Aromatic Chemistry Research Articles

Comparison of pre-fermentation and post-fermentations alcohol adjustments on aromatic chemistry and sensory composition of Sauvignon blanc wine

Harvest and alcohol adjustment effects were evaluated for Sauvignon blanc grapes harvested at three potential alcohols (11, 13 and 15% (v/v)) by gas chromatography–mass spectrometry and descriptive analysis. Alcohol concentration was controlled for pre-fermentation by dilution or chaptalization and post-fermentation by dealcoholization. The initial experimental alcohol was treated as the control and the dealcoholized wine the treatment. Wine treatments sharing the same alcohol target and harvest date as the dealcoholized wine were designated as the negative control. All aroma compounds measured increased because of higher ethanol or declined because of dealcoholization. Similar aroma concentrations were observed to be a factor of alcohol concentration, apart from volatile thiols which were influenced by harvest. Statistical analysis of sensory and aroma compounds showed a corresponding relationship between low versus high alcohol wines. Dealcoholization appears to be an effective tool for altering wine aroma and winemaking style with comparable aroma loss to pre-fermentation adjustment.

"The Sulfur Dance" Around Arenes and Heteroarenes - the Reversible Nature of Nucleophilic Aromatic Substitutions.

We disclose the features of a category of reversible nucleophilic aromatic substitutions in view of their significance and generality in dynamic aromatic chemistry. Exchange of sulfur components surrounding arenes and heteroarenes may occur at 25 °C, in a process that one may call a "sulfur dance". These SNAr systems present their own features, apart from common reversible reactions utilized in dynamic covalent chemistry (DCC). By varying conditions, covalent dynamics may operate to provide libraries of thiaarenes with some selectivity, or conversion of a hexa(thio)benzene asterisk into another one. The reversible nature of SNAr is confirmed by three methods: a convergence of the products distribution in reversible SNAr systems, a related product redistribution between two per(thio)benzenes by using a thiolate promoter, and from kinetic/thermodynamic data. A four-component dynamic covalent system further illustrates the thermodynamically-driven formation of a thiacalix[2]arene[2]pyrimidine by sulfur component exchanges. This work stimulates the implementation of reversible SNAr in aromatic chemistry and in DCC.

Phenalenyl growth reactions and implications for prenucleation chemistry of aromatics in flames.

The energetics and kinetics of phenalene and phenalenyl growth reactions were studied theoretically. Rate constants of phenalene and phenalenyl H-abstraction and C2H2 addition to the formed radicals were evaluated through quantum-chemical and rate-theory calculations. The obtained values, assigned to all π radicals, were tested in deterministic and kinetic Monte Carlo simulations of aromatics growth under conditions of laminar premixed flames. Kekulé and non-Kekulé structures of the polycyclic aromatic hydrocarbons (PAHs) evolving in the stochastic simulations were identified by on-the-fly constrained optimization. The numerical results demonstrated an increased PAH growth and qualitatively reproduced experimental observations of Homann and co-workers of non-decaying PAH concentrations with nearly equal abundances of even and odd carbon-atom PAHs. The analysis revealed that the PAH growth proceeds via alternating and sterically diverse acetylene and methyl HACA additions. The rapid and diverse spreading in the PAH population supports a nucleation model as PAH dimerization, assisted by the non-equilibrium phenomena, forming planar aromatics first and then transitioning to the PAH-PAH stacking with size.

Sensitivity analysis of aromatic chemistry to gas-phase kinetics in a dark molecular cloud model.

The increasingly large number of complex organic molecules detected in the interstellar medium necessitates robust kinetic models that can be relied upon for investigating the involved chemical processes. Such models require rate coefficients for each of the thousands of reactions; the values of these are often estimated or extrapolated, leading to large uncertainties that are rarely quantified. We have performed a global Monte Carlo and a more local one-at-a-time sensitivity analysis on the gas-phase rate coefficients in a 3-phase dark cloud model. Time-dependent sensitivities have been calculated using four metrics to determine key reactions for the overall network as well as for the cyanonaphthalene molecule in particular, an important interstellar species that is severely under-produced by current models. All four metrics find that reactions involving small, reactive species that initiate hydrocarbon growth have large effects on the overall network. Cyanonaphthalene is most sensitive to a number of these reactions as well as ring-formation of the phenyl cation (C6H5+) and aromatic growth from benzene to naphthalene. Future efforts should prioritize constraining rate coefficients of key reactions and expanding the network surrounding these processes. These results highlight the strength of sensitivity analysis techniques to identify critical processes in complex chemical networks, such as those often used in astrochemical modeling.

