Iodine value

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The value of iodine (or iodine adsorption value or iodine number or index iodine ) in chemistry is the iodine mass in grams consumed by 100 grams of chemicals. Iodine numbers are often used to determine the amount of unsaturation in fatty acids. This unsaturation is in the form of a double bond, which reacts with the iodine compound. The higher the iodine number, the more C = C bonds present in the fat. It can be seen from the table that coconut oil is very saturated, which means good for making soap. On the other hand, flaxseed oil is very unsaturated, which makes it a drying oil, ideal for making oil paint.

Video Iodine value

Table of iodine value

Maps Iodine value

Methodology

This particular analysis is an example of iodometry. The iodine solution is yellow/brown. When this is added to the solution to be tested, however, each chemical group (usually in this test C = C double bond) that reacts with iodine effectively reduces the strength, or magnitude of the color (by taking iodine out of the solution). Thus the amount of iodine needed to make the solution maintain a distinctive yellow/brown color can be effectively used to determine the amount of iodine-sensitive groups present in the solution.

Reaksi kimia yang terkait dengan metode analisis ini melibatkan pembentukan diiodo alkana (R dan R 'melambangkan alkil atau kelompok organik lainnya):

${\ displaystyle \ mathrm {R {-} CH {=} CH {-} R ' I_ {2} \ longrightarrow R {-} CHI {-} CHI {- } R '}}  ÂÂ$

The precursor alkene (RCH = CHR ') is colorless and so is the organoiodin product (RCHI-CHIR').

In a typical procedure, fatty acids are treated with Hanu's extras? or Wijs solution, each of which is a solution of iodine monobromide (IBr) and iodine monochloride (ICl) in glacial acetic acid. Unreacted iodine monobromide (or monochloride) is then allowed to react with potassium iodide, converting it to iodine, whose concentration can be determined by titration with sodium thiosulfate.

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Method for determining iodine value

Huebl's iodine

Introducing iodine value is HÃÆ'¼bl which is titrated fat in the presence of mercury chloride with iodine, but with actual reagents (possibly iodine chloride) formed therein from mercury chloride and iodine. Pure iodine accumulates unrelated to alkenes, which is why the current definition of iodine is only formal.

Wijs iodine value after

Addition of iodine chloride and back titration with sodium thiosulfate by DIN 53241-1: 1995-05.

Iodine by H. P. Kaufmann

(Bromination of double bonds in the dark, reducing excess bromine with iodide, iodine backtitration with thiosulfate)

Fat is mixed with the advantages of bromine. This bromine is added to the double bond in unsaturated fats. This reaction should be performed in the dark, since radical formation of bromine is suppressed by light. This will cause undesirable side reactions, and thus falsify bromine consumption.

${\ displaystyle \ mathrm {Br_ {2} \ R_ {1} {-} CH {=} CH {-} R_ {2} \ longrightarrow R_ { 1} {-} CHBr {-} CHBr {-} R_ {2}}}$

Kemudian bromin yang tidak digunakan direduksi menjadi bromida dengan iodida.

${\ displaystyle \ mathrm {Br_ {2} 2 \ I ^ {-} \ longrightarrow I_ {2} 2 \ Br ^ {-}}}  ÂÂ$

Sekarang, jumlah yodium yang terbentuk ditentukan oleh titrasi dengan larutan natrium tiosulfat.

${\ displaystyle \ mathrm {I_ {2} 2 \ S_ {2} O_ {3} ^ {2 -} \ longrightarrow 2 \ I ^ {-} \ S_ {4} O_ {6} ^ {2-}}}  ÂÂ$

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Metode analisis terkait

• Nilai saponifikasi
• Nilai peroksida
• Nomor asam
• Nomor bromin
• Nilai hidroksil
• Nomor hidrogen

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Referensi

Source of the article : Wikipedia