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25 Cards in this Set
- Front
- Back
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What are some characteristics of the naming of alcohols and thiols?
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phenols and thiophenols are compounds with their -OH and -SH bonded to an aromatic ring
Enols and Enethiols are compounds with their -OH or -SH bonded to a vinylic, sp2 hybridized carbon |
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What are some industrial and pharmaceutical applications of alcohols?
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Methanol is one of the most impt. industrial chemicals:
-called WOOD alcohol, prepared historically by heating wood -causes blindness at 15 mL -causes death at 100-250 mL -industrially used as a solvent and starting material for production of formaldehyde and acetic acid Ethanol: -first organic chemicals to be prepared and purified -produced by fermentation of grains and sugars -for nonbeverage use is obtained by acid-catalyzed hydration of ethylene Phenols: -occur in living organisms -diverse adhesives and antiseptics -methyl salicylate is a flavoring agent -urushiols are allergic constituents of poison oak and poison ivy |
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What are some uses of Ethers?
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-Diethyl ether has a long history of medicinal use as anesthetic and industrial use as solvent
-anisole is a pleasant-smelling aromatic ether |
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What is formed when Alcohols and Phenols act as weak bases and weak acids?
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weak bases - reversibly protonated by strong acids to yield oxonium ions
weak acids - dissociate slightly in dilute aqueous solutions, they donate a proton to water and an alkoxide or phenoxide ion is formed |
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What do alcohols react with and why?
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They react with alkali metals with strong bases such as sodium hydride and sodium amide BECAUSE they are weak acids.
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Why are Phenols and Thiols more acidic than alcohol?
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Phenols are more acidic than alochols because the phenoxide anion is resonance-stabilized
with a electron withdrawing substituent they are MORE acidic |
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What are different ways alcohols are synthesized?
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Hydoboration/oxidation yields the product of syn, non-markovnikov hydration
Oxymercuration/reduction yields the product of Markovnikov hydration |
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How do you produce a 1,2 diol?
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1. hydroxylation of an alkene with OsO4 followed by reduction with NaHSO3
-the OsO4 reaction occurs with syn stereochemistry to give a cis diol 2. Acid-catalyzed hydrolysis of an epoxide -Epoxide opening occurs with anti stereochemistry to give a trans diol |
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How are alcohols formed from Aldehydes and Ketones?
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Aldehydes reduce to give primary alcohols
Ketones reduce to give secondary alcohols NaBH4, Sodium borohydride, is usually used to reduce aldehydes and ketones because it is safe LiAlH4, Lithium aluminum hydride,, is much faster but more dangerous The reaction involves the addition of a nucleophilic hydride ioin to the positively polarized, electrophilic carbon atom forming an alkoxide intermediate |
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How are alcohols formed by aldehydes and ketones in biological reactions?
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aldehydes and ketones are reduced to either NADH or NADPH (pro-R transferred)
-coenzyme acts as a hydride ion donor -acid protonates the intermediate anion -reduction of acetoacetyl ACP to Beta hydroxybutyryl ACP -this is a step in the biological synthesis of fats |
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How do Grignard agents reaction with Carbonyl compounds?
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RMgX acts as a carbon-based nucleophile anion or carbanion (analogous to hydride ion intermediate is alkoxide)
alkyl, aryl, and vinylic halides reaction with magnesium in ether or THF to generate Grignard Reagents the INDIRECT addition of stabilized carbon nucleophiles to carbonyls is used in almost ALL metabolic pathways Grignard + formaldehyde = primary alcohol Grignard + aldehydes = secondary alcohols Grignard + Ketones = tertiary alcohols Grignard + esters = tertiary alcohols Grignard does not reaction with carboxylic acids (forms hydrocarbon and magnesium salt) |
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How are alcohols converted to alkyl halides?
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tertiary alcohols react with HCl and HBr by SN1 through carbocation intermediate
primary and secondary reaction with SOCl2 or PBr3 by SN2 through backside attack of chlorosulfite or dibromophosphite |
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What are dehydrations of alcohols?
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dehydrations give alkenes
acid-catalyzed: -follows zaitsev's rule and yields more stable alkene as major product -of a tertiary = E1; 3 step; react fastest because most stable carbocation; primary and secondary require much higher temperatures Phosphorous Oxychloride (POCl3): -allows dehydration of secondary alcohol without need for strong acid -in basic amine solvent pyridine, POCl3 is able to dehydrate secondary and tertiary alcohols (E2) E1cB: -OH 2 carbons away from carbonyl ex. biosynthesis of aromatic AA tyrosine - |
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How are alcohols converted to esters?
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alcohols react with carboxylic acids to give esters
in lab can be carried out with using strong acid as catalyst; reactivity enhanced by first converting it into a carboxylic acid chloride when the reacts with alcohol in living organisms: -substrate is thioester or acyl adenosyl phosphate |
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What are Alcohols oxidized too and how?