Metal Free Dötz‐Type Aminobenzannulation Reaction via 1,1‐Dipoles Cross‐Coupling

AbstractAryl amines are of constant interest in organic synthesis owing to their ubiquity in natural products, pharmaceuticals, and organic materials. However, C−H amination or pre‐functionalization frequently results in uncontrollable site selectivity, over activation and the generation of inseparable mixtures of regio‐isomers. Here we present a novel metal free Dötz‐type aminobenzannulation reaction that circumvents the selectivity issues inherent in aromatic chemistry, as well as the use of stoichiometric unstable organolithium reagents and toxic chromium complexes. The concept of utilizing readily available isocyanides and Morita–Baylis–Hillman (MBH) carbonates to achieve 1,1‐dipoles cross‐coupling to construct ketenimine is the key to success, which has been experimentally and computationally verified. The tandem 6π‐electrocyclization/aromatization process offers a versatile method for synthesizing functionalized anilines, fused aryl amines and fused heteroaryl amines.

Metal Free Dötz-Type Aminobenzannulation Reaction via 1,1-Dipoles Cross-Coupling.

Aryl amines are of constant interest in organic synthesis owing to their ubiquity in natural products, pharmaceuticals, and organic materials. However, C-H amination or pre-functionalization frequently results in uncontrollable site selectivity, over activation and the generation of inseparable mixtures of regio-isomers. Here we present a novel metal free Dötz-type aminobenzannulation reaction that circumvents the selectivity issues inherent in aromatic chemistry, as well as the use of stoichiometric unstable organolithium reagents and toxic chromium complexes. The concept of utilizing readily available isocyanides and Morita-Baylis-Hillman (MBH) carbonates to achieve 1,1-dipoles cross-coupling to construct ketenimine is the key to success, which has been experimentally and computationally verified. The tandem 6π-electrocyclization/aromatization process offers a versatile method for synthesizing functionalized anilines, fused aryl amines and fused heteroaryl amines.

Characterization of the Ensemble of Lignin-Remodeling DyP-Type Peroxidases from Streptomyces coelicolor A3(2)

Lignin is Nature’s major source of aromatic chemistry and is by many seen as the green entry-point alternative to the fossil-based chemical industry. Due to its chemically recalcitrant structure, the utilization of lignin is challenging, wherein enzymes might be the key to overcome this challenge. Here, we focus on the characterization of dye-decolorizing peroxidases from Streptomyces coelicolor A3(2) (ScDyPs) in the context of enzymatic modification of organosolv lignins from aspen and Miscanthus × giganteus. In this study, we show that the ScDyPB can remodel organosolv lignins from grassy biomass, leading to higher molecular weight species, while ScDyPAs can deconstruct hardwood lignin, leading to an overall reduction in its molecular weight. Additionally, we show that ScDyPB is effective in polymerizing low-molecular-weight phenolics, leading to their removal from the solution.

Synthesis and characterization of Craig-type antiaromatic species with [4n + 2] π electrons

Antiaromaticity is extended from aromaticity as a complement to describe the unsaturated cyclic molecules with antiaromatic destabilization. To prepare antiaromatic species is a particularly challenging goal in synthetic chemistry because of the thermodynamic instability of such molecules. Among that, both Hückel and Möbius antiaromatic species have been reported, whereas the Craig one has not been realized to date. Here, we report the first example of planar Craig antiaromatic species. Eight Craig antiaromatic compounds were synthesized by deprotonation-induced reduction process and were fully characterized as follows. Single-crystal X-ray crystallography showed that these complexes have planar structures composed of fused five-membered rings with clearly alternating carbon-carbon bond lengths. In addition, proton NMR (1H NMR) spectroscopy in these structures showed distinctive upfield shifts of the proton peaks to the range of antiaromatic peripheral hydrogens. Experimental spectroscopy observations, along with density-functional theory (DFT) calculations, provided evidence for the Craig antiaromaticity of these complexes. Further study experimentally and theoretically revealed that the strong exothermicity of the acid-base neutralization process was the driving force for this challenging transformation forming Craig antiaromatic species. Our findings complete a full cycle of aromatic chemistry, opening an avenue for the development of new class of antiaromatic systems.

