Amines, reaction with acrylonitrile

Nonetheless, it was a fairly short step from octopus compounds to dendrimers, and the step was taken by Vogtle in the late 1970s when he attempted to use a cascade reaction to prepare a molecule of the dendrimer type that would now be considered a dendron rather than a fully developed dendrimer. It began with the addition of acrylonitrile to an anfine, followed by reduction of the nitrile to amine. This was followed by a further reaction with acrylonitrile, and the process was repeated several times to yield highly branched macromolecules. There were initially problems with the reduction step but these were overcome, and the preparation of these poly(propylene imine) dendrimers was later commercialized. 

Another type of polyol often used in the manufacture of flexible polyurethane foams contains a dispersed soHd phase of organic chemical particles (234—236). The continuous phase is one of the polyols described above for either slab or molded foam as required. The dispersed phase reacts in the polyol using an addition reaction with styrene and acrylonitrile monomers in one type or a coupling reaction with an amine such as hydrazine and isocyanate in another. The soHds content ranges from about 21% with either system to nearly 40% in the styrene—acrylonitrile system. The dispersed soHds confer increased load bearing and in the case of flexible molded foams also act as a ceU opener. 

Other reactions that show preference for the acidic N-3—H group include Mannich aminomethylation by treatment with formaldehyde and an amine (38) to yield compound (8), reaction with ethyleneimine (39) to give (9), and Michael-type additions (40) such as the one with acrylonitrile to give (10) ... 

Primary cycloaUphatic amines react with phosgene to form isocyanates. Reaction of isocyanates with primary and secondary amines forms ureas. Dehydration of ureas or dehydrosulfuri2ation of thioureas results in carhodiimides. The nucleophilicity that deterrnines rapid amine reactivity with acid chlorides and isocyanates also promotes epoxide ring opening to form hydroxyalkyl- and dihydroxyalkylaniines. Michael addition to acrylonitrile yields stable cyanoethylcycloalkylarnines. 

Gyanoethylation. The reaction of primary fatty amines with acrylonitrile followed by hydrogenation produces diamines and ttiamines (4,7,31,32,37,38). 

In the manufacture of highly resident flexible foams and thermoset RIM elastomers, graft or polymer polyols are used. Graft polyols are dispersions of free-radical-polymerized mixtures of acrylonitrile and styrene partially grafted to a polyol. Polymer polyols are available from BASF, Dow, and Union Carbide. In situ polyaddition reaction of isocyanates with amines in a polyol substrate produces PHD (polyhamstoff dispersion) polyols, which are marketed by Bayer (21). In addition, blending of polyether polyols with diethanolamine, followed by reaction with TDI, also affords a urethane/urea dispersion. The polymer or PHD-type polyols increase the load bearing properties and stiffness of flexible foams. Interreactive dispersion polyols are also used in RIM appHcations where elastomers of high modulus, low thermal coefficient of expansion, and improved paintabiUty are needed. 

Manufacturing processes and equipment are similar to those employed for alcohol ethoxylate preparation. In the absence of steric hindrance, ethylene oxide reacts with both hydrogens of primary amines at relatively low temperatures (90—120°C) without added catalysts (105). When the nitrogen atom is hindered, as it is in the Triton RW products, only one of the amino hydrogens reacts with ethylene oxide. Once this reaction is complete, a basic catalyst is added and ethoxylation proceeds in the manner of the alcohol-based nonionics. In IV-alkyl-l,3-propanediamine, all three amino hydrogens are available for reaction with ethylene oxide. N-Alkyl-1,3-propanediamines are prepared from fatty monoamines and acrylonitrile, followed by reduction of the resulting 3-cyanoethylalkyl amine. 

Further reaction of the bromide 33 with acrylonitrile in the presence of PI13P affords the disubstituted product 34 [21]. Selection of amines used in the reaction is critical. Fumaroyl dichloride (35) undergoes oxidative addition, decarbonylation and insertion of acrylate to produce octatrienedioate (36) [22]. 

The essence of the cascade synthesis is depicted in Scheme 2.1. Two procedures, alkylation and reduction, comprised the [a — b — a — b — ] sequence. Thus, treatment of a diamine with acrylonitrile afforded tetranitrile 3. Cobalt-mediated nitrile reduction gave tetraamine 4. Further amine alkylation provided the second generation octanitrile 5. The nonskid-chain-like [2] synthesis is shown in Scheme 2.2. Construction of polycyclic 6 was accomplished by repetitive alkylation, reduction, acylation, and reduction (a — b c— d—>a- b— ...) sequences. Again, repetitive and multiple reaction sequences were employed for the generation of new molecular assemblies. Most notable about these syntheses is that for the first time, generational molecules were prepared and characterized at each stage of the construction process. 

Carbonyl compounds undergo PET reaction with electron donating substrates viz., alkenes, amines and thio-compounds. Except in the photoreactions with electron poor alkenes, such as acrylonitrile [165,166], carbonyl compounds usually act as an electron accepting partners. The chemical reaction pathways... 

Pyridylethyl derivatives of 2 are formed by reaction of a- or y-vinyl-pyridine with 2.107 Treatment of 1 or 2, as well as the 5-arylidene derivatives, with acrylonitrile in the presence of pyridine results in formation of 84 by cyanoethylation on the ring nitrogen (Scheme 2) however, cyanoethyla-tion of 5-aryl-2-iminothiazolidinones involves the exocyclic nitrogen.108 Aminoalkylation (Mannich reaction) of 2 or 2-aryl-4-thiazolidinones with formaldehyde and amines in warm alcoholic solvents affords the desired 3-alkylated product 85 (Scheme 2),109,110 whereas 3-aryl-2-iminothiazoli-dinones react with substituted anilines and aliphatic amines and formaldehyde to give the 2-arylaminomethyl derivatives 86 [Eq. (25)].111... 

Since polyamines are industrially available compounds, we returned to our first successful cacade synthesis in 19781 where we produced dendritic oligoamines. It seemed attractive to pursue this synthesis with new preparative and analytical methods, which then were limited. As starting materials, we selected the commercially available tris(2-ami-noethyl)amine (TREN) due to its inherently branched structure. The synthesis was accomplished in a manner identical to that conducted 16 years ago, affording a 90% yield of the first-generation dendrimer 46 by reaction of TREN with acrylonitrile and catalytic amounts of acetic acid (Scheme 10). 

In the past years, only a few reports have dealt with a chiral auxiliary induced diastereoselective aza MBH reaction. In 1994, Kiindig et al. explored the reaction of methyl acrylate and acrylonitrile with enantiopure planar chiral o substituted Cr(CO)3. Under the catalysis of DABCO, the corresponding aza MBH adducts were obtained in good yields. Removal of the metal provided chiral amines in high yields and enantiomeric excesses [12]. Later on, Aggarwal ef al. used enantiopure Nsulfinimines in the aza MBH reaction with methyl acrylate in the presence of 3 hydroxyquinuclidine (3 HQD) and Lewis add. The desired adducts, functionalized P sulfonated amino acid derivatives, were obtained with good diastereoselectivities (Scheme 13.4) [13]. 

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