Tag: M.W=200-250

Zhu, Qilei published the artcileCatalytic C(β)-O Bond Cleavage of Lignin in a One-Step Reaction Enabled by a Spin-Center Shift, Related Products of alcohols-buliding-blocks, the publication is ACS Catalysis (2021), 11(22), 14181-14187, database is CAplus.

A challenge to the utilization of lignin as a feedstock for aromatic fine chems. lies in selective cleavage of copious β-O-4 linkages. A photocatalytic strategy for the selective cleavage of the C(β)-O bonds of model substrates and natural lignin extracts is achieved by a redox-neutral, catalytic cycle that does not require stoichiometric reagents. Mechanistic studies reveal the generation of a thiyl radical, which is derived from a cystine-derived H-atom transfer catalyst, initiates a spin-center shift (SCS) that leads to C(β)-O bond cleavage. The SCS reactivity is reminiscent of the C(β)-O bond cleavage chem. that occurs in the active site of ribonucleotide reductase.

ACS Catalysis published new progress about 70110-65-5. 70110-65-5 belongs to alcohols-buliding-blocks, auxiliary class Benzene,Alcohol,Ether,Benzene Compounds, name is 2-Phenoxy-1-phenylpropane-1,3-diol, and the molecular formula is C20H28B2O4S2, Related Products of alcohols-buliding-blocks.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Luo, Zhicheng published the artcileTransition metal-like carbocatalyst, COA of Formula: C15H16O3, the publication is Nature Communications (2020), 11(1), 4091, database is CAplus and MEDLINE.

Catalytic cleavage of strong bonds including hydrogen-hydrogen, carbon-oxygen, and carbon-hydrogen bonds is a highly desired yet challenging fundamental transformation for the production of chems. and fuels. Transition metal-containing catalysts are employed, although accompanied with poor selectivity in hydrotreatment. Here we report metal-free nitrogen-assembly carbons (NACs) with closely-placed graphitic nitrogen as active sites, achieving dihydrogen dissociation and subsequent transformation of oxygenates. NACs exhibit high selectivity towards alkylarenes for hydrogenolysis of aryl ethers as model bio-oxygenates without over-hydrogeneration of arenes. Activities originate from cooperating graphitic nitrogen dopants induced by the diamine precursors, as demonstrated in mechanistic and computational studies. We further show that the NAC catalyst is versatile for dehydrogenation of ethylbenzene and tetrahydroquinoline as well as for hydrogenation of common unsaturated functionalities, including ketone, alkene, alkyne, and nitro groups. The discovery of nitrogen assembly as active sites can open up broad opportunities for rational design of new metal-free catalysts for challenging chem. reactions.

Nature Communications published new progress about 70110-65-5. 70110-65-5 belongs to alcohols-buliding-blocks, auxiliary class Benzene,Alcohol,Ether,Benzene Compounds, name is 2-Phenoxy-1-phenylpropane-1,3-diol, and the molecular formula is C15H16O3, COA of Formula: C15H16O3.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Ooguri, Akihiro published the artcileNickel-Catalyzed Cycloaddition of Salicylic Acid Ketals to Alkynes via Elimination of Ketones, Category: alcohols-buliding-blocks, the publication is Journal of the American Chemical Society (2009), 131(37), 13194-13195, database is CAplus and MEDLINE.

An intermol. nickel-catalyzed addition reaction has been developed where salicylic acid ketals react with alkynes to afford substituted chromones. A mechanistic rationale is proposed, implying β-elimination of ketone from ring strained seven-membered nickelacycle to generate a five-membered oxa-nickelacycle intermediate.

Journal of the American Chemical Society published new progress about 328-90-5. 328-90-5 belongs to alcohols-buliding-blocks, auxiliary class Trifluoromethyl,Fluoride,Carboxylic acid,Benzene,Phenol, name is 2-Hydroxy-4-(trifluoromethyl)benzoic acid, and the molecular formula is C8H5F3O3, Category: alcohols-buliding-blocks.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Fawcett, Alexander published the artcileStrain-Release-Driven Homologation of Boronic Esters: Application to the Modular Synthesis of Azetidines, Computed Properties of 608534-44-7, the publication is Journal of the American Chemical Society (2019), 141(11), 4573-4578, database is CAplus and MEDLINE.

