Cyclohexane, acidity

Look for the presence of these compounds by ASTM D-664-A or through specific analytical techniques used to identify cyclopentane/cyclohexane acids. 

ALKANES Methane Decane Undecane Hexadecane Heptadecane Octadecane Nonadecane Eicosane Heneicosane Docosane Tricosane Pentacosane Hexacosane Octacosane Triacontane Dotriacontane Trimethyl cyclohexane Dimethyl cyclohexane ACIDS... 

We noted in Chapter 10 two rather symmetrical arrangements of 7 nearest neighbours found in oxy- and fluoro-compounds of transition metals, namely, pentagonal bipyramidal (ZrF "), and monocapped trigonal prism (NbF ). The ions formed from ethylenediamine tetracetic acid and the closely related diamino cyclohexane acid are potentially sexadentate ligands, for there are 4 0 atoms and... 

Some natural fatty acids contain a carbocyclic unit which may have three (cyclopropane and cyclo-propene acids), five (prostaglandins-see Section 1.4 and cyclopentene acids) or six carbon atoms (cyclohexane acids). Aspects of this topic have been reviewed (Christie, 1970 Lie Ken lie, 1979 and Badami and Patil, 1982). Other cyclic acids occur in tall oil (Section 3.3.36). 

The unsaturated fatty acids are also transformed, via the radicals formed during heating to higher temperatures (e.g. during frying), into cyclic fatty acids with five- and six-membered rings. Cyclic acids derived from oleic acids are saturated compounds. The products formed from linoleic acid have one double bond. These products include cyclopentene acids and cyclopentane and cyclohexane acids with one cis double bond in the side chain. Linolenic acid forms products with two double bonds, such as cyclopentene and cyclohexene acids with one cis double bond in the side chain. 

Beckmann rearrangement of cvc7ohexanone oxime. M.p. 68-70 C, b.p. I39 C/12 mm. On healing it gives polyamides. Used in the manufacture of Nylon[6]. Cyclohexanone oxime is formed from cyclohexane and niirosyl chloride. U.S. production 1978 410 000 tonnes, capryl alcohol See 2-octanol. caiH Uc acid See oclanoic acid. 

The majority of acids contained in the diesel cuts are cyclic and come from cyclopentane or cyclohexane. They are better known as naphthenic acids / ... 

Structural keys describe the chemical composition and structural motifs of molecules represented as a Boolean array. If a certain structural feature is present in a molecule or a substructure, a particular bit is set to 1 (true), otherwise to 0 (false). A bit in this array may encode a particular functional group (such as a carboxylic acid or an amidelinkage), a structural element (e.g., a substituted cyclohexane), or at least n occurrences of a particular element (e.g., a carbon atom). Alternatively, the structural key can be defined as an array of integers where the elements of this array contain the frequency of a specific feature in the molecule. 

This reaction applies to many i,2 diketones, and is termed the Benzilic Acid Rearrangement. It provides a ready method for the preparation of disubstituted a4iydroxy-carboxylic acids. When applied to a cyclic 1,2-diketone, the ring system is necessarily reduced by one carbon atom for example, cyclohexan-i,2 ... 

The compound (III) can however lose ethanol by an internal Claisen ester condensation (p. 264) to give the cyclohexane derivative (IV), which, being the ester of a (3-keto acid, in turn readily undergoes hydrolysis and decarboxylation to give 5,5Hiimethyl cyclohexan-i,3Hiione (V) or Dimedone, a valuable reagent for the detection and estimation of formaldehyde. 

Whilst the solution is still hot, add dilute hydrochloric acid until the stirred solution is just acid to litmus, and then distil off as much ethanol as possible, using the water-bath. Now add more dilute hydrochloric acid to the residual hot solution until it is just acid to methyl-orange. The 5,5-dimethyl-cyclohexan-1,3-dione separates as an oil which solidifies on cooling. Filter the product at the pump, wash it with ice-cold water, and dry it in a desiccator. Yield of the pale cream-coloured crystals, 12 g. m.p. 136-145 (preliminary softening). 

The following acid-catalyzed cyclizations leading to steroid hormone precursors exemplify some important facts an acetylenic bond is less nucleophilic than an olelinic bond acetylenic bonds tend to form cyclopentane rather than cyclohexane derivatives, if there is a choice in proton-catalyzed olefin cyclizations the thermodynamically most stable Irons connection of cyclohexane rings is obtained selectively electroneutral nucleophilic agents such as ethylene carbonate can be used to terminate the cationic cyclization process forming stable enol derivatives which can be hydrolyzed to carbonyl compounds without this nucleophile and with trifluoroacetic acid the corresponding enol ester may be obtained (M.B. Gravestock, 1978, A,B P.E. Peterson, 1969). 

