HISTORY OF DETERGENT
The first detergents were used by the man most likely the clays and, after the discovery of fire, the plant ash.
The ashes were used for cleaning purposes until the early twentieth century. The laundresses were using wood ash cakes, mixed with water and filtered with cloths or bags after decant impurities.
Since the ash is rich in carbonates, silicates, sulfates (as well as phosphates and chlorides) of alkali metals and alkaline earth washerwomen doing this "leachate" they were merely extracted from the ashes of the alkali-soluble salts.
The cleansing action of water they used
was therefore due to their "alkalinity" and the presence of substances that behaved (albeit milder) as additives in addition to today
modern detergents (eg. agents anti back dirt).
's real origin of soap is not known with precision, even if the technology
to build it had been known since ancient times. The alkaline solution obtained from ash legnovenivano, in fact, used for the saponification tallow or waste vegetable oils or animal fats.
early as 600 BC the Phoenicians were unable to obtain a material boiling fat curdled goat's milk with extract of wood ash. The Egyptians instead mixed with an alkali
oil resulting in a kind of soap. This method was also known in Palestine so that the use of leaching is mentioned in the Bible (Malachi Chapter 3 of
Bible: "But who may abide the day of his coming? Who shall stand when he appears?
He is like refiner's fire and like the 'soap suds). The Greeks used it for washing saponify sodium vegetable oils, however, as throughout the East resorted to the ground or to a fulling soap for washing wool.
The Romans finally used potassium for washing soap from animal fats (such as fat
goat). These precursors of the soaps were in fact the plasters used mainly as cosmetics.
The use of soap detergent to do, in fact, began to spread only in the eighteenth century. It should be noted, however, the basis of their production there was the same
reaction that nowadays the modern manufacturers of soap applied on an industrial scale.
LAND
from Follonica and Saponara
for cleansing fabrics (wool) is applied (as above), to 'so-called clay smettica, which has the curious property of absorbing energy and fatty oils weakly adherent to the fabrics and which can then be easily removed with water (in fact, this clay does not form a "dough", but breaks down into fine powder). The clay
smettica is best known as a land of fulling (or Stone off the ground, or the soldier).
The reason for the curious property that shows fat clays nell'adsorbire
resides in their chemical structure characterized by two tetrahedral layers containing silicon and oxygen atoms which is contained in an octahedral layer consists of aluminum and oxygen.
The vertices of the tetrahedra are directed towards the center of the structure whose top and bottom parts are made of oxygen atoms coplanar. Between two adjacent structural units can be inserted foreign molecules such as water or organic molecules. The molecules trapped in the lattice causes an expansion of that which is
reversible as long as you can move the molecules incorporated.
Another alternative for cleaning tissue consisted substances, saponins, derived from particular types of plants such as:
1) the Sapindus surinamensis (belonging to the family of Sapindaceae) known as tree soap and is particularly common in the Antilles. The aril of the fruit and roots of this plant
are particularly rich in saponins and were used by American Indians as soap;
2) the Saponaria officinalis (belonging to the family of cariofillacee)
perennial grass species common in Europe and Asia, 30 to 60 cm high. The leaves are bright green, oval-lanceolate. The rhizome of soap, and to a lesser extent the whole plant,
contains a significant percentage of saponin which produces abundant foam, before the spread of synthetic detergents, from soap powder to wash it drew a great
(the name comes from the Latin sapo, soap detergent to remember the properties of the plant).
But what are the saponins?
Saponins are glycosides, ie, molecules consisting of a sugar and a
part "glucose" said aglycone (sugar-free ") to the sugar linked via an ether bond. The aglycone of saponin is usually a steroid or a triterpene sapogenins and is called, while sugar is generally made up of glucose, galactose, or a pentose, or a methylpentane. Since the sugar in the bond can be above or below the plane of the molecule, called beta-glucosides
those in which the above and other-glucosides. Saponins compounds are generally colorless and amorphous (hardly crystallizable), soluble in water, which modifies the surface tension (to a lesser extent of soap), making it capable of generating foam and emulsifying insoluble substances such as oils (oil-in form water), the
hydrocarbon resins. Enter into the composition of some washing, shampoo, shaving soaps, liquid fire extinguishers, etc.. The link between sugar and aglycone can be split to
acid hydrolysis or enzyme action. Hydrolysis free one, or more often several monosaccharides, often next to a crystallizable sapogenins. ZLE Figures 1 and 2 show an example
Dioscina contained in the saponin of Dioscorea Tokoro
belonging to the family of Dioscoreaceae and the corresponding aglycone (sapogenins) the diosgenin.