Azetidines are important motifs in medicinal chem., but there are a limited number of methods for their synthesis. Herein, the authors present a new method for their modular construction by exploiting the high ring strain associated with azabicyclo[1.1.0]butane. Generation of azabicyclo[1.1.0]butyl lithium followed by its trapping with a boronic ester gives an intermediate boronate complex which, upon N-protonation with acetic acid, undergoes 1,2-migration with cleavage of the central C-N bond to relieve ring strain. The methodol. is applicable to primary, secondary, tertiary, aryl, and alkenyl boronic esters and occurs with complete stereospecificity. The homologated azetidinyl boronic esters can be further functionalized through reaction of the N-H azetidine, and through transformation of the boronic ester. The methodol. was applied to a short, stereoselective synthesis of the azetidine-containing pharmaceutical, cobimetinib.

Journal of the American Chemical Society published new progress about 608534-44-7. 608534-44-7 belongs to alcohols-buliding-blocks, auxiliary class Other Aromatic,Boronic acid and ester,Boronate Esters,Boronic Acids,Boronic acid and ester, name is 2-(2,3-Dihydro-1H-inden-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, and the molecular formula is C15H21BO2, Computed Properties of 608534-44-7.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Capra, P. published the artcileWetting and adhesion evaluation of cosmetic ingredients and products: correlation of in vitro-in vivo contact angle measurements, HPLC of Formula: 70445-33-9, the publication is International Journal of Cosmetic Science (2017), 39(4), 393-401, database is CAplus and MEDLINE.

Objective : The aim of this work was to use the contact angle measurement in order to predict the behavior of ingredients and finished cosmetic products on skin to improve skin feel and product texture. Method : Different classes of cosmetic ingredients and formulations were evaluated. The contact angle measurements were carried out by the sessile drop method using an apparatus, designed and set up in laboratory Glass, Teflon and human skin were the reference substrates. In a preliminary phase, TEWL parameter, sebum content and hydration of human skin were measured to set up method. Results : Data demonstrated that glass substrate may be used as replacement of the skin:critical surface tension of skin and glass were about of 27 and 31 dyne cm^-1, resp. Non-ionic surfactant with increasing HLB was evaluated: a correlation between contact angle measured and HLB was not observed because of different and complex mol. structure. In detail, ethylhexyl hydroxystearate (θ_glass = 17.1°) showed lower contact angle value with respect to Polysorbate 20 (θ_glass = 28.1°). Sodium laureth sulfate and stearalkonium chloride were also evaluated: anionic mol. showed more affinity for glass with respect to Teflon (θ_glass = 21.7° and θ_Teflon = 52.3°). Lipids and silicones showed different affinity for substrate according to hydrophilic groups and hydrocarbon chain: contact angles of silicones remained unchanged independently from substrate. Finished cosmetic products (O/W, W/O emulsions, cleansing oil, dry skin oil) showed different profiles according to surfactant and its affinity for continuous phase of the formulation. Comparing the values of the contact angle on skin of non-ionic surfactants, as ethylhexyl hydroxystearate and Polysorbate 20, they showed values lower (near to zero) than ones of sodium laureth sulfate and Stearalkonium Chloride (21.7° and 66.8°, resp.). Finally, finished cosmetic products tested on human skin showed different profile: corresponded contact angle values were less than 20°. The product tended to be quickly adsorbed on human skin. Conclusion : Systematic study carried out by evaluating the wettability of single cosmetic ingredients on different substrates allowed to find correlations between the use of certain ingredients and the final performance of a cosmetic product.

International Journal of Cosmetic Science published new progress about 70445-33-9. 70445-33-9 belongs to alcohols-buliding-blocks, auxiliary class Aliphatic Chain, name is 3-((2-Ethylhexyl)oxy)propane-1,2-diol, and the molecular formula is C11H24O3, HPLC of Formula: 70445-33-9.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Takahashi, Hiroto published the artcileRhodium(III)-Catalyzed Oxidative Intramolecular 1,1-Oxyamination of Alkenes with Protected Amino Acids to Produce Oxazoloisoindole-2,5-diones, Formula: C8H5F3O3, the publication is European Journal of Organic Chemistry (2021), 2021(12), 1891-1895, database is CAplus.

