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Synthesis and Structure of Alkyl N-AcylimidatesAlkyl N-acylimidates 1 are prepared more easily and in higher yields than before by reaction of alkyl imidate hydrochlorides 5 with acyl halides 7 in the presence of 2.2 mol of base (14 examples). The X-ray analysis of a crystalline derivative (ldbd) shows, that the C=N-and the C = 0 parts are twisted significantly (torsional angle 77.6"). The stereochemical, dynamic, and electronic properties of the compounds 1 are interpreted by means of ab initio 3-21 G calculations on conformers of the parent system HO -CH = N -CH = 0 (8). Low rotational (ca. 6 kcal/mol) and inversional (max. 8 kcal/mol) barriers indicate the many favourable electronic interactions between the C = N-and the C = 0 groups in such N-functionalised imine dcrivatives. The compounds 1 are significantly higher in energy than bisacylamines and are therefore suggested to be superior, more reactive synthetic C -N -C building blocks. The spectroscopic properties (IR, 13C-and 'H NMR, MS) arc given and discussed.I N-Acylimidsaureester 1, die durch die Atomreihung -0 -C = N -= 0 gekennzeichnet sind, lassen auf Grund ihrer Haufung an funktionellen Zentren zahlreiche Reaktionsmoglichkeiten erwarten. So bieten sich z. B. fur nucleophile Ang r s e die Kohlenstoffatome der Carbonyl-und der Imidfunktion an. Auf diese Weise konnten eine Reihe fiinf-und sechsgliedriger Heterocyclen synthetisiert 0 VCH Verlagsgesellschaft mbH, D

Summary With the ever-growing demand for more efficient dehydration and desalting of crude oil, classic demulsifiers no longer perform satisfactorily in most cases, and new chemical systems are required. This paper describes new emulsionbreakers, generally polyester amines, and paper describes new emulsionbreakers, generally polyester amines, and gives detailed laboratory studies of their advantages, over classic demulsifiers: more complete migration to theinterface, improved emulsion breaking and coalescence, improved effluent waterquality, and partial corrosion inhibition. These new demulsifiers combined withclassic emulsion breakers have been successfully tested. Introduction Almost 60 million B/D of crude oil is produced worldwide. At least 60million B/D of water is coproduced from the oil-bearing reservoirs. Modem oil production requires efficient dehydration and desalting of crudeoil, as well as treatment of effluent water to an environmentally acceptablelevel. To ensure smooth oil productio operations, demulsifiers must be used, but only at low dosage levels. Chemical demulsifiers are specially tailored toact where they are needed-at the oil/water interface. Their high efficiencymakes their use a very attractive, economic way to separate oil and water. Over the years, better products and processes have resulted in a greatreduction in the demulsifier concentration required. This trend is stillcontinuing. Improvements in demulsification technology are concentrated in thefollowing areas: synthesis of new demulsifiers; development of laboratory andfield techniques for testing demulsifier combinations; and better design of surface treating facilities--i.e., more favorable conditions for chemical emulsiondestabilization, forced coalescence in pipelines and treating units, settling, and cleaner phase separation. Demulsifier Chemistry Table 1 is a brief listing of the chemicals used to demulsify crude oilemulsions since the beginning of the century. The industrial availability of ethylene oxide (EO) in the 1940's allowed the production of fatty acid, fattyalcohol, and alkylphenol ethoxylates. production of fatty acid, fatty alcohol, and alkylphenol ethoxylates. This was the first time that nonionics were usedfor this purpose. With the creation of ethylene oxide/propylene oxide (EO/PO) blockcopolymers, the first "genuine" demulsifiers were available. Addition of EO and/or PO to linear or cyclic (acid or base catalyzed) p-alkylphenolformaldehyde resins and to diamines or higher functional amines yields classes of modified polymers that perform quite well at relatively low concentrations. Furthermore, these demulsifier bases were converted to high-molecular-weightproducts by reaction of one or more with difunctional compounds such productsby reaction of one or more with difunctional compounds such as diacids, diepoxides, di-isocyanates, and aldehydes, delivering a host of potentialemulsion breakers. However, a need still exists for new, more efficient demulsifiers andfinishing agents. We synthesized such a system from commercially availableproducts. Fig. 1 shows the basic chemistry of these compounds. The newdemulsifiers are best described as "poly-esteramines"; they areobtained by polycondensation of an EO/PO poly-esteramines"; they areobtained by polycondensation of an EO/PO block copolymer, an oxalkylated fattyamine, and a dicarboxylic acid. A linear terpolymer with this idealizedstructure results. The nitrogen atoms are accessible to cationization. Polyesteramines are converted by alkylation to quaternized polyesteramine withno problems. problems. This three-component system obviously offers a broadrange of variations. By altering the molar ratios and interchanging one or more of the three agents, we can quite easily control the molecular weight, theshape of the polymer, and the hydrophile/lipophile balance value. For example, it is possible to create a highly branched polyesteramine by incorporation of apolyfunctional EO/PO polyesteramine by incorporation of a polyfunctional EO/POpolymer. The hydro- and oleophobic properties are determined by the polymer. The hydro- and oleophobic properties are determined by the EO/PO ratios, thelength of the alkyl chain in the fatty amine, and the type of carboxylicacid. Fig. 2 illustrates the approximate molecular-weight distribution of singlecomponents, EO/PO blocks, and polyesteramines. It reinforces the idea thatthese effective demulsifiers are not clearly defined molecules, but polymerswith a broad molecular-weight distribution. The degree of quaternization andcharge density also can be influenced. With this chemical "box ofblocks," it is possible to construct or to tailor demulsifiers for nearlyall problems possible to construct or to tailor demulsifiers for nearly allproblems in crude oil dehydration and desalting. The development of multiform structures from single blocks in Fig. 1 appearsrather complex. The chosen structure of these high-performance polyesteraminedemulsifiers becomes clearer once the properties and functions of the singleprecursors involved are properties and functions of the single precursorsinvolved are examined individually. It has been known for a long time that EO/PO-block copolymers and all theirvariants are exceptionally active interfacially. Therefore, they are the activecomponents in the demulsification process; they effect the migration to andspreading at the interface of process; they effect the migration to andspreading at the interface of oil-in-water emulsions. The dominant property of fatty amines and their quaternary cationicderivatives is their substantiveness. They adhere to all types of surfaces, acharacteristic behavior used in demulsification. At interfaces of crude oil emulsions, organic matter (asphaltenes, oilresins, naphthenic acids, paraffins, and waxes) and inorganic material (clay, carbonates, silica, and metallic salts) accumulate. Fatty amines andquaternaries adsorb preferentially at these surfaces. The dicarbonic acid ismainly a chemical link that helps combine the above-mentioned compounds andthus their properties. The mechanism of demulsification by polyesteramines maybe deduced from these properties. After migration to the oil/water interface, the oligomeric or poly-mericdemulsifier molecule is fixed by the amine quaternary component poly-mericdemulsifier molecule is fixed by the amine quaternary component by adsorption. The EO/PO-block copolymer is not freely mobile because it is attached to theamine by the dicarbonic acid. Consequently, it is held at the interface, wherethe emulsion destabilization occurs. Thus, the interfacial activity isincreased. This concept provides a plausible explanation for the good performance ofthese polyesteramines at low concentrations. The fast, performance of thesepolyesteramines at low concentrations. The fast, complete, and lastingadsorption of the polyesteramine at the metal surface is caused by its highdegree of substantiveness. The amines and moieties also contribute to a sharp interface and to asmaller oil-in-water turbidity. They may be viewed as partial structures of aclassic invert emulsion breaker attached to a classic demulsifier. The resultsof our laboratory work and field testing support this statement. Laboratory Testing Improved evaluation methods play an important role in the development of newdemulsifiers. Demulsification tests must be carefully designed to simulateexisting oilfield dehydration and desalting conditions as closely aspossible. SPEPE P. 334

