PROPERTIES OF ETHERS

Ethers are polar molecules. Compared to alcohols, ethers have very low boiling points mainly because they cannot form hydrogen bonds (intermolecular). The boiling points of ethers are close to alkanes of comparable weights. Ethers are not very reactive. 

Most ethers, particularly the dialkyl ethers, react with atmospheric oxygen in a radical-chain process to form unstable, shock-sensitive, and explosive per- 

Physical properties Dimethoxy Diethoxy methane methane Mono glyme Di- glyme Tri- glyme Tetra- glyme Ethyl glyme Ethyl diglyme Butyl glyme 

Solubility solvent in water (g/100 g) Complete 4.2 Complete Complete Complete Complete 20.3 Complete 0.3 

Solubility water in solvent (g/100 g) Hansen solubility parameters Complete 1.3 Complete Complete Complete Complete 3.3 Complete 1.4 

Source data compiled from product literature of the Hoechst Celanese Corporation, and the Ferro Corporation, Grant Chemical Division. 

---

It IS instructive to compare the physical properties of ethers with alkanes and alcohols With respect to boiling point ethers resemble alkanes more than alcohols With respect to solubility m water the reverse is true ethers resemble alcohols more than alkanes Why" ... 

Combustion in air is of course a chemical property of ethers that IS shared by many other organic compounds Write a balanced chemical equa tion for the complete combustion (in air) of diethyl ether... 

A second dangerous property of ethers is the ease with which they undergo oxi dation in air to form explosive peroxides Air oxidation of diisopropyl ether proceeds according to the equation... 

Until the 1950s ether carboxylates were almost in very limited amounts in the textile industry. It was only in 1957 [9] that the first ethercarobxylates were mentioned, in combination with other surfactants such as alkyl sulfates and ether sulfates, for use in shampoos. In spite of the special properties of ether carboxylates, their use was low in the industry as well as in cosmetics at that time. This was also due to the fact that at that time properties such as toxicity, biodegradability, and mildness to the skin did not have the high priority they do now. 

However, in a 1963 lecture it was pointed out that ether soaps had special characterics [10], i.e., good biodegradability, mildness to the skin, and less corrosiveness to metals, and that we should expect these soaps to play an important role in the future. However, the real breakthrough of the ether carboxylates came in the 1980s, when environmental properties of surfactants became even more important along with other properties of ether carboxylates such as chlorine stability, anticorrosiveness, lime soap dispersibility, electrolyte stability, alkaline stability, and so on. 

A major part of the physicochemical properties of ether carboxylic acids can be ascertained from the structure by comparing it with that of fatty acid soap, ethoxylated alcohol, and other anionics [64,73] ... 

Several investigators therefore compared the properties of ether carboxylates with different fatty chains and ethoxylation degrees with soaps based on different fatty chains [2,51,52,57,59,61,62,64,65]. 

The surface-active properties of ether carboxylates have been compared with soaps as well as with those of nonionic and anionic surfactants in addition, the influence of fatty chain and degree of ethoxylation has been investigated. 

The foam properties of ether carboxylates are dependent on the fatty chain and ethoxylation degree. High foaming effect can be achieved with a longer fatty chain, with an optimal effect using C12-C14 chain, and a relatively short EO degree, with an optimum at about 4.5 EO [10,51,57] (Table 8). 

To use the physicochemical properties of ether carboxylates in the practice for product development, Meijer [64] made some working schemes which can be used as guidelines (Tables 10 and 11). 

Fuel octane number, 72 392, 395 Fuel oil, as a petroleum product, 78 669 Fuel oil additives amine oxides, 2 473 fatty amines, 2 534 Fuel properties, of ethers, 70 574 Fuel sources, chemical industry, 70 136 Fuel spills, hydrazine, 73 588 Fuels production, hydrocracking for, 76 842-844 Fuel sulfur, 70 54... 

Table 10.2 Properties of ethers blended in diesel and in mixtures of biodiesel and diesel.

Table 1.7 describes some physical properties of ethers. Like alcohols, ethers are polar molecules. Ethers, however, cannot form hydrogen bonds with themselves. The physical properties of ethers depend on these characteristics. 

In this section we examine some of the physical properties of ethers. 

The spectroscopic properties of ethers are unexceptional. Like alcohols, they have no electronic absorption beyond 185 nm the important infrared bands are the C—O stretching vibrations in the region 1000-1230 cm-1 their proton nmr spectra show deshielding of the alpha hydrogens by the ether oxygen (6Hcaoc 3.4 ppm). The mass spectra of ethers and alcohols are very... 

Anesthetic properties of ether were first used by Dr. Crawford W. Long as he surgically removed two tumors from the neck of an anesthetized patient. 

An important property of ethers of phosphoric acids is that they can mix with many insecticides, fungicides and acaricides which do not contain phosphorus, while their activity is preserved. These mixtures are used to... 

As with other functional groups, we will discuss how ethers are formed and how they react. Ethers (other than epoxides) are relatively unreactive, however, and they are not frequently used as synthetic intermediates. Because they are stable with many types of reagents, ethers are commonly used as solvents for organic reactions. In this chapter, we consider the properties of ethers and how these properties make ethers such valuable solvents. 

The special properties of ethers (polarity, lone pairs, but relatively unreactive) enhance the formation and use of many reagents. For example, Grignard reagents cannot form unless an ether is present, possibly to share its lone pairs of electrons with the magnesium atom. This sharing of electrons stabilizes the reagent and helps keep it in solution (Figure 14-4). 

---