Helical Synthetic Nanographenes with Atomic Precision

ConspectusUnderstanding and harnessing the properties of nanoscale molecular entities are considered as new frontiers in basic chemistry. In this regard, synthetic nanographene with atomic precision has attracted much attention recently. For instance, taking advantage of the marvelous bonding capability of carbon, flat, curved, ribbon-type, or cone-shaped nanographenes have been prepared in highly controllable and elegant manner, allowing one to explore fascinating molecular architectures with intriguing optical, electrochemical, and magnetic characteristics. This stands in stark contrast to other carbon-rich nanomaterials, such as graphite oxides or carbon quantum dots, which preclude thorough investigations because of complicate structural defects. Undoubtedly, synthetic nanographene contributes strongly to modern aromatic chemistry and represents a vibrant field that may deliver transforming functional materials crucial for optoelectronics, nanotechnologies, and biomedicine.Nonetheless, in many cases, synthesis and characterization of nanographene compounds are highly demanding. Low solubility, high molecular strain, undesired selectivity, as well as incomplete or excessive C-C bond formation are common impediments, that require formidable efforts to control the molecular geometry, to modulate the edge structure, to achieve accurate doping, or to push the upper size boundary. These endeavors are indispensable for establishing structure-property relationships, and lay down foundation for exploring synthetic nanographenes at a high level of sophistications.In this Account, we summarize our contributions to this field by presenting a series of helical synthetic nanographenes, such as hexapole [7]helicene (H7H), nitrogen-doped H7H, hexapole [9]helicene (H9H), superhelicene, and supertwistacene. This kind of giant synthetic nanographene reaches the size domain of carbon quantum dots, albeit has precise atomic structure. It provides a unique platform to study aromatic chemistry and chirality at the nanoscale. We discuss synthetic methods and point out, in particular, the strengths and pitfalls of Scholl oxidation, which are expected to be valuable for making synthetic nanographenes in general. In addition, we illustrate their exciting electrochemical and photophysical performance, which include, but are not limited to, reversible multielectron redox chemistry, record high panchromatic absorption, impressive photothermal behavior, and extremely strong Cotton effect. These unusual characteristics are convincingly traced back to their three-dimensional conjugated architectures, highlighting the critical roles of π-electron delocalization, heteroatom-doping, substitution, and molecular symmetry in determining nanographenes' properties and functions. Lastly, we put forward our understanding on the challenges and opportunities that lies ahead and hope this Account will inspire ever more ambitious achievements from this attractive area of research.

An experimental and theoretical investigation of the N(2D) + C6H6 (benzene) reaction with implications for the photochemical models of Titan.

We report on a combined experimental and theoretical investigation of the N(2D) + C6H6 (benzene) reaction, which is of relevance in the aromatic chemistry of the atmosphere of Titan. Experimentally, the reaction was studied (i) under single-collision conditions by the crossed molecular beams (CMB) scattering method with mass spectrometric detection and time-of-flight analysis at the collision energy (Ec) of 31.8 kJ mol-1 to determine the primary products, their branching fractions (BFs), and the reaction micromechanism, and (ii) in a continuous supersonic flow reactor to determine the rate constant as a function of temperature from 50 K to 296 K. Theoretically, electronic structure calculations of the doublet C6H6N potential energy surface (PES) were performed to assist the interpretation of the experimental results and characterize the overall reaction mechanism. The reaction is found to proceed via barrierless addition of N(2D) to the aromatic ring of C6H6, followed by formation of several cyclic (five-, six-, and seven-membered ring) and linear isomeric C6H6N intermediates that can undergo unimolecular decomposition to bimolecular products. Statistical estimates of product BFs on the theoretical PES were carried out under the conditions of the CMB experiments and at the temperatures relevant for Titan's atmosphere. In all conditions the ring-contraction channel leading to C5H5 (cyclopentadienyl) + HCN is dominant, while minor contributions come from the channels leading to o-C6H5N (o-N-cycloheptatriene radical) + H, C4H4N (pyrrolyl) + C2H2 (acetylene), C5H5CN (cyano-cyclopentadiene) + H, and p-C6H5N + H. Rate constants (which are close to the gas kinetic limit at all temperatures, with the recommended value of 2.19 ± 0.30 × 10-10 cm3 s-1 over the 50-296 K range) and BFs have been used in a photochemical model of Titan's atmosphere to simulate the effect of the title reaction on the species abundances as a function of the altitude.

