Cyclic Formals Research Articles

Synthesis and polymerization of cyclic formals of oligooxyethylene diols

AbstractPolymers of general formula [−(CH2CH2O)m‐CH2O‐]n with well‐defined m value may be obtained by cationic ring‐opening polymerization of easily available cyclic formals of di‐, tri‐, tetra‐, penta‐ (and possibly higher) ethylene glycols. There are no significant kinetic or thermodynamic restrictions for their polymerization. Polymers with [(‐CH2CH2O)m‐CH2O‐]n structure may be treated as intermediates between polymers of ethylene oxide (POE) and polymers of 1,3‐dioxolane (PDXL), both of which find applications in the biomedical field as well as components of solid polymer electrolytes. Largely unexploited [(‐CH2CH2O)m‐CH2O‐]n polymers may broaden the scope of the application of polyacetals in both these areas.

Concurrent cationic vinyl-addition and ring-opening copolymerization of vinyl ethers and oxiranes

Our recent results in the concurrent cationic vinyl-addition and ring-opening copolymerization of vinyl ethers (VEs) and oxiranes are summarized with particular emphasis on the strategies required to generate crossover reactions between different types of monomers. Most importantly, carbocation generation via the ring-opening reaction of the oxonium ion is indispensable for the crossover reaction from oxirane to VE. This article also summarizes concurrent cationic vinyl-addition, ring-opening and carbonyl-addition terpolymerization, the copolymerization using an alkoxyoxirane through the alkoxy group transfer mechanism and the long-lived species-mediated polymerization using cyclic formals.

Synthesis, structure, and transformations of cyclic glycerol formals

Glycerol reacts with paraformaldehyde to give a mixture of 4-hydroxymethyl-1,3-dioxolane and 5-hydroxy-1,3-dioxane. Some transformations (alkylation and replacement of the OH groups with the Cl atoms) of the synthesized compounds were performed. The differences in NMR and mass spectra of the corresponding 1,3-dioxolanes and 1,3-dioxanes were revealed and discussed.

Novel reaction between cyclic formal and ethylene oxide

AbstractNovel reactions between trioxane and ethylene oxide were discovered, and three novel cyclic formals were isolated and identified. These novel cyclic compounds clarified the initiation mechanism of the copolymerization of trioxane and ethylene oxide. This type of reaction was not limited to the reaction between trioxane and ethylene oxide but was also generalized to the reaction between the cyclic formal and ethylene oxide. Although an NMR method for analyzing the ethylene oxide sequences of the acetal copolymer from trioxane and ethylene oxide has not yet been established, the three newly found novel cyclic compounds, composed of 1 mol of ethylene oxide and 1 mol of trioxane, 2 mol of ethylene oxide and 1 mol of trioxane, and 3 mol of ethylene oxide and 1 mol of trioxane, were useful for analyzing the ethylene oxide sequences. These compounds gave only one consecutive oxyethylene unit, two consecutive oxyethylene units, and three consecutive oxyethylene units in three consecutive oxymethylene units, respectively, and gave different 1H NMR spectra for each oxyethylene unit. Considering these data, we synthesized three polymeric model compounds that had one consecutive oxyethylene sequence, two consecutive oxyethylene sequences, and three consecutive oxyethylene sequences in an oxymethylene main chain. By a linear combination of the 1H NMR spectrum of each oxyethylene unit of the three polymeric model compounds, we succeeded in determining the ethylene oxide sequences by the 1H NMR method for the copolymer from trioxane and ethylene oxide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 520–533, 2004

Kinetics and Mechanism of the Cationic Polymerization of Trioxane. III. Copolymerization with Cyclic Formals

