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Ochem

89 results

Ochem
balace equation for the follwing 1. Li + O2 2. K + O2 3. Na + O2 4. RbCl + Na

ochem
how to determine equivalent hyfrogens in hnmr?

OChem
A disaccharide has how many monomers? I think it is two?

ochem
at room temperature is caffeine soluble in water or dichloromethane

ochem
What's an equation of the hydrolysis of one ester group in tannins by CaCO3?

ochem
What's an equation of the hydrolysis of one ester group in tannins by CaCO3?

ochem
is cis-1,2-dimethylcyclohexane a conformational isomer of trans-1,2-dimethylcycloehexane? Please explain.

ochem
In a sn2 reaction why do we need sp3 hybrid orbital and not sp2 for the substrate

Ochem
Give two reasons why the crude product in most reactions is not pure.

Ochem
Phenacetin has the structure shown below. Write an equation for its preparation starting from 4-ethoxyaniline.

Ochem
If 1.43 g of 4-ehoxyaniline and an excess of the acylating agent were used to prepare phencetin, what is the theoretical yield of product?

Ochem
What volume of 6.83% (wt./vol.) NaOCl solution is required to oxidize 223 mg of 9-fluorenol to 9-fluorenone? Please help me set this up!

ochem
For a Grignard reaction, if you start with 3.97 mL of pure bromobenzene and 0.733 g of 1-phenylethanone, what is the theoretical yield of 1,1-diphenylethanol? Please help.

ochem
Why is that that a third order alkyl halide reacts faster in SN1 mechanism? Why is it the opposite for SN2? (is it just steric hindrance? )

Ochem Lab
Suggest an appropriate reducing reagents for the following substrates and predict the reaction:(1) 2-hexanone, (2)ethyl 4-nitrobenzoate, (3) hexanal

Ochem
What volume of 6.43% (wt.vol.) NaOCl solution is required to oxidize 221 mg of 9-fluorenol to 9-fluorenone? I'm not to sure of where to start with this problem. Please help!

OCHEM
When 2-methyl-2-butene is bubbled into dilute sulfuric acid at room temperature, it appears to dissolve. What new substance has been formed?

ochem
A sample of Limonene has a specific rotation of +76.9. What is the % ee and molecular composition of this sample?

Ochem
how many grams of NaOCl are in 12.14 mL of a 6.65% (wt./vol.) NaOCl solution? Please help me set this up... I have no idea what to do.

OChem
For Extraction using a separatory funnel, what is poured into the funnel first the solution that is to be extracted or the solvent?

Ochem
Identify the following compound from its IR and proton NMR spectra. C6H10O: NMR: 3.31 (3H, s); 2.41 (1H, s); 1.43 (6H, s) IR: 2110, 3300 cm^-1 (sharp)

ochem
propose structual formulas for pheophytin a and pheophytin b

OChem
Why would diethylammonium chloride insoluble in ether? Is the only reason why the salt is insoluble because of polarity, or are there other reasons why? Please explain.

Ochem
By looking at the chemical structures of acetaminophen, aspirin, caffeine, ibuprofen, and naproxin sodium, how are you able to determine the relative polarity of each? Does it have something to do with the symmetry of the structure? Please help!

OCHEM DR BOB PLEASE HELP!!!!!!!!!1
Why is it possible to use melting point to distinguish the different stereochemistry of the products? (Hint: what is the relationship of the different stereoisomers of the product?)

Ochem
Which of the following is NOT a proper name for an organic compound (because it doesn't identify the longest possible carbon chain)? 2-methylpentane 3-methylpentane 2-ethylhexane 2,3-dimethyl butane

Ochem
Write the equation for the reaction that occurs when sodium carbonate is added to the mixture of the reaction and water (hint: a gas is evolved). This is for benzocaine experiment

ochem
bromide is a better nucleophile toward the intermediate bromonium ion than ethanol. what product would be obtained if ethanol did carry out this nucleophilic attack?

ochem
Give the reaction products of sodium borohydride (followed by water addition at the end of the reaction) with the following compounds: a) Acetone b) m-nitroacetophenone c) 3-buten-2-one

ochem
Predict a reasonable melting point of a mixture prepared by combining 25mg of biphenyl (mp=70-71C) with 75mg of acetyl salicylic acid (mp=138-140C). Answer should have temps in it.