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Primary alcohol = aldehyde or carboxylic acid:
-Pyridinum chlorochromate (PCC, C5H6NCrO3Cl) in dichloromethane (CH2Cl2) to form aldehydes -Chromium trioxide (CrO3) in aqueous acid (H30, acetone) forms carboxylic acid Secondary alcohol = ketones -Na2Cr2O7 in aqueous acetic acid for large scale oxidation -Pyridinium chlorochromate or PDC used for milder at lower temps Tertiary alcohols dont react |
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What are characteristics of oxidation of alcohols?
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closely related to E2 reaction
alcohol and a Cr(VI) reagent react to form a chromate intermediate expulsion of chromate leaving group to yield the carbonyl product in biology: -carried out by NAD+ and NADP+ -base removes -OH and alkoxide ion transfers a hydride ion to the coenzyme -oxidation of sn glycerol 3 phosphate to dihydroxyacetone phosphate (metabolism of fats) |
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What are characteristics of oxidation of phenols?
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E2 reaction
form Quinones (or cyclohex-2,5-diene-1,4-dione) Fremy's salt (potassium nitrosodisulfonate [(KSO3)2NO]) used as oxidant takes place under mild conditions through a radical mechanism |
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What are properties of Quinones?
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have oxidation-reduction, or redox, properties
easily reduced to hydroquinones (p-dihydroxybenzenes) by NaBH4 and SnCl2 hydroquinones can easily be reoxidized back to quinones by fremy's salt redox properties impt in living cells, example is Ubiquinones (coenzyme Q): -oxidizing agents that mediate electron-transfer process in energy production -electrons transported from reducing agent NADH to molecular oxygen, mediate this process -NADH oxidized to NAD+ --> O2 reduced to water --> energy produced --> ubiquinone unchanged |
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What are properties of some thiols and some reactions?
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Thiols produce odors
Skunk scent caused by simple thiols 3-methylbutane-1-thiol and but-2-ene-1-thiol volatile thiols such as ethanethiol added to gas to liquefy propane in case of leaks produced by alkyl halides by SN2 with sulfur nucleophile (-SH) product thiol can undergo a second SN2 with an alkyl halide to give a sulfide by-product: -Thiourea used as nucleophile in prep of thiol from alkyl halide to circumvent problem of sulfide production -intermediate alkylisothiourea salt formed --> hydrolyzed by subsequent reaction with aqueous base, urea breaks off |
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What can thiols be oxidized/reduced to and how? What is an example?
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can be oxidized to disulfides by Br2 or I2
can be reduced back by Zinc and an acid example = oxidative degradation: -glutathione removes harmful oxidants and oxidized to gluathione disulfide in the process by H2O2 and can be reduced back by FADH2 |
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How are ethers prepared?
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-Diethyl ether prepared by sulfuric acid-catalyzed dehydration of alcohols, limited to primary alcohols because secondary and tertiary dehydrate by E1
-reaction occurs by SN2 displacement of water from protonated ethanol by oxygen of a second ethanol |
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What is the Williamson Ether synthesis?
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most useful method
alkoxide ion reacts with a primary alkyl halide or tosylate in SN2 alkoxide is prepared by reaction of alcohol with strong base such as NaH primary halides and tosylates works best because E2 would take over with more hindered substrates variation: -use of Ag2O as a mild base -no need for metal alkoxide intermediate -free alcohol reacts directly with alkyl halide ex. glucose reacts with CH3I in presence of Ag2O |
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What has no effect on ethers and how can they be cleaved?
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Halogens, dilute acids, bases, and nucleophiles have no effect on most ethers
cleave by strong bonds (HBr and HI NOT HCl) either SN1 or SN2 (primary and secondary) ethers with a tertiary, benzylic, or allylic group cleave by SN1 or E1 mechanism (produce stable intermediate carbocations, fast reaction used in laboratory for peptide synthesis) epoxides undergo SN2 with base easily due to angle strain |
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How are Thiols formed?
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treatment of a thiol with a base such as NaH gives the corresponding thiolate ion (RS-)
thiolate ion undergoes reaction with a primary or secondary alkyl halide to give a sulfide SN2 reaction sulfur compounds are more nucleophilic than they oxygen analogs (ether), valence of sulfure is farther than oxygen so less tightly held dialkyl sulifides react with primary alkyl halides by SN2 mechanism to give sulfonium ions |
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How are thiols formed in biological reactions?
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AA methionine reactions with ATP to give S-adenosylmethionine
SN2 reaction, leaving group is triphosphate ion S-adenosylmethionine transfers a methyl group to Nor Epi to give Adr (by sulfonium ion) Sulfides easily oxidized: -treatment with H2O2 yields Sulfoxide -Sulfide oxidzed with a peroxyacid yields a sulfone DMSO is a well known sulfoxide used as a polar aprotic solvent |