The first industrial production of soap - the hydrolysis of glicereridi
The reaction that underlies the production of soaps and hydrolysis of the glycerides.
Glycerides are fatty or better, chemically speaking, of triesters (more often called triglycerides or triacylglycerols) from carboxylic acids and glycerine.
first industrial production using the waste of olive oil for soap which first arose in areas planted with olive trees. Later, in medieval times, other raw materials such as coconut oil, palm and other vegetable fats and animals imported from India, Australia and South Africa are becoming increasingly important and soap, they moved towards the port area most important in southern Europe, from the beginning Genoa and Marseille, then Savona and Venice.
Even in England, the soap industry developed rapidly thanks to new manufacturing processes of sodium carbonate
Solvay method according to the famous (in the industrial production of soda ash was the forerunner of soda, raw material for the manufacture of soap).
was Michel-Eugène Chevreul (1786-1889) the first chemist to recognize in 1823 that the
soap making process leading to the formation of glycerol and that the material
soap was made of salt ' fatty acid and fat by acid as had been believed before him. His work is the famous "Recherches chimiques sur les corps gras d'
orgine animal."
In modern industry soap, the fat is hydrolyzed by heating with sodium hydroxide, while the precipitation of soap is favored by adding salt. The liquid is recovered
distilled glycerin, which is widely used in the pharmaceutical and cosmetics for its moisturizing properties (due to the hydroxyl groups-OH that bind
hydrogen bonds with water and prevent the ' evaporation).
A soap is, therefore, consists of a 'polar ends (- COO.) Soluble in water and a hydrocarbon chain (R), hydrophobic and soluble in nonpolar compounds (eg. Oils);
quest 'last, as already mentioned, can contain from 3 (C3) to 18 (C18) carbon atoms, however, are usually preferred chains with a number of carbon atoms
between 12 and 18. Chains poorly soluble soaps produce too long, otherwise you will get irritating soaps and detergents scarce property.
a soap solution, then, can not be considered a real solution in which the molecules of solute and wander separately on their own, but rather a "dispersion": The soap is in fact dispersed in the form of spherical clusters, micelles , each of which can contain hundreds of molecules of soap.
The importance Soap is its ability to emulsify fat nature of the dirt, forming micelles around the fat: the non-polar hydrocarbon part of the soap,
fact, dissolve in polar substances such as a drop of oil, while the 'is directed towards the polar ends of water (a polar solvent).
synthetic detergents
The first synthetic detergent was obtained by Jean Baptiste Dumas (1800-1884) and Eugène Melchior Peligot (1811-1890) in 1836. It was a sulfuric dell'acol cetyl ether.
However, even five years ago Edmond Fremy (1814-1894) was sulfonate various oils. During this period
Chevreul explained the mechanisms of soap making soap with a strong boost to enhanced inter alia by the process
just put in 1790 by Nicolas Leblanc (1742-1806) for the preparation of the carbonate sodium (a precursor of caustic soda).
The scarcity of fat during the First World War (1914-1918) led to the search for synthetic detergents.
One of the first, was the Nekal, alkyl sulfonate, produced in Germany in 1916. Alkyl group was composed of three carbon atoms (propyl group) or 4 carbon atoms (butyl group).
The detergent power was not high, but the synthesis of this compound gave the
industry of synthetic detergents. In 1930 H. Th Boehme obtained sulfonated lauryl alcohol, put on the market for the first time under the name of CANDIDOL and in Italy with
Lauryl name. The sulfonated lauryl alcohol, prepared by hydrogenation of esters of fatty acids in coconut oil, was equipped with an excellent dispersing power,
emulsifier, detergent and foam and did not give rise to precipitation in the presence of hard water ( words its calcium and magnesium salts were soluble, contrary to
the case for soap).
The only drawback was the lack of stability in
acid.
In 1942, the Americans, not starting from natural fatty acids, but by petroleum hydrocarbons prepared the first completely synthetic detergents: the alkylaryl sulphonates
Sodium thus paving the way for the synthesis of various detergents.