Kinetics and mechanism of three cationic copolymerization systems of trioxane (TO) and 1,3-dioxolane (DO) and/or 1,3,5-trioxepane (TOP) including TO/DO 2.0/0.1, TO/DO/TOP 2.0/0.1/0.055, and TO/TOP 2.0/0.1 in a unit of mol/L in 1,2-ethylene dichloride at 30 °C were investigated via evaluations of yields of copolymers and conversions of monomer and comonomer(s) using a gravimetric method and gas chromatography, respectively. The reactivity of DO or TOP was higher than that of TO toward the copolymerizations. Two byproducts, namely, TOP (or DO) and tetroxocane (TOC), were formed during the copolymerization of TO and DO (or TOP). The equilibrium concentrations of TO, DO, TOP, and TOC were ca 0.40, 0.02, 0.02, and 0.02 mol/L, respectively, for the TO/DO and TO/TOP systems whereas relatively high equilibrium concentrations of DO and TOP at ca 0.035 mol/L were for the TO/DO/TOP system. As compared with TO homopolymer, the thermal stability of the copolymers was increased with increasing conversion. The finding that the TO/DO/TOP system having a relatively high amount of cyclic formals consumed in the copolymerization exhibited a relatively low thermal stability suggested that the transacetalization reactions proceeded mainly via oxocarbenium species other than cyclic oxonium species, as compared with the TO/DO and TO/TOP systems.

Novel ring-expansion reaction between cyclic formal and ethylene oxide

Novel direct reactions between trioxane and ethylene oxide were discovered, and three novel cyclic formals were isolated and identified. These novel cyclic compounds clarified the initiation mechanism of the copolymerization of trioxane and ethylene oxide. This type of direct reaction is not only limited to the reaction between trioxane and ethylene oxide, but it was also found to be generalized to the reaction between the cyclic formal and ethylene oxide.

NMR Spectra of Cyclic Formals Formed during the Early Stage of the Copolymerization of Trioxane and Ethylene Oxide

During the early stage of the copolymerization of trioxane and ethylene oxide, we found the formation of three novel cyclic compounds: 1,3,5,7-tetraoxacyclononane (TOCN), 1,3,5,7,10-pentaoxacyclododecane (POCD), and 1,3,5,7,10,13-hexaoxacyclopentadecane (HOCP). These novel cyclic compounds were new direct reaction products of 1 mole of trioxane and 1 mole of ethylene oxide, 1 mole of trioxane and 2 moles of ethylene oxide, and 1 mole of trioxane and 3 moles of ethylene oxide, respectively. We compared the 1H-NMR and 13C-NMR spectra of each cyclic compound and precisely assigned the signals of each spectrum using NOESY (nuclear Overhauser enhancement spectroscopy) and HETCOR (heteronuclear correlated spectroscopy). We also compared the 1H-NMR spectra of POCD and HOCP with the corresponding cyclic formals with one oxymethylene unit, diethylene glycol formal (DEGF) and triethylene glycol formal (TEGF). Interestingly, we found that DEGF and TEGF, which have only one oxymethylene unit, showed no proton splitting of the oxyethylene units, while POCD and HOCP, which have three consecutive oxymethylene units, have split signals for the oxyethylene units.

ChemInform Abstract: Selective Protection of 1,2‐ and 1,3‐Diols via Acylative Cleavage of Cyclic Formals.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Initiation Mechanism of the Copolymerization of 1,3,5-Trioxane and Ethylene Oxide

Initially, the initiation mechanism for the copolymerization of 1,3,5-trioxane (TO) and ethylene oxide proposed the formation of 1,3-dioxolane from the reaction of ethylene oxide with formaldehyde, and this mechanism was believed plausible for a long time. Recently, we carefully studied the bulk copolymerization of TO and ethylene oxide using boron trifluoride-dibutyl ether as the initiator. Two novel cyclic formals, 1,3,5,7-tetraoxacyclononane (TOCN) and 1,3,5,7,-10-pentaoxacyclododecane (POCD), from the initiation reaction of the copolymerization of TO and ethylene oxide were isolated and identified. From this discovery, we proposed a new initiation mechanism for the copolymerization of TO and ethylene oxide. Ethylene oxide reacts directly with TO to form TOCN and POCD. From TOCN, 1,3,5-trioxepane (TOXP) is formed, and from TOXP, 1,3-dioxolane is formed.