Ochem
Give the products (if any) expected from the treatment of the following compounds with ozone followed by aqueous hydrogen peroxide. Do not include any byproducts. 1) 2-methyl-2-pentene 2) cyclooctene Please help! I'm not sure on where to start with this problem.

ochem
Which of the cyclohexane conformation is more stable? (chair of boat) What factors cause the observed differences in strain energy between the two conformations of the cyclohexane studied above?

ochem
Calculate the amount (volume) of 5.25% (wt./vol.) NaOCl solution (commercial bleach) required to oxidize 100 mg of 9-fluorenol to 9-fluorenone. Whenever appropriate, use balanced chemical equations as a part of your calculation.

OCHEM
How would the 1H NMR spectrum of 1,3-dibenzoylpropane differ from that of the product, trans-1,2-dibenzoylcyclopropane? would the chemical shifts of the protons alpha and beta to the carbonyl groups be appreciably different? explain.

Ochem
In the reaction between p-aminophenol and acetic anhydride to form acetaminophen, what was the purpose of adding water to the reaction mixture? There are a couple of possible answers, and this requires a detailed explanation for credit. thanks!

Ochem
Diethyl ether is used as a solvent for the reaction of diethylamine with m-toluoyl chloride. Why is a solvent necessary for this reaction?

Ochem
Most fatty acids with double bonds are found in animals or plants? Are these fatty acids solid or liquid at room temperature?

OChem
Anhydrous conditions are vital for a successful Grignard synthesis. To demonstrate this point calculate the mass of the water it would take to destroy the phenylmagnesium bromide you will synthesize. What is he volume of this amount of water? -How exactly do you do this?

ochem
After reacting racemic phenylethylamine with R,R-tartaric acid, several of our class samples contained needle-like crystals instead of prismatic crystals. What did this indicate about the success of the separation?

ochem lab
this deals with TLC chromatography: if 2 compounds have same Rf under identical conditions, does it show that they have identical structures? i think it does. but im not sure why. thanks mucho.

ochem
Which of the trans-1,4-dimethylcyclohexane is more stable? ("di-axial" or the "di-equitorial") What factors cause the observed differences in strain energy between the two conformations of trans-1,4-dimethylcyclohexane studied above?

OChem
Anhydrous conditions are vital for a successful Grignard synthesis. To demonstrate this point, calculate the mass of water it would take to destroy the phenylmagnesium bromide that synthesized from 0.48 mL of bromobenzene and 112.5 mg of magnesium. What is the volume of this ...

ochem
If you recrystallize a compound with a 1/2 ethanol/water mixture and water remains in the compound after recrystallization, would that change the melting range of the pure compound?

Ochem
For the reaction between chloroacetic acid and 4-chlorophenolate to synthesize 4-chlorophenoxyacetic acid, why is this reaction a sn2 reaction?

OChem
1. Why does not fluorene dissolve in 1.5M sodium hydroxide solution? 2. What experimental difficulty would you encounter if you had neclected to include a drying step before evaporating the ether solution of the neutral organic compound (fluorene)?

ochem
A student dissolved 30 mg of a crude unknown in 2 ml of 95% ethanol at room temperature. After chilling in an ice bath and washing crystal with small amount of ice-cold ethanol, she recovered 5mg. Why was the recovery so low?

Ochem Lab
why is it important to spot samples directly on the marks made on the TLC plate? This is for Thin Layer Chromotography. Is this important so that the solvents move directly up the plate and can be identifies easily? Thanks

OCHEM
Write the mechanism for (E)-2-5-dimethyl-hex-3-ene and bromine? Assign the R, S configuration for each of the products and determine the stereochemical relationship of each set of products. I think the products will be trans but I am not quite sure how the mechanism work. Any ...

ochem lab
What is the expected observed rotation of a 9.1 x 10-5 M solution of compound X? Note: compound X has a specific rotation of [α]D20 = -49o and a molecular weight of 235.2 g/mol. In addition, the path length of the cell used to take the polarimetry measurement was 5.0 cm.

Ochem
Which Alkene is capable of stereoisomerism: 1-pentene, 2-methyl-1-pentene, 2-methyl-2-pentene, 2-pentene, or 2,3-dimethyl-2-butene?

OCHem
The amount of methylcycloheane with the substituent in the equatorial orientation at room temperature (25C) would be The Gibbs free energy for axial methyl to equatorial methyl is -7.28Kj/mol (the universal gas constant is 8.314 j/deg-mol). I cant remember how to solve this...

OChem
Could someone explain these two reaction mechanisms (I know they are substitution): 1) 1-propanol reacted with H2SO4 and NaBr 2) 2-pentanol reacted with H2SO4 and NaBr does the carbocation rearrange for the second reaction? thanks for the help!

OChem
A mixture of acetone and ethyl acetate of unknown ratio begins to boil at 65 degrees celcius (760 torr). What is the composition of this binary mixture in terms of the mole fraction of acetone and that of ethyl acetate?

