Carbohydrates Part V: Reactions of Monosaccharides

Summary

This educational video delves into the chemical reactions of monosaccharides, focusing on oxidation processes. It explains the conversion of glucose's aldehyde group to a carboxylic acid using Benedict's solution, which contains copper sulfate. The video also covers the enzymatic oxidation of the alcohol group on carbon six to form glucuronic acid and the reduction of glucose to sorbitol, a sugar alcohol used as a sweetener. The discussion includes the role of copper ions as oxidizing agents and the nature of redox reactions.

Takeaways

• 🔬 Monosaccharides can undergo different oxidation processes, transforming their chemical structures.
• 🍬 Glucose, a common monosaccharide, can exist in both open chain and cyclic forms, affecting how it reacts.
• 🧪 Benedict's solution, containing copper sulfate, facilitates the oxidation of glucose's aldehyde group to a carboxylic acid.
• 🛡 Copper ions act as oxidizing agents in the oxidation process, getting reduced from Cu2+ to Cu+.
• 🔄 Redox reactions involve both reduction and oxidation; in the case of glucose, the aldehyde group is oxidized.
• 🌐 The oxidation of glucose results in the formation of gluconic acid, an aldonic acid, when only the aldehyde group is affected.
• ⚔ Strong oxidizing agents like nitric acid can oxidize both the aldehyde and alcohol groups of a monosaccharide, forming aldoric acids.
• 🍇 Glucaric acid is produced when glucose is oxidized by strong agents, affecting both functional groups.
• 🧬 Enzymatic oxidation selectively oxidizes the alcohol group on carbon six of glucose, forming glucuronic acid.
• 🔄 The reduction of glucose involves the conversion of its aldehyde group to a primary alcohol, resulting in a sugar alcohol like sorbitol.

Q & A

What is the primary focus of the video presentation?

The video presentation primarily focuses on the reactions of monosaccharides, specifically discussing the different oxidation processes that monosaccharides like glucose can undergo.

What are the two forms of monosaccharides mentioned in the script?

The two forms of monosaccharides mentioned are the open chain projection form and the cyclic form, also known as the Haworth form.

What is the role of Benedict's solution in the oxidation of monosaccharides?

Benedict's solution facilitates the oxidation of monosaccharides to produce acidic sugar. It contains copper sulfate, which participates in the reaction by providing copper ions that act as oxidizing agents.

How does the oxidation of the aldehyde group in glucose result in the formation of carboxylic acid?

The aldehyde group of glucose is oxidized to a carboxylic acid, resulting in the formation of gluconic acid. This process is known as oxidation, where the aldehyde end is transformed.

What is the term for a monosaccharide that has undergone oxidation at its aldehyde component?

A monosaccharide that has undergone oxidation at its aldehyde component is called an aldonic acid.

What happens when a strong oxidizing agent like nitric acid is used on a monosaccharide?

When a strong oxidizing agent like nitric acid is used, both the aldehyde group and the alcohol group on carbon number six of the monosaccharide are oxidized, resulting in the formation of an aldoric acid, such as glucaric acid.

What is enzymatic oxidation, and how does it differ from other types of oxidation mentioned in the script?

Enzymatic oxidation is a selective oxidation process facilitated by enzymes or biological catalysts. It differs from other oxidation processes in that it specifically targets the alcohol group on carbon number six, leaving the aldehyde group unaffected.

What is the product of the enzymatic oxidation of glucose, and what type of acid is it classified as?

The product of the enzymatic oxidation of glucose is glucuronic acid, which is classified as an aldonic acid.

How does the reduction of a monosaccharide differ from its oxidation?

Reduction of a monosaccharide involves the gain of electrons and hydrogen, which is the opposite of oxidation. In the context of the script, the aldehyde group of glucose is reduced to a primary alcohol, resulting in the formation of a sugar alcohol like sorbitol.

What is the role of hydrogen gas in the reduction of monosaccharides?

Hydrogen gas serves as a reducing agent in the reduction of monosaccharides, facilitating the conversion of the aldehyde group to a primary alcohol.

What is sorbitol, and what is its common use?

Sorbitol, also known as glucitol, is a sugar alcohol produced by the reduction of glucose. It is commonly used as a sweetening agent in products like chewing gum.

Outlines

00:00

🔬 Oxidation of Monosaccharides

This paragraph introduces the oxidation reactions of monosaccharides, specifically focusing on glucose. It explains the transformation between the open chain (aldose) and cyclic (furanose or pyranose) forms of monosaccharides. The oxidation process involves the conversion of the aldehyde group to a carboxylic acid, facilitated by Tollens' or Benedict's solution, which contains copper sulfate. The role of copper ions as oxidizing agents is highlighted, where they are reduced from Cu2+ to Cu+ during the reaction. The paragraph also mentions that the alcohol group on carbon six remains unaffected during this oxidation, resulting in the formation of aldonic acids, such as gluconic acid from glucose.

