Phthalimide on copper

Results from Core-Level Studies of Phthalimide-on-Copper. 

Results for Metal-Ligand Systems Phthalimide-On-Copper... 

The UPS valence band spectra of multilayer and monolayer samples of phthalimide (pirn) and methyl-phthalimide (mpim) on copper have been compared with the calculated DOVS for corresponding systems. Very good agreement is found between theory and experiment for all the systems included in this study. This made it possible to interpret the features appearing in the UPS spectra in terms of specific molecular orbitals. Furthermore, by analyzing the MO s, the nature of the ligand-metal bonding is uncovered. 

Figure 4. C Is, 0 Is, and N Is XPS spectra of benzene-phthalimide (BPIM) on copper.

Phthalide. In a 1 litre bolt-head flask stir 90 g. of a high quality zinc powder to a thick paste with a solution of 0 5 g. of crystallised copper sulphate in 20 ml. of water (this serves to activate the zinc), and then add 165 ml. of 20 per cent, sodium hydroxide solution. Cool the flask in an ice bath to 5°, stir the contents mechanically, and add 73-5 g. of phthalimide in small portions at such a rate that the temperature does not rise above 8° (about 30 minutes are required for the addition). Continue the stirring for half an hour, dilute with 200 ml. of water, warm on a water bath imtil the evolution of ammonia ceases (about 3 hours), and concentrate to a volume of about 200 ml. by distillation vmder reduced pressure (tig. 11,37, 1). Filter, and render the flltrate acid to Congo red paper with concentrated hydrochloric acid (about 75 ml. are required). Much of the phthalide separates as an oil, but, in order to complete the lactonisation of the hydroxymethylbenzoic acid, boil for an hour transfer while hot to a beaker. The oil solidifles on cooling to a hard red-brown cake. Leave overnight in an ice chest or refrigerator, and than filter at the pump. The crude phthalide contains much sodium chloride. RecrystaUise it in 10 g. portions from 750 ml. of water use the mother liquor from the first crop for the recrystaUisation of the subsequent portion. Filter each portion while hot, cool in ice below 5°, filter and wash with small quantities of ice-cold water. Dry in the air upon filter paper. The yield of phthalide (transparent plates), m.p. 72-73°, is 47 g. 

The chemical properties of phthalocyanines depend mosdy on the nature of the central atom. Phthalocyanines are stable to atmospheric oxygen up to approximately 100°C. Mild oxidation may lead to the formation of oxidation iatermediates that can be reduced to the original products (29). In aqueous solutions of strong oxidants, the phthalocyanine ring is completely destroyed and oxidized to phthalimide. Oxidation ia the presence of ceric sulfate can be used to determine the amount of copper phthalocyanine quantitatively (30). 

Urea acts not only as an ammonia source but also forms decomposition products, such as biuret and higher condensation products. 14C labeling has indicated that the carbon atom of the urea molecule is not incorporated into the phthalocyanine structure. Employing a phthalic anhydride molecule bearing one radioac-tively labeled carbonyl function affords labeled copper phthalocyanine and phthalimide (as a side product), while the liberated carbon dioxide was found not to show any radioactivity. Labeled carbon dioxide, on the other hand, has been obtained in corresponding experiments using 14C labeled urea. 

Phthalimide was hydrogenated catalytically at 60-80° over palladium on barium sulfate in acetic acid containing an equimolar quantity of sulfuric or perchloric acid to phthalimidine [7729]. The same compound was produced in 76-80% yield by hydrogenation over nickel at 200° and 200-250 atm [43 and in 75% yield over copper chromite at 250° and 190 atm [7730]. Reduction with lithium aluminum hydride, on the other hand, reduced both carbonyls and gave isoindoline (yield 5%) [7730], also obtained by electroreduction on a lead cathode in sulfuric acid (yield 72%) [7730]. 

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-... 

As mentioned above, urea and PA are the most cheap phthalocyanine precursors and are produced on an industrial scale, so it is not surprising that numerous articles and patents have been dedicated to the study of their interactions [6,30,41-48], Flowever, only copper and some other strong metals (in relation to the PcM formation and stability) form their phthalocyanines using these precursors. There are almost no reports in the available literature about attempts to electrosynthesize PcF12 or PcM starting from urea and phthalic anhydride, except for a recent work [32] where the interaction between these two precursors, as well as phthalimide, in various nonaqueous solutions by conventional chemical and electrochemical methods is studied in detail (Example 18). 

Therefore, the solvent used for successful electrosynthesis of PcCu should be inert in relation to PA and, on the other hand, should have electroconductivity. The compounds used as promoters [41] could theoretically serve as such solvents. Tetramethylurea (TMU) and l-methyl-2-pyrolidinone were chosen by the authors of Ref. 32 among other promoters used in the work [41]. The first one has a nature close to that of the principal precursor (urea), and thus should not influence the reaction course negatively. The TMU has sufficient conductivity to permit electrolysis in its medium, and reasonable viscosity. The boiling point of 174-178 C is ideal for such research, since conventional syntheses of Pc from urea and PA are carried out at similar temperatures. The results of TMU use as a solvent are presented in Table 5.7. The results seem promising, and this solvent is recommended to study Pc formation in its medium in further research work. In the case of l-methyl-2-pyro-lidinone, no phthalocyanine formation was observed. No phthalocyanine was observed also in the following systems (1) urea, PA, TBA, TMU (without copper) (2) urea, PA, TBA, TMU, Sb, or Mg (anodes (3) TMU, urea (or without urea), phthalimide, TBA (in all cases with or without electrolysis). 

As an approach to a better understanding of adhesion mechanisms between polyimide and copper, we have studied the interaction between a set of model molecules for a polyimide and vapor deposited polycrystalline copper. Thin films and adsorbates of benzene, phthalimide, methyl-phthalimide, benzene-phthalimide, and malonamid, which are representative of separate parts of the polyimide repeat unit, were deposited in situ on clean copper and examined by means of X-ray and Ultraviolet photoelectron spectroscopy (XPS and UPS). In contrast to the previously observed bonding to the carbonyl oxygen in polyimide, as Cu is deposited on polyimide, our results show that most of these polyimide model molecules bond to Cu, through electron transfer, with the imide nitrogen atom as the primary reaction site. 

Because the reactions of related in -cyclohexadienyl complexes are synthetically valuable, the reactions of this ligand have been studied extensively. An outline of how this chemistry can be conducted on the Fe(CO)j fragment is shown in Equation 11.51. A variety of cyclohexadienes are readily available from Birch reduction of substituted aromatics. Coordination and abstraction of a hydride, typically by trityl cation, leads to cationic cyclohexadienyl complexes. These cyclohexadienyl complexes are reactive toward organolithium, -copper, -cadmium, and -zinc reagents, ketone enolates, nitroal-kyl anions, amines, phthalimide, and even nucleophilic aromatic compounds such as indole and trimethoxybenzene. Attack occurs exclusively from the face opposite the metal, and exclusively at a terminal position of the dienyl system. This combination of hydride abstraction and nucleophilic addition has been repeated to generate cyclohexa-diene complexes containing two cis vicinal substituents. The free cyclohexadiene is ttien released from the metal by oxidation with amine oxides. ... 

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