Selective Protection of 1,2- and 1,3-Diols via Acylative Cleavage of Cyclic Formals

Selective Protection of 1,2- and 1,3-Diols via Acylative Cleavage of Cyclic Formals

Living cationic polymerization of isobutyl vinyl ether by EtAlCl2 in the presence of ether additives: Cyclic ethers, cyclic formals, and acyclic ethers with oxyethylene units

AbstractThe living cationic polymerization of isobutyl vinyl ether (IBVE) was investigated in the presence of various cyclic and acyclic ethers with 1‐(isobutoxy)ethyl acetate [CH3CH(OiBu)OCOCH3, 1]/EtAlCl2 initiating system in hexane at 0°C. In particular, the effect of the basicity and steric hindrance of the ethers on the living nature and the polymerization rate was studied. The polymerization in the presence of a wide variety of cyclic ethers [tetrahydrofuran (THF), tetrahydropyran (THP), oxepane, 1,4‐dioxane] and cyclic formals (1,3‐dioxolane, 1,3‐dioxane) gave living polymers with a very narrow molecular weight distribution (MWD) (M̄ω/M̄n ≤ 1.1). On the other hand, propylene oxide and oxetane additives resulted in no polymerization, whereas 1,3,5‐trioxane gave the nonliving polymer with a broader MWD. The polymerization rates were dependent on the number of oxygen and ring sizes, which were related to the basicity and the steric hindrance. The order of the apparent polymerization rates in the presence of cyclic ether and formal additives was as follows: nonadditive ∼ 1,3,5‐trioxane ≫ 1,3‐dioxane > 1,3‐dioxolane ≫ 1,4‐dioxane ≫ THP > oxepane ≫ THF ≫ oxetane, propylene oxide ≫ 0. The polymerization in the presence of the cyclic formals was much faster than that of the cyclic ethers: for example, the apparent propagation rate constant k in the presence of 1,3‐dioxolane was 103 times larger than that in the presence of THF. Another series of experiments showed that acyclic ethers with oxyethylene units were effective as additives for the living polymerization with 1/EtAlCl2 initiating system in hexane at 0°C. The polymers obtained in the presence of ethylene glycol diethyl ether and diethylene glycol diethyle ether had very narrow molecular weight distribution (M̄ω/M̄n ≤ 1.1), and the M̄n was directly proportional to the monomer conversion. The polymerization behavior was quite different in the polymerization rates and the MWD of the obtained polymers from that in the presence of diethyl ether. These results suggested the polydentate‐type interaction or the alternate interaction of two or three ether oxygens in oxyethylene units with the propagating carbocation, to permit the living polymerization of IBVE. © 1994 John Wiley & Sons, Inc.

Nitration by oxides of nitrogen, part 3: Reactions of dinitrogen pentoxide with mono- and dioxacycloalkanes with 5-, 6- & 7-membered rings

Reaction of medium ring cyclic ethers with N 2 O 5 in halogenated solvents gave only low yields of the corresponding dinitrates. On the other hand, cyclic formals (1,3-dioxolane and its homologues) gave moderate yields of unstable ring-opened products (hemiformal nitrates), together with variable amounts of rearranged products containing formate ester groups. The formates are believed to result from attack of N 2 O 5 on the heterocycle by a hydride abstraction route

Synthesis of polyformals from nitro‐ and fluordiols. Substituent and chainlength effects

AbstractA series of primary and secondary diols carrying nitroalkyl, nitro, and fluoro substituents was reacted with formaldehyde under conditions of acid catalysis. Short‐chain primary diols gave cyclic formals while predominantly linear polymers were obtained beginning with pentane‐1,5‐diols and hexane‐1,6‐diols, depending upon the nature of the substituents. No polymers were formed from secondary diols with 1‐nitroalkyl substituents. The effect of monomer structure on polymer formation is discussed. The polymers obtained were characterized by GPC and end group analysis.