05:02

🧪 Formation of Aldaric Acids and Enzymatic Oxidation

The second paragraph delves into the oxidation of both the aldehyde and alcohol functional groups in monosaccharides, using strong oxidizing agents like nitric acid. This leads to the formation of aldaric acids, exemplified by the conversion of glucose to glucaric acid. The paragraph then contrasts this with enzymatic oxidation, where only the alcohol group on carbon six is oxidized, resulting in the formation of uronic acids like glucuronic acid. The aldehyde group remains unaffected in this selective oxidation process.

10:04

🍬 Reduction to Produce Sugar Alcohols

The final paragraph discusses the reduction of monosaccharides, which is the reverse of oxidation. It details the transformation of the aldehyde group in glucose to a primary alcohol, resulting in the formation of a sugar alcohol like glucitol (also known as sorbitol). This process is facilitated by hydrogen gas acting as a reducing agent. The paragraph emphasizes that this reduction reaction is the opposite of oxidation, where electrons and hydrogen are gained. Sorbitol, the product of this reduction, is highlighted as a sweetening agent commonly used in chewing gum.

Keywords

💡Monosaccharide

A monosaccharide is a simple sugar that cannot be hydrolyzed into simpler sugars. It is the basic building block of more complex carbohydrates. In the video, glucose is used as an example of a monosaccharide, highlighting its role in various oxidation processes.

💡Oxidation

Oxidation refers to a chemical reaction where an atom or molecule loses electrons. In the context of the video, oxidation is used to describe the process where the aldehyde group of glucose is converted to a carboxylic acid, indicating an increase in oxygen or a loss of hydrogen.

💡Cyclic form

The cyclic form of a monosaccharide, such as glucose, refers to its structural arrangement where the carbon chain is closed to form a ring. The video discusses how this form can undergo oxidation, emphasizing the transformation from a cyclic to an open chain during the process.

💡Aldehyde group

An aldehyde group is a functional group with a carbonyl center (C=O) bonded to at least one hydrogen atom and one alkyl or hydrogen group. In the video, the aldehyde group of glucose is highlighted as the site of oxidation, leading to the formation of gluconic acid.

💡Carboxylic acid

A carboxylic acid is an organic compound containing a carboxyl group (-COOH). The video explains that the oxidation of the aldehyde group in glucose results in the formation of a carboxylic acid, specifically gluconic acid.

💡Benedict solution

Benedict solution is a qualitative chemical test used to identify the presence of reducing sugars. The video mentions that Benedict solution, containing copper sulfate, is used to facilitate the oxidation of glucose, indicating the participation of copper ions in the reaction.

💡Redox reactions

Redox reactions involve both reduction and oxidation processes occurring simultaneously. The video script explains that the oxidation of glucose is a redox reaction, where copper ions are reduced while the aldehyde group of glucose is oxidized.

💡Aldonic acid

Aldonic acids are formed when a monosaccharide's aldehyde group is oxidized to a carboxylic acid. The video uses the term to describe the product of glucose oxidation, gluconic acid, which is an aldonic acid.

💡Aldoric acid

Aldoric acids are formed when both the aldehyde group and the alcohol group of a monosaccharide are oxidized. The video explains that strong oxidizing agents like nitric acid can cause this dual oxidation, resulting in a dicarboxylic acid such as glucaric acid.

💡Enzymatic oxidation

Enzymatic oxidation is a biological process facilitated by enzymes that catalyze the oxidation of certain functional groups. The video describes how the alcohol group on carbon number six of glucose can be selectively oxidized to form glucuronic acid, an example of enzymatic oxidation.

💡Sugar alcohol

Sugar alcohols, or polyols, are sugar-like compounds that provide sweetness but have fewer calories than sugar. The video discusses the reduction of glucose to form sorbitol, a sugar alcohol used as a sweetener, illustrating the concept of reduction in contrast to oxidation.

Highlights

Introduction to reactions of monosaccharides

Different oxidation processes of monosaccharides

Glucose molecule's cyclic and acyclic forms

Oxidation to produce acidic sugar using Benedict solution

Role of copper sulfate in Benedict solution

Transformation of aldehyde group to carboxylic acid

Copper ion's role as an oxidizing agent

Redox reactions involving copper ions and glucose

Formation of gluconic acid from glucose oxidation

Oxidation of both aldehyde and alcohol groups by strong oxidizing agents

Production of glucaric acid through aldoric acid formation

Enzymatic oxidation of the alcohol group on carbon six

Conversion of glucose to glucuronic acid

Reduction of monosaccharides to produce sugar alcohols

Use of hydrogen as a reducing agent in reduction reactions

Transformation of aldehyde to primary alcohol in reduction

Production of sorbitol from glucose through reduction

Sorbitol's use as a sweetening agent in chewing gum

Transcripts

hello everyone welcome to this video

which i will be talking about the

reactions of monosaccharide

in today's presentation we will see the

different

oxidation process that this sugar or

particularly a monosaccharide could

undergo so for example we have here

a molecule of glucose so we

have a howard or a

cyclic form of monosaccharide and we

have a feature form

of monosaccharides so we could

easily uh see the transformation in

in feature form so a feature form is the

open open chain projection

while howard form is a

closed chain or a cyclic cyclic form

so it says here oxidation to produce

acidic sugar can be facilitated by

either tolerance or benedict solution

this benedict solution particularly

contains

copper sulfate that's why in this

reaction you can see the participation

of copper ion

what happens here is the aldehyde end

of a glucose this is your glucose

the aldehyde end or the aldehyde group

of

the glucose will be

transformed into what we call carboxylic

acid so the aldehyde is oxidized so the

process

is called oxydation

okay so remember that uh when

aldehyde is oxidized the product is

carboxylic acids okay so

what is the participation of the copper

ion

copper ion this copper ion

serves as oxidizing

[Music]