Modern detergents, or rather in terms of chemicals, surfactants are divided into four different classes:
1) Anionic: are so called because the water is present in the form ion with negative charge. Among these the best known are the alkylbenzene (or more generally arylsulphonic alkyl), the alkyl sulphate, and alchileterisolfati.
The former are produced by reaction of benzene in the presence of a suitable acid catalyst with an olefin, eg. the so-called dodecene. You get a dodecyl benzenes that
treated with sulfuric acid and then with soda, giving rise to sodium dodecyl benzene sulphonic acid (found in dishwashing detergents and laundry).
is to be noted that the first alkyl benzenlsolfonati
(ABS) showed poor biodegradability marketed as presented
a highly branched alkyl chain. The bacteria is, in fact, easier to degrade, metabolizing linear chains rather than chains in which the carbon atoms are not
linked to hydrogen atoms. For this reason, currently used are straight chain alkylbenzene (and are marked with the initials LAS).
2) Cationic Surfactants: Cationic surfactants are so called as free compounds in solution with a positive electric charge (cations).
Their cleaning power is limited but the peculiarity of this type of surfactant is antibacterial, in fact adhere to negatively charged surfaces such as
membranes of many bacteria.
usually consist of quaternary ammonium salts, but in some cases, the polar head is made of a pyridinium salt, the counter-ion, however, can be chloride or bromide.
These types of surfactants can include benzyl dimethyl benzyl ammonium chloride and cetyl trimethyl ammonium bromide.
This class of surfactants as well as bactericides are used as for example in anti-static fabric softeners, which impart the positive charges on the fibers which are
reject, taking on a hazy and yet leaders are treated piùsoffici to the touch.
The same mechanism is exploited for the production of hair conditioner, the active ingredient in these products is always a kind of cationic surfactant.
There are several processes for the production of quaternary ammonium compounds, one of the simplest is the reaction between a tertiary amine with a halide.
More specifically, the quaternary compound which is the most common lauryl dimethyl benzyl ammonium chloride (one of the most common bactericides on the market), is prepared from
benzyl chloride and lauryl dimethyl amine
This a substitution reaction Sn2 called
3) Nonionic surfactants: this type of surfactants are so called because they do not ionize in aqueous solution.
The most important is certainly the alcohol ethoxylates (obtained by ethoxylation of higher alcohols) with general formula:
CH3-(CH2) n-CH2-(O-CH2-CH2) m-OH where n
generally varies between 10 and 13, while the number of oxyethylene groups varies between 3 and 9.
properties of alcohol ethoxylates are highly dependent on the values \u200b\u200bof m and n. For example, alcohols which have more than 50% by weight of oxyethylene groups are
generally soluble in water, while those with less than 50% by weight are usually soluble in oil. The alcohol ethoxylates have extensive application in the field of detergency
thanks to their particular compatibility (greater than anionic) to other components and additives used in detergents.
remember, moreover, alkylphenol ethoxylates latter are obtained by condensation of ethylene oxide or propylene with an alkyl phenols (such as nonylphenol) and have excellent emulsifying properties, detergents, wetting agents etc.. The use of alkyl phenols, however, has been gradually declining in recent years because of their
poor biodegradability.
Among the nonionic surfactants are worth mentioning because of their natural origin and high biodegradability, the ALCHILPOLIGLUCOSIDI (APG) obtained from the reaction of a sugar (usually glucose) and a fatty alcohol.
For glucose is often part of starch (a polysaccharide hydrolyzed to glucose) derived from grain, while alcohol can be naturally derived (eg, coconut fatty acids) or synthetic (ethylene).
Sugar is the hydrophilic part of surfactant, while the hydrophobic alkyl chain is formed by the length of which affected the chemical and physical
dell'alchilpoliglucoside: short chains provide products with excellent wetting properties, whereas long-chain associated high foaming power and remarkable ability
detergent ..
4) amphoteric or zwitterionic surfactants: take this name as a water-free compounds with both electric charges (positive and negative) may therefore play action
acidic or basic depending on the pH of the solution .
Characterized by high foaming power by virtue of the fragments present in the molecule carboxylic
is stable in acidic that alkaline cleaners are compatible with cationic, nonionic and anionic.
Among such surfactants include the betaines can be used for example in the bubble bath because of their characteristics eudermic, are both excellent foam stabilizers.
A also belong to this class of surfactants and imidazoline propionates, are essential components in the formulations of degreaser for hard surfaces, such as the dipropionate also manifest anti-corrosive properties against ferrous materials.
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