1) Alcohol Fermentation Reactions of Chapter 10 Worksheet and Key Alcohol fermentation is a series of chemical reaction that convert sugar molecules, such a glucose, into ethanol and C 2. The overall reaction of ethanol formation from a sugar molecule called glucose is shown below: C 6H 12 6 2 CH 2H + 2 C 2 glucose ethanol carbon dioxide 2) Nucleophilic Substitution The general form of the equation for an S N 2 reaction for the production of alcohol is shown below (X represents F, Cl, Br, or I). alkyl halide hydroxide ion alcohol halogen ion 3) Hydration of Alkenes A hydrogen atom from H 2 is added to one of the double bonded carbon atoms and the -H from the H 2 is added to the other double bonded carbon atom in the alkene to produce the corresponding alcohol. The general form of the chemical equation for the hydration of an alkene reaction is shown below: When an asymmetric alkene undergoes a hydration reaction, there are two different alcohol molecules produced - the product that is produced in greater quantity is called the major product, the product made in lesser quantity is called the minor product. It is possible to predict the major and minor products for the hydration of an asymmetric alkene using Markovnikov's Rule. 1
4) The Dehydration of Alcohols A hydroxyl group (H) is removed from a carbon atom and an H is removed from a carbon that is adjacent to the carbon that was bonded to the hydroxyl group. A double bond forms between these two carbons. The general form of the chemical equation for the hydration of an alcohol reaction is shown below: alcohol alkene When an asymmetric 2 o or 3 o alcohol undergoes a dehydration reaction, there are two different alkene molecules produced (major and minor products). 5) The xidation of Alcohols When an alcohol is oxidized, the hydrogen from the hydroxy group (H) and a hydrogen attached to the carbon that is carrying the hydroxy group are both removed, and the C- single bond is changed to double bond. The general form of the equation for the oxidation of an alcohol is shown below. xidation of Primary (1 o ) Alcohols xidation of a primary (1 o ) alcohol produces an aldehyde: a primary alcohol an aldehyde 2
Certain oxidizing agents, such as Cr 3 or Mn 4-, and/or enzymes can further oxidized aldehydes to produce carboxylic acids. 1 o alcohol aldehyde carboxylic acid xidation of Secondary (2 o ) Alcohols The oxidation of a secondary alcohol produces a ketone as shown below. Tertiary (3 o ) alcohols cannot be converted to aldehydes or ketones by oxidation. 6) The xidation of Aldehydes Aldehydes can be oxidized to carboxylic acids. The general form of the chemical equation for the oxidation of an aldehyde is shown below. aldehyde carboxylic acid 7) The Reduction of Aldehydes and Ketones Reduction of aldehydes and ketones is the reverse of the oxidation of alcohol reactions. The general form of the equation for the reduction of an aldehyde or ketone is shown below. aldehyde or ketone alcohol 3
Aldehydes are reduced to primary alcohols. aldehyde a primary (1 o ) alcohol Ketones are reduced to secondary alcohols. ketone a secondary (2 o ) alcohol 8) The Reaction of Aldehydes or Ketones with Alcohols: Hemiacetal and Acetal Production An aldehyde or a ketone will react with an alcohol to form a hemiacetal. aldehyde or ketone alcohol hemiacetal The hemiacetal that is formed can react with a second alcohol molecule to form an acetal and an H 2 molecule. hemiacetal alcohol acetal H 2 4
Questions: 1) Draw the condensed structure for the organic molecule that is produced when butanal is oxidized. 2) Draw the condensed structure for the aldehyde that is produced when ethanol is oxidized. 3) Draw the condensed structure for the organic molecule that is produced when 2-butanol is oxidized. 4) Write the chemical equation for the formation of (a) the hemiacetal, and, (b) the acetal when 2-methyl-propanal reacts with methanol. 5) Draw the condensed structure for the organic molecule that is produced when propanone is reduced. 6) Write the chemical equation for the hydration of cis-3-hexene and explain why there is only one possible product (no major or minor product) for this particular reactant. 5
