Isomerism Questions and Answers

12 Identify compound s in which gauche conformer is more stable than staggered B Chloropropane C Ethylene glycol D Succinic acid A 1 2 Difluoroethane No 42 JA OB OC OD

Use the molecular orbital diagram for the diatomic molecule SiN below to determine what will happen to the silicon nitrogen bond if you make the neutral molecule into the anion SiN E LL 1 SIN 1 11 11 t 11 111 11 The bond in SiN will be longer and weaker The bond in SiN will be shorter and weaker The bond in SiN will be longer and stronger The bond in SiN will be shorter and stronger

27 The back side attack on 2 bromobutane by methoxide CH 30 gives the product shown below Which Fischer projection represents 2 bromobutane used as the reactant in this reaction e elxb Et a Me H HD HBr HD OCH3 product Et Me H 1 d Et b H Br Me Me c Br H Et Br Me H H Et d Me

Pick the one with different degree of unsaturation A B C D

Which medicine is produced as a nitrate salt O A serotonin B O C securinine O D mexamine O E reserpine physostigmine Strychnos nux vomica is rich in one of these alkaloids Select the right one O A physostigmin O B reserpine O C strychnine D securinine

3 Total compound a 1 2 214 3 6 4 8 geometri isomers in the given 49 ffu af Hicefort C CH DC CD HC C 1 2 2 4 1376 4 8 C CH DC CD HC 50 CH 3m Ma 2 are t 2 2 23 2 1 1 2 CH C CH CH CH CN CH TIUPA

2 asymmetry 3 External compensation 4 Two asymmetric carbon atoms The pair of structures given below represents CH CH CH H CH CH HO 1 Enantiomers 3 Identical CH HOW H 2 Diastereomers 4 Position isomers 1 antas 4 2 faran e 3 24 fari 4 fura 21 H mi CH HO 1 1 ufafara 3 47 F 2

The compound s which show Keto enol tautomerism is ar II III I only II only hr min II and III only

1 I II 3 I II III 4 II III IV Which of the following statements about the conformer that result from rotation about the C C3 bond of butane is correct 1 Torsional strain is absent in the eclipsed forms 2 Steric strain is absent in the eclipsed forms 3 The gauche conformer is an eclipsed one 4 The highest energy conformer is one in which methyl groups are eclipsed by hydrogens 5 None of the above

The heat of hydrogenation for 3 methylbutene and 2 pentene are 30 kcal mol and 28 kcal mol respectively The heats of combustion of 2 methylbutane and pentane are 784 kcal mol and 782 kcal mol respectively All the values are given under standard conditions Taking into account that combustion of both alkanes give the same products what is AH in kcal mol for the following reaction under same conditions a 0 Y b 4 c 2 d 2

Which of the following is are incorrect IUPAC name a 4 chloro 3 methyl cyclopentanol 1 b 1 amino 3 bromo hexan 1 one c 4 chloro 3 methyl cyclohexane carboxylic acid d 3 bromo 1 methyl hexan 1 ol Key A B D

NO Single Correct A Which of the following show tautomerism NO b a CH CH NO CH CH C CHCCHO CH A a d d A Da CH

Which of the following pairs will show the same magnetic moment spin only 1 3 Cr H O and Fe H O NO 2 Mn CN and Fe CN 6 3 3 Ni CO and Zn NH3 4 2 4 All of these Vanes ACA 00 0 7 0 00 2

The stereochemistry configuration of enantiomers are called R and S To assign this nomenclature to a chiral carbon in the following molecule CH H H C OH w CH CH C H CH you first have to assign the ranking of the four groups attached to the chiral carbon of the molecule The H atom has the lowest rank which is assigned number 4 Rank the remaining 3 groups from highest to lowest that is 1 2 3

Which dissolves NaCl more quickly hot water or cold water Explain W

What are the absolute configurations of the two chiral centers of the following molecul Sel NH OI R and II R OI S and II S O I S and II R OI R and II S

What is the IUPAC name of this structure CH3 H3C LOH O 1 fluoro 6 ethylheptan 3 ol O 7 fluoro 2 ethyl heptan 5 ol O 7 fluoro 3 methyloctan 6 ol O 1 fluoro 6 methyloctan 3 ol

