The Synthesis of Brominated Tetrafluoro[2.2]paracyclophanes

Bondarenko, Lidija; Kampf, Jeff W.; Lahann, Jörg

doi:10.1002/ejoc.200600598

Cited by 3 publications

(5 citation statements)

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“…It is noteworthy that an electron-deficient oxygen atom, as part of a nitrate ester, can direct EAS. When 1 was subjected to more forceful bromination conditions (excess Br 2 , Fe metal, CH 2 Cl 2 ), we monitored the reaction and observed tetrabromination of the top ring 9 before evidence of bottom ring bromination (Scheme and Figure S3 show the crystal structure of 9 ). , …”

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confidence: 99%

“…When 1 was subjected to more forceful bromination conditions (excess Br 2 , Fe metal, CH 2 Cl 2 ), we monitored the reaction and observed tetrabromination of the top ring 9 before evidence of bottom ring bromination (Scheme 2 and Figure S3 show the crystal structure of 9). 34,35 We then sought a stronger electron-withdrawing group that would afford a more dramatic demonstration of the external activating effect of the hydroxyl group. One of the most potent deactivators is the trifluoromethyl group, which reduces the relative reactivity of an arene ring by more than 40000-fold.…”

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Through-Space Activation Can Override Substituent Effects in Electrophilic Aromatic Substitution

et al. 2017

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Electrophilic aromatic substitution (EAS) represents one of the most important classes of reactions in all of chemistry. One of the "iron laws" of EAS is that an electron-rich aromatic ring will react more rapidly than an electron-poor ring with suitable electrophiles. In this report, we present unique examples of electron-deficient arenes instead undergoing preferential substitution in intramolecular competition with more electron-rich rings. These results were made possible by exploiting the heretofore unknown propensity of a hydrogen-bonding OH-arene interaction to switch to the alternative HO-arene interaction in order to provide activation. In an extreme case, this through-space HO-arene activation is demonstrated to overcome the deactivating effect of a trifluoromethyl substituent, making an otherwise highly electron-deficient ring the site of exclusive reactivity in competition experiments. Additionally, the HO-arene activation promotes tetrabromination of an increasingly more electron-deficient arene before the unactivated "control" ring undergoes monobromination. It is our hope that these results will shed light on biological interactions as well as provide new strategies for the electrophilic substitution of aromatic rings.

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Through-Space Activation Can Override Substituent Effects in Electrophilic Aromatic Substitution

et al. 2017

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“…[23] In principle, the presence of bromine may allow subsequent modifications of the polymer, albeit harsh conditions may have to be employed. On the other hand, compound 3 was synthesized as described previously for similar compounds, [19,24] using …”

Section: Precursor Synthesis and Characterizationmentioning

confidence: 99%

“…Compound 1 was synthesized according to a previously established synthesis chemistry [23] . Precursor 3 was synthesized by Friedel-Crafts acylation of [2.2]paracyclophane with the corresponding acid chloride (heptadecafluorononanoyl chloride 98%, Apollo Scientific Ltd., Cheshire, UK).…”

Section: Experimental 41 Precursor Synthesismentioning

confidence: 99%

Partially Fluorinated Poly‐p‐xylylenes Synthesized by CVD Polymerization

Elkasabi

Nandivada

Chen

et al. 2009

Chemical Vapor Deposition

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This paper describes partially fluorinated poly-p-xylylenes prepared by CVD polymerization. The synthesis, characterization, and surface modification of two partially fluorinated polymer coatings, namely poly(4,12-dibromo-1,1,9,9-tetrafluoro-pxylylene) (2) and poly(4-heptadecafluorononanoyl-p-xylylene-co-p-xylylene) (4), is described. Polymer 2 is synthesized from 4,12-dibromo-1,1,9,9-tetrafluoro[2.2]paracyclophane (1), which is fluorinated at the aliphatic bridge, while 4-heptadecafluorononanoyl[2.2]paracyclophane (3), which contains a perfluorinated keto group at the aromatic ring, is used to synthesize polymer 4. Furthermore, the keto-functionalized polymer 4 introduces both extreme hydrophobicity and surface reactivity towards hydrazide-containing ligands.

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“…Although there are a few examples of benzylic modified [2.2] paracyclophane, these synthetic routes are not commercially scalable or the resulting polymers have instability issues, for example, HF or HCl elimination. [3,4] By going to a monomer precursor route to the parylene polymers, new precursor chemistries are made possible, which are both easy to synthesize and scalable for manufacturing. In particular, a new route which uses alkoxy chemistry has been invented and is modeled on the tetraethoxysilane deposited silicon dioxide prevalent in the semiconductor industry.…”

Section: Introductionmentioning

confidence: 99%

CVD of Poly(α,α′‐dimethyl‐p‐xylylene) and Poly(α,α,α′,α′‐tetramethyl‐p‐xylylene)‐co‐poly(p‐xylylene) from Alkoxide Precursors II: Thermal Oxidative Stability

Senkevich

2011

Chemical Vapor Deposition

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The Achilles heel of the parylene polymers is their oxidative stability at room temperature with UV exposure and at elevated temperature >115 8C in air. This weakness is attributed to the aliphatic carbon-carbon single bond in the main-chain backbone. Fluorinating this chemistry helps the oxidation substantially, but the precursor then becomes nearly prohibitive to use due to cost of the precursor and the processing cost. Another option is to explore the methylation of this benzyl position. Poly(a,a 0 -dimethyl-p-xylylene) and poly(a,a,a 0 ,a 0 -tetramethyl-p-xylylene)-co-poly( p-xylylene) are deposited on the parylene platform via alkoxy precursors. Their oxidation as a function of temperature to 300 8C; and time at 150 8C is explored via variable angle spectroscopic ellipsometry (VASE) and infrared spectroscopy (IRS). Results show very little difference between the two polymers as a function of oxidation temperature, and better results compared to what was previously observed with the poly( pxylylene) homopolymer, however the oxidation of poly(a,a 0 -dimethyl-p-xylylene) at 150 8C as a function of time is less positive with 16% thickness loss over 1000 h with the post-deposition annealed sample.

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The Synthesis of Brominated Tetrafluoro[2.2]paracyclophanes

Abstract: The bromination of the two isomeric tetrafluoro[2.2]paracyclophanes was investigated under various conditions. We found selective conditions for mono-and dibromination of 1,1,9,9-tetrafluoro[2.2]paracyclophane in high yields. Furthermore, three tetrabromo isomers were characterized.

Cited by 3 publications

References 21 publications

Through-Space Activation Can Override Substituent Effects in Electrophilic Aromatic Substitution

Through-Space Activation Can Override Substituent Effects in Electrophilic Aromatic Substitution

Partially Fluorinated Poly‐p‐xylylenes Synthesized by CVD Polymerization

CVD of Poly(α,α′‐dimethyl‐p‐xylylene) and Poly(α,α,α′,α′‐tetramethyl‐p‐xylylene)‐co‐poly(p‐xylylene) from Alkoxide Precursors II: Thermal Oxidative Stability

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