Ochem
Could someone explain this? Thanks! Which of the following is a correct IUPAC name? a. 3-bromo-2-chlorotoluene b. 6-bromo-4-chlorotoluene c. 2-chloro-3-bromotoluene d. 2-chloro-4-bromotoluene

OChem
Confused! Please help!! Assume an organic compound has a partition coefficient between water and diethyl ether equal to 6.63. If there are initially 9.05 grams of the compound dissolved in 80.0 mL of water, how many grams will remain in the aqueous layer after extraction with ...

ochem
Rank fastest to slowest reaction with HBr: A) H3C-C---C-CH3 (alkyne; that's a triple bond between the carbons) B) H CH3 (alkene; trans) = H3C H C) H3C CH3 (alkene; 3 methyl substituents) = H3C H Please explain why. Thanks!

ochem
Can you suggest some possible reasons for using a mixture of water and ethanol (1:1 mixture H2O/EtOH) as crystallizing solvent rather than using either pure ethanol or pure water?

OChem
What's the purpose of "PREPARATION OF A SYNTHETIC PLANT HORMONE Adapted from "p-Chlorophenoxyacetic Acid – Preparation of a Synthetic Plant Hormone." thanks

ochem
Consider a sample that is a mixture composed of biphenyl, benzoic acid, and benzyl alcohol. Predict the order of elution of the components in this mixture on the TLC plate when solvent system a, b or c is used. a)Cyclohexane: Methylenechloride:100%:0% b)Cyclohexane: ...

ochem
A sample of Limonene has a specific rotation of +76.9. What is the % ee and molecular composition of this sample? R(+)- is +125.6 and S (-)- 122.1. I'm confused I don't know whether I should divided by 125.6 or 122.1. %ee=(76.9/125.6)*100=61%. Is this correct? I'm clueless as ...

ochem
when the concentration of CHBr3 and NaOH are both .145, the rate of the reaction is .0040 M/s. What is the rate of the eaction if the concentration of CHBr3 is doubled?if the conc. is halved?if the two conc. are both increased by a factor of five? CH3Br+NaOH-->CH3OH+NaBr

ochem
when the concentration of CHBr3 and NaOH are both .145, the rate of the reaction is .0040 M/s. What is the rate of the eaction if the concentration of CHBr3 is doubled?if the conc. is halved?if the two conc. are both increased by a factor of five? CH3Br+NaOH-->CH3OH+NaBr

Ochem
prepare 5 grams of benzyl alcohol. the average yield reported for this synthesis is 50%. calculates how much benzyl chloride you need to start with, use about a 10% excess of koh, and employ the solvent in a ratio of about 100ml of methanol for every 10 grams of benzyl ...

OChem
What intermolecular forces are important in the binding of organic molecules to the absorbent in absorption chromatogrpahy? Select all that apply. A) London forces B) Van der Waals forces C) Covalent Bonding D) Hydrogen bonding E) Dipole-dipole interactions F) Lewis acid-base ...

Ochem
If you start with 2.97 g of zest and obtain 459 mg of pure limonene, what is your percent recovery? I was thinking of dividing .459g by 2.97g and then multiplying by 100 to get the percent recovery. But then I realized that the zest and limonene aren't the same. So how would I...

OChem
If the limonene reactant described in question 2 is composed of a single enantiomer, how many stereoisomers of the product will be formed in the reaction? If there are more than one stereoisomers what would their relationship be? Question 2: Suppose a student is measuring the ...

OChem
What does it mean for a conformation to be more stage than another conformation in terms of the strain energy? Based on your answer, which of the above conformations of n-butane (eclipsed, gauche, anti) is more stable? What factors cause the observed differences in strain ...

OChem
Calculate the amount (volume) of 5.25% (wt./vol.) NaOCl solution (commercial bleach) required to oxidize 100 mg of 9-fluorenol to 9-fluorenone. Whenever appropriate, use balanced chemical equations as a part of your calculation. I know that I need to start off with the ...

OCHEM
A student needed to determine the percent composition of a mixture that contained fluorene and benzoic acid. The student took 245 mg of the mixture and used the extraction method to separate the components. Then both compounds were recrystallized and dried. The experiment ...

ochem
list from strongest acid to weakest acid HC(triple bond)CCH3 H2C=CH2 H3CNH2 CH4 H2O i thought the order went HC(triple)CCH3 H3CNH2 H2O H2C=CH2 CH4 but it comes out as wrong and i don't know why >

OChem
The solubility of acetanilide is 3.53 g in 100 mL of chloroform at 0 °C, and 29.1 g in 100 mL of chloroform at 60 °C. What is the maximum percent recovery that can be achieved for the recrystallization of acetanilide from chloroform? Hint: During a recrystallization, some of...

