Detergent hydrophobic part

Phospholipids are detergents they have a hydrophobic part (the fatty acid tail) and a hydrophilic part (the head) (Fig. 3-1). The phospholipids... 

If the virus is treated with proteolytic enzymes the fuzzy layer formed by the viral spikes is removed (Osterrieth, 1965 Compans, 1971 Gahm-berg et al, 1972 Sefton and Gaffney, 1974 Utermann and Simons, 1974). Remnants of both El and E2 are left in the bilayer. These have a hydrophobic amino acid composition, and are soluble in lipid solvents such as chloroform-methanol. The amphiphilic nature of the spike protein is also evident from its capacity to bind Triton X-100 (0.6 g/g protein) which binds to the hydrophobic part to form a water-soluble protein-detergent complex (Simons et al., 1973a). The ability of amphiphilic proteins to bind Triton can be used to separate them from hydrophilic proteins using an extraction procedure recendy described... 

The most useful characteristic of the micelle arises from its inner (alkyl chain) part (Figure 3.17). The inner part consists of alkyl groups that are closely packed. It is known that these clusters behave as liquid paraffin (Cn H2n+2). The alkyl chains are thus not fully extended. Hence, one would expect that this inner hydrophobic part of the micelle should exhibit properties that are common to alkanes, such as ability to solubilize all kinds of water-insoluble organic compounds. The solute enters the alkyl core of the micelle and it swells. Equilibrium is reached when the ratio between moles soluteimoles detergent is reached corresponding to the thermodynamic value. 

For good detergency the length of the ethenoxy chain should carefully balance the hydrophobic part of the molecule. In the above example, from eight to ten such groups appear to be optimum. The ethylene oxide for these products comes from petroleum ethylene, either by direct oxidation or decomposition of ethylene chlorohydrin (17). 

Soluble amphiphiles are also known as detergents, tensides, or surfactants. Perhaps the most descriptive of these words is the word surfactant, which is a contraction of the phrase surface active agent . The term soap is usually restricted to the alkali metal salts of long-chain fatty acids (Table 12.1). The term amphiphile indicates that one part of the molecule likes a certain solvent while the other part likes another solvent and the two solvents are immiscible. Usually one solvent is water and the water-loving part is called hydrophilic. The other part is hydrophobic. It does not like to be in water and prefers to be in an oily environment or air. The hydrophobic part usually consists of a long, straight alkyl chain (CH3(CH2) c i nc = 8-20). For special applications the hydrocarbons might be completely or partially fluo-rinated. 

Surface-active agents, or surfactants, all share interesting physicochemical characteristics at surfaces and interfaces. Surfactants (detergents and dispersants) are long chain hydrocarbons with polar headgroups which are called dipoles. Surfactants are molecules which consist of two well defined parts one which is oil-soluble hydrophobic and another which is water-soluble hydrophilic. The hydrophobic part is non-polar and usually consists of aliphatic or aromatic hydrocarbons. The hydrophilic part is polar and interacts strongly with water. 

An electron donor or acceptor site is usually needed in organic synthons for covalent synthesis. The covalent connection of both leads to a new molecule in an essentially irreversible synthetic reaction. Organic synkinons for non-covalent synkinesis usually contain a hydrophilic and a hydrophobic part and/or proton donor or acceptor sites. Non-covalent connection of such amphiphiles leads to a molecular assembly in a reversible synkinetic reaction. Amphiphiles are not only surface active molecules ( surfactant, detergent ), but much more important, they create surfaces. This becomes particularly evident in microemulsions and in suspensions of vesicles and micellar fibres, but is also true in nanoholes and pores, on monolayer surfaces and for many other supramolecular structures. 

Nonionic surfactants are one of the most important and largest surfactant groups. They are amphiphilic molecules composed, in most cases, of poly(ethylene oxide) (PEO) blocks as the water-soluble fragment and fatty alcohols, fatty acids, alkylated phenol derivatives, or various synthetic polymers as the hydrophobic part [1], This class of surfactants is widely used as surface wetting agents, emulsifiers, detergents, phase-transfer agents, and solubilizers for diverse industrial and biomedical applications [2],... 

Chemically they are just opposite to the anionic surfactant and hence are unsuitable for use as detergents or wetting agents. The hydrophobic part of the molecule of the cationic surfactant is the organic ammonium or pyridinium compound containing one or more hydrophobic residues as shown below ... 

The main component of detergents is surfactant. The eldest known surfaetant is soap. Chemically soap is an alkaline salt of fatty acid. Characteristic of soap (and surfactant) is the molecular structure consisting of apolar - hydrophobic - part (fatty acid) and a polar - hydrophilic - part (-COONa), causing surface activity in aqueous solution. 

The development of detergents based on the combination of fats and oils as the hydrophobic part and carbohydrates as the hydrophilic part gained importance with the discussion to reduce the petrochemical (fossil) resources in detergent production [10]. Important criteria for the use of these derivatives are price, quality, and availability of the raw material, and the processing costs [11]. 

---