Traditional aromatherapy in the clinical context of a therapeutic community for the treatment of substance use disorders

Western medicine and psychotherapy have historically overlooked the potential of engaging the sense of smell for therapeutic purposes. However, in other medical traditions, such as that of the Peruvian Amazon, specific therapeutic interventions based on the use of aromatic plants are commonly performed in conjunction with other healing modalities. Traditional specialized healers locally known as perfumeros conduct such healing sessions. This research describes how this kind of traditional Amazonian aromatherapy is used in the context of Takiwasi center, a therapeutic community specialized in the treatment of substance use disorders. Participant observation was carried out by shadowing the healers in charge of specific aromatherapy sessions including the so-called plant baths, sahumerio, and saunas. Additionally, semi structured interviews were conducted with several members of Takiwasi’s therapeutic staff, and non-peer reviewed publications and audio-video materials present in the Takiwasi archive were consulted and used as original data for this research. Data on users that received a plant bath from July 2019 to February 2021, were also acquired and discussed. The cosmology beyond this kind of traditional aromatherapy includes concepts such as “energetic body” and “spiritual entities”, opening the discussion on something beyond the mere materialistic aspect of aromatic chemistry and pharmacology.

Prenucleation chemistry of aromatics: A two-ring precursor?

Prenucleation reaction chemistry of polycyclic aromatic hydrocarbons was examined in detailed, site-specific kinetic Monte-Carlo simulations, tracking a single aromatic structure evolving from naphthalene in soot environments of two laminar premixed flames. The numerical results offer a possible reconciliation of a recent flame-based suggestion that one- or two-ring aromatics are the precursors to soot with the otherwise accumulating evidence that soot nucleation begins with mid-size aromatics. The resolution rests in the numerical observation of rapid destruction of the two-ring aromatic molecule, naphthalene, and its replacement with cyclopenta-added derivative structures. The analysis of the reaction events identified important contributions to aromatics evolution from methyl addition to edge five-membered rings. The computed curvature of the growing aromatics exhibited a similar dependence on the molecular size in two substantially different flame environments, thus raising a possibility of universality in aromatic-structure evolution.

We Need to Talk about Kekulé: The 150th Anniversary of the Benzene Structure

AbstractAlthough the paper published by Kekulé in 1865 is generally accepted as the seminal document regarding the elucidation of the structure of benzene, it was not for another seven years that Kekulé introduced a “collision theory” which, in his view, made the 1,3,5‐cyclohexatriene formulation at last acceptable. 2022 is therefore an appropriate year to celebrate the 150th anniversary of his proposal. The present Perspective focusses in particular on how Kekulé’s mind has evolved during that short period of time. After a short introduction, followed by a historical note about the emergence of aromatic chemistry and the role of Kekulé as founder of structural organic chemistry, this Perspective discloses in three chapters the step‐by‐step unveiling of the 1,3,5‐cyclohexatriene structure and focusses on Kekulé’s own dubiety about this formula. Eventually, in 1872 Kekulé’s benzene saga is completed in the article in which he discloses his final theory on the structure of benzene. In the last section, a short review is presented on the later quest for a fully symmetric single‐formula representation of benzene.

Application of Chromatographic Technology to Determine Aromatic Substances in Tobacco during Natural Fermentation: A Review

Flavor is an important index to evaluate the sensory quality of tobacco. The process of fermentation is a key step in the production of aromatic substances in tobacco leaves and an important factor in improving their quality. Worldwide, reams of research show that chromatographic technology plays an irreplaceable role in the tobacco aromatic chemistry. Nevertheless, the degradation mechanism of latent aromatic compounds and the formation mechanism of characteristic aromatic substances have not been fully and systematically elucidated. In this study, the latest progress of basic methods, techniques, and research results of the separation, analysis, and identification of aromatic substances in fermented tobacco leaves were reviewed, and the next research and application directions were prospected. It is expected to provide theoretical reference for the study of molecular mechanism of tobacco flavor, reveal the degradation mechanism of potential aroma compounds, and help improve the quality of tobacco.