Although turnover of the catalyst is low, even unreactive cyclohexane[526] and its derivatives are oxidatively carbonylated to cyclohexanecarboxylic acid using KiS Og as a reoxidant in 565% yield based on Pd(II)[527]. Similarly, methane and propane are converted into acetic acid in 1520% yield based on Pd(II) and butyric acid in 5500% yield [528],... 

Folyphosphoric acid trimethylsilyl ester (PPSE)[1] can be used in sulfolane, CH,Cl2 or nitromethane. It is similar to polyphosphoric acid but the overall conditions arc milder and the work-up more convenient. PPSE has been used in the cydization of ris-arylhydrazones of cyclohexane-l,2-diones to give indolo[2,3-a]carbazole analogues[2],... 

A solution of 2,3-dimethylindole (145 g, 1 mol) in dry dioxan containing hydroquinone (100 mg) was treated with JV,JV,JV-trimethylbenzylammonium ethoxide (5 ml of a 40% solution in MeOH) and warmed to 35 C. Freshly distilled acrylonitrile (150 ml, 2.5 mol) was added at a rate such that the temperature did not rise above 40°C. The solution was then stirred overnight and diluted with 10% aq. acetic acid (11). The solution was extracted with CH Clj and the extract was washed with water and dried (MgS04). extract was then mixed with silica gel (800 g) and the solvent removed in vacuo. The silica was placed in a Soxhlet extractor and extracted with cyclohexane. The extract deposited the product as colourless needles (125 g, 63% yield). 

Zr Arsenazo, carbonate, citrate, C20J , cyclohexane-1,2-diaminetetraacetic acid, EDTA, F ,... 

The reaction rate is increased by using an entraining agent such as hexane, benzene, toluene, or cyclohexane, depending on the reactant alcohol, to remove the water formed. The concentration of water in the reaction medium can be measured, either by means of the Kad-Eischer reagent, or automatically by specific conductance and used as a control of the rate. The specific electrical conductance of acetic acid containing small amounts of water is given in Table 6. 

Since adipic acid has been produced in commercial quantities for almost 50 years, it is not surprising that many variations and improvements have been made to the basic cyclohexane process. In general, however, the commercially important processes stiU employ two major reaction stages. The first reaction stage is the production of the intermediates cyclohexanone [108-94-1] and cyclohexanol [108-93-0], usuaHy abbreviated as KA, KA oil, ol-one, or anone-anol. The KA (ketone, alcohol), after separation from unreacted cyclohexane (which is recycled) and reaction by-products, is then converted to adipic acid by oxidation with nitric acid. An important alternative to this use of KA is its use as an intermediate in the manufacture of caprolactam, the monomer for production of nylon-6 [25038-54-4]. The latter use of KA predominates by a substantial margin on a worldwide basis, but not in the United States. 

Although many variations of the cyclohexane oxidation step have been developed or evaluated, technology for conversion of the intermediate ketone—alcohol mixture to adipic acid is fundamentally the same as originally developed by Du Pont in the early 1940s (98,99). This step is accomplished by oxidation with 40—60% nitric acid in the presence of copper and vanadium catalysts. The reaction proceeds at high rate, and is quite exothermic. Yield of adipic acid is 92—96%, the major by-products being the shorter chain dicarboxytic acids, glutaric and succinic acids,and CO2. Nitric acid is reduced to a combination of NO2, NO, N2O, and N2. Since essentially all commercial adipic acid production arises from nitric acid oxidation, the trace impurities patterns ate similar in the products of most manufacturers. 

Other processes explored, but not commercialized, include the direct nitric acid oxidation of cyclohexane to adipic acid (140—143), carbonylation of 1,4-butanediol [110-63-4] (144), and oxidation of cyclohexane with ozone [10028-15-5] (145—148) or hydrogen peroxide [7722-84-1] (149—150). Production of adipic acid as a by-product of biological reactions has been explored in recent years (151—156). 

Adipic acid is a very large volume organic chemical. Worldwide production in 1986 reached 1.6 x 10 t (3.5 x 10 lb) (158) and in 1989 was estimated at more than 1.9 x 10 t (Table 7). It is one of the top fifty (159) chemicals produced in the United States in terms of volume, with 1989 production estimated at 745,000 t (160). Growth rate in demand in the United States for the period 1988—1993 is estimated at 2.5% per year based on 1987—1989 (160). Table 7 provides individual capacities for U.S. manufacturers. Western European capacity is essentially equivalent to that in the United States at 800,000 t/yr. Demand is highly cycHc (161), reflecting the automotive and housing markets especially. Prices usually foUow the variabiUty in cmde oil prices. Adipic acid for nylon takes about 60% of U.S. cyclohexane production the remainder goes to caprolactam for nylon-6, export, and miscellaneous uses (162). In 1989 about 88% of U.S. adipic acid production was used in nylon-6,6 (77% fiber and 11% resin), 3% in polyurethanes, 2.5% in plasticizers, 2.7% miscellaneous, and 4.5% exported (160). 

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