7) Draw the condensed structure of the major and minor products for the dehydration reaction of 2-pentanol. 8) Write the chemical equation for the hydration of cyclopentene. 9) Complete the following reactions. If there is more than one possible product, draw both products and label the major and minor product. If no reaction is possible, write N REACTIN. a) CHCH 2 CH 2 Br + H - b) write the product formed using excess oxidizing agent CHCH 2 CH 2 H [] c) H [] CCH 2 6
d) Draw the hemiacetal product. C H + CH 2 CHCH 2 H CH 2 e) CH 2 C C CH 2 + H 2 H f) H [] CHCH 2 g) Draw the acetal product. CH 2 CHCH 2 C H + CH 2 H 7
h) H [H 3 + ] CH CHCH 2 i) [R] CH 2 C CH 2 + H 2 j) [R] C H k) CH 2 C CH 2 + 2 CH 2 H l) Dehydration 8
m) Reduction n) Draw the hemiacetal product. 10) Fill in the missing reactant(s): a) + CH 2 CH 2 H + Br - b) H H + H 2 CH 2 C C CH 2 Major Product H c) [] CH 2 CCH 2 d) CH 2 + 2 CH 2 H CH 2 CH 2 CH 2 C CH 2 + H 2 H 9
e) [H 3 + ] CH 2 CH 2 CH C + H--H Major Product f) Draw the alcohol that is oxidized when excess Mn 4 - is used as an oxidizing agent. g) [] CH CH 2 CH 2 CH 2 C H CH CH + H 2 h) H C H + C CH 2 CH H i) H [R] + H 2 CH 2 CHCH 2 CH 2 10
j) Major Product + H 2 Minor Product k) [] l) [R] CH 2 H m) CH 2 CH 2 C CH 2 CH 2 + H 2 11
Key 1) Draw the condensed structure for the organic molecule that is produced when butanal is oxidized.. [] CH 2 CH 2 C H CH 2 CH 2 C H 2) Draw the condensed structure for the aldehyde that is produced when ethanol is oxidized. CH 2 H [] C H 3) Draw the condensed structure for the organic molecule that is produced when 2-butanol is oxidized. H [] CH 2 CH CH 2 C 4) Write the chemical equation for the formation of (a) the hemiacetal and, (b) the acetal when 2-methyl-propanal reacts with methanol. H CH C H + H CH C + H CH C + H 2 H H 5) Draw the condensed structure for the organic molecule that is produced when propanone is reduced. H [R] C + H 2 CH 12
6) Write the chemical equation for the hydration of cis-3-hexene and explain why there is only one possible product (no major or minor product) for this particular reactant. H H CH 2 C C CH 2 + H 2 CH 2 C C CH 2 H H H H There is only one product because the alkene is symmetric. No matter what carbon receives the H, the product is 3-hexanol. 7) Draw the condensed structure of the major and minor product for the dehydration reaction of 2- pentanol. H CH CH CH 2 + H--H [H 3 + ] Major Product CH CH 2 CH 2 8) Write the chemical equation for the hydration of cyclopentene. CH 2 CH CH 2 CH 2 + H--H Minor Product + H 2 9) Complete the following reactions. If there is more than one possible product, then draw both products and label the major and minor product. If no reaction is possible, write N REACTIN. a) CHCH 2 CH 2 Br + H - CHCH 2 CH 2 H + Br - b) write the product formed using excess oxidizing agent [] CHCH 2 CH 2 H CH CH 2 C H 13
c) H [] CCH 2 N REACTIN, 3 o ALCHLS CAN NT BE XIDIZED d) draw the hemiacetal product H C H + CH 2 CHCH 2 H C CH 2 CH CH 2 CH 2 H CH 2 e) H H CH 2 C C CH 2 + H 2 CH 2 C C CH 2 Major Product H H H H CH 2 C C CH 2 H Minor Product f) H [] CHCH 2 CCH 2 g) Draw the acetal product. CH 2 CH 2 CHCH 2 C H + 2 CH 2 H CH 2 CHCH 2 C CH 2 + H 2 H 14
h) i) j) k) CH C CH 2 + H--H H [H 3 + ] Major Product CH CHCH 2 CH 2 CH CH CH 2 + H--H Minor Product H [R] CH 2 C CH 2 + H 2 CH 2 C CH 2 H H [R] C H C H H CH 2 CH 2 C CH 2 + 2 CH 2 H CH 2 C CH 2 + H 2 CH 2 l) Dehydration + H 2 m) Reduction 15
n) Draw the hemiacetal product. 10) Fill in the missing reactant(s): a) CH 2 CH 2 Br + H - CH 2 CH 2 H + Br - b) H H CH 2 C C CH 2 + H 2 CH 2 C C CH 2 Major Product H H c) H [] CH 2 CHCH 2 CH 2 CCH 2 d) CH 2 CH 2 CH 2 CH 2 C H + 2 CH 2 H CH 2 CH 2 CH 2 C CH 2 + H 2 H 16
e) Two possible answers: H [H 3 + ] CH 2 CH 2 CH CH CH 2 CH 2 CH C + H--H Major Product R H [H 3 + ] CH 2 CH 2 CH 2 C CH 2 CH 2 CH C + H--H Major Product - f) Draw the alcohol that is oxidized when excess Mn 4 is used as an oxidizing agent. [] CHCH 2 CH 2 CH 2 CH 2 H CH CH 2 CH 2 CH 2 C H g) H CHCH 2 CH CH + H 2 h) H C H + CHCH 2 H C CH 2 CH H i) H [R] CH 2 CCH 2 CH 2 + H 2 CH 2 CHCH 2 CH 2 17
j) Major Product + H 2 Minor Product k) [] l) [R] C H CH 2 H m) CH 2 CH 2 C CH 2 + 2 CH 2 H CH 2 C CH 2 + H 2 CH 2 18