Ntawm cov saturated monocarboxylic acids, formic acid, acetic acid, thiab propionic acid muaj zog qaub saj thiab irritation. Nws muaj 4 ~ 9 C atoms thiab muaj cov ntxhiab tsw thiab yog cov kua roj oily. Nws muaj ntau tshaj 10 C's raws li cov khoom zoo li paraffin, uas tsis tshua muaj volatility thiab tsis muaj ntxhiab tsw.
Qhov no yog vim muaj cov hydrogen bonds ntawm cov molecules ntawm formic acid. Raws li txoj kev xws li electron diffraction, qis acids muaj nyob rau hauv daim ntawv ntawm dimers txawm nyob rau hauv vapor vim muaj hydrogen bonds. Lub intermolecular hydrogen daim ntawv cog lus ntawm formic acid yog 30KJ / mol, thaum lub intermolecular hydrogen daim ntawv cog lus ntawm ethanol yog 25KJ / mol.
Lub melting point ntawm linear saturated monocarboxylic acid hloov zigzag nrog nce tus naj npawb ntawm C atoms nyob rau hauv lub molecule, thiab lub melting point ntawm lub C atomic acid yog siab tshaj li ntawm ob nyob ib sab khib C atomic acids, uas yog vim li cas. rau qhov tseeb hais tias nyob rau hauv cov saw muaj txawm C atoms, cov saw kawg methyl pawg thiab carboxyl pawg tau muab faib rau ob sab ntawm cov saw, thaum nyob rau hauv lub khib C atomic saw, nws yog nyob rau tib sab ntawm C saw, tus qub muaj ntau dua symmetry, uas yuav ua rau cov siv lead ua lattice ntawm carboxylic acid ntau nruj nreem, thiab lawv muaj ib tug ntau dua attraction thiab ib tug ntau dua melting point.
Cov pab pawg carboxyl yog ib pawg hydrophilic thiab tuaj yeem tsim cov ntawv cog lus hydrogen nrog dej, yog li cov carboxylic acids qis tuaj yeem ua rau miscible nrog dej hauv txhua qhov sib piv; Raws li cov txheeb ze molecular mass nce, pawg hydrophobic (hydrocarbon pawg) yuav loj dua thiab cov solubility hauv dej yuav me dua.
X-ray cov kev tshawb fawb ntawm cov saw ntev fatty acids tau ua pov thawj tias C chains nyob rau hauv cov molecules yog teem nyob rau hauv ib tug zigzag zoo, thiab ob pawg intermolecular carboxyl yog txuam nrog hydrogen bonds, thiab cov bimolecules txuam yog teem tsis tu ncua txheej txheej, thiab nyob rau hauv nruab nrab ntawm txhua txheej yog ib pawg carboxyl uas muaj feem xyuam rau ib leeg, thiab lub gravitational attraction yog heev muaj zog, thiab cov khaubncaws sab nraud povtseg nyob ib sab nrog tsis muaj zog. gravitational alchemies, uas yooj yim rau swb ntawm ib leeg, uas kuj yog vim li cas vim li cas ntau dua fatty acids muaj lubricity.