saponification - comparing lab and industrial conditions

[aiji]

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I am really confused for a research assignment on saponification. Can someone explain to me what it means to: "Compare the conditions for saponification in the laboratory with the industrial preparation of soaps."

The use of 'conditions' is really throwing me off.

Firstly, are the esters being used in the laboratory the triglycerides/fats and oils? Because in a lab, the esters used are volatile hence refluxing is needed, while industrially the fats and oils uses are not. How can you compare if they are different reactants?

Secondly, when it says conditions, should I include the complete description of both processes in lab and industry?

Lastly, for comparing should I compare the 'conditions' (ie. what conditions? - -") or the differences between both processes. (eg. Refluxing, mixing by steam, the extraction of glycerol from brine solution.. or are those the conditons? T-T)



Any help will be greatly appreciated.

[theChemCoach]

Hi,

The BEST place to get additional information on soaps for the industrail chemistry module is the following webpage, established by the University of Sydney for HSC students.

http://www.kcpc.usyd.edu.au/discover...ification.html

Read through the information, and you will find answers to all your questions.

Its an excellent resource!

good luck studying.

george

[aiji]

Originally Posted by theChemCoach

Hi,

The BEST place to get additional information on soaps for the industrail chemistry module is the following webpage, established by the University of Sydney for HSC students.

http://www.kcpc.usyd.edu.au/discover...ification.html

Read through the information, and you will find answers to all your questions.

Its an excellent resource!

good luck studying.

george

Ah, thankyou so much. It really helps. I was trying to get to that sight before and it was a dead link. This one works. Thankyou again.

[_blank]

To compare the school laboratory and industrial saponification conditions - I looked at the link but I'm still confused. Do we compare the school to the Kettle Batch AND Fatty Acid Neutralization? Or just to one?

[aiji]

Originally Posted by _blank

To compare the school laboratory and industrial saponification conditions - I looked at the link but I'm still confused. Do we compare the school to the Kettle Batch AND Fatty Acid Neutralization? Or just to one?

Yeah I compared both. This is from my assignment.. PX

Saponification in a laboratory involves mainly liquid esters which are insoluble and volatile. They are needed to be boiled in a solution of sodium hydroxide and the reaction usually performed within a reflux condenser. The reaction mixture after completion is usually a homogenous mixture, since carboxylate anions and alcohols are soluble in water. Seperating the products of the chemical reaction would depend on solubility and boiling points. Carboxylic acid with a low solubility in water can be acidified to convert the carboxylate anions to the acid which precipitates out and can be filtered. Distillation or fractional distillation could be used to separate alcohols with a significantly different boiling point than water, while a solubility that is low enough can be separated after cooling in ice.

Industrially, raw materials are used which require some processing and purification before or after the formation of soap. In the industrial process of saponification, reflux is not necessary since fat or oil being used and the glycerol formed are not volatile.
The Fatty Acid Neutralisation process is considerably different from saponification in a laboratory. Soaps are made by a two-step process of initial hydrolysis to form fatty acids and then the final saponifcation by neutralisation to form soap. This reaction is undertaken at elevated temperatures and pressures so that water is quite soluble in the fats and oils being used, while a metal catalyst is often added to improve the rate of reaction. The fatty acids formed tend to rise to the top of a reaction vessel, with water flowing to the bottom carrying glycerol with it. The by-product can then be removed from the reactor pushing the equilibrium towards the products. The reaction mixture of fatty acids obtained are then neutralised by the addition of NaOH or KOH. Salt water is often added to control the texture of the solidified soap.

A Kettle Batch process uses a direct saponification reaction, where a large open steel tank holding up to 13 000 kg of a blended mixture of fats and oils, boils its mixture. The injection of high temperature and pressure steam heats the mixture to boil, as well as to keep it well-stirred. A batch process is a reaction where everything is added at the beginning, the reaction proceeds until it reaches completion and then the products are removed. Fats and oils, caustic soda (NaOH), salt and water are added in the beginning of the reaction. Upon completion, additional salt is added to control the way the soap solidifies. The mixture is washed, steamed and allowed to settle, removing the glycerol which usually takes several days to complete.
The soap is removed to be further processed into the final product (ie. Adding additives such as perfumes and colouring, pressed and packaged). The glycerol obtained from the brine solution by neutralization excess NaOH and distilling, can also be used for other industrial purposes.

A summary of all that:

Laboratory

• uses a direct saponification reaction
• highly refined materials used (eg. purified olive oil) that are bought from the supermarket
• heating and stirring is achieved using a flame and stirring rod
• glycerol is removed by washing and discarded

Fatty Acid neutralisation

• the reaction performed is a two step process
• raw materials are used and require processing
• uses a blend of fats and oils in the reactor
• heating and stirring is achieved using steam
• hydrolysis reaction is undertaken at high T&P
• hydrolysis reaction uses water as the hydrolysing agent
• salt is added to control the way the soap solidifies (ie. texture)
• glycerol is removed for other uses

Kettle Boiled Batch Process

• uses a direct saponification reaction
• raw materials are used and require processing
• uses a blend of fats and oils in the reactor
• heating and stirring is achieved using steam
• everything is added in the beginning
• salt is added to control the way the soap solidifies (ie. texture)
• glycerol is removed for other uses