1,1‐Dialkoxy‐2‐azapropenylium Salze 1 können durch O‐Alkylierung am Carbonylkohlenstoff von N‐Methylencarbamidsäureestern 4 mit Trialkyloxonium‐Salzen 5 erhalten werden, falls eine N‐Alkylierung sterisch erschwert ist (4a); andernfalls werden die Iminium‐Salze 6 gebildet. Eine allgemeinere Darstellungsmethode für die Salze 1 beruht auf der Umsetzung von N‐(Alkoxymethyl)‐imidokohlensäureestern 8 mit Acylium‐Ionen (Acylspaltung). Die Salze 1 sind thermische nicht sehr beständig Phenylester‐Derivate gehen leicht in 4H‐1,3‐Benzoxazin‐Derivate 11 über. – Die Kristallstrukturanalyse von 1aa ergibt eine allenische Struktur mit orthogonalen π‐Systemen, wobei der C–N–C‐Bindungswinkel auf ca. 150° reduziert ist (sterische Effekte). – Quantenmechanische Ab‐initio‐Berechnungen sagen hohe sterische Flexibilität der Salze 1 voraus, wobei beim Grundkörper allenische Strukturen (16a) geringfügig (ca. 2–3 kcal/mol) gegenüber allylischen Formen (16d) bevorzugt sind. Thermodynamisch günstiger als die Salze 1 (bzw. 16) sind die isomeren Iminium‐Salze 6 bzw. 17. – Je nach Substitutionsmuster beobachtet man in Lösung (IR‐, dynamische NMR‐Spektroskopie) allenische (1a) oder allylische Strukturen (1b).

CationsThe title system (I/II) is experimentally accessible by regiospecific alkylation at the carbonyl oxygen of alkyl N-acylimidates 4 using txialkyloxonium salts. According to an X-ray investigation (3a), the salts 3 form a compromise structure between both isomeric forms, the alkoxy substituents being in exo positions in s-cis-conformations (C -N -C-bond angle 133.0", torsional angle 70.4'). Quantum mechanical calculations (3-21G ab initio) for the parent substance N-formylformimidic acid 6 a predict preferred nitrogen protonation giving 7a. Oxygen protonation leading to the allenic struNure 8a is disfavoured by 11.4 kcal/mol. The allenic-(8a) and the ally1 structure (9a) differ by only ca. 5 kcal/mol and indicate therefore enormous structural flexibility of the title system. ' H NMR spectra support the existence of chiral isomers of 3a at low temperatures; at higher temperatures rapid equilibration takes place.Im Rahmen unserer Untersuchungen zur Strukturchemie von 2-ha-alleniumIonen und 2-A~a-allyl-Kationen~~~) und zum Gleichgewicht zwischen diesen beiden isomeren, reaktiven Zwischenstufen konnten wir zeigen, dal3 aromatisch substituierte Derivate bevorzugt in der linearen, allenartigen Struktur ~orliegen~.~); Elektronendonorsubstituenten, z. B. eine Alkoxygruppe4. 5), stabilisieren die gewin-0 VCH Verlagsgesellschaft mbH, D