Methyl tosylate Initiated

Scheme 8.25 Schematic representation of the methyl-tosylate-initiated CROP of cyclic irnino ethers indicating the isomerization from an imino ether to an amide moiety during polymerization as well as the R functionality of the monomer that determines the polymer side-chain functionality.

In addition, the propagating species of MeOZO polymerization with the methyl tosylate initiator is reacted with a higher alkyl primary amine to produce another type of non-ionic surfactant [9]. ... 

The living cationic ring opening polymerization (CROP) of 2-oxazolines was first reported in the 1960s [61, 62]. The polymerization can be initiated by an electrophile such as benzyl halides, acetyl halides, and tosylate or triflate derivatives. The typical polymerization mechanism for 2-alkyl-2-oxazoline initiated by methyl tosylate is shown in Scheme 6. 

Scheme 6 Schematic representation of the CROP of 2-ethyl-2-oxazoline (EtOx) initiated by the methyl tosylate...

A library of 4 chain extended homopolymers and 12 diblock copoly(2-oxazoline)s was prepared from 2-methyl, 2-ethyl, 2-nonyl, PheOx in a very short period of time [90]. The CROP was initiated by methyl tosylate and performed in acetonitrile at 140 °C in a single-mode microwave synthesizer. A total number of 100(50 + 50) repeating units was incorporated into the respective polymer chains. The concentration of the solutions and predefined polymerization times for each monomer and comonomer are summarized in Table 11. 

A theoretical model was developed to correlate molecular weight distribution of this system. This was compared to the experimental gel permeation chromatography trace with the theoretical model modified to Include the effect of the PEG central block, the spreading of the trace as it went through the columns and the slope of the log MW versus retention volume line. A good fit was found with kl/kp = 0.0070. When methyl tosylate was used to polymerize 2-lsobutyl oxazollne, a similar treatment of the data showed kl/kp = 0.22. The effect of the PEG Is explained as due to solvation of the Initial adduct by the neighboring ether group. 

Methyltosylate initiated polymerization In order to determine if the PEG part plays any significant role in initiation, a polymerization was carried out with methyl tosylate as initiator using M/I of 5.92. At complete consumption of monomer, unreacted methyl tosylate was still present (see Figure 4). The polymer produced had a broad molecular weight distribution, 1.39. kp/kl was estimated by... 

The polymer produced with methyl tosylate as initiator has one N-CHg group per chain and this methyl group could be observed in the NMR spectrum. By comparing the Integrals of N-CHj (a) and CH, (b) of the isobutyl side chains, the degree of polymerization was calculated. 

Litt claimed formation of block copolymers of 2-lauroyl-2-oxazoline and 2-methyl-2-oxazine by sequential polymerization 122). Methyl tosylate was the initiator and the polymerization was terminated by water. The proposed structure of the copolymer is ... 

Ring-opening polymerization reactions of several 2-substituted-2-oxazolines (i.e. 2-methyl, 2-ethyl, 2-nonyl, and 2-phenyl) in the presence of methyl tosylate as catalyst have been described by Schubert et al. (Scheme 14.14) [33-35]. The reactions were performed in the temperature range 80 to 200 °C inside a single-mode micro-wave reactor. In a typical run, 25 mL stock solutions of monomer-initiator-solvent were prepared before the polymerization. These stock solutions were divided among different reaction vials so each experiment was performed on a 1-mL scale. 

The same technique of the ring-opening polymerization under microwave irradiation conditions was subsequently applied to the synthesis of a library of diblock copoly(2-oxazoline)s in which a total number of 100 (50 + 50) monomer units were incorporated into the polymer chains [36]. As a result, 16 polymers were obtained with narrow polydispersity indexes (PDI < 1.30). The reactions were initiated by methyl tosylate and conducted in acetonitrile solution at 140 °C. After polymerization of the first monomer the reaction vessels were re-transferred to an inert atmosphere of argon, the second monomer was added, and the reaction mixture was again irradiated in a microwave reactor. 

Bulk CROP of a soy-based 2-oxazoline (SoyOx) monomer has been performed using a scientific microwave unit, with methyl tosylate (MeOTs) serving as an initiator (Scheme 3.9). Full conversion was achieved within 8 min, leaving the double bonds of the fatty acids side chains unaffected and thus available for further cross-linking by UV irradiation. Statistical copolymers of SoyOx with 2-ethyl-2-oxazoline were also prepared. Rubbery cross-linked materials showing shape-persistent swelling upon absorption of water from the air could be prepared with as little as 13 wt% (5 mol%) of SoyOx. ... 