Comparative study on ignition characteristics of n-propylbenzene, 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene behind reflected shock waves

Alkyl aromatics comprise a significant portion of real fuels. Among various alkyl aromatics, the C9H12 aromatic fuels including n-propylbenzene and trimethylbenzenes are representative alkyl aromatics, which are widely detected in real fuels, and they are widely employed as surrogate compounds in modeling real fuels. Thus, the combustion kinetic study of C9H12 fuels is necessary and urgent for fuel combustion. In this work, comparative experimental and kinetic modeling study of the high-temperature ignition of three C9H12 fuels is performed. New ignition delay time (IDT) measurements are carried out in a high-pressure shock tube (HPST) for 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene. The studied pressure is 2, 5 and 10 bar, the equivalence ratios are 0.5, 1.0 and 2.0, and the temperature range is from 1090 K to 1600 K for IDT in HPST. The experimental results are simulated using an updated detailed kinetic mechanism. Reaction path analysis and sensitivity analysis are performed to provide insight into the chemical kinetics controlling the ignition of the three C9H12 fuels. The present experimental data set and kinetic model results should be valuable to improve our understanding of the combustion chemistry of alkyl aromatics and to offer practical guidance for the surrogate model development of real fuels.

Ultraviolet and vacuum ultraviolet photo-processing of protonated benzonitrile (C6H5CNH+)

Context. The recent detection in pre-stellar sources of cyano-substituted and pure hydrocarbon cycles has emphasized the importance of aromatic chemistry in the earliest stages of star formation. Ultraviolet (UV) and vacuum-UV (VUV) radiation is ubiquitous in space and thus the photo-processing of small cyclic ions may open a window onto rich chemical networks and lead to the formation of larger aromatics in space. Aims. The aim is to investigate the fate of protonated benzonitrile species after UV and VUV photoexcitation and the subsequent potential impact on stellar and interstellar chemistry. Methods. Protonated benzonitrile was isolated in a linear ion trap prior to irradiation with UV and VUV radiation (4.5–13.6 eV) from the DESIRS beamline at synchrotron SOLEIL. The study was extended down to 3.5 eV using a cryogenic Paul ion trap coupled to an OPO laser at the PIIM laboratory. Photodissociation action spectra were obtained by monitoring the photofragment yields as a function of photon energy. Results. The UV/VUV photodissociation action spectra of protonated benzonitrile show structured bands from 3.8 to 9 eV. The primary dissociation channel of protonated benzonitrile corresponds to HCN/HNC loss and formation of the phenylium cation (C6H5+); whereas at high energies, a minor channel is observed that correlates with HC3N loss and formation of C4H5+. Conclusions. The UV and VUV photodestruction of protonated benzonitrile leads to the formation of a highly reactive cationic species, C6H5+, predicted to be an important precursor of larger aromatic molecules in space, such as polycyclic aromatic hydrocarbons. The inclusion of C6H5+ – a precursor of benzene and, by extension, of benzonitrile – as the result of formation via the photodissociation of protonated benzonitrile in current astrochemical models could improve the predicted abundance of benzonitrile, which is currently underestimated.

Development and evaluation of a new compact mechanism for aromatic oxidation in atmospheric models

Abstract. Aromatic hydrocarbons, including benzene, toluene, and xylenes, play an important role in atmospheric chemistry, but the associated chemical mechanisms are complex and uncertain. Sparing representation of this chemistry in models is needed for computational tractability. Here, we develop a new compact mechanism for aromatic chemistry (GC13) that captures current knowledge from laboratory and computational studies with only 17 unique species and 44 reactions. We compare GC13 to six other currently used mechanisms of varying complexity in box model simulations of environmental chamber data and diurnal boundary layer chemistry, and show that GC13 provides results consistent with or better than more complex mechanisms for oxygenated products (alcohols, carbonyls, dicarbonyls), ozone, and hydrogen oxide (HOx≡OH+HO2) radicals. Specifically, GC13 features increased radical recycling and increased ozone destruction from phenoxy–phenylperoxy radical cycling relative to other mechanisms. We implement GC13 into the GEOS-Chem global chemical transport model and find higher glyoxal yields and net ozone loss from aromatic chemistry compared with other mechanisms. Aromatic oxidation in the model contributes 23 %, 5 %, and 8 % of global glyoxal, methylglyoxal, and formic acid production, respectively, and has mixed effects on formaldehyde. It drives small decreases in global tropospheric OH (−2.2 %), NOx (≡NO+NO2; −3.7 %), and ozone (−0.8 %), but a large increase in NO3 (+22 %) from phenoxy–phenylperoxy radical cycling. Regional effects in polluted environments can be substantially larger, especially from the photolysis of carbonyls produced by aromatic oxidation, which drives large wintertime increases in OH and ozone concentrations.