It has been established that an electron-deficient bis(ethoxycarbonyl)-substituted cyclopentadienyl (Cp^E) rhodium(III) complex catalyzes the oxidative intramol. 1,1-oxyamination of alkenes with N-benzoyl amino acids to produce oxazoloisoindole-2,5-diones. Exptl. and theor. mechanistic studies revealed that this oxidative 1,1-oxyamination proceeds via not the aza-Wacker reaction but the formation of a rhoda(III)oxazolidine initiated by the carboxylic acid-directed N-H bond cleavage.

European Journal of Organic Chemistry published new progress about 328-90-5. 328-90-5 belongs to alcohols-buliding-blocks, auxiliary class Trifluoromethyl,Fluoride,Carboxylic acid,Benzene,Phenol, name is 2-Hydroxy-4-(trifluoromethyl)benzoic acid, and the molecular formula is C8H5IO, Formula: C8H5F3O3.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Kang, Seong-Mook published the artcileA novel synthetic HTB derivative, BECT inhibits lipopolysaccharide-mediated inflammatory response by suppressing the p38 MAPK/JNK and NF-κB activation pathways, Recommanded Product: 2-Hydroxy-4-(trifluoromethyl)benzoic acid, the publication is Pharmacological Reports (2014), 66(3), 471-479, database is CAplus and MEDLINE.

Activated microglia cells are well recognized as mediators of neuroinflammation, as they release nitric oxide and pro-inflammatory cytokines in various neuroinflammatory diseases. Thus, suppressing microglial activation may alleviate neuroinflammatory and neurodegenerative processes. In the present study, we synthesized and investigated the anti-neuroinflammatory effect of a novel HTB (2-hydroxy-4-trifuoromethylbenzoic acid) derivative in lipopolysaccharide (LPS)-stimulated microglial cells. Among the synthesized derivatives, the BECT [But-2-enedioic acid bis-(2-carboxy-5-trifluoromethyl-phenyl) ester] significantly decreased production of nitric oxide and other pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interleukin-6 in microglial cells. BECT also mitigated the expression of inducible nitric oxide synthase and cyclooxygenase-2 at both the mRNA and protein levels. Further mechanistic studies demonstrated that the HTB derivative inhibited phosphorylation of JNK and p38 mitogen-activated protein kinase and nuclear translocation of nuclear factor kappa-B in LPS-stimulated BV-2 microglial cells. Thus BECT, our novel synthesized compound have anti-inflammatory activity in microglial cells, and may have therapeutic potential for treating neuroinflammatory diseases.

Pharmacological Reports published new progress about 328-90-5. 328-90-5 belongs to alcohols-buliding-blocks, auxiliary class Trifluoromethyl,Fluoride,Carboxylic acid,Benzene,Phenol, name is 2-Hydroxy-4-(trifluoromethyl)benzoic acid, and the molecular formula is C8H5F3O3, Recommanded Product: 2-Hydroxy-4-(trifluoromethyl)benzoic acid.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Roth, A. R. published the artcileTests of repellents against tabanids, Computed Properties of 70445-33-9, the publication is Entomol. Research Branch, Agr. Research Service U.S. Dept. Agr. (1954), 10 pp., database is CAplus.

With white mice as the host animals, 258 synthetic compounds were tested in the laboratory as repellents of the deer fly (Chrysops discalis). Only a few showed promise as long-lasting repellents, 2-amino-3-isobornyloxy-2-methyl-1-propanol and Santomerse DT being most effective. Five of the best materials, along with various pyrethrum and allethrin sprays, were tested against mixed populations of tabanids on calves in the field. The same 2 compounds were most effective. All materials tested except the pyrethrins damaged the hair and skin of the calves slightly. Pyrethrum sprays were very effective only at high concentrations

Entomol. Research Branch, Agr. Research Service U.S. Dept. Agr. published new progress about 70445-33-9. 70445-33-9 belongs to alcohols-buliding-blocks, auxiliary class Aliphatic Chain, name is 3-((2-Ethylhexyl)oxy)propane-1,2-diol, and the molecular formula is C11H24O3, Computed Properties of 70445-33-9.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Freudenberg, Karl published the artcileSynthetic experiments connected with lignin, Application In Synthesis of 70110-65-5, the publication is Annalen der Chemie, Justus Liebigs (1953), 40-53, database is CAplus.

