Carboxylic asidi

Mitundu ya mankhwala, yomwe ma molekyulu ali ndi gulu limodzi la carboxyl (carbonyl-gulu la aldehydes ndi ketoni pamodzi , komanso hydroxyl-functional group of alcohols) mumapangidwewa adalandira dzina lofanana - carboxylic acid. Njira yawo ingayimiridwe monga R-COOH, kumene R ndi gulu la ma hydrocarbon lomwe limagwirira ntchito. Mankhwala amtundu uliwonse, mosiyana ndi mavitamini ambiri amadzimadzi, ndi ofooka ndipo amalekanitsidwa mwa ions.

Zitsanzo zosavuta ndi formic acid (methane) H-COOH. Dzinali limafotokozedwa ndi mbiri ya positi yake yoyamba mu 1670 a nyerere zofiira ndi John Ray. Carboxylic acid ndi magulu awiri kapena angapo a carboxyl adzatchedwa dibasic (kapena dicarboxylic), tribasic (kapena tricarboxylic), ndi zina zotero. Chitsanzo chosavuta ndi oxalic acid ndi mayendedwe ake C2H2O4, mu molekyulu yomwe muli magulu awiri a carboxyl. Monga hexafluoric acid, n'zotheka kupereka mellitic (hexacarboxylic) asidi, njira yake C12H6O12. Molekyuli ili ndi magulu asanu ndi limodzi a carboxyl, omwe analowetsa maatomu a hydrogen mu ringeni ya benzene.

Ma organic acids, monga lamulo, amapezeka m'chilengedwe. Mwachitsanzo, hexacarboxylic acid imapezeka mu mwala wa uchi umene umapezeka mu makala a bulauni).

Pali mitundu yambiri yofunikira ya chilengedwe. Izi zikuphatikizapo citric acid C6H8O7 (zakudya zina zochepa zowonjezera E330-E333), zomwe zinapangidwa kuchokera ku madzi a mandimu osapsa m'chaka cha 1784 ndi katswiri wa zamankhwala wa Sweden K. Scheele. Tartaric acid C4H6O6 ndi chakudya chowonjezera cha E334). Izi zimapezeka m'magawo ambiri. Amapezeka mu madzi atsopano a zipatso zambiri.

Ngati tiganiziranso mitundu yambiri yokhala ndi mavitamini, ndiye kuti kusintha kwanthawi zonse kumakhala ndi kukula kwa maselo olemera. Zomwe zimagwiritsidwa ntchito pazigawo zonse zimadalira momwe zimakhalira ndi ma molekyulu, ndiko kuti, makamaka zimatsimikiziridwa ndi isomerism ya carboxylic acid. Omwe akuyimira oyambirira omwe ali ndi mayina a homologous anapangidwa kuchokera ku formic acid, kuphatikizapo acetic ndi propionic, amatanthauza zakumwa. Iwo ali ndi fungo lakuthwa ndipo amatha kusungunuka mosavuta m'madzi. Atsogoleri apamwamba ndiwo zowonongeka, zomwe sizimasungunuka m'madzi.

Mankhwalawa a carboxylic acids makamaka amadziwika ndi zotsatira za carbonyl gulu pa hydroxyl gulu. Choncho, mankhwalawa, mosiyana ndi alcohols, ali ndi chidziwitso chodziwika bwino.

Mwachitsanzo, mu njira zamadzimadzi zingathe kusokonekera mu ions, zomwe zikuwonetsa kudayirira kwa madzi pambuyo powonjezera litmus kukhala wofiira. Izi zikuwonetsa kukhalapo kwa zida za hydrogen. Izi zikutanthauza kuti njira zawo zamadzimadzi zimakhala zosavuta (pH zosachepera 7).

Mukamagwirizana ndi zitsulo kapena mabotolo, zida za carboxylic zimatha kupanga salt: 2CH3-COOH + Mg → (CH3-COO) 2Mg + H2 ↑.

Mavitamini a mthupi amathanso kupangidwanso ndi carbonates, kuchotsa carbonic acid: 2CH3-COOH + MgCO3 → (CH3-COO) 2Mg + H2O + CO2 ↑.

Amachita mosavuta ndi ammonia, kupanga ma salt: CH3-COOH + NH3 → CH3-COONH4.

Mitundu yambiri ya ma acids amathandizidwa ndi kukhalapo kwazomwe zimakhalapo mwazo ndi zotsatira zolakwika. Mwachitsanzo, pogwiritsa ntchito chlorine pa acid acetic, pang'onopang'ono amachotsa atomu imodzi ya hydrogen ndi maatomu a chlorini ndi kupeza chloroacetic acid, ndiye dichloroacetic acid ndi trichloroacetic asidi, pali kuwonjezeka kwa acidic katundu mwa iwo.

Mankhwala amtundu uliwonse akhoza kupezeka m'njira zingapo. Njira yofala kwambiri imachokera kuchitidwe cha okosijeni. Poyamba zizindikiro zowonjezera, zakumwa za alcohols kapena aldehydes zimatengedwa. Njira ina yopangira organic acid ndi hydrolysis ya nitriles, yomwe imapezeka pamene imatenthedwa ndi kuchepetsa mchere wamchere.