What is the major product of this reaction 1 equiv HCI 80 C 8 O CI CI z CI

reaction consumes 5 0 g of A and 6 0 g of B How many grams of C and D should be obtained Multiple Choice O C Not enough information is given to answer this question 10 23 1A 3B2C 4D

Mother said little Pearl the sunshine does not love you It runs away and hides itself because it is afraid of something on your bosom It will not flee from me for I wear nothing on my bosom yet Nor ever will my child I hope said Hester And why not mother asked Pearl stopping short Will it has not come of its own accord when I am a woman grown What is the implicit meaning conveyed by Pearl in the excerpt O Pearl notices that the scarlet letter on her mother s bosom has paved the way for lack of sunshine in her mother s life Pearl realizes that the scarlet letter on her mother s bosom is unique to her mother which other women in town do not have Pearl admires her mother s needlework of the scarlet letter and wants one for her when she reaches adulthood O Pearl Is afraid of the scarlet letter on her mother s bosom and expresses it subtly

Which best describes the stereochemistry of the product s formed when the compound shown below undergoes catalytic hydrogenation with an excess of H CH OH H excess Pd Two stereoisomers are produced that are diastereomers of one another A single meso compound is the only product formed OTwo stereoisomers are produced that are enantiomers of one another O Four stereoisomers are produced

4 5 6 CH CH H C C O CH CH 7 CH CH CH CHCH3 OH CH OH OCH CH3

Determine the molecular geometry of BC13 Obent O trigonal pyramidal trigonal planar

Draw the major and minor product that could be formed when 1 chloro 1 3 butadiene reacts with acrylonitrile Include any relevant stereochemical configurations CI CN P Draw Major Product Q I

Why is the statement A natural product having a p 40 3 has been isolated and purified either of the following substances could be this natural product false HO HO OH CO H OH or HO HQ H HO H H H H H OH

Functional group identification Match the numbered molecules with the functional group being asked You need to provide all possible answer correct minus wrong CH3 H C FCH 1 limonene H C CH3 4 ibuprofen H C 7 aspirin CH3 CO H OH 2 muscone H C CH3 5 camphor CH3 CH3 H C CH3 8 geraniol A Which have carbon carbon double bonds B Which have a ketone carbonyl group C Which have an aldehyde carbonyl group D Which have amino groups E Which have aromatic rings F Which have a hydroxyl group G Which have ether groups H Which have an ester group 1 Which have an amide group J Which have a carboxylic acid group OH HO 3 nicotine H O O CH3 6 vanillin H C H 9 acetaminophen

Select one Dimensional Analysis 1 Unit Conversions Question 9 One way to represent an oxygen molecule is with a sketch like the one below The black arrow represents the average molecular speed at room temperature of 480 meters per second m s That unit of speed might be difficult to relate to You decide to convert it to miles per hour Which of the following choices shows how to convert this speed to miles per hour 18 O miles 480 1609m hr 1074 miles hr 480 1609 miles 1074 miles x hr 480 1609 3500 960 miles none of these conversions are correct OO oxygen gas 480 m s

8 The structure of the compound is shown below was found to be biologically active Answer the following questions pertaining to the structure below 20 points CH3 HN 010 H 0 O H 0 CH H CH3 a Draw a line structure from the given Kekule structure on the right b Identify and label three functional groups in the structure c Indicate two nucleophilic nu sites in the structure d Indicate two electrophilic sites el in the structure d Identify any all chiral center s with an e Draw below a pair of diasteriomers of the compound What is the relationship between the two compounds that you drew Are they enantiomers or diasteriomers of each other Will a 50 50 mixture of them rotate plane polarized light in the structire

b c 5 Draw the most stable conformer of each of the following 15 points Use Newman projections for straight chain compound and chair for cyclic compounds 3 4 dimethyhexane when viewed through C 3

CHM 2010 1 9 pts On the line drawn below provide the systematic IUPAC name for the following structure Be sure to include stereochemistry R S cis trans or E Z when appropriate Show all work for full credit Br H 2 5 pts Clearly label below each compound whether it is the acid base conjugate acid or conjugate base Then using pka values in the table given determine which way the equilibrium will favor and redraw the equilibrium arrow in the box provided H O NH4 H3O NH3

gas is cooled from 40 C to 15 C If it is kept at a constant pressure and the initial volume is 3 50 L what is the final volume a 1 3 L Ob 15 8 L Oc 3 7 L d 3 3 L

