1,2-Dicarboxylic acids, preparation

Isomerization, see also NaphthaIene-2,6-dicarboxylic acid, preparation Aldqximes — Amides Nickel acetate tetrahydrate. Dienes Phenylpotassium. Epoxides Lithium diethylamide. Magnesium bromide etherate. Nonconjuoateo enones p-Tolu iesulfonic acid. Olefins (cis-trans)-. Iodine. Selenium. Olefins (bond migration) N-Lithioethylenediamine. Lithium diethylamide. Potassium l-butoxide. Sodium tetrafluoroboric s d. Thioglycolic acid. Polyenes Sulfur dioxide. 

Iodine added to a stirred suspension of the dry Ag-salt of norhornQn -endo-dicarboxylic acid (prepared by treatment of its soln. in aq. NaOH with Ag-nitrate) in dry dimethyl sulfoxide, stirred 0.5 hr., Ag-acetate added, and stirred 12 hrs. at 60° dilactone. Y 92%. F. e. s. M. Kato et al., J. Org. Chem. 40, 1932 (1975). 

General methods for the synthesis of poly(amide-anhydrides) and poly(amide-esters) based on naturally occurring amino acids were described (Domb et at, 1990). The polymers were synthesized from dicarboxylic acids prepared by amidation of the amino group of an amino acid with a cyclic anhydride, or by the amide coupling of two amino acids with a diacid chloride. Low molecular weight polymers from methylene bis(p-carboxybenzamide) were symthesized by melt condensation (Hartmann et al, 1989). A series of amido containing polyanhydrides based on p-aminobenzoic acid were sy nthesized by melt condensation. The polymers melted at 58 to 177°C and had a molecular weight of 2500 to 12400. 

Hence, it was concluded that the dicarboxylic acid prepared in the first step of the three-step polymerization synthesis must be of the highest purity (99.9%). This was successfully established by first preparing an "ash free", salt free acid product (Example 1). The salt free monomer was prepared by suspending the highly insoluble sodium salt in a strongly acidic aqueous solution. This procedure was repeated one to two more times, since it was found that 10 to 15 percent ash remained after one treatment (Elemental analysis. Table 1). 

Treatment of 2-trifluoromethylimidazole-4,5-dicarboxylic acid, prepared by the oxidation of 2-trifluoromethylbenzimidazole, with SF4-HF also afforded 2,4,5-tris(tri-fluoromethyl)imidazole in moderate yield. Synthetic manipulations of dicarboxylic acid also gave A -methyl-2-(trilfluoromethyl)imidazole-4-carboxylic acid [12],... 

Sulphuric add test. Heat 0 5 g. of citric acid or a citrate with 1 ml. of H2SO4 CO and COg are evolved and the mixture turns yellow, but does not char. Acetone dicarboxylic acid, OC(CH2COOH)g, is also formed, and is tested for after heating the mixture for 1 minute cool, add a few ml. of water and make alkaline with NaOH solution. Add a few ml. of a freshly prepared solution of sodium nitroprusside and note the intense red coloration (see Test 4 a) for ketones, p. 346). 

Decane-1 10-dicarboxylic acid from sebacic acid. Convert sebacic acid into the acid chloride by treatment with phosphorus penta-chloride (2 mols) and purify by distillation b.p. 146-143°/2 mm. the yield is almost quantitative. Dissolve the resulting sebacoyl chloride in anhydrous ether and add the solution slowly to an ethereal solution of excess of diazomethane (prepared from 50 g. of nitrosomethylurea) allow the mixture to stand overnight. Remove the ether and excess of diazomethane under reduced pressure the residual crystalline 1 8-bis-diazoacetyloctane weighs 19 -3 g. and melts at 91° after crystaUisation from benzene. 

Polyphenylene polymers can be prepared by this coupling. For example, the preparation of poly(/i-quaterphenylene-2,2 -dicarboxylic acid) (643) was carried out using aqueous NaHCO and a water-soluble phosphine ligand (DPMSPP)[5I I]. Branched polyphenylene was also prepared[5l2). 

Write equations showing how 3 methyl 1 5 pentanediol could be prepared from a dicarboxylic acid or a diester I... 

Dicarboxylic acids have been prepared from dihalides by this method... 

If a polyamide is prepared in the presence of a large excess of dicarboxylic acid, the average chain will have a carboxyl group at each end ... 

Polycarbonates. Polyarjiates are aromatic polyesters commonly prepared from aromatic dicarboxylic acids and diphenols. One of the most important polyarylates is polycarbonate, a polyester of carbonic acid. Polycarbonate composite is extensively used in the automotive industry because the resin is a tough, corrosion-resistant material. Polycarbonates (qv) can be prepared from aUphatic or aromatic materials by two routes reaction of a dihydroxy compound with phosgene accompanied by Hberation ofHCl(eq. 5) ... 

G-20 Dicarboxylic Acids. These acids have been prepared from cyclohexanone via conversion to cyclohexanone peroxide foUowed by decomposition by ferrous ions in the presence of butadiene (84—87). Okamura Oil Mill (Japan) produces a series of commercial acids based on a modification of this reaction. For example, Okamura s modifications of the reaction results in the foUowing composition of the reaction product C-16 (Linear) 4—9%, C-16 (branched) 2—4%, C-20 (linear) 35—52%, and C-20 (branched) 30—40%. Unsaturated methyl esters are first formed that are hydrogenated and then hydrolyzed to obtain the mixed acids. Relatively pure fractions of C-16 and C-20, both linear and branched, are obtained after... 