oxidizing agent let's put that

here ox a oxidizing agent now in the

process

what you can see is the copper 2 plus

which serves as oxidizing oxidizing

agent

has been reduced

copper oneplus so

these uh reactions are actually

redox in nature when you say redox

that is reduction and oxidation

reduction with respect to the copper two

plus

that is converted to copper

one okay that is reduction so

copper has been reduced to

copper 1 plus

with respect to oxidation it's the

aldehyde that has been oxidized

to carboxylic acid

notice that the six carbon or the oh the

alcohol in carbon number six

remains unaffected

okay so generally when when a

monosaccharide

undergoes oxidation in

in its aldehyde component

generally the the the acid is called

all aldonic

aldonic acid okay so

for example we have a glucose here that

underwent oxidation the

acid the glucose acid is called

gluconic acid okay

so from glucose it becomes gluconic

acid this

reaction here what we can see is

the oxidation of

two functional groups it says here

strong oxidizing agents such as nitric

acid can

oxidize both ends of the monosaccharide

at the same time

so what are those ends this is the

aldehyde group

and this is the alcohol group on carbon

number six remember this is our carbon

number one

and this is our carbon number six so a

strong oxidizing agent such as

strong acid can both oxidize the two

functional group

so notice the transformation of the

aldehyde

it is converted to carboxylic acid

likewise the alcohol on carbon number

six

is also converted to a carboxylic acid

so this is actually a dye

carboxylic dicarboxylic acid

so such reaction

such a reaction is known as formation of

aldoric acid so

specifically when we have glucose that

underwent

oxidation to produce the alderic acid

the product is called glucaric

acid you just have to add aric

acid all right

in this reaction we can see that uh

it's the sixth carbon

or the hydroxyl group in the sixth

carbon

undergoes oxidation remember in the

first

reaction we have seen that

the only the aldehyde that underwent

oxidation in the second reaction we have

seen that

both ends the aldehyde in the the

aldehyde

and the alcohol group on carbon number

six both of them

went um oxidation

however in this um in this process

what we can see here is the oxidation

of the alcohol on carbon number six

so this is called enzymatic oxidation

which is

um facilitated by enzymes or biological

enzyme

notice that in or the aldehyde

remains unaffected still aldehyde but

it's only the carbon number six or the

oh

the hydroxyl group or the alcohol in

carbon number six

underwent oxidation

to form glucoronic acid so

an alcohol is oxidized to

carboxylic acid so generally

a sugar that undergoes oxidation on its

alcohol group

on carbon number six called aldo

ronic acid so you just have to add

uronic acid from glucose

to uronic acid

so this process is a selective selective

process

the second type of reaction is called

reduction to produce

sugar alcohol remember reduction is

somewhat uh

opposite of oxidation so reduction

is by definition is gain

gaining of electron and

hydrogen so in this transformation

we can see that it's the opposite of

oxidation that will take place

all right it says here the

carbonyl group present in a

monosaccharide

either an aldos or ketos can be reduced

to carboxylic group using hydrogen

as a reducing agent so here

let me uh let's write the

the process so a primary alcohol

primary alcohol remember in your organic

chemistry

gets oxidized to aldehyde

so let's write here oxidation o that

represents oxidation

okay and then the aldehyde

is also oxidized to

carboxylic carboxylic acid

okay carboxylic

acid let's just put right there all

right and then uh

the reverse arrow can still be possible

can

is also possible so if the forward

reaction is called oxidation the reverse

reaction is called

reduction so we will reduce the

carboxylic acid back to

aldehyde and that what exactly happens

here okay

and uh what happens in this reaction is

from aldehyde from aldehyde

to a primary alcohol

so we have here if we are going to

reverse this reaction we said earlier

that primary alcohol

let's write primary al

cohol okay a primary alcohol

is oxidized to aldehyde that's the

forward

however the reverse reaction is

aldehyde is reduced

to a primary alcohol so take note of the

process called reduction that's why the

title is reduction

to produce sugar alcohol okay so we have

here

um a transformation of glucose

so what what is the transformation that

happens here

the aldehyde is converted

or transformed into a primary

alcohol okay however the

as you notice the alcohol in carbon

number six

remains the same so what is the role of

hydrogen gas here

it says it serves as reducing

reducing agent so glucitol

is a dye alcohol dye alcoholic

molecule it's commonly known as orbital

which

serves as or used as sweetening agent in

chewing gum