Question

(A) Observations about the known compounds (hypothetical - considering you actually did the experiment in the lab): 10 pts 1. You analyzed 2-pentene in the lab by following the Flow chart uploaded in Canvas. Record your observations as follows (your observations must be in accordance with what you expect of this compound). Experiment Observation Compound analyzed Inference (what FG could be absent or present) 2-pentene Performed ignition/combustion test Performed Beilstein test

help with table much appreciated Organic chem II

Answer 1

For 2-pentene,

Experiment	Observation	Inference	Theory behind experiment
Performed combustion/ignition test	Yellow flame observed but no soot	Aromatic ring or alkynes absent	Compounds with higher degree of unsaturation such as alkynes and aromatic compounds burn with yellow sooty flame. Saturated compounds (alkanes) burn with bluish flame while alkenes with yellow flame
Performed Beilstein test	No green/blue color observed in flame	Halogens are absent	Halogens react with copper in copper wire to form copper halides. Presence of copper halide imparts green color to flame.
Placed 2 drops of compound in testube. Add 1 mL of water and stirred to solublize. Then warmed it to 60-70oC	Immiscible, floats on cold as well as warm water	Low molecular weight alcohols, amines, carboxylic acids absent	Polar organic compounds with small molecular weight are immiscible in water
Added 1 mL of 5% NaOH and stirred	Immiscible	Compound is neither weak nor strongly acidic. So, phenol and carboxylic acid groups are absent.	Weakly acidic groups like phenols and strongly acidic groups like carboxylic acid react with NaOH to form conjugate bases which are soluble.
Added few drops of 5% NaHCO3 and observe if tiny bubbles are formed	No bubbles observed	Carboxylic acid (-COOH) group is absent	Strongly acidic groups such as -COOH react with NaHCO3 to evolve CO2 gas which appear as tiny bubbles
Added few drops of 5% HCl and stirred	Immiscible	Amines absent	Amines are basic in nature and react with HCl to form ammonium salts which are soluble in water
Dissolved 3 drops of compound in 2 mL of reagent grade ethanol and added 3 mL of DNP reagent	Precipitates are not observed	Aldehydes/Ketones absent	2,4-DNP reacts with aldehydes and ketones to form hydrazones which appear as red, yellow or orange precipitates .
Added 3 drops of compound to testube then added 5 drops of acetone and 5 drops of chromic acid	No color change	Alcohols and aldehydes absent	Alcohols and aldehydes are oxidized by chromic acid and Cr(VI) in chromic acid gets reduced to Cr(III) which appears green in color
Dissolved 2 drops of compound in 0.5 mL DCM. Added 4 drops of 2% bromine in DCM	Reddish brown color of bromine disappears	Unsaturated compounds i.e. Alkenes or alkynes are present	Bromine (Br2) imparts reddish brown color in DCM. When unstaurated compound is present, Br adds along the double or triple bond and reddish brown color disappears
Dissolved 1 drop of compound in 0.5 mL acetone. Added 1% KMnO4 solution.	Purple color of KMnO4 disappers	Unsaturated compounds i.e. Alkenes or alkynes are present	KMnO4 oxidizes alkenes and alkynes and itself gets reduced to MnO2 which appears as brown ppt.

Reaction that gave positive information about 2-pentene

+ Br2 - Br 2-pentene bromine (reddish brown) 2,3-dibromopentane ОН + KMnO4 + MnO2 brown ppt OH 2-pentene purple color 2,3-dihydroxypentane