Since the pyridazine ring is generally more stable to oxidation than a benzene ring, oxidation of alkyl and aryl substituted cinnolines and phthalazines can be used for the preparation of pyridazinedicarboxylic acids. For example, oxidation of 4-phenylcinnoline with potassium permanganate yields 5-phenylpyridazine-3,4-dicarboxylic acid, while alkyl substituted phthalazines give pyridazine-4,5-dicarboxylic acids under essentially the same reaction conditions. 

The best way to make pyrimidine in quantity is from 1,1,3,3-tetraethoxypropane (or other such acetal of malondialdehyde) and formamide, by either a continuous (58CB2832) or a batch process (57CB942). Other practical ways to make small amounts in the laboratory are thermal decarboxylation of pyrimidine-4,6-dicarboxylic acid (744), prepared by oxidation of 4,6-dimethylpyrimidine (59JCS525), or hydrogenolysis of 2,4-dichloropyrimidine over palladium-charcoal in the presence of magnesium oxide (53JCS1646). 

The cleavage of fused pyrazines represents an important method of synthesis of substituted pyrazines, particularly pyrazinecarboxylic acids. Pyrazine-2,3-dicarboxylic acid is usually prepared by the permanganate oxidation of either quinoxalines or phenazines. The pyrazine ring resembles the pyridine ring in its stability rather than the other diazines, pyridazine and pyrimidine. Fused systems such as pteridines may easily be converted under either acidic or basic conditions into pyrazine derivatives (Scheme 75). 

Substitutedisoxazole-3,5-dicarboxylic acids have been prepared from ethyl nitroacetate and an aldehyde (63BCJii50). A related reaction leads to diethyl 4-hydroxyisoxazole-3,5-dicarboxylate (334) and involves the reaction of acetonedicarboxylic acid ester (333) with nitrosyl chloride (78JHC1519). 

Bis(3,4-diethyl-2-pyrrolylmethyl)-3,4-dietliyl-l//-pyrrole (2), prepared in situ from the di-t-butylester of the 5,5 -dicarboxylic acid (/), reacts with 4//-1,2,4-triazole-3,5-dialdehyde (3) in di-chloromethane in the presence of trifluoroacetic acid and 2,3-dichloro-5,6-dicyano-/)-benzoquino-ne as an oxidation reagent. Dark blue crystals are obtained after chromatographic purification. The dark violet chloroform solution fluoresces purple at 360 nm and gives the NMR experiments 39. Which compound and which tautomer of it has been formed ... 

In 1978 Hiils (Mumcu et al ) described the properties of a block copolymer prepared by condensation of polytetramethylene ether glycol with laurin lactam and decane-1,10-dicarboxylic acid. The materials were introduced as XR3808 and X4006. The polyamide XR3808 is reported to have a specific gravity of 1.02, a yield stress of 24 MPa, a modulus of elasticity of 300 MPa and an elongation of break of 360%. The Swiss company Emser Werke also introduced similar... 

The present method for preparing aromatic dicarboxylic acids has been used to convert phthalic or isophthalic acid to tereph-thalic acid (90-95%) 2,2 -biphenyldicarboxylic acid to 4,4 -biphenyldicarboxylic acid 3,4-pyrroledicarboxylic acid to 2,5-pyr-roledicarboxylic acid and 2,3-pyridinedicarboxylic acid to 2,5-pyridinedicarboxylic acid. A closely related method for preparing aromatic dicarboxylic acids is the thermal disproportionation of the potassium salt of an aromatic monocarboxylic acid to an equimolar mixture of the corresponding aromatic hydrocarbon and the dipotassium salt of an aromatic dicarboxylic acid. The disproportionation method has been used to convert benzoic acid to terephthalic acid (90-95%) pyridine-carboxylic acids to 2,5-pyridinedicarboxylic acid (30-50%) 2-furoic acid to 2,5-furandicarboxylic acid 2-thiophenecar-boxylic acid to 2,5-thiophenedicarboxylic acid and 2-quinoline-carboxylic acid to 2,4-quinolinedicarboxylic acid. One or the other of these two methods is often the best way to make otherwise inaccessible aromatic dicarboxylic acids. The two methods were recently reviewed. ... 

Similar compounds to those described above have been prepared by the same group using the bis-cesium salts of pyridine-3,5-dicarboxylic acids. In a number of experiments Piepers and Kellogg showed that Cs plays an irreplacable role as compared with Na", K and Rb for the formation of [the macrocycle shown below] . 

By converting the A" -3-ketone into its 2-hydroxymethylene derivative, selective ozonolysis to the 2,3-seco-2,3-dicarboxylic acid can be carried out in the presence of the A -double bond. Weisenborn has thus prepared A-nortesto-sterone and A-norprogesterone. In the latter case, selective formyla-tion at C-2 was achieved by first reducing the 20-ketone to the 20-ol (4). 

Perfluorodimethyladamantane is prepared from adamantane dicarboxylic acid by treatment with sulfur tetrafluoride followed by energetic fluorination with cobalt trifluoride over two temperature ranges [S] (equation 15)... 

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