Dehydration with phthalic anhydride

Dehydration of P-nitro alcohols provides an important method for the preparation of nitroalkenes. Because lower nitroalkenes such as nitroethylene, 1-nitro-1-propene, and 2-nitro-l-propene tend to polymerize, they must be prepared carefully and used immediately after preparation. Dehydration with phthalic anhydride is the most reliable method for such lower nitroalkenes.42,43 Such lower nitroalkenes have been used as important reagents for Michael acceptors or dienophiles in the Diels-Alder reaction, which will be... 

Dehydration of nitroalcohols and their esters. Nitroalcoliols obtained by the Henry rnethod can be readily dehydrated with phthalic anhydride (Vol. t. 

Nitroethane and formalin react to form 2-nitro-l-propanol (847o yield), which is dehydrated with phthalic anhydride (727 yield). 

It is a dibasic acid, and forms stable metallic salts. Distillation with soda lime gives benzene. Readily dehydrated to phthalic anhydride. Its reactions are similar to phthalic anhydride in which form it is almost invariably used. 

Condensation of an appropriately substituted phenylacetic acid with phthalic anhydride in the presence of sodium acetate leads to aldol-like reaction of the methylene group on the acid with the carbonyl on the anhydride. Dehydration followed by decarboxylation of the intermediate affords the methylenephthal-ides (12). Treatment of the phthalides with base affords directly the indandiones, probably via an intermediate formally derived from the keto-acid anion (13). The first agent of this class to be introduced was phenindandione (14) this was followed by anisindandione (1S) and chlorindandione (16). ... 

Cyclohexadiene has been prepared by dehydration of cyclohexen-3-ol,3 by pyrolysis at 540° of the diacetate of cyclohexane-1,2-diol,4 by dehydrobromination with quinoline of 3-hromocyclohexene,6 by treating the ethyl ether of cyclohexen-3-ol with potassium bisulfatc,6 7 by heating cyclohexene oxide with phthalic anhydride,8 by treating cyclohexane-1,2-diol with concentrated sulfuric acid,9 by treatment of 1,2-dibromocyclo-hexane with tributylamine,10 with sodium hydroxide in ethylene glycol,10 and with quinoline,6 and by treatment of 3,6-dibromo-cyclohexene with sodium.6... 

Nitro-l-propene Preparation is accomplished by dehydration of 2-nitro-l-propanol with phthalic anhydride (73%)45 or acetic anhydride-AcONa46 bp 56-57 °C/80 mmHg. 

Reaction XXIX. (a) Condensation of a Phenol with Phthalic Anhydride to form a Phthalein. (A., 183, 1 202, 68.)—The phthaleins result from the condensation of phthalic anhydride (1 mol.) with phenols (2 mols.) on heating with dehydrating agents—sulphuric acid, fused zinc chloride (to 120°) or anhydrous oxalic acid (to 115°). These compounds are particularly important some are dyes of great technical value. The simplest representative of the class is phenolphthalein. 

In only one case, the dehydration of 3-(j8-hydroxyethyl)quinuclidine with phthalic anhydride and benzenesulfonic acid, did Ernest succeed in isolating from the mixture of isomeric 3-ethylidene- (115)... 

The procedure usually is unsuitable for tertiary alcohols since the reaction with phthalic anhydride or succinic anhydride either fails or results in dehydration of the alcohol. A few tertiary alkyl phthalates, however, have been prepared and resolved by first converting the alcohols to sodium or potassium salts and allowing these to react79 80 with phthalic anhydride. This modification has been applied successfully to dUa- and /S-santalols81 and cB-linalool.81 As already mentioned, glycols cannot be resolved by this procedure because they form polymeric esters when heated with phthalic or succinic anhydride. Phenols also usually form phthaleins or other condensation products instead of simple acid esters. 

Phthaleins. Dyes of this class are usually considered to be triarylmethane derivatives. Phenolphthalein [77-09-8] (23, R = CO) and phenol red [143-74-8] (23, R = S02) are used extensively as indicators in colorimetric and titrimetric determinations (see Hydrogen-ion activity). These compounds are prepared by the condensation of phenol with phthalic anhydride or o-sulfobenzoic anhydride, respectively, in the presence of a dehydrating agent. 

Methoxyl, cyano, and nitro groups may also be present in the molecule during pyrolysis. Examples are y-methoxycrotononitrile (83%), acrylonitrile (64%), 1-cyano-l, 3-butadiene (70%), and a series of conjugated nitroalkenes. The esters of /3-nitro alcohols are pyrolyzed at 195° or merely refluxed with sodium bicarbonate in dilute aqueous methanol. By the latter procedure the yields of conjugated nitro alkenes are. 90-95%. Direct dehydration by heating the nitro alcohols to 180° with phthalic anhydride has also been used. ... 

Aromatic nitriles are also prepared by heating amides with phosphorus pentoxide, phosphorus oxychloride, phosphorus pentachloride, thionyl chloride, and ammonium sulfamate. In addition, the action of a double salt of aluminum and sodium chlorides, NaCl- AlClj, gives excellent yields of nitriles from both aliphatic and aromatic amides. Heating an amide with phthalic anhydride causes dehydration. A novel synthesis consists in treating a mixture of an aromatic acid and p-toluene-sulfonamide with phosphorus pentachloride the yields of nitriles range from 63% to 79%. ... 

The hardness of the alkyd resins was increased by Bhow and Payne [14], who styrenated the fatty acids and then reacted the product with phthalic anhydride and glycerol. According to these investigators, styrenated dehydrated castor oils were liquid when less than 70% styrene was added, and solid at higher concentrations of styrene. 

Baeyer, in the hope of synthesising plant products, had the idea of condensing phenols with aldehydes and thought that phthalic anhydride might act as a mild dehydrating agent. By heating resorcinol with phthalic anhydride he obtained fluorescein, and with phenol and phthalic anhydride the simplest member, phenolphthalein, of what he called phthaleins of phenols. ... 

In a recipe supplied by Payne, a solution of 4 moles of styrene and 3% benzoyl peroxide was slowly added over a 30-minute period to a xylene solution of dehydrated castor oil at 239°F (115°C). These solutions were then heated at 284°F (140°C) for 1 hour. The 6.5% unreacted styrene monomer was removed by vacuum distillation prior to traction with phthalic anhydride 449.6°F (232°C) for 80 minutes. However, in the most widely used method, styrene and the benzoyl peroxide are added to a previously prepared resin. Harrison, Tolby, and Redkamp maintained that unless long-oil alkyds were used, the styrenated alkyds were primarily blends of polystyrene and the alkyd resins. 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

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