Phthalimide from phthalic anhydride

As early as 1907, A.V. Braun and J. Tscherniak first obtained phthalocyanine from phthalimide and acetic anhydride [5]. The prepared blue substance, however, was not investigated further. In 1927, de Diesbach and von der Weid, in an attempt to synthesize phthalonitrile from o-dibromobenzene and copper cyanide in pyridine at 200°C, obtained a blue copper complex. The substance was found to be exceptionally fast to acid, alkali, and high temperature [6], Approximately one year later, in trying to manufacture phthalimide from phthalic anhydride and ammo-... 

The direct formation of A-substituted phthalimides from phthalic anhydride and alkyl azides, via the intermediate RN=PPh, compound, is catalysed by the presence of tetra-n-butylammonium cyanide [34],... 

Phthalocyanines were discovered by accident. During the manufacture of phthalimide from phthalic anhydride and ammonia in a reactor vessel, a blue impurity was observed,... 

History. Braun and Tschemak [23] obtained phthalocyanine for the first time in 1907 as a byproduct of the preparation of o-cyanobenzamide from phthalimide and acetic anhydride. However, this discovery was of no special interest at the time. In 1927, de Diesbach and von der Weid prepared CuPc in 23 % yield by treating o-dibromobenzene with copper cyanide in pyridine [24], Instead of the colorless dinitriles, they obtained deep blue CuPc and observed the exceptional stability of their product to sulfuric acid, alkalis, and heat. The third observation of a phthalocyanine was made at Scottish Dyes, in 1929 [25], During the preparation of phthalimide from phthalic anhydride and ammonia in an enamel vessel, a greenish blue impurity appeared. Dunsworth and Drescher carried out a preliminary examination of the compound, which was analyzed as an iron complex. It was formed in a chipped region of the enamel with iron from the vessel. Further experiments yielded FePc, CuPc, and NiPc. It was soon realized that these products could be used as pigments or textile colorants. Linstead et al. at the University of London discovered the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines from 1929 to 1934 [1-11]. The important CuPc could not be protected by a patent, because it had been described earlier in the literature [23], Based on Linstead s work the structure of phthalocyanines was confirmed by several physicochemical measurements [26-32], Methods such as X-ray diffraction or electron microscopy verified the planarity of this macrocyclic system. Properties such as polymorphism, absorption spectra, magnetic and catalytic characteristics, oxidation and reduc-... 

In Britain during 1932-1933, a major discovery took place at what would soon be an ICI acquisition, Scottish Dyes. By chance, a blue colorant was obtained during preparation of phthalimide from phthalic anhydride and ammonia. Though not an aromatic amino compound, the stable product is important in the history of dye discovery. It was a phthalocyanine compound, of the type first prepared in 1907. ICI manufactured the copper analogue, known as Monastral fast blue. Introduced in 1934, it represented the first member of the only new structural class of synthetic dye in the 20th century83. 

In 1928, at Grangemouth, Scotland, at the works of Messrs. Scottish Dyes Ltd., traces of a dark blue insoluble complex were noticed in the iron vessels used to prepare phthalimide from phthalic anhydride and ammonia (65, 221). This product was subsequently shown to be ferrous phthalo-cyanine. Since then literally thousands of patents and publications concerning the phthalocyanines have appeared. It is probable that the phthalocyanines have been the subject of more physical studies than any other single class of compound, partly as a result of their unique structure and partly because of their high thermal and chemical stability. 

In 1932, a dark blue by-product was isolated during the industrial production of phthalimide from phthalic anhydride and ammonia in an iron vessel. This unexpected by-product was eventually identified as iron(II)phthalocyanine Now we know that the iron had templated the formation of this macrocycle [8]. Curtis investigated the condensation of acetone 4 and 1,2-diaminoethane 3 in the presence of metal cations and showed that the macrocycles 5 and 6 could be prepared both by templated and untemplated processes (Scheme 1-2) [9, 10],... 

A similar mechanism has also been proposed to pertain to the formation of phthalimide from phthalic anhydride and nitroarenes in the presence of CO (Scheme 12) [76] ... 

A third synthetic approach which came up in the years 1967-1970 was polycondensation of diisocyanates with tetracarboxylic anhydrides (Formula 6.4, top). Syntheses of phthalimides from phthalic anhydride and isocyanates were known since 1900 [50], but it took more than six decades until this reaction was adopted to the preparation of polyimides [51-55]. This approach is flexible, because it is... 

In 1929, Linsted obtained samples of this complex from ICI chemists (Scottish Dyes Ltd was now owned by ICI). ICI had developed two routes leading to the phthalocyanine iron complex. One method started from phthalic anhydride, iron, and ammonia, while the second pathway proceeded from phthalimide, iron sulfide, and ammonia. In 1933/34, elucidation of the phthalocyanine structure was credited to Linstead. The corresponding copper and nickel phthalocyanines had been prepared in the meantime. ICI introduced the first Copper Phthalocyanine Blue to the market as early as 1935, and the Ludwigshafen subsidiary of the IG Farben-industrie followed suit with a corresponding product. 