The following model substances are in part related to the dimers obtained by F. in experiments with coniferyl alc. (C.A. 47, 12296g), which are considered “secondary building stones” in lignin formation. Veratraldehyde condensed with CH₂(CO₂H)₂ gave quant. yields of 3,4-(MeO)₂C₆H₃CH:CHCO₂H, whose Et ester (obtained in 94% yield) with Br in CHCl₃ in artificial light yielded the dibromide, m. 110°; this was refluxed 7-8 hrs. with 3 moles KOH in alc., cooled, filtered, neutralized gradually (at about 0°) with concentrated HCl, refiltered, and concentrated in vacuo. Any salts that had been filtered, combined with those separating on concentration, were dissolved in H₂O and acidified with 20% H₂SO₄, giving 20-30% 3,4-(MeO)₂C₆H₃CCCO ₂H (I), m. 156° (Fulton and Robinson, J. Chem. Soc. 1903, 1463). Carefully purified 4,3-Me(MeO)C₆H₃OH (13.8 g.) and 50 cc. MeOH containing 2.3 g. Na, evaporated in vacuo, heated 5 hrs. at 100° with 22 g. I Me ester, 50 cc. PhMe, and 13.8 g. creosol, allowed to stand 12 hrs. at room temperature, extracted with Et₂O, shaken repeatedly with aqueous H₂SO₄, and the excess creosol extracted from the Et₂O with aqueous NaOH, followed by washing, drying, evaporation, and fractionation, gave 17 g. Me β-(3-methoxy-4-methylphenoxy)-3,4-dimethoxycinnamate (II), prisms, m. 107-8°. At -70 to -80°, 5 g. crude II in 100 cc. dry Et₂O with 0.3 g. LiAlH₄ in 26 cc. Et₂O gave a precipitate which, when decomposed with H₂SO₄, yielded a mixture of creosol, dimethoxycinnamyl alc. (III), and α-(2-methoxy-4-methylphenoxy)-3,4-dimethoxycinnamyl alcohol (IV). III and IV could not be separated by distillation, or by adsorption in C₆H₆ on Al₂O₃ but the separation was effected on a paper chromatogram with C₆H₆ (R_f of III and IV being 0 and 0.9, resp.). IV was noncrystalline, but gave a red, crystalline p-PhN₂C₆H₄CO derivative, m. 118-19°; and a crystalline phenyl-urethan, m. 134-5°. The phenylurethan of III m. 107-8°. PhOCH₂CO₂Me (22 g.) and 14 g. BzH reacted vigorously with 3 g. Na wire and 40 cc. dry Et₂O. After 12 hrs. 8.2 g. glacial AcOH, 60 cc. H₂O, and 20 cc. Et₂O were added successively, giving 38% PhCH(OH)CH(OPh)CO₂Na (V), the Et₂O and alc. washings from which, when concentrated and esterified, yielded 48% PhCH:C(OPh)CO₂Me (VI), b₁₁ 210°, m. 60-1°. The free acid from V, oil (not characterized) gave the Me ester (VII), m. 61° (from petr. ether); Ac derivative of VII, m. 69-70°; S-benzylthiuronium salt (corresponding to V), m. 188°. VI in Et₂O, under N at -70° with LiAlH₄, gradually warmed to -20° with aqueous H₂SO₄ gave PhCH:C(OPh)CH₂OH, viscous oil; phenyl urethan, m. 104°. VII, similarly reduced (at -20°) gave PhCH(OH)CH(OPh)CH₂OH, b₁ 197°, m. 74-5°. Using Giacosa’s technique [J. prakt. Chem. 19, 396(1879)] but with longer initial heating, creosol, ClCH₂CO₂H, and NaOH gave 67% 4,2-Me(MeO)C₆H₃OCH₂CO₂H, m. 115°; Me ester (VIII), b₁₁ 167°; amide, m. 134-5°. Veratraldehyde (15.8 g.), 20 g. VIII, and 2.2 g. powd. Na under Et₂O, first cooled, then heated several hrs. on a steam bath and acidified with AcOH, gave 3,4-(MeO)₂C₆H₃CH:CRCO₂Me (IX) [R in this and other compounds = 4,2-Me(MeO)C₆H₃O], which, reduced with LiAlH₄ at -70° yielded the alc., C₁₉H₂₂O₅ (isolated by treating the intermediate salt, under Et₂O, with Dry Ice), oil, setting to a resin; 3,5-dinitrobenzoale, yellow needles, m. 158-9° (from BuOH). When 15.8 g. veratraldehyde, 20 g. VIII, 2.2 g. Na, and 50 cc. Et₂O were kept at about 0° and then acidified with aqueous AcOH, the product was a mixture, b_0.01 225°, of IX and 3,4-(MeO)₂C₆H₃(OH)CHRCO₂Me, m. 137° (from aqueous MeOH). To 8 g. Na (powdered under 100 cc. absolute