Equivalent of a base

By Titration.—A crystalline salt of the base with some mineral or organic acid is prepared and purified, and the acid present in a weighed 

Bast s Method.—This method is easily carried out, using an ordinary thermometer graduated in 0-5°, and gives results accurate to within 5%. It is not applicable to compounds which are not freely soluble in camphor or which react therewith or which decompose under the conditions. (B 55, 1051, 3727.) 

The method depends on the very high molecular constant (400) shown by camphor. 

The Molecular Depression Constant (K) for camphor is determined by using a substance of known molecular weight, say, naphthalene, and applying the following formula  

The determination of this constant should precede that of each molecular weight. 

---

CjHiaNO, [Mc3NCH= CH2] OH. A liquid forming a crystalline trihydrate, It is present free and combined in brain and other animal and vegetable products and is formed as a product of putrefaction of lecithin. It can be prepared synthetically from choline and decomposes easily to trimethylamine. neutralization, heat of The amount of heat evolved when I g equivalent of an acid is neutralized by 1 g equivalent of a base. For strong acids and strong bases in dilute solution the only reaction which occurs is H -h OH ---> H2O and the heat of neutral-... 

Trinitrochlorobenzene (76) treated with 1,3-propanedithiole and one equivalent of a base provided compound 479 and its treatment with additional base was reported to provide only small yields of benzodithiepine 480 (74CC672). A more recent work described that good yield (80%) of 480 was obtained by a treatment of 479 with triethylamine in benzene (76ZOR844). Similar treatment of 81 provided first spiro complex 481, which refluxed in acetone in the presence of triethylamine gave good yield of the denitrocyclization product 482 (Scheme 77) (92ZOR1496). 

Esters, like aldehydes and ketones, are weakly acidic. When an ester with an a- hydrogen is treated with 1 equivalent of a base such as sodium ethoxide, a reversible carbonyl condensation reaction occurs to yield a /3-keto ester. For example, ethyl acetate yields ethyl acetoacetate on base treatment. This reaction between two ester molecules is known as the Claisen condensation reaction. (We ll use ethyl esters, abbreviated "Et," for consistency, but other esters will also work.)... 

The equivalent of a base is that mass of it which contains one replaceable hydroxyl group, i.e. 17.008 g of ionisable hydroxyl 17.008 g of hydroxyl are equivalent to 1.008 g of hydrogen. The equivalents of sodium hydroxide and potassium hydroxide are the mole, of calcium hydroxide, strontium hydroxide, and barium hydroxide half a mole. 

What volume of 1.23 N H, P04 will 2.40 equivalents of a base neutralize completely Explain why you did not need to know the formula of the base to answer this question. 

Enthalpy of Neutralisation It is defined as the enthalpy change accompanying the neutralisation of one gram equivalent of a base by an acid in dilute solution at that temperature, e.g.,... 

Obviously, the elimination goes through a-chloroenamines, which have themselves become useful synthones 70,71). Using two or more equivalents of a base, ynamines are formed in a straightforward manner (38, 39) 66,72). 

Indok synthesis. Gassman and van Bergen have used a modification of the above-mentioned procedure for synthesis of 2-substituted indoles from anilines. The aniline IS treated as above with a chlorinating reagent at — 65° and then an equivalent of methyl-thio-2-propanone at the same temperature. An equivalent of a base (usually triethyl-amine) is added. Workup affords the indole derivative (2) in 60-70% yield. The thio-methyl group is removed with Raney nickel (>70% yield). The keto sulfide can be varied thus nse of methyl phenacyl sulfide [CH3SCH2C(=0)C5H5]4 in the synthesis leads to 2-phenylindoles. 

Why is 1 equivalent of a base such as NaOH required for the reaction between an amine and an anhydride to go to completion What would happen if no base were present ... 

For acid-base reactions, an equivalent of an acid is the quantity that supplies 1 mol of H and an equivalent of a base is the quantity reacting with 1 mol of H ... 

The reactions are often carried out in an alcohol at room temperature, and the amidine is generally liberated from its hydrochloride by treatment with one equivalent of a base. Reaction times are short and the yields are high. It is also possible to employ isoureas, isothioureas and guanidines as the amidine component. The unstable 2-phenylisoureas (R3 = OPh) are prepared in situ. 

Normality is another unit of concentration that is sometimes used, especially when dealing with acids and bases. The use of normality focuses mainly on the H and OH" available in an acid-base reaction. Before we discuss normality, however, we need to define some terms. One equivalent of an acid is the amount of that acid that can furnish 1 mol ofH ions. Similarly, one equivalent of a base is defined as the amount of that base that can furnish 1 mol ofOH ions. The equivalent weight of an acid or a base is the mass in grams of 1 equivalent (equiv) of that acid or base. 

Neutralization reaction Equivalent of an acid Equivalent of a base Equivalent weight Colligative property... 

Equivalent of a base the amount of base that can furnish one mole of hydroxide ions (OH ). 

The equivalent of an acid is that quantity which will form a neutral salt with one equivalent of a base and, in like manner, the equivalent of a base is that (quantity which forms a neutral salt with one equivalent of an acid. 

The heat of neutralisation is the amount of heat evolved when one gram equivalent of an acid is neutralised by one gram equivalent of a base to give one gram equivalent of a neutral salt. Thus, in dilute solution, an acid or base is considered to be completely ionised, and the neutralisation reaction is Na + ) + OH(-) + H( + ) + Q(-) ==> Na(+) + a(-) + P... 

It was found in this way that in the presence of an excess of silica sol, no free aluminum hydroxide is precipitated by the addition of a base to aluminum salt solutions. Instead, at an acidity level higher (ca. 1 pH unit lower) than corresponds to the precipitation of aluminum hydroxide, the primary products of hydrolysis of aluminum ions are consumed by the interaction with silica sol particles. One equivalent of acid is produced for each atom of aluminum consumed in this reaction, indicating the formation of an aluminosilicic acid, so that ultimately four equivalents of a base are required to reach neutrality for each aluminum atom present. AH aluminum ions are consumed by this reaction if an excess of silica sol is present (see Fig. 14). No visible precipitate is formed and the insoluble alkali salt remains in the sol form it can be converted to gel or coagulated... 

An equivalent is defined according to the type of reaction being examined, but the number of equivalents of solute is always a whole number multiple of the number of moles of solute, and so the normality of a solute is always a whole-number multiple of its molarity. An equivalent is defined so that one equivalent of one reagent will react with one equivalent of another reagent. For acid-base reactions (see competency 7), an equivalent of an acid is the quantity that supplies 1 mol of and an equivalent of a base is the quantity reacting with 1 mol of... 

What is one equivalent of an acid What does an equivalent of a base represent How is the equivalent weight of an acid or a base related to the substance s molar mass Give an example of an acid and a base that have equivalent weights equal to their molar masses. Give an example of an acid and a base that have equivalent weights that are not equal to their molar masses. What is a normal solution of an acid or a base How is the normality of an acid or a base solution related to its molarity Give an example of a solution whose normality is equal to its molarity, and an example of a solution whose normality is not the same as its molarity. 

---