Provide the reagents necessary for the following transformation H O CH CECH A H O H O HgSO4 B 1 BH3 2 H O2 NaOH A B H C CH CH H

Draw one of the possible diastereomers of the molecule shown below Use a dash or wedge bond to indicate stereochemistry of substituents on asymmetric centers where applicable NH Draw a Diastereomer a Q I I I I I I

Write the main product s for each of the following reactions Are the reactions regioselective Explain Are the reactions stereoselective Explain Are these reactions stereospecific Explain Br TbONa T OH TbONa THAU

Problem 2 Draw a peptide bond between two amino acids a circle the carboxyl and amino group involved in bonding use red ink b circle OH and H that will be removed during peptide bond formation use blue ink c draw final structure of a peptide use green ink to indicate peptide bond 1 a b NH NH OH and HO NH

lithium to form a new stable product Ho many equivalents of lithium do you expe to react provide a bried explination 2 24 Snapchat 1 of 1 cdn fbsbx com 5G Do

The disaccharide shown here CH OH OH OH CH OH OH OH OH has a free anomeric carbon O could oxidize Cu ions has a B 1 6 glycosidic linkage contains both D and L sugars has a linkage like those in amylose has an 1 4 glycosidic linkage

Given the formula representing a molecule HHHHH H C C C CICIN HHHHH A chemical name for this compound is pentanamide 1 pentanol Pentanone 1 pentan H TH

91 Dimensional Analysis 1 Unit Conversions Question 9 Suppose the polar ice caps were retreating at an acceleration rate of 2 0 inches year 2 12 Which choice below is the best estimate of this acceleration in the units m sec ond Select one 54 x 10 7 second 54 x 104 m second 5 x 10 second

Which statement is UNTRUE O Double diastereoselection involves a chiral substrate and a chiral reagent In double diastereoselection a mismatched pair leads to very high levels of diastereoselection O In substrate controlled diastereoselection only the substrate is chiral not the reagent In reagent controlled diastereoselection only the reagent is chiral not the substrate

Check t V x under each molecule in the table below that is an isomer of this molecule If there are no isomers check the none of the above box under the table X

A mixture with an 60 enantiomeric excess e e contains of the major enantiomer and of the minor enantiom O 90 10 O 80 20 O 50 50 O 75 25

a Select one Atomic Structure 2 Electronic Structure Question 1 Which statement describes patterns in how metals behave when forming ions a O Metals tend not to lose or gain any electrons O Metals tend to first lose and then gain electrons Metals tend to gain electrons O Metals tend to lose electrons

What is the specific rotation of pure S carvone if a sample of R carvone of 78 ee has a specific rotation of 44 CH5 ee O 56 O 34 O 34 observed a a of pure enantiomer X 100

Identify the following molecule H H NA HIG H 0 O a glycerolol O b tri fatty acid O c wax O d triglyceride CH3 CH 3 CH3

The following is a diagram of energy states and transitions in the hydrogen atom ENERGY A B C D E CC infinity n n 3 n 2 use the References to access important values if n n 1 Match each of the responses below with the correct arrow from the figure 1 The emission line with the longest wavelength 2 The absorption line with the longest wavelength 3 The emission line with the highest energy 4 The absorption line with the lowest energy 5 The emission line with the lowest frequency 6 The line corresponding to the ionization energy of hydrogen

20 mL of 0 5 M HAn is combined with 10 mL of 0 2 M NaOH Complete the table below and calculate the Ka of the acid assuming the solution pH 5 00 and the total solution volume is 250 ml Enter the answer in the usual way

important values it needed for this question student determines the manganese II content of a solution by first precipitating it as manganese II hydroxide and then decomposing the hydroxide to manganese II xide by heating How many grams of manganese II oxide should the student obtain if his solution contains 37 0 mL of 0 570 M manganese II nitrate g

problem 22 51 draw the organic products formed in each reaction Explain a e please 22 51 Draw the organic products formed in each reaction COOH c C6H5CN OH b CHCOCI SOCI N H excess 1 CH3CH CH MgBr 2 H O d CH3 2CHCOOH CH3CH CHOH CH3 NHCOCH3 H O TOH H SO4

12 5 For each of the following pairs of alcohols identify the one that is more acidic and explain your choice c OH OH OH OH b 12 OH