Acetic acid

Los yog organic monobasic carboxylic acid, lub molecule uas muaj ob carbon atoms thiab ib tug carboxyl pab pawg neeg (tau txais nws lub npe vim hais tias nws muaj cov carbonyl thiab carboxyl pawg), hu ua ethane (by analogy nrog lub alkane nrog tib tus naj npawb ntawm cov pa roj carbon atoms) los yog acetic acid. Nws, zoo li tag nrho cov sab aliphatic mej zeej ntawm lub chav kawm ntawv ntawm cov organic tebchaw, muaj ib tug pungent tsw. Nws tshuaj mis yuav tsum muab sau raws li: CH3COOH. Thaum yam kev mob ambient ib tug tsis muaj kob kua. Ceev - 1.05 g / cm³. Hniav puas loj yog sib npaug zos rau 60,05 g / mol. Nws melts ntawm ib tug kub ntawm 16,75 ° C (hauv qab no lub solidified muaju zoo xws li cov dej khov, thiaj hu ua ice). Boils ntawm ib tug kub ntawm 118,1 ° C. Lub refractive index yog sib npaug zos rau 1.372.

Cov neeg sawv cev ntawm no hauv chav kawm ntawv ntawm cov organic tebchaw yog weaker dua hydrochloric los yog sulfuric acid, tab sis thaum muab piv nrog carbonic acid, qhov loj tshaj plaws yog acetic acid. Cov tshuaj zog txiav txim los ntawm nws cov mej zeej ntawm lub carbonyl molecules thiab hydroxyl pawg. Lawv feem xyuam rau txoj thiaj li mus rau txhua lwm yam uas cov tshuaj thaj chaw ntawm cov ntaub ntawv uas tsuas yog siv rau ib tug me me raws li reminiscent ntawm lub thaj chaw ntawm carbonyl tebchaw (aldehydes, amides, ketones, esters) los yog alcohols. Ionization tshwm sim O-H linkages vim rub electrons carbonyl pab pawg neeg. Yog li ntawd, cov kev twb kev txuas yog ntau yooj yim rau dissociate tshaj nyob rau hauv alcohols. Lub xaav ntawm electrons los ntawm cov hydroxyl pab pawg neeg mus rau ib tug carbonyl cov thiaj li cov pa roj carbon atom ntawm qhov zoo xwb, ua rau nws yooj yim mus tua nws nrog ib tug nucleophile. Yog li ntawd, muaj ntau yam tshuaj interacting yooj yim nrog carbonyl tebchaw tsis hnov mob nrog CH3COOH.

Yuav kom ib tug me me raws li acetic acid yuav dissociate tsim hydrogen ions: CH3COOH + H2O ↔ CH3CO2ˉ + H3O +. Nws yog yus muaj los ntawm neutralization nrog bases, uas tau nyob rau hauv ntsev tsim: NaOH + CH3COOH → CH3COONa + H2O . Carboxylic acid ntsev yog feem ntau dej soluble. Qhov no feature tswj lub extraction ntawm tej yam ntuj tso qhov chaw. Yog li ntawd acid nyob rau ntawm cov thawj cais los ntawm cov organic tshuaj. Piv txwv li, ethane twb tau los ntawm qaub cawu cub. Muaj zog hydrogen bonds yog tsim ntawm molecules ntawm CH3COOH, li no nyob rau hauv cov organic solvents thiab nyob rau hauv cov roj theem, nws tshwm sim raws li ib tug dimer.

Acetic acid thiab dej yog miscible nyob rau hauv tag nrho cov proportions. Nws hloov nws lub zog nyob rau hauv lub concentration. Moderately txhoj puab heev ntawm co, xws li hlau, magnesium thiab zinc. Qhov no yields hydrogen thiab ntsev-hu ua acetates: Mg + 2 CH3COOH → (CH3COO) 2Mg + H2 ↑. Txij li thaum txhuas ntaub ntawv ib tug acid-resistant passivation zaj duab xis ntawm txhuas oxide, lub txhuas tank, nrog rau cov stainless steel tso tsheb hlau luam siv rau thauj CH3COOH.

Nyob rau hauv kev lag luam, acetic acid yog ua los ntawm oxidation ntawm ib tug aldehyde ntawm lub tib lub npe: 2CH3COH + O2 → 2CH3COOH. Los ntawm 800 kg ntawm aldehyde npaj tuj CH3COOH. Tab sis tsis ntev los no txoj kev ua - ib tug ua kua theem oxidation ntawm butane nrog cua oxygen ntawm ib tug kub ntawm 150-170 ° C thiab ib tug siab ntawm 50 atmospheres: CH3CH2CH2CH3 + 2O2 → 2CH3COOH + 2 H2O. Nyob rau hauv qhov tseeb, cov tshuaj tiv thaiv yog ntau ntau tham tshaj qhia. Dhau li acetic acid, uas ua ib tug xov tooj ntawm byproducts. Ob cov kev raug thawb tawm (vim hais tias siab dua cov roj nqi) los ntawm cov carbonylation ntawm methanol: CO + CH3OH → CH3COOH. Cov txheej txheem tau nyaij nyob rau hauv lub xub ntiag ntawm ib lub hauv paus uas yog ib lub ntsev ntawm rhodium, thiab promoters (activators) - iodide ions. Lub peev xwm ntawm ib co kab mob yog fermented ethyl cawv, raws li los ntawm oxidation nyob rau hauv CH3COOH, siv nyob rau hauv biochemical ntau lawm: C2H5OH + O2 → CH3COOH + H2O . Tus txheej txheem yog heev thiab yuav siv sij hawm qhov chaw nyob rau hauv ob peb ua sawv.

Acetic acid yog manufactured nyob rau hauv raws li GOST 19814-74 (hluavtaws thiab regenerated) GOST 18270-72 (siab purity) thiab GOST 61-75 (reactive). Qhov no yog ib qho tseem ceeb tshuaj reagent thiab muaj yam tshuaj uas yog tsuas yog siv nyob rau hauv qhuav, yog siv rau yas, hluavtaws fibers, dyes, zaj duab xis thiab lwm tus neeg. Nws yog ib lub raw khoom rau zus tau tej cov yas acetate uas yog siv nyob rau hauv tus txheej txheem ntawm muab sevilene (raws li ethylene comonomer). Kev siv ntawm acetic acid vim nws tshuaj thiab lub zog. CH3COOH ntsev yog mordants uas yuav pab tau rau kho cov dyes rau lub fiber.

Nyob rau hauv tsev neeg diluted acetic acid yog feem ntau siv raws li ib tug descaling neeg sawv cev. Nyob rau hauv cov zaub mov kev lag luam nws yog siv nyob rau hauv lub code E260 zaub mov additives xws li acidity regulator thiab raws li ib tug condiment. Khoom noj khoom haus additive pom zoo rau siv nyob rau hauv lub EU, US, Australia thiab New Zealand. Nyob rau hauv cov zaub mov kev lag luam nws yog siv rau pickling khoom nyob rau hauv daim ntawv ntawm vinegar nrog lub concentration ntawm CH3COOH nyob rau hauv dej ntawm 3 mus rau 15% los yog vinegar nrog ib tug loj feem ntawm qhov yooj yim tshuaj ntawm 70%. Ob peb esters ntawm acetic acid siv nyob rau hauv lub confectionery kev lag luam.