Poly(2-oxazoline)s can be prepared by living cationic ring-opening polymerization of the 2-oxazoline monomers utilizing an electrophilic initiator, such as methyl tosylate or methyl triflate. Attack of the monomer onto this initiator leads to the formation of a cationic oxazohnium species and subsequent monomer attack leads to ring-opening while the newly added monomer ends up as a cationic oxazolinium chain end. As such, well-defined polymers can be obtained and the chain-end functionalities can be controlled during initiation and termination (Aoi and Okada, 1996). 

Considering the monoaminomercuration-demercuration of 1,4-hexadiene with /V-me-thylaniline leads to V-methyl-lV-(l-methylpent-3-enyl)aniline, the stereoselective synthesis of /V-alkoxycarbonyl or /V-tosyl s-2,5-dimethylpyrrolidine from the same diene has been explained172 on the basis of an initial amidomercuration reaction on the terminal bond followed by the second addition of mercury(II) salt to the internal double bond, on the less sterically hindered site (equation 171). 

A multi-step reaction sequence was then realized to prepare the precursor (178) for the pivotal macrocyclization reaction. Alternate stepwise chain elongations were achieved according to Schemes 28 and 29. Reaction of the tosylate prepared from the alcohol 162 with lithium acetylide afforded the alkyne 174 (Scheme 28). Following the introduction of a tosylate at the upper branch, a one-carbon chain elongation of the terminal alkyne afforded the methyl alkynoate 175. A methyl cuprate 1,4-addition was used to construct the tri-substituted C double bond stereoselectively. For this purpose, the alkynoate 175 was initially transformed into the Z-configured a,/ -unsat-... 

The second way differs from the first in that the methylation of nitrogen is accomphshed before the cyclocondensation reaction. In order to do this, the initial 2-amino-5-chlorobenzo-phenone is first tosylated by p-toluenesulfonylchloride and the obtained tosylate (5.1.3) transformed into the N-sodium salt, which is then alkylated by dimethylsulfate. The resulting 2-A -tosyl-A -methyl-5-chlorobenzophenone (5.1.4) is hydrolyzed in an acidic medium, giving 2-methylamino-5-chlorobenzophenone (5.1.5), which undergoes cyclocondensation by reaction with ethyl ester of glycine hydrochloride, forming the desired diazepam (5.1.2) [1-5]. 

The synthesis of AMO involves treatment of 3,3-bis(chloromethyl) oxetane (BCMO) with sodium azide in the DMF medium at 85 °C for 24 h. Similarly, AMMO which is a monofunctional analog of AMO is synthesized by the azidation of chloro/tosylate product of 3-hydroxymethyl-3-methyl oxetane (HyMMO) with sodium azide in DMF medium at elevated temperatures. These energetic monomers are readily polymerized to liquid curable prepolymers with the help of boron trifluoride etherate/l,4-butanediol initiator system and the outlines of synthesis [147-150] of poly(BAMO) [Structure... 

Cycloaddition reactions of phenyl and tosyl azides to the strained double bond in cyclopropenes have been investigated.170il The reaction products from 3,3-dimethylcyclopropene indicate that the initially formed intermediate is a normal 1,3-dipolar adduct. Tetrachlorocyclopropene yields the primary adducts with several aryl azides. 70b However, cyclopropenedicarboxyl ester gives only unstable triazolines with phenyl and methyl azides.170 ... 

The reactivity of cellulose toward tri(p-toluenesulfonyl)methane chloride was recently examined [89]. The tosyl reagent is more reactive than trityl chloride, and the primary hydroxyl position exhibited 43 times more reactivity than the secondary hydroxyl groups. The products were used as intermediates in the synthesis of selectively modified cellulose derivatives [89]. As mentioned earlier, a high DS, organosol trimethylsilylcellulose has been prepared in DMAc/LiCl [10]. The condensation of polysaccharides with triphenyl-methyl (trityl) chloride proceeds generally with preference for the primary hydroxyl positions. The tritylation of cellulose occurs initially 58 times faster at the hydroxyl group at C6 than at either C2 or C3 [90]. 

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