Acetolysis of cyclic acetals: regioselective acylative cleavage of cyclic formals

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAcetolysis of cyclic acetals: regioselective acylative cleavage of cyclic formalsWilliam F. Bailey and Alberto D. RiveraCite this: J. Org. Chem. 1984, 49, 25, 4958–4964Publication Date (Print):December 1, 1984Publication History Published online1 May 2002Published inissue 1 December 1984https://doi.org/10.1021/jo00199a040RIGHTS & PERMISSIONSArticle Views647Altmetric-Citations24LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (968 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Kinetics and mechanism of bromination of cyclic acetals with 1,4-dioxane dibromide

It is shown that the reactivities of cyclic formals in the case of bromination with dioxane dibromide increase in the order 1,3-dioxepane > 1,3-dioxalane ≫ 1,3-dioxane, which is explained not only by steric factors but also by the ease of cleavage of the C4-O3 bond of the dioxacyclane ring. The bromination of cyclic acetals takes place through prior enolization of the cyclic acetal with subsequent electrophilic addition of bromine to the double bond.

Kinetik und mechanismus der kationischen polymerisation von trioxan: Ein katalysierter kristallwachstumsprozeß

AbstractThe kinetics of the cationic polymerization of trioxane initiated by perchloric acid is analyzed as a simultaneous polymerization and crystallization process. The details of the crystal growth such as nucleation, distribution of crystal sizes, development of growth spirals etc. have been investigated by electron and light microscopic techniques. The mechanism of polymerization can be understood as a catalyzed crystal growth. A well defined population of crystals is formed during a nucleation event at the start of the polymerization. An adsorption equilibrium with regard to the catalyst is then established in the presence of the rather large surface area of the growing polymer crystals. Assuming a Langmuir‐type adsorption behaviour, the observed growth features (growth spirals) can be quantitatively interpreted on the basis of the BCF‐theory of crystal growth. The current concepts on the molecular mechanism of cationic polymerization of cyclic formals have been modified such as to take into account that each chemical step of the polymerization is a building step of the crystal too.

NMR studies on the growing species in the cationic polymerization of cyclic formals: An oxycarbenium ion formed in the reaction of 1,3‐dioxane with triethyloxonium tetrafluoroborate

NMR studies on the growing species in the cationic polymerization of cyclic formals: An oxycarbenium ion formed in the reaction of 1,3‐dioxane with triethyloxonium tetrafluoroborate

Cationic Polymerization of Cyclic Ethers Initiated by Macromolecular Dioxolenium Perchlorate

Cationic polymerization of tetrahydrofuran (THF) with 2-methyl-1,3-dioxoleum perchlorate proceeded as a living system without chain transfer and termination, and the initiation reaction was shown to be the bonding mechanism. Poly-THF with terminal dioxolenium perchlorate group was synthesized from poly(tetramethylene glycol) by stepwise reaction with adipoyl chloride, ethylene bromohydrin, and silver perchlorate. The quantitative formation of macromolecular dioxolenium salt was proved from the polymerization behavior of the THF. Polymerization of 3,3-bischloromethyloxetane by the initiator yielded block copolymer, and no chain-transfer reaction except the termination reaction was observed. Polymerization of 7-oxabicyclo[2.2.1]-heptane by the initiator yielded homopolymer as well as block copolymer, and a significant amount of chain transfer reaction was observed. Polymerizatian of dioxolane and tetraoxane by the initiator yielded little block copolymer, demonstrating the different mechanism of the initiation reaction in the case of cyclic formals.

Determination of the basicity of some cyclic ethers and cyclic formals

AbstractThe tendency of some cyclic ethers and cyclic formals (“oxacyclic compounds”) to form protonated complexes was studied by means of UV spectroscopy. The degree of basicity (pKBH+) was evaluated on the basis of the HAMMET indicator functions.The process of complex formation was followed at different values of the HAMMET function in dilute spectroscopically pure sulfuric acid. The pKBH+ values of four of the seven examined compounds correlated very well with the pKBH+ values obtained by a method different in principle. This was taken as an indication of the objectivity of the evaluation of the basicity of the “oxacyclic compounds” by spectral methods regardless of the fact that these compounds are very weak bases and form colourless protonated complexes.

Mechanism of the oxonium polymerization of cyclic ethers and formals under different conditions

Mechanism of the oxonium polymerization of cyclic ethers and formals under different conditions