Solubilities in water

The solubility of diethyl ether in water is much higher than that of pentane, but the solubilities of ethers and alkanes approach one another as their molecular weights increase. The ether functional group contributes less to the overall properties of high molecular weight molecules, which resemble alkanes in their solubility. 

Ethers are very soluble in concentrated solutions of acids such as sulfuric acid. Their increased solubihty results from protonadon of the ether oxygen to give an oxonium ion. 

It is an informative exercise to consider these papers in the light of the plots of Xhx (or Nhx) vs Phx for water and other liquids S. 

Rodebush and Ewart declared that whereas the solubility of hydrogen chloride in water is large, it is no more than that predicted for an ideal solution in benzene, a liquid which cannot be coordinated by the hydrogen ion. However, one must contrast this with the data for hydrogen iodide. At 20 C and Phi = 1 atm, the Nhi value for benzene is a little larger than that for water. 

A study of the Nhx vs Phx plots for water at 0°C shows an involvement of HX with the water structure as HX is added, Phx remaining low until Nhx = 0.2 has been added. This effect may be interpreted in a simple way as follows (the regular arrangement given is merely for convenience in delineation)  

About four molecules (H2O units) of water are required to produce what may be deemed to be the maximum concentration of ions per mole of HCl. Further addition of HX causes a more rapid rise in phx. and finally for Phx = 1 atm, at least two (H2O) units are required to hold one HX unit, the second half of the HX being 

You should note that all of these property differences are generalisations. Although ionic compounds tend to have higher melting points than covalent ones, you do get some ionic compounds with low melting 

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C2H4N2O3, NH2CONHCOOH. Unknown in the free state as it breaks down immediately to urea and COi- The NH4, Ba, Ca, K and Na salts are known and are prepared by treating ethyl allophanate with the appropriate hydroxide. The esters with alcohols and phenols are crystalline solids, sparingly soluble in water and alcohol. They are formed by passing cyanic acid into alcohols or a solution of an alcohol or phenol in benzene. The amide of allophanic acid is biuret. Alcohols are sometimes isolated and identified by means of their allophanates. 

C22H23N3O9. An organic reagent used for the detection and estimation of aluminium. It is a brownish-red powder, soluble in water which gives a red lake with aluminium which can be estimated colorimetrically. It can also be used for detecting scandium and indium. 

The amino-acids are colourless, crystalline substances which melt with decomposition. They are mostly soluble in water and insoluble in alcohol. 

Soluble in water and alcohol. It is a very feeble base. It occurs in beets and mangolds and many other plants, and can conveniently be prepared from beet molasses. 

CH2Br COOH. White crystalline solid, m.p. 50"C, b.p. 208 C. Soluble in water and alcohol. Prepared by the action of dry bromine on dry ethanoic acid in presence of small amounts of red phosphorus. Produces sores upon the skin used in chemical syntheses. See Reformatski reaction. 

Isobutyric acid, dimethylacetic acid, 2-methylpropanoic acid, (CHjjjCH COOH, colourless syrupy liquid with an unpleasant odour b.p. 154°C. Prepared by oxidation of 2-methylpropanol with K2Cr207 and H2SO4. Salts soluble in water. Used in alkaline solution for sweetening gasoline. 

H2N (CH2]5 NH2. a syrupy fuming liquid, b.p. 178-180 - C. Soluble in water and alcohol. Cadaverine is one of the ptomaines and is found, associated with pulrescine, in putrefying tissues, being formed by bacterial action from the amino-acid lysine. It is found in the urine in some cases of the congenital disease cystinuria. The free base is poisonous, but its salts are not. 

Chromium(IH) chloride, chromic chloride, CrClj. Violet solid (Cr plus CI2, hydrate plus SOCI2) only soluble in water in presence of Cr. Forms many complexes including the hydrates [Cr(H20)6]Cl3 - violet, [Cr(H20)jCl]Cl2,H20 - green, [Cr(H20)4Cl2]Cl,2H20 - green. 

M.p. 222 C. Soluble in water, insoluble in alcohol. Citrulline is an intermediate in the urea cycle in the excretion of excess nitrogen from the body. 

NH4][ON(NO)C6Hj]. a reagent originally suggested for use in the detection of Cu but now used for the separation of Fe/Ti and Zr which it precipitates from acid solutions. Cupferron is a brownish-while crystalline substance, soluble in water. 

HSCH -CHNHj-COjH. Cysteine is a reduction product of cystine. It is the first step in the breakdown of cystine in the body, one molecule of cystine splitting to give two molecules of cysteine. Cysteine is soluble in water but the solution is unstable, and is reoxidized to cystine. 

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