Phthalimide is available from phthalic anhydride and the two carbonyl groups both help to stabilise the anion (27) so that the potassium salt is a stable compound. This anion (27) is blocked so that it can react only once with an alkyl halide forming the substituted phthalimide (28) which can be cleaved by hydrazine (NH2NH2) to release the primary amine (29),... 

The synthesis of 2,3,4,5-tetrahydro-lH-2-benzazepine-l,5-diones by the photochemical addition of alkenes to phthalimides has been known for a number of years. More recently this method has been extended to the reaction of N-alkylphalimides prepared from phthalic anhydride and amino acids, with a further example being published during the period under review <94T3627>. 2,3-Dihydro-l/f-2-benzazepine-l,3-diones have been prepared by the reaction of... 

Condensation of o-aminoacetophenone with maleic, succinic or phthalic anhydrides gave 117 whose bromination with CuBr2 gave the bromides 118. Column chromatographic separation of the respective maleimide derivative on silica gel gave the bromoquinoline 119 whereas the phthalimide derivative was obtained from 118 by cyclization with EtsN (93MI11). On the... 

An isoindol1 none moiety forms part of the aromatic moiety of yet another antiinflammatory propionic acid derivative. Carboxylation of the anion from -nitro-ethylbenzene (45) leads directly to the propionic acid (46). Reduction of the nitro group followed by condensation of the resulting aniline (47) with phthalic anhydride affords the corresponding phthalimide (48). Treatment of that intermediate with zinc in acetic acid interestingly results in reduction of only one of the carbonyl groups to afford the isoindolone. There is thus obtained indoprofen (49). ... 

Phthalocyanines have been synthesized with nearly all metals of the periodic table.77 Normally they are formed in a single-step reaction from available derivatives of phthalic acid, in particular phthalic acid (see Section 2.1.1.1.), phthalic anhydride (see Section 2.1.1.2.), phthalimide (see Section 2.1.1.3.), 2-cyanobenzamide (see Section 2.1.1.4.), phthalonitrile (see Section 2.1.1.5.), isoindolinediimine (see Section 2.1.1.6.), or 1,2-dibromobenzene (see Section 2.1.1.7.), usually in a high-boiling solvent or by heating the neat components.1 4... 

Dissolve 0 6 g. of the primary amine and 0-6 g. of pure phthalic anhydride in 6 ml. of glacial acetic acid and reflux for 20-30 minutes. (If the amine salt is used, add 1 g. of sodium acetate.) The N-substituted phthalimide separates out on cooling. RecrystaUise it from alcohol or from glacial acetic acid. 

Method 2. Intimately mix 99 g. of pure phthalic anhydride and 20 g. of urea, and place the mixture in a 1 litre long-necked, round-bottomed flask. Heat the flask in an oil bath at 130-135°. When the contents have melted, effervescence commences and gradually increases in vigour after 10-20 minutes, the mixture suddenly froths up to about three times the original volume (this is accompanied by a rise in temperature to 150-160°) and becomes almost solid. Remove the flame from beneath the bath and allow to cool. Add about 80 ml. of water to disintegrate the solid in the flask, filter at the pump, wash with a little water, and then dry at 100°. The yield of phthalimide, m.p. 233° (. ., it is practically pure) is 86 g. If desired, the phthalimide may be recrystaUised from 1200 ml. of methylated spirit the first crop consists of 34 g. of m.p. 234°, but further quantities may be recovered from the mother liquor. 

The phthalide used by the submitters and by the checkers was a commercial product, obtained from E. I. du Pont de Nemours and Company, Wilmington, Delaware. This product is no longer available. Phthalide may be prepared in 82.5 per cent yields by hydrogenation of phthalic anhydride in benzene at 270° under 3000 lb. pressure in the presence of copper chromite 1 or, in yields of 61-71 per cent, from phthalimide according to the procedure given in Org. Syn. 16, 71 Coll. Vol. 2, 1943, 526. 

The baking process has remained much the same until the present day at a stoichiometric ratio of 1 4, phthalic anhydride or phthalic acid reacts with an ammonia releasing compound. The reaction may also start from other suitable materials, such as phthalic acid derivatives, including phthalic acid esters, phthalic acid diamide, or phthalimide. Appropriate ammonia releasing agents include urea and its derivatives, such as biuret, guanidine, and dicyanodiamide. The fact that a certain amount of urea decomposes to form side products makes it necessary to use excess urea. Approximately 0.2 to 0.5, preferably 0.25 equivalents of copper salt should be added for each mole of phthalic anhydride. 0.1 to 0.4 moles of molybdenum salt per mole of phthalic anhydride is sufficient. The reaction temperature is between 200 and 300°C. 

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