PhMe) were added successively 25 g. abs EtOH and 50 g. vanillin, and the resulting Na derivative was filtered, triturated with and suspended in PhMe, well-cooled, and treated with freshly distilled ClCH₂OMe; this kept at least 6 hrs. at room temperature, washed with 2% NaOH, and fractionated gave 41 g. methoxymethylvanillin (X), b_1.5 145-7°, m. 39-40°. Freshly prepared X (9.8 g.) fused with 10.5 g. VIII, the product cooled, treated with 1.15 g. Na wire and 40 cc. Et₂O, allowed to stand overnight, 3.1 g. AcOH in 40 cc. H₂O added, and the mixture extracted with Et₂O gave 9 g. 4,3-(MeOCH₂O)(MeO)C₆H₃CH(OH)CHRCO₂Me, b_0.05 175-7°. With 30 g. 14-day-old X (or with fresh X containing small amounts of vanillin), the reaction was sluggish and required heating for completion, giving as the principal product 3,4-MeO(MeOCH₂O)C₆H₃CH: CRCO₂Me (XI), m. 112-13° (from aqueous MeOH). With a drop of H₂SO₄, AcOH, and Ac₂O, 2 g. XI at 0° gave, after 1.5 hrs., 1.3 g. 3,4-MeO(AcO)C₆H₃CH:CRCO₂Me (XII), m. 80° (from aqueous EtOH); when cooling was omitted, but the reaction continued for 8 hrs., the yield of XII was 87%. XII reduced with LiAlH₄ under N at -20°, followed by a fully described extensive purification, including chromatographic fractionation on powd. cellulose, gave 3,4-MeO(HO)C₆H₃CH:CRCH₂OH (XIII), b_0.0001 140° (bath temperature), prisms, m. 90-1° (from CH₂Cl₂-petr. ether). Hydrogenated in MeOH with 5% Pd-BaSO₄, XII gave the dihydro derivative, C₂₁H₂₄C₇, b_0.01 197°, which, reduced with LiAlH₄, yielded the dihydro derivative of XIII, C₁₈H₂₂O₅, b_0.01 150°. Vanillin (10 g.), 6.25 g. CH₂ClCO₂H, 8.5 g. KOH, and 30 cc. H₂O heated 4 hrs. at 100° and acidified with aqueous HCl gave quantitatively 2,4-MeO(OHC)C₆H₃OCH₂CO₂H, m. 188-9° [Elkan, Ber. 19, 3045(1886)], 8 g. of which with 10 g. CH₂(CO₂H)₂ in 50 cc. pyridine containing small amounts of piperidine heated 2 hrs. at 100° yielded quantitatively 3,4-MeO(HO₂CCH₂O)C₆H₃CH:CHCO₂H, m. 234° (also formed in 73% yield from ferulic acid, CH₂ClCO₂H and NaOH); di-Me ester (XIV), m. 104-5°. Veratraldehyde, (3 g.), 5 g. XIV, 0.41 g. Na powder, 20 cc. Et₂O, and several drops absolute MeOH, heated several hrs. and acidified with aqueous AcOH, gave 2 g. Me α-[2-methoxy-4-(β-carbomethoxyvinyl)phenoxy]-3,4-dimethoxycinnamate, b_0.01 260°, m. 129°. XIV and X refluxed with Na in Et₂O gave, after acidification and fractionation of the Et₂O extract, 31% Me O-methoxymethyl-α-[2-methoxy-4-(β-carbomethoxyvinyl)phenoxy]ferulate (XV), b_0.01 275°, m. 100-1° (from MeOH). By replacing the MeOCH₂ group in XV by Ac, the O-Ac analog (XVI), C₂₄H₂₄O₉, b_0.0001 180° (bath temperature), m. 117-18°, was formed. XVI (18 g.) in Et₂O reduced by stepwise addition of LiAlH₄ at room temperature, followed by adding moist Et₂O, Na₂S₂O₄, and Dry Ice to the aqueous phase, and fractionation in high vacuum of the Et₂O extract, gave about 100 mg. resinous. 3,4-MeO[3,4-MeO(HO)C₆H₃CH:C(CH₂OH)O] C₆H₃CH:CHCH₂OH (XVII). The tetrahydro derivative of XVI, sirup, b_0.001 160° (bath temperature); the tetrahydro derivative of XVII, colorless sirup, b_0.001 150° (bath temperature). Inasmuch as both acetone-lignin and the dehydrogenation polymers of coniferyl alc. yielded 1.5-2% HCHO when distilled with H₂SO₄, a similar treatment was applied to a number of the synthetic compounds listed above. None of these gave more than faint traces of HCHO, with the single exception of PhCH(OH)CH(OPh)CH₂OH, which yielded 1.3% HCHO. From this and previous studies (C.A. 42, 882a). F. and M. have indicated what types of structure, in O-containing derivatives of PhPr, are capable of giving rise to HCHO. 19 references.

