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CHM 585/490

Chapter 20

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Soaps and Bulging Drum Case Story

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Soaps

• Contain both a hydrophilic (water loving) end and a hydrophobic (water repelling) portion.

• Hydrophilic end is the carboxylate salt

• Hydrophobic end is the aliphatic end

• U.S. soap & detergent industry about $10 billion

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Saponification

O

O

(CH2)nCH3

O

O

(CH2)nCH3

O

O

(CH2)nCH3

H2C

HC

H2C

NaOH

O

O

(CH2)nCH3

O

O

O

H2C

HC

H2C

H

H

H

H

O

O

(CH2)nCH3H

O

O

(CH2)nCH3H

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Fats

• Tallow- beef by-product; most commonly utilized animal fat in the processing of soaps

• Coconut Oil – from the dried fruit of the coconut tree

• Palm kernal oil – from palm tree nuts

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Percentage of Acids from Different Fats

Tallow Coconut Palm kernal

Lauric C12 50 50

Myristic C14 3 18 18

Palmitic C16 27 8.5 8

Stearic C18 20 3 2

Oleic C18 unsaturated

43 6 14

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Soap

• RCO2- Na+ Typical soap

• RCO2- K+ Soft soap

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Cationic SurfactantsQuats

O

O

(CH2)nCH3H H2N

O

(CH2)nCH3

NH3C (CH2)nCH3N

H2C (CH2)nCH3H2N

CH3ClH2C (CH2)nCH3N

CH3

CH3

H3C+

Cl-

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Synthetic Detergents

• RSO3- Na+

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Hypothesis IResidual ethylene oxide was

degassing from the ethoxylated alcohol during storage at elevated

temperatures

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ROH O

linear alcoholR = C12 - C14

ethylene oxide

+ x R(OCH2CH2)xOH

ethoxylated alcoholx = 0-6

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Headspace GC

• No ethylene oxide detected

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Hypothesis 2

• Ethoxylated alcohol was breaking down via auto-oxidative mechanism in the presence of oxygen, elevated temperatures and trace metals

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Summary

• Wet chemical Analyses – Degradation products not detected

• GC – product quality good• Atomic Absorption

– Fe 0.5ppm– Co 0.6 ppm – Ni < 3 ppm

• Headspace GC – no differences detected

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Conclusions

• Residual ethylene oxide is not the source of explosive gas

• Auto-oxidative breakdown of ethoxylated alcohol is not producing a problem

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Hypothesis 3

• Breakdown of a stabilizer (sodium borohydride) is causing the explosive gas

• BH4- + 4H2O B(OH)4

- + 4 H2

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Conclusions

• Gas in headspace was hydrogen

• Breakdown of stabilizer to produce hydrogen was responsible for the bulged drums and results from excessive water in the product

• Recommend that borohydride be removed from the product

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U.S. Detergent Market

40%

8%5%8%

7%

6%

5%

21%

Tide (P&G) (40%)

Gain (P&G) (8%)

Cheer (P&G) (5%)

Purex (Dial) (8%)

All (Unilever) (7%)

Arm & Hammer(Church and Dwight)(6%)

Wisk (Unilever) (5%)

Other (21%)

C&E News 1/26/04

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VP R&D for detergents at Procter & Gamble?

• Guess who?

• Dr. Grime

• I’m not making this up!

• (C&E News 1/26/04)

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Many Ingredients (such as)

• Bleaching Compounds• Builders• Enzymes• Suds suppressors• Brighteners• Softeners (clays)• Dye Transfer Inhibiting Agents• Surfactants• Fragrances

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Bleaching Compounds

• Percarbonates often used:

O

O

O O O

R R

O

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Bleaching Compounds

S

O

O

O OO

C9H19

Used in Tide and Gain

C &E News 1/26/04

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Builders

To assist in controlling mineral hardness and

to assist in the removal of particulate soils.• Liquid formulations typically comprise from

5% to 30%, by weight, of detergent builder.• Granular formulations typically comprise from

15% to 50% by weight.

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Builders

• Often alkali metal silicates, particularly those having a SiO2:Na2O ratio in the range 1.6:1 to 3.2:1

• Zeolites (aluminosilicates) also commonly used

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• Enzymes can be included in the formulations for a wide variety of fabric laundering purposes, including removal of protein-based, carbohydrate-based, or triglyceride-based stains.