Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Niharika Kalita posted an Question
June 22, 2020 • 02:56 am
![]()
20 points
20 points
- IIT JAM
- Chemistry (CY)
Distinguish between 1°,2°,3° alkyl halides in terms of chemical reactions or tests.
Distinguish between 1°,2°,3° alkyl halides in terms of chemical reactions or tests.
2 Answer(s)
Answer Now
- 0 Likes
- 3 Comments
- 0 Shares
-
Ashish sharma
![best-answer]()
Qualitative tests for alkyl halides are useful in deciding whether the compound in question is a primary, secondary, or tertiary halide. In general it is quite difficult to prepare solid derivatives of alkyl halides, so we limit this discussion to the two qualitative tests: (A) the reaction with alcoholic silver nitrate solution and (B) the reaction with sodium iodide in acetone. You are to run tests A & B on the following compounds: 1-Bromobutane, 2-Bromobutane, 2-Bromo-2-methylbutane, 1-Chlorobutane, 2-Chlorobutane, 2-Chloro-2-methylbutane, and your halide products A. Alcoholic Silver Nitrate If a compound is known to contain a halogen (bromine, chlorine, or iodine), information concerning its environment may be obtained from observation of its reaction with alcoholic silver nitrate. The overall reaction is shown in the following equation: Ethanol RX + AgNO3 ---------------> AgX + RONO2 Such a reaction will be of the SN1 type. Tertiary halides are more reactive in an SN1 reaction than secondary halides, which are in turn more reactive than primary halides. Differing rates of silver halide precipitation would be expected from halogen in each of these environments, namely, primary < secondary < tertiary. These differences are best determined by testing in separate test tubes authentic samples of primary, secondary, and tertiary halides with silver nitrate and observing the results. Alkyl bromides and iodides react more rapidly than chlorides, and the latter may require warming to produce a reaction in a reasonable period. Aryl halides are unreactive toward the test reagent, as are any vinyl or alkynyl halides generally. Allylic and benzylic halides, even when primary, show reactivities as great as or greater than tertiary halides because of resonance stabilization of the resulting allyl or benzyl carbocations.
-
Suman Kumar
See this
![cropped415628281925306340.jpg]()
![cropped8815363744765694324.jpg]()
![eduncle-logo-app]()
I want in terms of chemical tests or reactions like in alcohols like we have turbidity test to distinguish between 1°,2°,3° alcohols.
![eduncle-logo-app]()
There is no as such observatory test. But you can distinguish by rate of Sn1 & Sn2
![eduncle-logo-app]()
Lucas test in alcohols is a test to differentiate between primary, secondary, and tertiary alcohols. It is based on the difference in reactivity of the three classes of alcohols with hydrogen halides. Tertiary alcohols react immediately with Lucas reagent and turbidity appears. Secondary alcohols react within five or so minutes (depending on their solubility). Primary alcohols do not react appreciably with Lucas reagent at room temperature. Hence, the time taken for turbidity to appear is used to differentiate among the three classes of alcohols.
Do You Want Better RANK in Your Exam?
Start Your Preparations with Eduncle’s FREE Study Material
- Updated Syllabus, Paper Pattern & Full Exam Details
- Sample Theory of Most Important Topic
- Model Test Paper with Detailed Solutions
- Last 5 Years Question Papers & Answers
Sign Up to Download FREE Study Material Worth Rs. 500/-
Ashish sharma![best-answer]()
Sodium iodide in Acetone Another method for distinguishing between primary secondary, and tertiary halides makes use of sodium iodide dissolved in acetone. This test complements the alcoholic silver nitrate test, and when these two tests are used together, is possible to determine fairly accurately the gross structure of the attached alkyl group. The test depends on the fact that both sodium chloride and sodium bromide are not very soluble in acetone, whereas sodium iodide is. The reactions that occur are SN2 substitutions in which iodide ion is the nucleophile; the order of reactivity is primary > secondary > tertiary. acetone RCl + NaI ------------> RI + NaCl acetone RBr + NaI ------------> RI + NaBr With the reagent, primary bromides give a precipitate of sodium bromide in about 3 min at room temperature, whereas the primary and secondary chlorides must be heated to about 500C before reaction occurs. Secondary and tertiary bromides react at 50EC, but the tertiary chlorides fail to react in a reasonable time. It should be noted that this test is necessarily limited to bromides and chlorides.