other and they seperate into two distinct layers (like oil and water) the biodiesel and glycerol extracted from the separator are then distilled remove any unreacted methanol, which is recycled back into t he reactor, then the glycerol and biodiesel

why is the production of biodiesel bad for glycerol market?

the glycerol is about 80% pure, this increase in production of biodiesel causes a decrease in the price of glycerol

what kind of catalyst is used in almost all biodiesel plants?

a base catalyst usually NaOH or KOH

why would a base catalyst be favoured in production of biodiesel?

the transesterfication plant can be operated at a high temperature and pressure, therefore it is quicker. (although keeping these up is expensive) we can use methanol. the % yield is 96-98% while lipase is only approx 80%(although at times can be 92%)

why would we us a lipid enzyme in the production of biodiesel?

this would be preferable because it can be used many times, while base can one one in one batch. it requires less energy as the transesterfication process is carried out oat lower temperatures and pressures

what is a limitation to using a base catalyst for the transesterfication process in the production of biodiesel

bases can produce soap if the ratio of catalyst to triglyceride is not carefully monitored (3:1 base to triglyceride) which would require further purification costs. soap formation can also effect yield

what is the limitation to using a lipase catalyst in the transesterfication process in the production of biodiesel?

yeild is lower 80% when base is 96-98, the slow rate of reaction of naturally occurring lipase can limit its use

what are the ways the industry is researching ways of increasing the Rate of reaction using lipase?

chemical modification of the enzyme, protein (genetic engineering), and using organic solvents

what temperature is base catalyst used in production of biodiesel?

60-70 degrees

what temperature is lipase catalyst used in the production of biodiesel?

20-37 degrees