Organic base

In general usage, the terms alkali and caustic are synonymous with the term base, and just as basic describes the properties of a base, alkaline describes the properties of an alkali. However, caustic is often used to specify a substance corrosive to metals, particularly aluminium, zinc, and tin for example, the inorganic base caustic soda syn. sodium hydroxide and caustic potash syn. potassium hydroxide. Organic bases include the amines. 

The strength of an acid or alkali in aqueous solutions is measured by its ability to dissociate (divide into its pair of ions). The unit of measurement (pH) indicates the acidic or alkaline strength compared to that of water. Mathematically, pH is the logarithm of the reciprocal hydrogen ion concentration, or logiol/[H ]. In pure water (H2O) according to the equation 

Corrosives may act directly on contact as corrosive liquids or solutions. They may also be generated by 

The action of corrosion depends on the chemical and the substrate attacked, but in general there are three possible types of corrosion  

Direct contact with an acid or base in which oxidation or reduction occurs according to electrochemical principles. 

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These compounds can be malodorous as in the case of quinoline, or they can have a plecisant odor as does indole. They decompose on heating to give organic bases or ammonia that reduce the acidity of refining catalysts in conversion units such as reformers or crackers, and initiate gum formation in distillates (kerosene, gas oil). 

The s)mthesis of zeolites is traditionally performed by crystallisation from a sol-gel mixture comprising reagents such as silica, sodium aluminate, sodium hydroxide and water. Another key component of the sol-gel mixture is a base whose main role is to regulate the pH of the mixture. If an organic base is used then a templating effect may also be observed... 

In the separations (2) and (3) above, it is often advisable to dissolve the original mixture in a water-insoluble solvent. Select a solvent which will dissolve the entire mixture, and then shake the solution with either (i) dil. NaOH or (ii) dil. HCl. Separate the aqueous layer, and to it add either (i) dil. HCl or (ii) dil. NaOH to liberate the organic acid or the organic base, as the case may be. The non-aqueous layer now contains the neutral component. Reextract this layer with either (i) dil. NaOH or (ii) dil. HCl to ensure removal of traces of the non-neutral component. 

Organic bases (amines) Solid potassium or sodium hydroxide quicklime barium oxide. 

Solubility in 5 per cent, hydrochloric acid. Add the acid to 0 10 g. of the solid or 0 20 ml. of the liquid in quantities of 1 0 ml. until 3 0 ml. have been introduced. Some organic bases (e.g., p-naphthylamine) form hydrochlorides that are soluble in water but are precipitated by an excess of acid if solution occurs at any time, the unknown is assigned to Group IV. If the compound appears insoluble, remove some of the supernatant liquid by means of a dropper to a semimicro test-tube (75 X 10 mm.), and add 5 per cent, sodium hydroxide solution until basic and observe whether any precipitate is produced the formation of a precipitate will place the compound in Group IV. 

Because tertiary alcohols are so readily converted to chlorides with hydrogen chlo nde thionyl chlonde is used mainly to prepare pnmary and secondary alkyl chlondes Reactions with thionyl chlonde are normally carried out m the presence of potassium carbonate or the weak organic base pyndme... 

Acyl chlorides react with carboxylic acids to yield acid anhydrides When this reaction is used for preparative purposes a weak organic base such as pyridine is normally added Pyridine is a catalyst for the reaction and also acts as a base to neutralize the hydrogen chloride that is formed... 

Polythiophene can be synthesized by electrochemical polymerization or chemical oxidation of the monomer. A large number of substituted polythiophenes have been prepared, with the properties of the polymer depending on the nature of the substituent group. Oligomers of polythiophene such as (a-sexithienyl thiophene) can be prepared by oxidative linking of smaller thiophene units (33). These oligomers can be sublimed in vacuum to create polymer thin films for use in organic-based transistors. 

Cmde products from organic-based processes contain organic impurities which affect color, odor, surface tension, and stabiUty, and ate normally pretreated to reduce the carbon content before final purification and concentration by various distillation methods. 

Resorcinol or hydroquinone production from m- or -diisopropylben2ene [100-18-5] is realized in two steps, air oxidation and cleavage, as shown above. Air oxidation to obtain the dihydroperoxide (DHP) coproduces the corresponding hydroxyhydroperoxide (HHP) and dicarbinol (DC). This formation of alcohols is inherent to the autooxidation process itself and the amounts increase as DIPB conversion increases. Generally, this oxidation is carried out at 90—100°C in aqueous sodium hydroxide with eventually, in addition, organic bases (pyridine, imidazole, citrate, or oxalate) (8) as well as cobalt or copper salts (9). 

Primary amides condense with hydroxybenzaldehydes in a manner similar to amines. This reaction is often conducted in the presence of sodium acetate or an organic base such as pyridine. For example, the reaction of sahcylaldehyde and propionamide produces sahcyhdene propionamide (58). 

Halides. Indium trichloride [10025-83-8] InCl, can be made by heating indium in excess chlorine or by chlorinating lower chlorides. It is a white crystalline soHd, deUquescent, soluble in water, and has a high vapor pressure. InCl forms chloroindates, double salts with chlorides of alkaLi metals, and organic bases. 

A related compound, the peroxohydrate of melamine, C H N, was made by Peroxid-Chemie but discontinued in the 1980s. In addition, a diperoxohydrate of the organic base DABCO is recogni2ed and has been used as an oxidant in organic chemistry, but such a system has been known to explode (101). 

Because almost any diacid can be leaddy converted to the acid chloride, this reaction is quite versatile and several variations have been developed. In the interfacial polymerization method the reaction occurs at the boundary of two phases one contains a solution of the acid chloride in a water-immiscible solvent and the other is a solution of the diamine in water with an inorganic base and a surfactant (48). In the solution method, only one phase is present, which contains a solution of the diamine and diacid chloride. An organic base is added as an acceptor for the hydrogen chloride produced in the reaction (49). Following any of these methods of preparation, the polymer is exposed to water and the acid chloride end is converted to a carboxyhc acid end. However, it is very difficult to remove all traces of chloride from the polymer, even with repeated washings with a strong base. 

Fig. 6. CopiArt proofing system (a) stmcture of positive working system, where A = organic base, = coupler, Q = microcapsule, and = diazo compound and (b) stmcture of negative working system, where A = photoinitiator, = leuco dye, Q — microcapsule, and...

Ca.ta.lysts, A small amount of quinoline promotes the formation of rigid foams (qv) from diols and unsaturated dicarboxyhc acids (100). Acrolein and methacrolein 1,4-addition polymerisation is catalysed by lithium complexes of quinoline (101). Organic bases, including quinoline, promote the dehydrogenation of unbranched alkanes to unbranched alkenes using platinum on sodium mordenite (102). The peracetic acid epoxidation of a wide range of alkenes is catalysed by 8-hydroxyquinoline (103). Hydroformylation catalysts have been improved using 2-quinolone [59-31-4] (104) (see Catalysis). 

Property Organic base sheet Type I Type II Type I Type II... 

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