OChem
1. if and when boiling points can be used to determine the purity of organic compounds. 2. if and when boiling points can be used to identify organic compounds. 3. when can fractional distillation be used to separate organic compounds

OChem
A mixture of fluorene and benzoic acid is dissolved in diethyl ether and mixed thoroughly with an aqueous solution of NaOH. After the layers separate, what will each of the layers contain? Label the layers. Indicate the main components, not species that could be present in ...

Chemistry (Ochem)
I know that there is such thing as inversion of stereochemistry,but is there such thing as inversion of stereocenter? Are stereocenter and stereochemistry the same thing or mean the same thing? Thank you, Vivian

OChem
Suppose a student obtained a 0.15g of cruse salicylic acid. How much water would be needed to just dissolve it at 75 degrees Celsius? How much salicylic acid would remain dissolved in that amount of water at just 10 degrees Celsius? What percent of the original mass of the ...

Ochem
What is the purpose of refluxing? Which reaction conditions are indicated with reflux? Will you apply heat? How do you know the temperature at which you should reflux? I think it is "A reflux system is used to condense vapours escaping from the hot flask. " Please help. Your ...

Chemistry/ OChem
Each of the solvents given should effectively separate of the following mixtures by TLC. Match the appropriate solvent with the mixture that you would expect to separate well with the solvent. Select your solvent from the following: hexane, methylene chloride, or acetone. (a) ...

OChem
A solution consisting of water and ethanol is found to have a refractive index of 1.3541 at 20 degrees C. The refractive indices at 20 degrees C of water and ethanol are 1.3330 and 1.3610, respectively. Determine the molar composition (in percent) of the mixture by assuming a ...

Ochem
What would be a newer more efficient method to do the qualitative analysis of an unknown. I am trying to find a good method and asses its greenness (Green chemistry) and say why it better than the common method used. please help as soon as possible. This is such an open ended ...

ochem
You have a mixture composed of 90% benzoic acid and 10% naphthalene. Benzoic acid has a melting point of 122.4 oC, while naphthalene has a melting point of 80.2 oC. You can say with certainty that the melting point of the mixture will be: A. greater than any of the two melting...

Ochem
A student needed to determine the percent composition of a mixture that contained fluorene and benzoic acid. The student took 283 mg of the mixture and used the extraction method to separate the components. Then both compounds were recrystallized and dried. The experiment ...

Chemistry/ OChem
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. a) a two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of .95. The solvent uses was acetone. b) a two-...

OCHEM
What would be the effect of decrease the carrier gas flow rate, raise the column temp, have on the retention time? What would be the effect of raise the column temp and decrease the carrier gas flow rate on the ability to resolve two closely spaced peaks? For the first ...

OChem
A sample of limonene has a specific rotation of +81.5. (Given that R-(+)-limonene = +125.5 and, S-(-)-limonene = -122.1). What is the %ee? ______%ee What is the molecular composition of this same sample? S isomer = ______% R isomer = ______% This is how I solved for the R and ...

ochem
Calcualte how many milliliters of carbon dioxide would be produced theoretically from 20g of sucrose of 25 degree C and 1 atmosphere pressure. I can use the formula PV=nRT 20g C12H22O11 * moles sucrose/342.3g suc. that would equal: .0584 moles. But what next. The experiment ...

Ochem
What volume of eugenol will be present in 30 mL of distillate? The essential oil found in cloves, eugenol, can be isolated by steam distillation because it is insoluble in water and has a measurable vapor pressure at 100 °C even though it has a much higher boiling point than ...

OChem Nomenclature
Here is a compound that I am trying to name... H H \ / C || CH3-CH2-C-CH2-CH2-CH2-CH3 I came up with 3-methylheptene, but the answer says 2-ethyl-1-hexene. Can someone please explain why I'm wrong? Thanks that showed up wrong - the methyl with the double bond should be on that...

ochem 2
1. Below are the IR and 1H NMR spectra for a compound with the molecular formula of C11H16O. List all the possible information coming from each spectra, and then use this to elucidate the structure from the possible compounds shown. Briefly explain your rationale. IR spectra: ...

Ochem
The following question is due to a reaction in organic chemistry ethanol from sucrose. I did not properly state in my last post where the reaction came from. I apologize for this (Dr.Bob). I repost the same question: Calculate how many milliliters of carbon dioxide would be ...

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