Business, 01.07.2019 01:00 coolfreekid3

How is it possible for the lucas test to give a false positive?

Answers: 1

Show answers

Answers

Answer from: nina4552

Lucas' reagent is a solution of anhydrous zinc chloride in concentrated hydrochloric acid. This solution is used to classify alcohols of low molecular weight. The reaction is a substitution in which the chloride replaces a hydroxyl group. A positive test is indicated by a change from clear and colourless to turbid, signalling formation of a chloroalkane.[1] Also, the best results for this test are observed in tertiary alcohols, as they form the respective alkyl halides fastest due to higher stability of the intermediate tertiary carbocation. The test was reported in 1930 and became a standard method in qualitative organic chemistry.[2] The test has since become somewhat obsolete with the availability of various spectroscopic and chromatographic methods of analysis. It was named after Howard Lucas (1885–1963).

Lucas testEdit

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 via an SN1 reaction:[3]

ROH + HCl → RCl + H2O

The differing reactivity reflects the differing ease of formation of the corresponding carbocations. Tertiary carbocations are far more stable than secondary carbocations, and primary carbocations are the least stable.

An equimolar mixture of ZnCl2 and HCl is the reagent. The alcohol is protonated by this mixture, and H2O group attached to carbon is replaced by the nucleophile Cl−, which is present in excess. Tertiary alcohols react immediately with Lucas reagent as evidenced by turbidity owing to the low solubility of the organic chloride in the aqueous mixture. Secondary alcohols react within five or so minutes (depending on their solubility). Primary alcohols do not react appreciably with Lucas reagent at room temperature.[3]Hence, the time taken for turbidity to appear is a measure of the reactivity of the class of alcohol, and this time difference is used to differentiate among the three classes of alcohols:

no visible reaction at room temperature and forming an oily layer only on heating: primary, such as 1-pentanol

solution forms oily layer in 3–5 minutes: secondary, such as 2-pentanol

solution forms oily layer immediately: tertiary, such as 2-methyl-2-butanol

Answer from: Quest

d. automatic stabilizers.

explanation:

Answer from: Quest

answer; experimentation;

Other questions on the subject: Business

Business, 22.06.2019 08:00, browneyedbaby20

Lavage rapide is a canadian company that owns and operates a large automatic car wash facility near montreal. the following table provides data concerning the company’s costs: fixed cost per month cost per car washed cleaning supplies $ 0.70 electricity $ 1,400 $ 0.07 maintenance $ 0.15 wages and salaries $ 4,900 $ 0.30 depreciation $ 8,300 rent $ 1,900 administrative expenses $ 1,400 $ 0.03 for example, electricity costs are $1,400 per month plus $0.07 per car washed. the company expects to wash 8,000 cars in august and to collect an average of $6.50 per car washed. the actual operating results for august appear below. lavage rapide income statement for the month ended august 31 actual cars washed 8,100 revenue $ 54,100 expenses: cleaning supplies 6,100 electricity 1,930 maintenance 1,440 wages and salaries 7,660 depreciation 8,300 rent 2,100 administrative expenses 1,540 total expense 29,070 net operating income $ 25,030 required: calculate the company's revenue and spending variances for august.

Answers: 3

continue

Business, 22.06.2019 12:20, mxrvin4977

In terms of precent, beer has more alcohol than whiskey true or false

Answers: 1

continue

Business, 22.06.2019 15:20, ashleyuchiha123

Gulliver travel agencies thinks interest rates in europe are low. the firm borrows euros at 5 percent for one year. during this time period the dollar falls 11 percent against the euro. what is the effective interest rate on the loan for one year? (consider the 11 percent fall in the value of the dollar as well as the interest payment.)

Answers: 2

continue

Business, 22.06.2019 19:30, buggamarshall85

The owner of firewood to go is considering buying a hydraulic wood splitter which sells for $50,000. he figures it will cost an additional $100 per cord to purchase and split wood with this machine, while he can sell each cord of split wood for $125. if, for this machine, design capacity is 50 cords per day, effective capacity is 40 cords per day, and actual output is expected to be 32 cords per day, what would be its efficiency?