Annalen der Chemie, Justus Liebigs published new progress about 70110-65-5. 70110-65-5 belongs to alcohols-buliding-blocks, auxiliary class Benzene,Alcohol,Ether,Benzene Compounds, name is 2-Phenoxy-1-phenylpropane-1,3-diol, and the molecular formula is C15H16O3, Application In Synthesis of 70110-65-5.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts

Marzi, Elena published the artcileFluorophenols and (trifluoromethyl)phenols as substrates of site-selective metalation reactions: to protect or not to protect, Formula: C8H5F3O3, the publication is European Journal of Organic Chemistry (2001), 2911-2915, database is CAplus.

O-Methoxymethyl (MOM) protected fluorophenols can be cleanly metalated and subsequently be submitted to site-selective electrophilic substitution. The 2- and 4-isomers exhibit ambivalent reactivity: deprotonation occurs at the position adjacent to the O when butyllithium is employed whereas the position adjacent to the F is attacked by the superbasic mixture of butyllithium and K tert-butoxide (LIC-KOR). The MOM-protected (trifluoromethyl)phenols react exclusively at O-neighboring positions. The meta isomer provides another example of optional site selectivity, undergoing H/metal exchange at the 2-position with the LIC-KOR reagent and at the 6-position with sec-butyllithium. Unprotected (trifluoromethyl)phenols can also be ortho-metalated after O-deprotonation, although the products are formed in only moderate yields.

European Journal of Organic Chemistry published new progress about 328-90-5. 328-90-5 belongs to alcohols-buliding-blocks, auxiliary class Trifluoromethyl,Fluoride,Carboxylic acid,Benzene,Phenol, name is 2-Hydroxy-4-(trifluoromethyl)benzoic acid, and the molecular formula is C8H5F3O3, Formula: C8H5F3O3.

Referemce:
https://en.wikipedia.org/wiki/Alcohol,
Alcohols – Chemistry LibreTexts