Durability and Failure Modes of Concrete Beams Strengthened with Polyurethane or Epoxy CFRP

Externally bonded carbon-fiber-reinforced polymer (CFRP) composites are increasingly being used for repair of concrete infrastructure. Both the mechanical performance and the long-term durability of such a repair have resulted in a significant body of research. However, polyurethane-based composites for concrete repair have seen only limited treatment to date. This paper investigates the effect of seven different environments on the durability and failure modes of two different wet lay-up CFRP systems applied to flexural reinforcement of concrete: a two-part epoxy and a preimpregnated, water catalyzed polyurethane with aromatic chemistry as a matrix. Durability of concrete, CFRP laminates, and small-scale CFRP-strengthened concrete flexural beams was investigated for each duration (125, 250, and 365 days) and accelerated conditioning environment. Inverse analysis with a numerical model was used to develop conditioned bond–slip models for each composite system. Results and failure modes of control and conditioned specimens showed that degradation of CFRP-strengthened beams was controlled by the conditioned concrete tensile strength and bond cohesive energy in the epoxy and polyurethane systems, respectively.

Aromatics and Cyclic Molecules in Molecular Clouds: A New Dimension of Interstellar Organic Chemistry.

Astrochemistry lies at the nexus of astronomy, chemistry, and molecular physics. On the basis of precise laboratory data, a rich collection of more than 200 familiar and exotic molecules have been identified in the interstellar medium, the vast majority by their unique rotational fingerprint. Despite this large body of work, there is scant evidence in the radio band for the basic building blocks of chemistry on earth-five- and six-membered rings-despite long-standing and sustained efforts during the past 50 years. In contrast, a peculiar structural motif, highly unsaturated carbon in a chainlike arrangement, is instead quite common in space. The recent astronomical detection of cyanobenzene, the simplest aromatic nitrile, in the dark molecular cloud TMC-1, and soon afterward in additional prestellar and possibly protostellar sources, establishes that aromatic chemistry is likely widespread in the earliest stages of star formation. The subsequent discovery of cyanocyclopentadienes and even cyanonaphthalenes in TMC-1 provides further evidence that organic molecules of considerable complexity are readily synthesized in regions with high visual extinction but where the low temperature and pressure are remarkably low. This review focuses on laboratory efforts now underway to understand the rich transition region between linear and planar carbon structures using microwave spectroscopy. We present key features, advantages, and disadvantages of current detection methods, a discussion of the types of molecules found in space and in the laboratory, and approaches under development to identify entirely new species in complex mixtures. Studies focusing on the cyanation of hydrocarbons and the formation of benzene from acyclic precursors are highlighted, as is the role that isotopic studies might play in elucidating the chemical pathways to ring formation.

Ubiquitous aromatic carbon chemistry at the earliest stages of star formation

Benzonitrile (c-C6H5CN, where ‘c’ indicates a cyclic structure), a polar proxy for benzene (c-C6H6), has the potential to serve as a highly convenient radio probe for aromatic chemistry, provided that this ring can be found in other astronomical sources beyond the molecule-rich prestellar cloud TMC-1. Here we present radio astronomical evidence of benzonitrile in four other prestellar, and possibly protostellar, sources: Serpens 1A, Serpens 1B, Serpens 2 and MC27/L1521F. These detections establish that benzonitrile is not unique to TMC-1; rather, aromatic chemistry appears to be widespread throughout the earliest stages of star formation, probably persisting at least until the initial formation of a protostar. The abundance of benzonitrile far exceeds predictions from models that well reproduce the abundances of carbon chains such as HC7N, a cyanpolyyne with the same heavy atoms, indicating that the chemistry responsible for planar carbon structures (as opposed to linear ones) in primordial sources is favourable but not well understood. The abundance of benzonitrile relative to carbon chain molecules displays sizable variations between sources within the Taurus and Serpens clouds, implying the importance of physical conditions and initial elemental reservoirs of the clouds themselves. Benzonitrile, a proxy for the aromatic ring molecule benzene, has now been detected at multiple locations in the Taurus and Serpens molecular clouds, suggesting a widespread aromatic chemistry in the interstellar medium. Chemical models underestimate the abundance of aromatic molecules, highlighting the need for further study.